Transcript for:
Exploring Liver Anatomy and Ultrasound Imaging

hi learners it's m from sono nerds and this video is on unit 3 liver anatomy physiology and ultrasound appearance section 3.1 liver introduction the liver is the largest peritoneal organ and responsible for a lot of bodily functions it also happens to be the cause of many diseases that can be diagnosed by ultrasound needless to say the sonographer must fully understand liver anatomy anatomical relationships and how it works as we study the liver anatomy and physiology we'll start with a more global look where it is in the body the coverings what surrounds it and then we'll take a closer look at the actual anatomy of the liver including microanatomy and macroanatomy this is going to lead well into learning about how the liver functions or the physiology of it once you've learned about the liver through diagrams we'll start to learn about how the liver looks by ultrasound we'll focus on identifying key structures and landmarks and their normal appearance we'll also include liver protocols and patient preps section 3.2 global anatomy of the liver now global anatomy might sound kind of like a funny term and i feel like i made it up not 100 sure on that but i just needed a term for the fact that we really need to learn everything around the liver before we can really start diving into the liver in ultrasound relational anatomy is going to be super important so sometimes it's easier to see a ligament to bring your eye to where a certain structure should be or maybe you know that organ x is typically located here and then you should see organ y inferior to it using clues about what you can see will help you to find the things that are hiding and be more confident that something might be missing or has changed because of disease we're going to go ahead and start with embryology then now embryology for the sonographer is not super important we don't need to do a dive deep into it but it's kind of nice to know where our organs originate from especially when we start to talk about congenital diseases and how things can kind of go wrong when those cells start to differentiate and move around from the initial tube that we start at so with the liver there's two things that you need to know one the liver begins to form at about four weeks gestation so it's one of the first organs that starts to form and that's because at week five it's going to start to partake in what we call hematopoiesis and that is the creation of red blood cells an adult is taken over by bone marrow but in the fetus it is done by the liver moving to the fully grown patient who is outside of the womb we can use the nine region system to understand where the liver is located now using that nine region system we are going to see that under the right hypochondrium is where most of the liver will lie it can extend partially into the epigastric region and if somebody has a really long left lobe it might even extend into the left hypochondriac region abutting the spleen the other major landmarks that sit around the liver is the diaphragm superior to it the thoracic spine posterior to it the right costal margin which we will see lateral and anterior to the liver and the rectus abdominis muscles sitting anterior as i mentioned earlier we need to know the relational anatomy of organs as they surround our organ of interest so looking at the liver there are quite a few organs that surround it and actually physically come in touch with the liver to the point where the liver has little indentations or fossa on its surface to hold these organs all the organs that we're going to cover here are visible by ultrasound and would serve as general landmarks to the liver so on the superior side of the liver kind of wrapping to the posterior we have the diaphragm the gallbladder sits behind the liver so it's posterior and towards the inferior edge the right kidney is also posterior and on the inferior edge the pancreas is going to sit just inferior to the left lobe of the liver and the stomach kind of hugs the left margin of the left lobe connecting to the duodenum which abuts the liver right at the medial segment of the left lobe near the porta habitus if we take a closer look at the liver surface we'll see that it has two coverings the first covering is glsen's capsule which is shown in green and the second covering is the peritoneum which is seen in orange glisten's capsule is a fibrous structure and it is home to the blood vessels nerve and lymphatics of the liver again it covers the liver completely and we can actually see it very well when we look at it under a microscope is very different tissue from the hepatocytes so we can think of glsen's capsule as a glove for the liver glsen's glove covers the whole thing like a glove would cover your hand the second covering of the liver is called the peritoneum and what's important about the peritoneum is that it does not cover the entire liver so peritoneum starts with the p think partial peritoneum covering remember that the peritoneum had two different parts to it i had the parietal layer which covered the abdominal wall and the visceral layer which covers the organs so does the visceral peritoneum that partially covers the liver now it covers everything on the liver except for the bear area and the bear area is the area that is in direct contact with the diaphragm and this is significant because no fluid can accumulate in this area glsen's capsule completely covers the liver like a glove the visceral peritoneum partially covers the liver everything except for the bare area now we learned in a previous unit that ligaments are created when the visceral and the parietal peritoneum fold back onto itself thus creating a fibrous band and the purpose of the ligaments are to anchor the organs to the abdominal wall or to one another now unfortunately a lot of the delivered ligaments are going to have a little bit more fancy name so we're going to have to take some time to memorize those and know them however most of the other ligaments in the body are organ-based and are going to describe the two organs that they connect for example the hepatogastric ligament connects the liver to the stomach so we've got hepato liver gastric stomach phenolenal ligament is going to connect the spleen to the kidney and the gastrointestinal ligament is going to connect the stomach to the spleen so the rest of the ligaments and the peritoneum are fairly straightforward but we do need to spend some time learning the ligaments of the liver and even though not all the ligaments are going to be seen by ultrasound we should still be able to recognize them by diagram location and how they connect the liver to other organs there are eight ligaments of the liver that you will need to know the coronary ligament the right triangular ligament left triangular ligament felsiform ligament ligamentum teres ligamentum venosum the gastro hepatic ligament and lastly the hepatoduodenal ligament i'm going to go step by step for each of these ligaments showing you where they are located in relationship to the liver and how they provide support to the liver and other structures first we have the coronary ligaments now there are actually two layers to the coronary ligament the anterior leaf and the posterior leaf the anterior leaf is going to sit on the superior border of the liver and connects it to the diaphragm the anterior coronary ligament is continuous with the right and left triangular ligament and it's also going to be on the superior border of the bare area in our image here then we have the anterior coronary ligament here it actually continues all the way across here so this is all the anterior coronary ligament that will attach to the diaphragm the posterior coronary ligament then sits at the posterior inferior border of the liver and connects also to the diaphragm now the posterior coronary ligament is also going to be continuous with the right and left triangular ligaments and creates the inferior border of the bare area so if this was all of our anterior coronary ligament we then have posterior coronary ligament on the back side remember both are going to connect to the diaphragm they surround the bare area and they are continuous with the right triangular ligament and the left triangular ligament which actually happened to be our next ligament so we have the right triangular ligament which is going to arise from the inferior lateral border of the bare area and also connect to the diaphragm remember it is continuous with the anterior and posterior coronary ligaments so here's our right triangular ligament connecting to the posterior connecting to the anterior coronary ligaments at the edge of the bare area now the left triangular ligament is on the other side of the liver here and it's going to arise from the superior border of the left lobe of the liver and connect again to the diaphragm this one is also continuous with the anterior and posterior coronary ligaments so we have the anterior ligament diving into the left triangular ligament which is also connected to the posterior coronary ligament note that these ligaments are better seen from the posterior view of the liver so we're going to flip the liver over and look at the anterior view of the liver on the anterior view of the liver we can see the felsiform ligament the falsiform ligament sits on the anterior side and it connects the liver to the abdominal wall this one is also going to be continuous with the coronary ligaments and the ligamentum teres so here we can see the falsiform ligament on the anterior portion of the liver connecting with the coronary ligament so if this is our diaphragm up here it's kind of lifted so we can see the coronary ligaments the falsiform ligament is going to be continuous with the coronary ligament and then we can see as it comes over it connects to the left triangular ligament and over to the right triangular ligament so these four ligaments end up being kind of a continuous band that connects to the diaphragm and the abdominal wall what's important about the falsiform ligament is that it does separate the subfrontic spaces which is why we don't have fluid that flows from the right sub front space into the left subtronic space they are separate and individual pockets for fluid accumulation i also mentioned that the falsiform ligament is continuous with the round ligament which is known as the ligamentum teres so this is the anterior view of the ligamentum teres but we are going to flip the liver around to take a different look at it from the posterior side the ligamentum teres is continuous with the falsiform ligament and it's going to extend off the anterior portion of the liver but then it does kind of wrap around to the inferior side of the liver connecting with the posterior portion of the liver so it's going to connect the liver to the abdominal wall and this round ligament is going to extend to the abdominal wall at the umbilicus and its connection to the umbilicus is important because at one point during fetal circulation the round ligament or ligamentum teres used to be patent and served as the left umbilical vein once the child is born this will close off and turns into a ligament so remember that the round ligament is also known as the ligamentum teres and has potential for revascularization in the event that the liver becomes overloaded with blood and help shunt blood away from the liver staying on the posterior side of the liver then we are going to take a look at the ligamentum venosum now the ligamentum vanosum sits right along the edge of the caudate lobe the ligamentum vadosum serves as a landmark again for the caudate lobe and its connection to the left lobe as it does run through the left intersegmental fissure and along with that it also connects to the left branch of the portal vein and the gastro hepatic ligament which is also known as the lesser momentum the other important part about the ligamentum venosum is that it also used to be part of fetal circulation known as the ductus venosus when we were talking about the ligamentum venosum we talked about it as a connection point for the gastrohepatic ligament so here is the gastro hepatic ligament this one is finally one that we can kind of break down to understand gastro bean stomach hepatic being liver so this is a ligament that connects the liver to the stomach important features of the gastro hepatic ligament include the fact that it does connect the ligamentum vinosum it is known as the lesser momentum which is going to include fat and lymph and vessels for part of the intestines and then it also kind of serves as the roof to the lesser sac of the peritoneum in this image we can see the lesser momentum connecting to the lesser curve of the stomach and then it runs posterior to the liver to connect to the ligamentum venosum next to the gastro hepatic ligament then is the hepatoduodenal ligament now this one also runs more on the posterior visceral side of the liver it is going to connect the liver hepato to the duodenum duodenal so it's a hepato duodenal ligament the patio duodenal ligament is going to arise from the porta hepitus of the liver it's going to be home to the portal triad which is going to include the bile ducts portal veins and hepatic artery so in this image you can kind of see them shadowed in the back there because this is all posterior to the liver we have a bile duct portal vein and hepatic artery other significant features of the hepatoduodenal ligament include the fact that it is the anterior border to the foramen of winslow if you recall the fragment of winslow is the opening in which the greater sac of the peritoneum connects to the lesser sac of the peritoneum so as this arrow kind of shows us this is coming out of the greater sac through the foramen of winslow which is also known as the epiploic foramen it'll travel under the patio duodenal ligament to get into the lesser sag which also sits behind or posterior to the gastro hepatic ligament to review then i have a handy chart here for you listing all eight ligaments that you should know by name including their connection points and key facts that you should know about each ligament many of these ligaments are not visible by ultrasound but many of them are and are going to serve as key landmarks for our liver images section 3.3 lobe division now that we've learned what's outside of the liver we can actually start to take a look at the liver itself first we are going to learn about how the liver is divided using external landmarks the ligaments so this is going to be anatomical lobe division when using external anatomical landmarks like the ligaments we can divide the liver into four lobes the two that you're probably the most familiar with are the right lobe and the left lobe but we actually have the quadrate lobe and the caudate lobe let's go ahead and learn a little bit more about each of these lobes and how they're divided from the other lobes of the liver on the anterior surface of the liver remember that we have the falsiform ligament for anatomical lobe division using anatomical structures we can divide the right lobe of the liver from the left lobe using the falsiform ligament the right lobe of the liver is the largest lobe of the liver typically about six times bigger than the left and is going to mostly be found in the right hypochondrium in this anterior view of the liver we can see the left lobe the fossil form ligament and the right lobe so the right lobe is divided from the left lobe by the fossil form ligament on the anterior surface of the liver when we flip the liver around and come from the posterior view of the liver we start to see more landmarks in the division so now we have the right lobe of the liver which is going to end at the ivc the caudate lobe the porta habitus and the gallbladder fossa so anything lateral to the ivc porta hepatis and gallbladder fossa is considered the right lobe anatomically flipping the liver back over to an anterior view let's talk a little bit about the left lobe now the left lobe is going to vary from person to person in regards to size some people have really really big left lobes that go all the way over to the spleen or extend really far down the body some people just have average left lobes that actually make it very easy to see the pancreas and some other midline structures and some people basically have tiny to non-existent lobes so the left lobe of the liver does not have a normal size to it but it is still recognizable as the left lobe divided from the right lobe because of the felsiform ligament on the anterior surface of the liver flipping the liver around then we can see we have the left lobe of the liver and we can start to see that there are more borders to identify the left lobe compared to the other lobes the big ones are going to include the ligamentum venosum which separates the caudate lobe from the left lobe and then we also have the ligamentum teres which separates the left lobe from the quadrate lobe staying on the posterior side of the liver we're going to take a look then at the caudate lobe the caudate lobe is on the posterior side of the liver in the superior position so if we look at the liver as a whole this is much more superior compared to this portion of the liver which would be inferior so again we're on the posterior side of the liver in a superior position the caudate lobe is bordered then by the ivc posteriorly we'll see the left lobe lateral to it again divided by the ligamentum venosum the left portal vein is actually going to run anterior to it not pictured in this image and the main portal vein is also going to be posterior to it so here's our main part of vein so this little section of liver is called the caudate lobe it was decided to be its own lobe because it has its own arterial supply and venous drainage compared to the left lobe and the right lobe but it is connected to the right lobe through the caudate process which is this area here this is going to connect over to the right lobe the ivc has kind of been removed so we can see that here and the other kind of odd thing about the caudate lobe is that sometimes it has this like little hunky thing that hangs off of it and that's called a papillary process so if we see like a little extension of the caudate lobe kind of going immediately into the body it can sometimes be mistaken as pathology but just know that if you can connect it back to that caudate lobe is most likely the papillary process staying on the posterior side of the liver we're going to talk about the last anatomical lobe and that is the quadrate lobe now the quadrate lobe sits on the posterior side of the liver more towards the inferior position so remember the caudate was superior quadrate is inferior now what's odd about the quadrate lobe is that typically it is not recognized as its own lobe quite often it is just included as part of the left lobe and we consider it the medial segment of the left lobe however the quadrate lobe does come with its own borders when we are looking at anatomical division we can see that the quadrate lobe is going to have the porta hepatis posterior to it so behind it the gallbladder fossa will sit towards the right side of it the ligamentum teres is towards the left and then it does form the edge of the liver at the inferior border as a quick review then we have the quadrate lobe posterior inferior position caudate lobe superior posterior position left lobe and right lobe section 3.4 liver vasculature the next logical anatomy lesson that we need to go into then is the liver vasculature it's going to be really important for you to know the names of all the vessels and how they course through the liver now this is going to be important because we talked about the anatomical lobe division being based on external landmarks the segmental lobe division which we will learn next is based on vascular landmarks so we need to cover the liver vasculature first so we can better understand the internal landmarks for segmental division starting with the porta habitus we need to know that this is kind of the gateway to the liver it's also known as the liver hilum and it is a little groove or fissure on the posterior inferior portion of the liver the port of habitus serves as a major landmark for three main structures that are going to enter and exit the liver we have the main portal vein which will be entering the liver at the porta habitus we have the main hepatic artery which also enters the liver at the porta habitus and then we have the common bile duct which exits the liver at the porta hepatis identifying the location of the port of hepatis clearly defines then where extra hepatic ducts and vessels versus the intrahepatic ducts and vessels in introducing the porta habitus we talked about three structures that are going to enter and exit through it the portal veins hepatic arteries and bile ducts these three structures together are called the portal triad and they are going to serve as very important features of some internal landmarks however externally we evaluate them quite often with ultrasound so we do need to be able to identify where the external or extra hepatic versions of these vessels are compared to the internal or intra-hepatic versions focusing on the external portion of it we have the main portal vein the main hepatic artery and the common bile duct in cross section when we see these three structures at the porta habitus they typically kind of take on what we call the mickey mouse appearance we have the main portal vein posterior to a main hepatic artery which sits more to the patient's left and the common bile duct which sits anterior to the main portal vein and sits a little bit more to the patient's right once we are able to identify the porta habitas and these extra hepatic structures we can actually follow them further extra hepatic to identify more structures like the pancreas and the duodenum or we can follow them internally to identify branches of these structures and different liver segments the portal veins will be bringing nutrient and toxin-rich blood into the liver the hepatic arteries bring oxygen-rich blood into the liver and then the bile ducts are actually going to be transporting bile out of the liver into the duodenum since we are talking about liver vasculature though we're going to focus on the hepatic artery and the portal veins to begin with let's first take a look at the hepatic artery and how it travels to the liver from the aorta if this is our aorta the first branch that the blood is going to travel through is the celiac axis from the celiac axis it has an option to head to the left gastric artery which will go to the stomach the splenic artery which will head to the spleen or the common hepatic artery blood traveling through the common hepatic artery then again comes to a choice of the gastroduodenal artery or continuing to the proper hepatic artery now the gastroduodenal artery is an important landmark because once the gastroduodenal artery commonly abbreviated as the gda branches off this is when we come into our proper hepatic artery known as the main hepatic artery this is the part that we can see externally at the porta hepatis once the proper hepatic artery or main hepatic artery enters through the porta habitus it will branch into the right hepatic artery and the left hepatic artery to feed each of the loads a special note about the right hepatic artery though is that it does have another branch called the cystic artery and that's going to head off to bring blood to the gallbladder is absolutely essential that you understand the path flow from the aorta to the liver of the hepatic artery as it is bringing that oxygenated filtered blood to the liver and actually brings about 20 to 30 percent of the total blood volume so let's go ahead and review the path flow one more time just in a different way so we have blood coming in from the aorta the aorta is going to meet its first branch that we're concerned with with ultrasound called the celiac axis now celiac axis has three branches the left gastric artery is not really visible by ultrasound so we're not as concerned about it but we are able to see both the splenic artery and the common hepatic artery the splenic artery is going to head off to the spleen the common hepatic artery is going to travel towards the liver now from the common hepatic artery there are a couple of branches again that we're not very concerned with as far as ultrasound goes because we're not very good at seeing them and that's going to include the right gastric artery and the supra duodenal artery the one that we really want to pay attention to though is the gastroduodenal artery or the gda once the gastroduodenal artery branches off we then can call the continuation of the common hepatic artery the proper hepatic artery the proper hepatic artery is also known as the main hepatic artery and that is going to enter through the portivities to branch into the left hepatic artery and the right hepatic artery these two blood vessels then are going to continue branching smaller and smaller and smaller as it enters into the liver bringing blood down to the very tiniest little hepatocytes bringing all that oxygen-rich blood to the hepatocytes for them to use however an important branch of the right hepatic artery is the cystic artery which is going to head over to the gallbladder to do the same thing bring that oxygen-rich blood to the gallbladder continuing with our portal triad vasculature we're going to take a look then at the portal veins now the portal veins are going to bring about 70 to 80 percent of the total blood volume into the liver so the hepatic artery brings about 20 to 30 portal vein brings about 70 to 80. and the blood that's coming in through the portal veins is going to be full of nutrients toxins and byproducts and that's because this blood is coming from the spleen and the intestines so the first thing that needs to happen is that the inferior mesenteric vein coming from the inferior intestinal area is going to join up with the splenic vein so when veins join it's called a confluence so the confluence of the inferior mesenteric vein joins with the splenic vein and it continues traveling towards the liver where it will join again with the superior mesenteric vein where the superior mesenteric vein and the splenic vein join is called the portal confluence that is going to give rise then to the portal vein outside of the liver we call this the main portal vein once the main portal vein crosses the porta hepatis it is going to branch into the left portal vein and the right portal vein and then those are further going to branch into anterior posterior branches on the right and medial and lateral branches on the left so here again we have the main portal vein coming in entering through the porta hepatis branching into the right portal vein and the left portal vein the left portal vein will continue to branch into the medial left portal vein and the lateral left portal vein where the right portal branch will branch into the right anterior portal vein and the right posterior portal vein now all these numbers and all these posterior anterior lateral medials are going to be important for later so remember this image because we're going to circle back to this in a little bit let's take a look at how the portal vein comes into existence remember we have the inferior mesenteric vein joining with the splenic vein the splenic vein is going to continue on to join with the superior mesenteric vein and when these two vessels come together they are going to form the portal confluence now the portal confluence is really just a fancy name for the beginning of the main portal vein main portal vein is going to travel towards the liver cross through the porta habitus and then branch into the left portal vein which will further go on to branch into the left medial portal vein and the left lateral portal vein the main portal vein is also going to branch into the right portal vein which will go on to further branch into the right anterior portal vein and the right posterior portal vein now there are another set of vessels that course through the liver that are not part of the portal triad and these are called the hepatic veins there are three main hepatic veins that drain the liver we have the right hepatic vein the middle hepatic vein and the left hepatic vein these three veins are going to confluence together at the ivc just before it goes into the right atrium when we initially learned about the caudate lobe i mentioned that it has its own blood supply and its own venous drainage which is why it ended up being its own lobe compared to the right and left lobes well the veins that drain the caudate lobe are called emissary veins and the emissary veins are going to drain the caudate lobe directly into the ivc now it's because of these special veins and the arterial flow that the caudate lobe is independent of the rest of the liver and we quite often see that the caudate lobe is spared during many disease processes that affect the rest of the liver so when we were talking about the portal system we talked about the inferior mesenteric vein and the superior mesenteric vein confluencing with the splenic vein but then we kind of switched to branches when we spoke about the actual portal system because it does kind of act like a quasi artery where it has branches it's bringing blood into an organ the hepatics again though are considered your typical veins because they are draining the organ of the blood returning it back to the heart so for the ivc we see that the right middle and left hepatic veins are going to confluence into the ivc during both lobes of the liver now though we don't see them on ultrasound we do know that the emissary veins are also going to confluence into the ivc to bring blood out of the caudate lobe in brief review we have blood vessels that bring blood into the liver and that is going to be the hepatic artery and the portal vein or blood vessels that are bringing blood out of the liver are going to include our hepatic veins and our emissary veins so we had to learn liver vasculature before we could learn segmental division and here is why because some of those vessels are going to be intra segmental which means that these are structures that are going to run through a segment and some of the vessels are inter-segmental which means that they run in between segments our intrasegmental structures that run through the segments are the structures that make up the portal triad so it's the portal vein hepatic artery and bile duct that are going to run through the segments and are considered intra-segmental opposite of that then we have the hepatic veins which run intersegmental and again intersegmental means to run in between segments this concept is incredibly important to understanding liver division and liver segmental anatomy so we need to come up with a good way to remember intrasegmental structures versus intersegmental structures so the way that i like to remember it is that intra segmental the tra intra segmental matches up with the portal triad which also has tra in it and they run through a segment and again we see that tra pattern so intrasegmental think portal triad through a segment compare that then to intersegmental which is the hepatic veins and they run in between segments notice how many e's we have through this so intersegmental hepatic veins between segments is a good visual or mental reminder of how to differentiate the portal triad as intrasegmental versus the hepatic veins as intersegmental and this is an awesome test question to ask which of these structures is not intrasegmental hepatic artery bile duct portal vein or hepatic vein you should know it is hepatic vein because the hepatic veins are inter segmental in the next section we're going to talk a lot more about how these internal landmarks are going to help us to differentiate the segments of the liver section 3.5 segmental division when we originally learned about how to divide the liver into lobes we were doing anatomical division using external landmarks like the ligaments to define those loads now segmental division is what's commonly used in medical applications and that's because it's going to use internal landmarks like the vessels and the bile ducts to more accurately divide the liver into segments that are functional now that functional piece is really important and that's because if a person needed to donate part of their liver they could take out segments the segments would work on their own for the person that they donated to on the flip side of that say as a sonographer we find a mass within a segment we use our knowledge of segmental division to show the radiologist how the mass is located within the liver they'll dictate the location of the mass in the segment that it occurs in and then the surgeons are going to be able to make a better game plan hopefully only needing to remove that segment to remove the mass and if they were to take that segment out the rest of the liver would function unaffected but to talk about segmental division we had to learn about liver vasculature first because those are the internal landmarks that we are going to be using to identify the divisions of the liver so remember we had portal triad were intrasegmental which meant they ran within a segment versus the hepatic veins which were inter segmental and ran in between the segments i know i kind of already alluded to the anatomical versus segmental division but recall that anatomical lobe division gave us the four lobes we had the right lobe left lobe caudate lobe and quadrate lobe while in segmental division we're only going to recognize three lobes the right lobe left lobe and caudate using segmental division we take each of those lobes and now create segments so the caudate lobe stays the caudate lobe but now the left lobe is going to be divided into the left lateral segment and the left medial segment where the right lobe is divided into the right anterior segment and the right posterior segment now after hearing the names of the segments you might be thinking to yourself i think we've heard those terms before and you'd be right we have we talked about them when we talked about the branches of the portal veins recall that we have the main portal vein heading into the liver it crosses the part of hepatitis and branches into the right portal vein and the left portal vein the right portal vein is going to head towards the right lobe of the liver and in the right lobe of the liver it will split into the right anterior portal vein and the right posterior portal vein the right anterior portal vein will feed the right anterior segment of the right lobe and the right posterior portal vein is going to head into the right posterior segment same idea on the left side the left portal vein is going to branch into the left lateral and left medial portal veins to go into the left lateral segment and the left medial segment remember that the portal veins go in to the segment so if you can see a portal vein there is one segment all the way around it because it is running through the middle of it hepatic veins then are the other way that we divide the segments remember we call the hepatic veins inter-segmental structures so that means they run in between the segments when you see the right hepatic vein you will be able to see both the anterior segment and the posterior segment of the right lobe when you're able to visualize the middle hepatic vein you'll be able to see the right anterior segment and the left medial segment and when you're seeing the left hepatic vein you're able to see the left medial segment and the left lateral segment now the reason you can see two segments when you are seeing a hepatic vein is again because they are inter-segmental you should be able to see a segment on either side of it as opposed to the portal veins you'll see one segment all the way around because it's going through the segment the other really important part about the hepatic veins is that they run through fissures and these fissures again help to divide the segments so the right hepatic vein runs through the right hepatic fissure the middle hepatic vein runs through the main lobar fissure and the left hepatic vein runs through the left hepatic fissure and partially through the ligamentum teres when you're asked what structure divides the liver into right and left your answer should be either the middle hepatic vein or the main lobar fissure when we are talking segmental division it is not the falsiform ligament knowing how the segments are created will actually give rise to koi nad's anatomy then coin has anatomy is going to further divide the segments these segments we typically refer to in roman numerals and they provide even more detail for location and surgical resection anatomical lobe division gave us four lobes left right caudate quadrate segmental lobe division gave us three lobes left right and caudate and then segmental division divided those three lobes into the five segments caudate lobe left lateral segment left medial segment right anterior segment and right posterior segment quinas is going to further divide the five segments in segmental anatomy into eight segments and it goes about it kind of in a goofy way so let's see how these five segments translate into coin ads eight segments first off we're going to see that segment number one is still a lobe so caudate is caudate as caudate and really all the lobe and segmental divisions that we have next we have the left lobe lateral segment being divided into the left lateral superior and the left lateral inferior and these are segments two and three and then the left lobe medial segment is going to be divided into the left medial superior and the left medial inferior these segments are designated as 4a and 4b now we're going to do a very similar thing over on the right side the right lobe anterior segment is going to be divided into the right anterior superior segment and then the right anterior inferior segment designated as segments eight and five and then the right low posterior segment also gets divided into the posterior superior segment and the posterior inferior segment and i get that that was just me reading a whole lot of rights and left superiors inferiors medials laterals but it actually does kind of follow a logical pattern so i just want to go through it one more time remember caudate lobe is caudate lobe no matter what that's number one now we're at left lobe lateral segment here it's going to go superior inferior we're going to first say the original segment that we got from our segmental division add the superior inferior so we have left lateral superior left lateral inferior same thing is going to happen with the medial segment we're going to get a superior and an inferior of the medial segment so we have left medial superior left medial inferior now the kind of tricky odd thing about this one this is segment 4a and 4b when we talk about there only being eight segments there actually is nine because of this division the segment for a is going to be above the umbilical portion of the portal vein where segment b is below the umbilical portion of the portal vein now i know we have not discussed the umbilical portion of the partial vein as it is a little bit further out of the scope that we need as sonographers but essentially when the portal vein comes in and it branches to the left side the initial part of the branch is the umbilical portion this is kind of where the ligamentum venosum comes in and it technically courses through the liver in a different way than the rest of the left portal vein does so we consider this little first branch of the portal vein to be the umbilical portion again way beyond anything that we need to know but that is how left medial superior and left medial inferior are divided all right so now we're gonna go look at that right lobe of the liver remember we're doing superior inferior superior inferior but this time on the right lobe we have anterior and posterior segments so first we divide the right lobe into its superior and inferior note that the number is assigned to this lobe are 8 and 5 and then the right lobe is going to divide into its superior and inferior being assigned the numbers 7 and 6. so if we look at the roman numerals we have one two three four a and b and then we do counter clockwise five six seven and eight the names of the segments follow along with the portal branches but this image actually shows us again how the hepatic veins serve as intersegmental dividers just to go through it again we have the left hepatic vein dividing lateral and medial segments the lateral segment is divided into superior and inferior the medial segment is divided into superior and inferior we can see segment one here this is the caudate lobe sitting on the superior posterior portion of the liver the middle hepatic vein comes through and divides the liver into its true right and true left lobes it also divides the medial left segment from the anterior right segment looking at that right anterior segment again we have superior inferior of the anterior segment assigned numbers eight and five and then we can see the right hepatic vein dividing the anterior and posterior segments of the right lobe on the posterior side again we have superior inferior with the right superior posterior segment and the right posterior inferior segment so as you're going through the segments again remember we are naming the original segment of the lobe so lateral medial anterior posterior and then all we're adding on on the end of that is super inferior superior inferior you can also use your hand if you think about tucking your thumb underneath your fingers your thumb would be your caudate lobe and this is on your right hand two and three would be your pointer finger four a and four b would line up with your middle finger those two first fingers make up the lateral and medial of the left lobe and then we would see the ring finger being segments eight and five and the pinky being segments seven and six and then i've just added in our ivc showing again how the hepatic veins run in between the segments where the portal vein is going to run into each segment your biggest takeaways from knowing the division of the liver is to remember portal triad is intrasegmental hepatic veins are inter segmental you should not only be able to name the segments of the liver but go further to name these segments of coin ads anatomy and assign roman numerals to each one and then lastly you need to know that the main lobar fissure and the main hepatic vein are the true division of the right lobe and the left lobe section 3.6 anatomical variants of the liver a variant occurs when the anatomy does not follow standard appearances most variants are going to be considered congenital meaning that someone is born with a variant typically variants are not going to affect function unless the variant is some sort of a genesis of an organ when multiple variants are visualized concern for some sort of syndrome diagnosis is elevated it is possible for a variant to affect the whole organ or just part of the organ looking at the liver a whole liver variant that we would consider would be something called situs inversus while this is something visible on ultrasound i do have a ct image on the screen to better show the structures and the relationship because we get more of a whole view of the body so as cited some verses it basically causes the organs in the body to be flip-flopped so the organs that are on your right side are now found on your left side and your left-sided organs are on your right side so in the variant called situs and versus totalis we will see the left side of the body containing the liver and the right side containing the spleen we also find that the heart normally pointed towards the left is now pointed towards the right we can have situs and versus levocardia which means that the heart is in the normal position pointed towards the left levocardia means left facing heart where the rest of the organs have been flip-flopped there can also be a variant that actually ends up being kind of ambiguous where we can't really say it's for surely flip-flop but what tends to happen is that some organs are on the wrong side or some just kind of start appearing more midline and can't really put a laterality on them so that is called then sinus ambiguous or in general just heterotaxy if the organs just aren't quite in the space that we expect them to be in looking at left lobe variants we talked earlier about how the left lobe of the liver really varies in size from person to person we don't have an expected size of it it is not uncommon for the left lobe of the liver not to form and when this happens this is called a genesis now if the whole liver did not form that would most likely result in an inner uterine demise if the embryo even got out of the embryo stage because remember in fetal development the liver is supposed to be making blood if the liver doesn't develop then the embryo doesn't have any red blood cells however if only part of a lobe doesn't form that's okay because remember we had those segmental divisions and the parts that did form are going to function just like a normal liver they're not dependent on the whole structure being there so we'll see left lobe agenesis or a very tiny left lobe in quite a few people we can see the image of that left lobogenesis in the top ct picture here we've got right lobe of the liver here we would expect left lobe of the liver to be in this space here but what we end up having is actually just maybe a little fragment of it and then the caudate lobe here and the rest of the right lobe opposite of left lobe agenesis we can have something called the beaver tail and the beaver tail variant is a really long extension of the left lobe and we can see that in the bottom ct picture here in this case we have the right lobe of the liver and this is the left lobe but we see the left lobe continuing all the way over to the spleen in the event that this happens sometimes the spleen looks like a mass on the left liver or the liver will look like a mass on the spleen so if we can connect this echogenicity back to the main portion of the left liver we would consider this just an extension a normal variant with a special name called the beaver tail now similar to a beaver tail on the left lobe is rydell's lobe on the right lobe now rydel's lobe we describe it as a tongue tongue-like extension of the inferior tip of the right lobe this is going to extend down the body towards the right hip so here we have a ct picture now this is a coronal image of the liver this is right lobe left lobe this is lung heart lung and what we're seeing here is an extension of the right lobe of the liver all the way down to this person's right hip this is the iliac crest right here so that's a long extension of the right lobe heading towards the right hip if we were to see this on ultrasound we would typically be long on the kidney seeing that superior side up here so the superior here matches up with superior here and then in our picture we would see the long rydell slope extending inferior in our picture towards the patient's feet so we would see an extension of the right lobe as it goes past the right kidney for most people the right kidney and the right liver kind of end at a similar space with rydell so we're just going to see a whole lot of liver just continuing on down we may also notice that there are some hepatic vein variants it's not uncommon for blood vessels to present with anatomical variants most of these are not going to be recognizable by ultrasound probably the biggest one that you're going to notice as a sonographer or how the right hepatic middle hepatic and left hepatic veins join together before going into the ivc for the most part most of them will have their own confluence with the ivc with the middle hepatic vein on the left hepatic vein kind of joining before they truly enter sometimes though you might see the left hepatic vein join much higher on the middle hepatic vein or you might see them all kind of joined together before going into the ivc those ones are going to be the more prominent ones that you'll see on ultrasound the other one is this type 1b and this is just a separate right hepatic vein that has formed helps to drain the right hepatic lobe but it's going to have its own entrance into the ivc a little bit lower than what we would expect i mostly present these hepatic vein variants to you not so that you will identify them any time that you see them but just know that it can happen especially if you're kind of looking at things and you think something just feels off in your images so that brings us to the end of our macro anatomy where we learn about the big structures of the liver we're going to switch gears and look at section 3.7 liver microanatomy now understanding microanatomy is going to help us better understand how the liver works because a lot of the physiology is down at the microscopic level as far as knowing your liver microanatomy goes really should just be able to name the key parts of the microanatomy and what their role is in liver function we already spent some time talking about the liver as a giant organ as we can see here if we were to break the liver down into functional units take a tiny little sliver of it and look at it under a microscope we would see that the liver is actually made up of what we call liver lobules so there are these kind of hexagonal shaped structures that work as a functional section put a bunch of those together you get your segments put a bunch of those together you get your lobes put the lobes together you get your whole liver and the liver lobules are made up of the microscopic components looking at this cross-section of the whole liver lobule we can see that it kind of has again that hexagonal appearance to it with these radiating hepatocytes towards a central area if we were to zoom in even closer on this then we would see that that central area is called the central vein where the blood flow from the portal veins and hepatic arteries are going to travel through it where the bile ducts are going to exit out of it and we see all these hepatocytes lining these structures to aid in the exchange of nutrients toxins bile components all of that stuff so there are just a handful of key microanatomy terms that you need to know because you're going to hear a few of them again as we talk about the physiology of the liver firstly remember that the lobule is the smallest functional unit of the liver the lobule were those hexagon shaped structures the hepatic lobules are the building blocks of the liver tissue the hepatic lobule has all three parts of the portal triad the bile duct the portal vein and the hepatic artery and then we'll see at the center of the labial essential vein and those central veins will eventually confluence together and create the hepatic veins which will then go to the ivc in the lobby we have the hepatocyte apatocite is a liver cell hepatocytes are capable of regeneration and carry out most of the liver functions the hepatocytes are arranged in a radial fashion in which they will extend from the outer edges of the lobule moving towards the central vein in between the rows of hepatocytes we will see sinusoids the sinusoids are a type of capillary where the portal vein and the hepatic artery come together now these are the smallest parts of the portal triad and they actually take on special names that's called a portal venule and a hepatic arteriole and we can see that they are going to come together after traveling past hepatocytes doing the exchanges through the cellular walls taking care of bodily functions all that blood is going to come together eventually and those are going to head towards the central vein within the sinusoids are special cells called copper cells the copper cells hang out in the sinusoids and are responsible for kind of grabbing on to some other junk and other toxins that might be floating through the blood system and getting rid of it so we consider these to be specialized macrophages macrophages are a type of cell that ingest substances and then process it to basically get rid of it the parasites are more responsible for filtration and toxin removal but the cup for cells aid in that function and help to get rid of particular materials as blood then flows through the sinusoids they do attach to the central vein there's a central vein located in the middle of each lobule and eventually all those central veins will come together to form the hepatic veins the central veins are responsible for taking the filtered blood out of the liver returning it with the rest of the blood from the body bring it to the heart so it can be oxygenated and redistributed to the body and lastly in the lobule we will see bioductuals just like the portal venules and hepatic arterials are the very tiniest parts of the vascular system the ductule is the tiniest part of the ductal system the parasites line the ductules and will dump in their bile components into the ducts which will then travel through the ducts the ducts will come together getting bigger and bigger and bigger as they head towards the porta hepatis eventually they will form the common hepatic duct which will bring the bile components into the gallbladder for storage and when the body needs the bile it will be released through the common bile duct the main purpose about learning microanatomy of the liver is because some of these terms will be discussed when we talk about the physiology of the liver and you should be able to name these important pieces of the lobule and briefly describe their function section 3.8 liver physiology liver physiology is incredibly complex and the liver is responsible for a ton of functions and when one of those functions isn't quite going the way it should be or is impaired then typically an ultrasound will be ordered there are seven main functions of the liver that you will need to know we will review each of them in a very limited way because as sonographers physiology plays a very limited role in our job we do need to know how pathology and physiology are related to one another and we should be able to read through lab values and kind of understand how that might affect what our images will look like but beyond that ultrasound really can't tell how organs are functioning so the function of an organ is not as key of a foundation as say anatomy the liver being one of the biggest organs in our body serves as one of the powerhouses of our body as well it is a very metabolically active organ and is responsible for so many functions that are vital to human life now the primary functions of the liver include metabolism of carbohydrates proteins and fat synthesis of plasma proteins the storage of glycogen vitamins and minerals blood detoxification and purification bile production and excretion serving as a blood reservoir and lymph reduction we're going to take a look at each of these seven functions in a little bit more detail let's first talk about the metabolism function of the liver the liver is going to aid in the breakdown or metabolism of carbohydrates proteins and fats and the liver plays an essential role in maintaining blood glucose levels so that's our blood sugar levels basically what happens when we eat carbohydrates the body is going to break down those carbohydrates into glucose or sugar that glucose is going to be absorbed into the bloodstream when the body recognizes that there is glucose in the bloodstream the pancreas is going to be told to release insulin and it is a combination of insulin and glucose that allows the glucose to enter into the blood cells and whatever glucose is left over after the cells use what they need heads to the liver to be stored as glycogen that glycogen hangs out in the liver until there is a signal in the body that the body needs more sugar to function the liver then will convert the glycogen into glucose insulin will be released again and the glucose will enter the cells this is where the cycle continues then whatever sugar is left over gets sent to the liver for storage as glycogen as blood sugar drops glycogen is converted back to glucose to be used by the cells the key takeaway from carbohydrate metabolism is that glucose is converted to glycogen for storage in the liver the liver also plays a giant role in how we break down proteins again when we eat proteins such as meat eggs milks dairies all of that anything that has a protein into it proteins are made of amino acids when we eat them our body is going to break them down into those tiny little bits those tiny little amino acids when those amino acids flow from the intestines through the portal system and into the liver they are going to enter into the hepatocytes and within the hepatocytes are two little chemicals known as transamniasis now these transamnases are used to break down the amino acids into the parts that the body wants the amino and get rid of the part the body doesn't want the acid now the two trans amneses and we're going to hear these later because these are important are ast and alt so ast and alt are going to work with those amino acid chains break them apart it's going to use the proteins to make new things and it's going to get rid of the acids out of the parasite that acid though is actually very toxic to the body because it comes out as ammonia so before the ammonia is released from the liver it converts it to something called urea and the urea can just float through the bloodstream unimpaired it'll head to the kidneys where the kidneys will filter the urea out into our urine and then we go to the bathroom and get rid of it so your main takeaway from protein metabolism that i want you to know is that the liver plays a role in the tiny building block breaking apart the amino acids and it does so using ast and alt and this will be important later when we talk about some lab tests lastly the liver also helps in breaking down lipids which are fats when we ingest fats the liver is going to help in metabolizing some of those fats there's actually different ways that the body can use fats that we ingest some of it's going to be used as energy some of it's going to get centaur adipose tissue for storage and some of it specifically the cholesterol part of it is going to be used for transportation cholesterol is great at transporting hormones around the body but the body only needs so much of it so any excessive cholesterol that is in the body is going to be moved into the ductal system and excreted through bile and when we speak about the excess it's just whatever the body can't use in many americans it's not uncommon for us to have high cholesterol which basically means that the body just has too much cholesterol more than they need for hormones more than they can get rid of through the bile and so it just kind of hangs out in the blood a lot longer which can actually be very damaging to the liver and the vascular system the second function of the liver is protein synthesis we learned that the liver helps in protein metabolism so the food that we eat gets broken down into those amino acids those amino acids are broken apart and it holds on to the aminos now the liver is going to take those aminos and make new proteins that's the protein synthesis and it's responsible for making a lot of proteins but the two that we need to talk about are albumin and the ones that provide blood clotting factors so let's first look at albumin now albumin is a special protein that is responsible for maintaining pressure in the circulatory system and it does this by keeping enough fluid in the vessels in the body in between the cells there's a little bit of fluid that hangs out in between the albumen's job is to draw that fluid out into the bloodstream so it creates enough pressure and volume within the cardiovascular system so we want enough albumin running around acting like a sponge to pull that extra fluid into the cardiovascular system to keep the blood volume up now if there's not enough albumin circulating then that fluid kind of gets stuck in between the cells and that is where it's going to start to leak into the peritoneum and then we start to see fluid buildup in the peritoneal sac this is why people who have liver malfunction or liver disease tend to accumulate what we call ascites that fluid within the peritoneal sac it's because the liver is not functioning very well therefore not producing the albumin which should be drawing that fluid out of the system and into the blood vessels the other job that albumin has is to act as a transportation system it's very good at transporting substances like drugs fats hormones and other toxins in the body it's going to bring those back to the liver for metabolism so it acts a lot like a semi truck so when albumin is low not only is the patient going to most likely experience fluid accumulation we're also going to start to see toxins build up in the body as well the other protein synthesis that we need to cover are the proteins that lend themselves to blood clotting factors now blood clotting factors are the way that the body self heals if we cut ourselves we expect that we will stop bleeding because the blood clots and plugs the hole and the reason that we get to that point is because of the proteins made in the liver now there are 10 factors that are made within the liver and the 10 factors kind of work together as a chain for these events to happen and eventually end up with a blood clot that stops the bleeding the two factors that you need to know and are probably most familiar with are fibrinogen and prothrombin when the body recognizes that there is a hole within a vessel prothomine is released into the body interacts with fibrinogen and it starts the cascade of building the blood clot the prothrombin is one of the proteins built by the liver with the help of vitamin k prothrombin ends up being one of the proteins that the liver is capable of creating testing the prothrombin in the blood is one of the ways that we can test how the liver is functioning is it functioning well enough to perform its protein synthesis duties if the liver is not functioning very well and not producing enough prothrombin we'll find that these patients are going to be more susceptible to excessive bleeding the third function of the liver is storage now we learned when we talked about carbohydrate metabolism that the liver is responsible for storing glycogen as part of that process when the body is in need of glucose the glycogen is converted and expelled as glucose into the body so the cells can use it but the liver is also responsible for storing many vitamins and minerals some of the key vitamins that the liver stores are vitamin a d e k and b12 a d e and k are all fat soluble vitamins meaning that they have to have fat around to be absorbed which is good that the liver helps in fat metabolism so it has fat available to store so it has fat available to store these vitamins vitamin k is especially important as we learned that it is part of the process for creating those blood clotting factors the liver also stores many minerals that it's going to use for sympathization such as zinc iron copper and magnesium again when the liver is not functioning well or if the patient has a storage disease might see that the liver is holding on to too much copper or too much iron and the liver is typically greatly affected in these diseases another critical role of the liver is to rid the body of foreign substances and excessive hormones recall that the copper cells in the sinusoids do perform some of this role but most of it is going to be done in the parasites the parasites are going to take xenobiotics which means anything that's not supposed to be in the body and expel it through the biliary tree as bile components or through the kidneys in the urine one of the special rules of the liver is the detoxification of bilirubin it works on helping the body get rid of this bilirubin and it gets rid of it via the bile system during the process of hemolysis a red blood cell is destroyed so hemo means the blood lysis means to basically break it apart so we destroy the red blood cell and what we end up getting is a heme cell and a globin cell the heme cell is going to go on to break down even further and that is going to be divided into iron and biliverdin the bilivern then breaks down even further into bilirubin and this is all kind of happening out in the body typically the spleen is responsible for destroying our red blood cells so the bilirubin now is hanging out in the blood system and the body doesn't really want the bilirubin out there it's not a whole lot of fun to have extra bilirubin in your system it can kind of muck up a bunch of things so the bilirubin's hanging out in the blood and what ends up happening is albumin comes by and picks up all this bilirubin now when bilirubin is out in the bloodstream hasn't visited the liver yet we call it unconjugated so the albumin's going to take that unconjugated bilirubin load it up and bring it to the liver when it gets to the liver it's going to enter into the hepatocytes and the hepatocytes are going to conjugate the bilirubin basically what that means is to add an oxygen to it so it's dissolvable in water once the parasites conjugate the bilirubin they're going to then push that out into the ductules where all of that will join together and head off to the gallbladder for storage conjugated bilirubin is a key part of bile bile then is stored in the gallbladder to where then will go into our intestines and be excreted from the body as feces and just a little bit of that conjugated bilirubin is going to make it back into the bloodstream but as that blood passes through the kidney filtration it will be filtered out and released as urine the key part about detoxification that i want you to remember is that unconjugated bilirubin is in the bloodstream hasn't been to the liver yet or conjugated bilirubin has already visited the liver and has been processed by the hepatocytes the fifth function of the liver then is to produce that bile and it does so partially with that breakdown of bilirubin but it's also going to add other things like electrolytes and bile cells bile acids cholesterol a bunch of other things leftover products from the hepatocytes are going to just get dumped into the biliary tree crate bile and head off to the gallbladder it is the bioductuals that will take in those substances from the hepatocytes those will join together to form the intrahepatic bile ducts and eventually those will converge to the point where they then meet up with the common hepatic duct and travel into the gallbladder via the cystic duct the bile then hangs out in the gallbladder until the body needs it for fat emulsification gallbladder will release the bile into the duodenum and that is how all of those extra substances that the hepatocytes wanted to get rid of eventually do get rid of them through our feces there's much more to talk about though about bile and its role in our digestive tract so we'll save that for the biliary tree physiology discussion the sixth function of the liver is to act as a blood reservoir now we learned that the liver has a lot of vascularity to it we have the hepatic arteries we have the hepatic veins and we have the portal veins recall that when the portal veins and the hepatic arteries join up in the lobules they kind of meet up at what we called the sinusoid and the sinusoid is kind of this gaping area that is expandable in fact all veins are expandable we call them dynamic and that is because they are able to expand and contract based on the pressure in the system and what the body needs so the liver being such a vascular structure has a lot of these spaces that can hold on to blood and that's exactly what they do so at any point the liver is typically holding on to about 10 to 15 of the body's total blood now in the event that somebody had some major hemorrhaging going on the liver would be able to contract those veins squeeze the blood that it's holding on to out into the body to attempt to keep the total blood volume up on the flip side of that if for some reason the system is experiencing excessive pressure the blood can start to pool in the liver and try to take some of the burden off of the circulatory system and the last function of the liver is lymph production lymph is basically made of proteins and water and it's going to be made by the parasites now there are little spaces along the sinusoids called the space of dc and in the space of dc is where those lymph products are going to kind of leak into instead of going into the sinusoid in the central vein these proteins and the water aren't quite small enough to get into the sinusoids so they hang out in the space of dc and those species of dcs are going to create small lymph vessels and those little lymph vessels are going to converge together to create the lymph system where they head off to the lymph nodes so basically the lymph system is mostly responsible for just kind of transporting proteins and water around the body and with the liver being so vascular it actually ends up having a lot of these lymph channels as well and because of its protein synthesis it ends up making a lot of proteins so it makes sense that the liver produces a lot in fact half of the lymph found in the body to finish up the liver physiology section we are going to move into section 3.9 liver chemistry how an organ is functioning is better determined by blood work than it is by ultrasound but ultrasounds are commonly ordered when blood work comes back abnormal so in this section we're going to use it kind of as an introduction to the lab tests that are associated with the liver and then we'll talk about some of the diseases that go along with those lab tests remember as a sonographer you're not going to need to know exact lab values but really what you should know is what is indicated if a value comes back abnormally high or abnormally low when we are looking at liver disease one of the things that we need to decide is is the liver disease hepatocellular based or is it obstructive based in the setting of hepatocellular disease the pedocytes are malfunctioning something that's going on that is causing the parasites to either not do the job that they're supposed to be doing or maybe they're breaking down in a really odd way or just something's not right with them and when something's not right with hepatocytes the liver is going to suffer typically we can treat hepatocellular disease in the medical way that means using supportive measures like lifestyle changes or we can medicate obstructive disease then is going to refer to a blockage of bile excretion remember that when we get rid of bile we are actually getting rid of a lot of the toxins and other materials that we want to move out of the body so if there is something obstructing the flow of bile those toxins and other junky stuff going to start backing up through the ductal system kind of get back into the hepatocytes and back into the bloodstream when an obstructive disease is present we are more likely going to be able to cure it by surgery to remove the obstruction when we use ultrasound and lab tests together we can actually paint a pretty good picture of what the patient is experiencing hepatocellular disease versus obstructive when a patient needs blood work related to their liver it's typically called a liver function test or a paddock panel might be ordered as just part of a routine regular physical or it also can be ordered in the setting of acute illness or injury depending on how the values are elevated or decreased the provider might be able to tell not only is there liver disease but might also be able to even diagnose the type of liver disease when blood is drawn it can be evaluated for certain substances that are related to the liver for example we talked about those amniotransferases ast and alt as being inside the hepatocytes part of the amino acid breakdown process and it's normal to have a little bit of ast and alt circulating throughout the blood but what happens when there's a lot of it well we start to be concerned that cells that have that ast and alt inside of them have somehow been destroyed and have broken open leaking their contents into the bloodstream so increased ast and increased alt lead us to believe that something is wrong with the liver blood tests can also look specifically for certain substances made by the liver for example albumin or prothrombin by using the liver function test we are able to then screen for liver infections such as hepatitis so we could actually test for the hepatitis antibodies or we can see how the liver is reacting to a possible infection we are also able to monitor for the progression of a disease for example if a patient does have viral hepatitis or alcoholic hepatitis and then we put in interventions like changing lifestyle or giving antiviral medications then we can use the liver function test to be able to determine are the changes working are there numbers getting better on the flip side then we can also measure the severity of a disease while it's not always true when we have severely elevated values we suspect that the disease is also rather severe for example in the setting of cirrhosis early onset cirrhosis might cause a slight elevation in some of the lft numbers as the disease progresses we're going to expect them to get higher we might also start to see some blood work that might indicate a cancer has developed we can also use liver function tests to monitor possible side effects when we were discussing the functions of the liver one of them was detoxification now the example that we went over was the process of bilirubin detoxification but the liver is also responsible for processing and metabolizing certain medications that we take as well for example people with autoimmune diseases quite often take a drug called methotrexate methotrexate is actually pretty damaging to the liver and so we would want to monitor liver function tests to see if the medication is causing more problems than good for the patient abnormal lfts are a super common reason why we have ultrasound exams ordered you can use the lab work and the patient's symptoms to help you better understand the disease processes that you might discover during your ultrasound examination some of the common tests that you will see in the liver hepatic workup are going to include liver enzyme blood tests and liver function blood tests now in general liver enzyme tests and liver function tests are just grouped under the liver function test however the liver enzymes are more indicative of hepatocellular death or other cellular death around the body or liver function tests are directly tied to functions known of the liver and can tell us how well the liver is working we assume that when liver enzyme values are elevated we'll also see poor liver function values as well so under the liver enzyme category we have five common tests we have aspartitate amniotransferase which is known as ast alanine amniotransferase which is known as alt alkaline phosphatase commonly abbreviated to elk phos or alp gamma glutamyl transferase is ggt and lactic acid dehydrogenase or ldh now these enzymes as we're going to learn are found in multiple organ systems however depending on how they are elevated in the combination that they present in we're more likely to see liver damage in association with them when we evaluate the liver functions we are actually looking at how the liver is able to perform its duties we learned that bilirubin detoxification is a function of the liver so how's it doing with the bilirubin is it able to conjugate the way it's supposed to prothrombin time it's responsible for making prothrombin is there enough prothrombin circulating in the blood same idea with albumin and other proteins is there enough in the body the liver is responsible for making them if it's not making enough then we start to think that the liver is not functioning appropriately in the next few slides we are going to cover all of the liver enzymes and their implications we're also going to cover prothrombin time and albumin leaving bilirubin for the biliary section before we get into what causes abnormal lfgs i do just want to touch on the fact that you are not going to be expected to know like normal ranges and if a value is out of range above or below more often than not you are going to have access to an electronic medical record for a patient when you go in there you can see their laboratory history depending on your electronic medical record reporting style you'll be able to easily identify values that are out of range for all the tests that we're going to talk about all of them except for albumin are abnormal when they are elevated albumin is abnormal when it's decreased you're going to be looking for emr indicated abnormal values for example in this image here we have all the tests located on the side here that this patient has had we then have the dates and the times of those blood draws the values that are in black are normal and are not concerning however when a value comes out of the lab's standard range and it's going to be flagged in this case you use h for high and l's for low and they can be presented in different ways in this case exclamation points are to draw your eye to that lab being abnormal and then it has an arrow next to it to indicate if it's high or as these ones are if they're too low when there are critical findings they often are indicated with a double exclamation point or in this case a double elevated arrow meaning that these are excessively high you are never going to need to know the average range as the range will change from lab to lab but you should be able again to recognize if a value has been flagged as abnormal and then what that abnormal value could possibly mean keeping this information in mind let's check out the liver enzymes that we need to be aware of now the two big ones are alt and ast ast stands for aspartate amniotransferase ast is normally found in the blood in small amounts it's an enzyme that is made by the red blood cells liver cells heart cells muscle cells pancreas and kidneys when a cell is destroyed it's going to release its contents including the ast that is why it's not uncommon for ast to be in small amounts in the blood because red blood cells are being destroyed all the time what becomes concerning is if that ast value increases out of normal range then we start to suspect that one of these body systems is experiencing cellular damage as a side note ast was originally referred to as sgot or serum glutamic oxaloacetic transamniase this is a much older term but sometimes you will still see it in lab reports similar to ast is alt or alanine amniotrans phrase now this is the same idea alt is another enzyme common for it to be in the blood in small amounts because it is made by multiple body systems including the liver which is the biggest producer of alt but we also see it in kidneys heart muscles and the pancreas if we see elevated alt values then we are concerned that there has been cellular damage in one of these body systems now this one's a little bit more specific to the liver so increased alt is more likely to stem from liver disease and just like ast alt also has a little bit more of an outdated term formerly called serum glutamic pyruvic transaminase or sgpt and while i can't account for what the boards are going to ask you currently for whatever reason knowing that sjot and ast are the same test and sgpt and alt are the same test has always been stressed and so again i would probably just try to commit that to memory but regardless whenever we are testing the blood for ast and alt we are trying to evaluate how much ast and alt are circulating in the body it is normal for low levels to be circulating through the body however elevated values are going to be abnormal and again that's because there has been cellular damage to one of these organ systems typically the higher the value the more damage that has occurred so some key takeaways when we look at the alt and the ast result first off since alt is mainly produced in the liver increased alt is going to be more specific to liver disease than ast so the way that i remember this is that alt has l in it altl for liver ast has more system organs that can produce it so i think of s as system going along with the body no matter what though alt and ast are almost always going to be increased in all liver diseases when ast is increased and alt are increased but the ast is more increased we consider that probably due to alcohol related reasons now the way that i remember that ast is higher when we are talking about alcohol is going back to that system thing when you drink alcohol it affects everything it makes your brain googly it can do things to your heart it does things to your livers it makes your body ache especially when you're hungover the next day so alcohol affects the system ast is a system released enzyme therefore i know increased ast is going to be higher with alcohol compared to alt when alt is increased and ast has increased but the alt has a higher increased value then we are more concerned that it is something to do with the liver possibly leading to like a liver viral hepatitis hepatitis is specific to the liver and just like alt is more specific to the liver that is how i associate the two if we see an increase in ast without an increase in alt typically that means that the patient has had a myocardial infarct which is known as a heart attack again when we think of ast as being more of a system-derived enzyme and it can be produced by multiple systems within the body if alt is not increased the liver is most likely okay it was one of those other body systems when a patient has a heart attack it means that their cells are no longer receiving oxygenated blood they are more likely to die and become damaged therefore they release the ast but this is not a steadfast rule when we see increased ast and associated increased ldh again without any alt increase that for sure rolls out a hepatocellular disease and we're looking at a different system organ completely another enzyme that we check with the liver is alkaline phosphatase alkaline phosphatase is another enzyme that we can find in the blood it is typically made by the liver and the bone for the most part but we also see that it's made by the intestines kidneys and a placenta if we see that a patient has decreased alp that's going to be more associated with malnutrition and does not indicate liver disease very high alp is going to be more associated with liver disease especially the obstructive type but it's not specific to the liver because we can also see increased alp with bone disease heart attacks kidney disease and in pregnant women gamma-glutamyl transferase is another enzyme that is found in the blood this is going to be an enzyme that is better at helping us to metabolize drugs and other toxins it's typically made within the liver and the gallbladder however it is also made in the spleen pancreas and kidneys elevated ggt typically means that there's been some sort of liver damage but we're going to need other tests to determine if the liver is the actual source adding in these two new enzymes to the liver panel helps us to determine some new key factors we know that if the ggt is increased and the alkaline phosphatase is increased we're most likely looking at liver disease due to biliary obstruction if we see an increase in ggt plus an increase in the alt then we're most likely dealing with hepatocellular disease so many of our patients experiencing some sort of liver disease their alt will be high their ast will be high ggt will be increased and if we see an increase in aop we're thinking more biliary if we don't see that alp then we're going to think more hepatocellular disease the last enzyme that we talked about was lactic acid dehydrogenase or ldh and ldh is another enzyme that is found in a lot of tissues around the body its main job is to help the cells convert sugar into usable energy now usually ldh is going to be low but we'll see that it's elevated with a few things including liver disease heart attacks trauma cancers and infections looking back on the enzymes that we discussed we can see then that a lot of them are not specific to the liver but rather more of a systemic test when we combine the values and look for patterns within the elevations then we can start to kind of piece together is this liver disease versus something else and what might possibly be causing it another lab test that is sometimes used in the setting of liver disease is afp or alpha fetal protein afp is normal in a pregnant woman as the fetal liver produces afp it is completely abnormal to have afp in men non-pregnant women and children anytime that we see elevated afp we need to be concerned about cancers as it is highly associated with liver cancer and germ cell cancers which typically are of the testicle and ovaries a moderate increase in afp has been seen with non-cancerous liver diseases but it is still an indication that if something is wrong with the liver here are the six blood tests that we discussed notice that all of them are abnormal when they are increased and then i've listed a few diseases out that could be causing those increases note that most of these are going to be hepatocellular disease unless they indicate some sort of obstruction as part of the disease name as a newer student this list might not be immediately helpful to you but as you start to get into your pathology studies you may want to refer back to this list as you begin to look closer at the pathophysiology let's switch gears over into the liver function test the first one that we'll talk about is albumin now remember that albumin is a protein that is found in the blood that is made by the liver and its main purpose is to act like a sponge draw an interstitial fluid into the bloodstream to elevate the blood volume albumin is also helpful in transporting materials around the body when a patient has low albumin we expect that there is going to be liver disease especially cirrhosis or some sort of renal disease about albumin is unique because it is the only liver test that we have discussed that is abnormal when it is decreased another protein that the body make is prothrombin and we test prothrombin through a prothrombin time or pt blood test now pt is a blood test that is going to measure how long it takes for blood to clot we can use these tests to check if a patient has some sort of bleeding problems or if a medicine they are taking to prevent blood clots is working prothrombin time is also known as inr which stands for international normalized ratio when a lab uses inr testing they are standardizing the results of the prothrombin time no matter the testing location so an inr at your hospital versus inr at another hospital should be the same value now typically in healthy individuals we want the pt or the inr to be short or low we want the blood to clot quickly so we don't bleed out if we were to have a procedure or surgery in patients that have long prothrombin time we're going to typically see that caused by blood thinning medications such as warfarin or coumadin they possibly have either low levels of blood clotting factors or low levels of vitamin k they might be in liver failure or we'll also see it in combination with low albumin or cholesterol so when the liver is not functioning it is not producing prothrombing correctly and therefore we are going to be less likely to be able to stop bleeding in the event of some sort of puncture as a safety measure patients who are known to be on blood thinners should always have their inr or pt checked prior to any procedure that is going to puncture the skin and that's going to include procedures that we perform in radiology like a thoracentesis pericentesis or a biopsy and here again is a handy chart just to kind of review the liver function test that we discussed again albumin is the only one that is abnormal when it is decreased prothrombin time is abnormal when it's elevated we'll talk a little bit more about bilirubin when we talk about the biliary physiology but i did include it in this list as it technically is a liver function test now that you are familiar with anatomy and physiology of the liver we can actually get into what the liver looks like by ultrasound so let's go ahead and start section 3.10 ultrasound of the liver in this section we are going to cover normal anatomy ultrasound measurements landmarks and the liver protocol the images that i will be going over with you are static images there is a video link in your workbook that you can use to see some live sweeps through the liver also other youtube videos and the internet are going to be great resources for seeing live images if you don't have access to an ultrasound machine currently let's first start talking about how the liver actually looks so when we describe normal liver parenchyma we expect the liver tissue to look homogenous smooth and fine grained so if we look at this picture here this is all the liver parenchyma prankma refers to tissue of an organ in this image we can see that is all very similar grays that's the homogenous part and then the smooth and fine grain part kind of refers to how the individual specks that we see within the liver how big they are and how contrasty they are to one another if they're all kind of the same size and the same gray we kind of consider that to be smooth you'll see in other diseases that a diseased liver will take on more of a coarse grained echo texture in those cases we see more of a speckle pattern to the lower parenchyma so if you have a nice healthy liver it should be all the same level gray with a very smooth appearance to it we can see the diaphragm on the superior border here and this is most likely a branch of a portal vein given the thicker white walls not only do we look at the liver echo texture but we also need to look at the liver echogenicity and the echogenicity is going to refer to the brightness of the tissue when we're evaluating abdominal organs we tend to do so by comparing echogenicity of organs to other organs of the main abdominal organs we find that the kidney cortex is the darkest liver and spleen are similar with liver may be just a smidgen darker and then the pancreas is the brightest or most echogenic organ you can remember this order by thinking of kids love soda pop with kidneys being the darkest and the pancreas being the brightest to do that comparison picture we want to make sure that we are getting a picture that shows not only the kidney and a lot of its cortex but a lot of the liver in that right kidney liver interface image this way we can easily compare the echogenicity of the liver to the cortex of the kidney now the cortex of the kidney is the darker part that surrounds the central sinus so in this image we have the right lobe of the liver we can see the diaphragm on the superior side this is the superior pole of the right kidney and the inferior pull of the right kidney we have the superior portion of the liver on this side coming down to the inferior pole of the liver on this side we want to show a large amount of liver tissue so we are able to compare it to the renal tissue ultrasound really is not the gold standard for measuring the liver it's actually really kind of hard to get all the borders in one image and variants of the liver can really throw off the measurements but that doesn't mean that we're not going to try or that we can't do it more often than not you'll probably be able to eyeball or just notice from your experience of seeing normal livers when the liver actually appears enlarged typically diagnosing hepatomegaly which means enlarged liver is done by ct when the liver is greater than 15 centimeters in the superior to inferior dimension when we measure more obliquely we consider anything over 18 to be abnormally large depending on your site's protocol you may be asked to measure the liver in one of two ways there's actually a study done in 2016 comparing the two ways trying to decide which one was more accurate so there are two windows that we typically use to measure the liver the first one is to be in a longitudinal plane on the chest lined up with the clavicle this is called the mid clavicular and this is going to best match with ct images the other window that we can use is called the mid axillary line so this is going to come more from a chrome approach again showing the superior to inferior axis when you go to measure either of these images that you obtain you are going to measure from the superior to inferior this is a true superior to inferior as it is parallel to the anterior liver wall and this aligns well with how ct measures the liver the other option that you have is to measure in the oblique superior inferior and that involves placing your first caliper on the inferior tip of the liver following the edge of the liver back to the diaphragm for your second caliper placement in the 2016 study they found that the mid axillary line ended up being the most accurate window for measuring the liver they also then found that the superior to inferior and where they were parallel with the abdominal wall provided the most consistent measurements between sonographer and cadaver measurements so again follow whatever you have been shown as your site's protocol in fact many sites don't measure the liver at all but rather eyeball it and will follow up with other imaging to get a true measurement of the liver next we're going to take a look at some ultrasound images of common anatomy that we see around the liver one of the more prominent things that you should be able to see in your liver images is the diaphragm a normal diaphragm should appear hyperechoic and smooth in this top picture we are in a transverse view on the liver we can see liver parenchyma this is the ivc with branches of the right hepatic and middle hepatic veins coming off of it because the diaphragm wraps around a little bit more posteriorly on the liver we are seeing this bright white line here as the posterior portion of the diaphragm wrapping around the liver the diaphragm is considered a strong reflector which is why it comes back very bright white on our images in this bottom image we are in the longitudinal plane more towards the left lateral lobe we again can see the diaphragm along the superior border of the liver these bright white lines are actually air within the stomach or bowel the ligamentum teres is another structure that we can see in our ultrasound images and we commonly use it as a landmark in our transverse inferior left lobe images so here we have the liver parenchyma and add to the bottom of it here is that ligamentum teres so the normal ligamentum teres is going to be very bright so hyperechoic and sometimes we'll actually see some shadowing behind it by including this in your trans left liver images this is a strong indicator that you have moved towards the inferior image in fact we can even see pancreas underneath it here let's look like it might be aorta and ivc the ligamentum venosum is another ligament that we are able to see in our ultrasound images and we use it quite often as a major landmark to identify where the caudate lobe is the ligamentum venosum appears as a thin white line that is going to appear between the left lobe of the liver and the caudate lobe so on our top picture here we're going to have the left lobe of the liver and lung this is the diaphragm here we can see that thin white line this is the ligamentum venosum posterior to that then is our caudate lobe and when we go posterior to that we actually are catching just a little bit of the probably ivc possibly the aorta underneath it here again we can see a little pancreas off to the side here and some of the splenic confluence so ligamentum vinosum caudate lobe sits just posterior to it in the bottom picture here we are in the transverse view at the level of the ligamentum vinosum we have our transverse left lobe here that thin echogenic line separating the left lobe from the caudate lobe and this is the caudate lobe right here posterior to the caudate lobe we can see the ivc and the aorta here the top picture reinforces the idea that we are looking at the superior portion and towards the posterior side of the liver to identify where that caudate lobe is another structure that we can see in the liver that we have discussed is something called the main lobar fissure remember we talked about the main lobar fissure as being home to the middle hepatic vein real claim to fame is that it is the division between the right lobe and the left lobe of the liver so here is that main lobar fissure we see it connected to the portal vein and to the neck of the gallbladder if we follow the main lobar fissure back all the way to the diaphragm then we can divide this picture into left lobe above it and the right lobe below it this is technically coin adds anatomy section 4b and this is 5 over here we like to use the aorta as one of our landmarks for visualizing the left flow of the liver as well typically we'll start all the way lateral grab a picture and then our next stop is at the aorta so the aorta is going to be a tubular structure typically a little bit more on the anechoic side because it is filled with blood it's it's posterior to the liver going to have very bright walls that are going to maintain a rigid shape as there is a lot of pressure within the aorta some other structures that we see around it is the left diaphragmatic crux which comes across here we can see the esophageal junction where the esophagus enters into the stomach here but anterior to all of this is our left lobe of our liver so we can see the inferior portion of the left flow of the liver to the superior portion where the diaphragm is and then we have the rectus abdominis muscles anterior and the aorta posterior the ivc is another blood vessel that we'll use as a landmark as we move between lobes of the liver so here we have the left lobe of the liver we can see the ligamentum venosum that thin bright line separating the left lobe of the liver from the caudate lobe and then posterior to the caudate lobe is the ivc now the ivc is going to have thinner wall it fluctuates a little bit more with the patient's respiration and we'll see it kind of open and shut during the cardiac cycle and with respiration we can follow the ivc directly into the right atrium we might also be able to see the left hepatic vein confluencing with the ivc in this view as well when we turn transverse on the body and gather our transverse liver images it's not uncommon for the aorta and the ivc to be in those pictures as well as you get better at imaging and kind of multitasking with your images you'll be able to evaluate the whole picture here we have the left lobe of the liver here a little bit of the right lobe of the liver coming in we can see the ioc in the aorta this is actually the celiac axis giving to the splenic artery and the common hepatic artery which will eventually turn into the main hepatic artery below the ivc and aorta we have a little bit of spine down here as well the porta habitus is not a structure that we are able to see within the liver but rather an area that we should be able to identify when you're looking for the porta habitus you're basically looking for where the liver parenchyma stops we can see liver tissue on this side as we jump down we can see a little bit of liver tissue on this side so what we are looking for is where these line up and that is our porta habitus once those vessels and ducts cross the port of habitus they become intra-hepatic this circle here is showing the main portal vein which is an extra hepatic structure crossing over into the liver and it actually becomes the right portal vein rather quickly this dotted line here kind of gives us a close-up view of the extra hepatic side versus the intra-hepatic side again we are following the liver tissue kind of following where it ends as that is the area of the port hepatis when we're looking at the liver vasculature and ducts of the liver when we are in grayscale they're typically going to appear as tubular anechoic structures it's their location appearance and doppler characteristics that are going to help to identify these structures by ultrasound portal triad is typically seen best in the area of the porta hepatis as this is where they are the largest in this image i have the portal vein posterior to the more left sided hepatic artery and the right-sided common bile duct we call this image the mickey mouse sign where the face is supportive vein and the ears are represented by the common bile duct and the hepatic artery other structures that we can see in this view have been labeled but we do have the liver anterior the gallbladder anterior and then we can see the ivc and the aorta visible in this plane as well whenever you see the aorta and the ivc in the longitudinal plane next to each other then you know that the sonographer is actually using a coronal approach so most likely the transducer is up here on the right flank imaging through the liver past the gallbladder to the port of hepatitis and then ivc aorta as we move to the left of the body this would be superior and this is inferior when we elongate out the portal vein and the bile ducts we'll see that they become more parallel structures to one another and then we can see the hepatic artery and this view actually remains as a cross section this is a classic view to be able to measure and locate your bile ducts pored happiness again becomes a very key landmark to identifying ducts that are outside of the liver and ducts that are inside the liver another structure that's very helpful to understand the difference between the common bile duct and the common hepatic duct is the hepatic artery when we see the hepatic artery and cross section in this view this is actually the cross section of the right hepatic artery so we have common bile duct porta avidus is right here at the level of that cross section of right hepatic artery and then we see the common hepatic duct entering into the liver this is the portal vein underneath it we have the main portal vein crossing the porta habitus and becoming typically the right portal vein almost immediately it's important to note that the common bile duct also has bright walls with an anechoic tubular appearance to it so we want to use color as they have in this right-sided picture to differentiate the blood vessels from the ducts the hepatic artery is also best viewed at the porta habitus again it's typically bigger in this area as it's going to start branching as it enters into the liver here we have the main portal vein crossing the part of hepatitis and entering into the liver anterior to the portal vein then we can see this structure here as the main hepatic artery now this is the main hepatic artery because we are still external to the liver it is still outside of the porta habitus once it crosses over the port of hepatitis and into the liver it's going to branch very quickly into the right and left hepatic arteries the main hepatic artery should have arterial blood flow with always moving forward flow the quick upstroke with systole that's when the heart contracts pushes all the blood out and then in the diastole part we are still going to see forward flow into the liver because the liver always needs blood flow going to it you'll find most of the organs in the abdomen are going to need arterial flow constantly and so this is a very typical waveform of an organ that needs blood all of the time note again that we do need color on these structures to help us identify where the blood vessels are then using the doppler tracing we can understand the waveform created by this particular vessel which as you learn more about the abdominal vasculature you will see is very typical for the hepatic artery here we've got some examples of the portal vein again we have main portal vein crossing the part of habitus and very quickly becoming the right portal vein so as it comes into the liver it branches very quickly this is the right portal vein headed to the right liver the left portal vein is kind of off view in this image however we can see it in this picture so again we have main portal vein crossing the porta habitus quickly branching into the right portal vein and the left portal vein using color on your portal veins will help to identify that they are indeed vascular structures so here we have color on a portal vein we are sampling it and you'll see that this has a very different profile compared to the hepatic artery this is a very normal expected waveform of the portal vein it's just kind of very steady flow heading towards the liver and what we call hepatopetal flow if it was flowing away from the liver we would call it hepatofuego flow we can follow the creation of the portal vein all the way from the splenic vein and superior mesenteric vein confluence then we can see it near the pancreas head typically it is best visualized right around the porta habitas and again should appear as an anechoic tube with very thick walls here we have some examples of hepatic veins it is not uncommon to be able to see at least two if not all three branches of the hepatic veins confluencing with the ivc the best place to view them is in a transverse view up high in the liver you'll notice that the walls are thinner and more isochoic to the liver parenchyma but they are still vascular tubes that run towards the ivc again we will want to use color to identify these as vascular structures and if we doppler or take a sample within these vessels we are going to get a waveform that's very pulsatile it's not the same pulsatility as an artery would be but it takes on more of a w shape to it as this is very very close to the heart and we're going to get some of that feedback being able to see the hepatic veins enter into the ivc has been known to be called the playboy bunny sign or the reindeer sign as you can see they kind of look like antlers as you were sweeping through the liver parenchyma you will notice that there are a lot of anechoic structures coming in and out of your images some are going to be in cross sections some are elongated out and it's difficult to tell especially as you move away from the ivc or move away from the porta habitus exactly what you're looking at so i want to make sure to give you some tips on how to identify hepatic veins and how to identify portal veins the biggest thing with hepatic being said if you were to follow them back you should be able to follow them all the way back to the ivc they typically have thin walls that are rather isochoic to the liver so it almost looks like they don't have walls at all when you are in transverse you're going to see more of a vertical orientation of the hepatic veins and remember these are intersegmental so let's go back to our picture of some hepatic veins here remember this is a transverse view we can see that the walls are very thin almost isochoic to the liver parenchyma now i want to point out that we are seeing brighter slightly thicker walls on this right hepatic vein we can see it here we can actually see it on this one here and this is because of ultrasound physics the beam is coming from the transducer in this direction any structures that are 90 degrees to your beam end up being very strong reflectors and react to the beam ultrasound in a different way than something that runs a little bit more parallel with it so this is actually a little bit of artifact through here that the walls look so thick on this hepatic vein note how the hepatic veins are running a little bit more vertical through the structure as they confluence back to the ivc now portal veins we should be able to follow and connect back to the portal hepatitis they're going to have thicker walls and they're going to be more echogenic when we're in transverse on the liver we'll see that they run a little bit more horizontal and these are intrasegmental structures going back to our image of the portal veins here again you can see that this right portal vein is coursing more horizontally through our transverse image and note how they have thicker walls that are more echogenic than what we expected to see on the hepatic veins knowing how to identify portal veins versus hepatic veins is going to be very important that is because once you can identify what those structures are you can then identify what the liver segments are around it and then you can also determine is it running between a segment or is it running through a segment you should be able to identify segments of the liver by a picture there's a good chance this is going to be part of your test so i want to make sure i give you a few tips on how to identify the segments by ultrasound now when we are in the transverse view we can go to the very top of the liver which is the dome or we can slide all the way down towards the patient's feet which is the inferior portion of the liver remember that when we divided the liver into quinade's anatomy we had superior parts of the segments and we had inferior parts of the segments so when we are more superior on the liver we should be seeing the superior segments when we're more inferior on the liver we're going to see the inferior segments here's a drawing of what it would look like if we were in a transverse view on the superior part of the liver i know that we are superior because we are seeing the ivc with the hepatic veins draining into it that's going to be your big clue being on the superior side of the liver we should be able to see segment number two which is left lobe lateral superior we will see segment 4a which is left medial lobe superior we'll see segment 8 which is right lobe anterior superior and we should see segment 7 right lobe posterior superior the caudate lobe is also on the superior side of the liver so we should be able to see the caudate lobe clearly segment number one so if we are connecting our hepatic veins back to the ivc we're on the superior side of the liver seeing the superior segments as we move down towards the patient's feet we're no longer going to be able to see the hepatic veins connect we're going to start to see other structures come in like the portal veins uh like the right kidney will be able to be seen and we're gonna move out of the superior segments into the inferior segments the inferior segments then consisted of segment number three which is left lateral inferior 4b which was left medial inferior segment 5 which was right anterior inferior and segment 6 which was right posterior inferior remember that when you can see hepatic veins you should have a segment on either side of it so become very comfortable with identifying hepatic veins and remember that superiorly they will connect with the ivc inferiorly they are not connected and you will start to see other structures like the gallbladder kidney that kind of stuff let's take a look at some actual ultrasound images so i can kind of show you what i'm talking about here are two transverse images of the liver now the top one we can see that we have the left hepatic vein middle hepatic vein and the right hepatic vein all joining into the ivc because we can see the ivc and this connection of the hepatic veins that means we are superior in the liver that means we are going to be able to see the superior segments remember that the hepatic veins run intersegmentally any place that we see a hepatic vein we should have two segments one on either side of it starting at the left hepatic vein here we should have segment two the left lateral superior segment four the left medial superior crossing over the main hepatic vein we are now switching into the right lobe of the liver this is segment 8 right anterior superior and then crossing over the right hepatic vein we move into the segment 7 right posterior superior so these are all superior segments lateral medial anterior posterior as i move the transducer down the patient's body towards their feet i'm going to move to the inferior segments of the liver now we have the ivc here i'm not seeing any structures coming into it this actually happens to be the portal vein and possibly a little bit of the bile duct or hepatic artery here we can see little bits of the hepatic veins there's a little bit here there's a little bit of one here we aren't seeing the left hepatic vein but what i am seeing is the ligamentum teres and the ligamentum teres actually also served as a landmark between the left lobe and the quadrate lobe so i know that this is going to be segment four so here going through this again remember we're on the inferior side of everything so the left lobe that i should be able to see on the lateral side is segment three left lateral inferior crossing over the ligamentum teres we're going to move into left medial inferior which is segment 4b crossing past the middle hepatic vein which is right here we get into the right lobe of the liver and we are now in the right anterior inferior segment segment five crossing over the right hepatic vein we then move into the segment six which is the right posterior inferior segment so to recap we are inferior on the liver which means we're going to have all inferior segments again lateral medial anterior posterior and with that we're going to move into our last section liver protocol every facility is going to operate their ultrasound apartments differently typically from my experience i have seen that a provider needs to complete an order be it paper or electronic and in that order they should be specifying the exact type of exam that they want performed now the three most common ultrasound protocols that are going to include the liver are going to be a liver protocol right upper quadrant protocol and an abdomen complete protocol as you can see as we move through the three different types of orders we're adding more organs to the order in the patient who only requires a liver protocol they most likely have either had a recent ct they're only concerned about biliary disease only concerned about liver disease i most commonly see liver protocols in patients who have a chronic liver disease such as hepatitis c or b and we're following them up every six months nothing more severe has developed due to their condition a right over quadrant protocol is very commonly ordered for patients who are experiencing right upper quadrant pain that is because the pancreas the biliary tree the kidney all can cause some pain that radiates up to that right side so we end up kind of covering more of an area taking a look at all those organs that could be contributing to the patient's symptoms in the abdomen complete then we are evaluating both the right and the left side getting a global look looking at the entire abdomen you should always be familiar with the protocol images that your radiologists and site prefer and make sure that you are performing their desired images another thing that you should see in the order are indications indications do not mean rule out something like rule out gallstones rule out dvt that's not an indication indications of those would be right over quadrant pain nausea and vomiting postprandial pain something along those lines there are quite a few indications that can lead to a liver ultrasound and they include but are not limited to anorexia which means not wanting to eat we also have fatigue and weakness which can be more signs of blood issues or like a cancer issue abdominal pain is a huge one we'll see that with pancreatitis gallstones uh kidney stones we can see some with some liver diseases as well so abdomen pain is a big one fever means that there's some sort of infection in the body abnormal liver function tests are going to be a very quick way to get an abdominal ultrasound we also include jaundice in there which is the yellowing of the skin which is a direct result of something going on with the liver and the biliary system another one would be hepatomegaly which means that the liver is enlarged and that is something that doctors can usually feel when they're doing a physical exam the patient might be post liver transplant they want to make sure that the connections are all appropriate and the liver is remaining healthy and then a lot of times we're just doing it to follow up previous imaging it's not uncommon for a patient to have a cyst visualized six months ago we're just following up to make sure that it hasn't grown or changed in those six months and lastly we might be doing an abdomen ultrasound to prepare for a biopsy this is not a definitive list but a very common list of reasons that we see for liver or an abdominal ultrasound to be ordered as a sonographer it's going to be important for you to choose the correct transducer that's going to give you the best detail but is appropriate for the patient body habitus typically we are going to use a curve linear or a convex transducer and we want it to be between the frequencies of one and seven dropping down to the one megahertz frequency is going to be better for the larger more obese patients or seven megahertz maybe even up to nine megahertz will be very appropriate for thin and pediatric patients when preparing the patient for their liver ultrasound especially if the ultrasound is going to include the biliary tree we want our patient to be npo which stands for nil per os which means nothing to eat or drink for at least six to eight hours that does include no chewing of gum no smoking and trying to reduce excessive talking because of these limitations on the exam most places will try to schedule these patients first thing in the morning so they're npo overnight and then we can get to them right away in the morning and they can go about their day as normal that doesn't always work out though so always try to get your routine patients done in the morning when possible sometimes you'll have an emergency or a stat patient added on at the end of the day you're just going to do the best that you can one big thing that you want to make sure that patients know is that they can take medications in the morning never skip their medications especially if they're necessary and then we want to be extra careful with our diabetic patients as that fasting can really mess with their blood sugar and we want to make sure that they are safe while they're in our care you may want to have an extra snack or a place for them to rest and eat before they leave your facility as far as setting up the patient on the bed make sure that they are supine to start with when we begin our exam you will be rolling them side to side as you need a pillow is going to be more comfortable for the patient i typically have my patients a little bit flatter because as they roll i don't want them to kind of crunch up in the middle i want them nice and elongated as much as possible however if you get a patient that cannot lay flat a slight incline or extra pillow under the head usually will do the trick in your workbook i have included these scanning tips make sure that you read through them and try them out when you get a chance to do some live scanning one of the bigger things i see with new sonographers is that they forget to roll their patient and to try new windows quite often they're like i can see the liver from here i'm not moving from this spot but in reality you might actually be able to see your anatomy from a different window with a breath in with the patient rolled so always try your different windows try your different techniques and then go with the one that gives you the most diagnostic image also remember to adjust every image do not just set your machine and forget about it change your gain change your focus and change your depth as needed for the images that you're taking on this slide i do have listed for you basic liver images that you will want to take remember that every school every facility is going to have their own protocol and images that they require is almost 100 based on facility preference what images are required to build to insurance and what the aium has suggested as basic liver images at minimum you will want to make sure that you are taking these 14 images of the liver as they will take you through lateral to medial and superior to inferior showing that you have evaluated the entire liver you can kind of think of your protocol images as the train stops but you know that the train didn't just jump from one stop to the next but it had to travel down the tracks through the countryside to get to the next stop and that's exactly what you're going to do as well look at your surroundings look at the parenchyma look at the countryside and then you're going to stop at the station and pick up the image to show that you came from a certain place and made it to your next stop if you come across pathology you're definitely going to add more pictures into your protocol and on top of that you can just add more pictures if you're seeing different things that you want to indicate and show to the reading provider and that brings us to the end of our liver lecture covering anatomy physiology and normal ultrasound appearance i know that was a lot of information the liver is one of the bigger more complex organs that we image as sonographers and there's just a lot to talk about with it so with that make sure that you go through your workbook activities and go through your nerd check questions there are a lot of them in the workbook again those are just open-ended study questions that you can use to kind of guide you through the material and double check your recall on the information