greetings let us learn about e endoscopic ultrasound or Ultra sonography so when you want to set up for a case and you want to bring the EU scope you need to ask the endoscopist whether they want to have a radial scope or a linear Scope when you go into the room the storage room to pick up the scope you're looking at the end of the insertion tube to figure out whether it is a radial scope or a linear scope so let us learn about the details of a radial scope for first so this looks the same similar to any other scope except the end of the insertion tube so let us look at it in a little more detail here is the end of the radial e scope or Echo endoscope as you can see here the plane of Imaging of a radial us us scope is perpendicular to the scope axis so this gives a 360° view of the area that you are surveying all the Scopes echoendoscopes uh we place a balloon at the end and uh it is important to make sure that there is there are no air bubbles when you fill that with saline so that is very important from an endoscopy technition point of view when setting up the E scope so we've learned about the radial echoendoscope uh we've learned that it scans perpendicular to the scope axis uh how about a linear echoendoscope again let us look at the end of the insertion tube in a little more detail uh here is the uh a linear e endoscope and when you look at the plane of Imaging uh this is parallel to the scope axis uh unlike the radial one uh which is perpendicular a linear one is parallel to the scope axis so that means you can actually see along the wall but not a 360° view like the radial scope we place a balloon and it is important to make sure when the balloon is filled with the fluid or saline there are no air bubbles in the balloon because air bubbles interfere with the ultrasound examination another feature that is special about the linear equ oscope is its ability to biopsy or take cytology specimens with a needle that is passed through the scope so now that we've learned about the differences between a radial echoendoscope and linear echoendoscope uh let us learn about their role in uh Imaging uh these Scopes are basically used to examine the wall of the GI tract because it these Scopes can tell the layers of the GI tract and they can also image outside the wall especially structures outside the wall whether they are lymph nodes uh blood vessels uh organs adjacent to uh the GI tract like pancreas liver spleen Etc so let us learn a little more taking esophagus as an example here is the esophagus you can see the wall of the esophagus you see the lymph nodes and when the esophagus develops cancer it starts from the mucosa and goes to the goes through the wall and tries to uh extend deeper so as you can see the tumor is going from the mucosa to the sub mucosa to the muscularis propria and to the advantia and as the tumor spreads it can involve the lymphatics and the lymph nodes leading to enlargement of lymph nodes the difference between a non-cancerous lymph node or a benign lymph node versus a cancerous lymph node is the change in the shape of a lymph node from an oval lymph node benign lymph node to a shorty round lymph node that is cancerous lymph node as you can see here so uh when we are evaluating a patient with a sophal cancer we try to figure out the tumor stage that is uh the cancer involving the wall of the esophagus that is the T stage and we also evaluate the involvement of the lymph nodes or the nodal stage or the N stage so we've learned a lot of about esophagal cancer tum stage lymph node stage e is not able to figure out whether there is a very distant metastasis involving the lungs or the liver and unless it is very close to that area especially left lob of liver so the metastatic uh spread to distant organs is evaluated by using either a CAT scan or an MRI or a scan now that we have learned about these aspects uh what is the difference between a regular EGD examination of the esophagus and ultrasound examination of the esophagus when you pass the endoscope uh into the esophagus and you find Cancer all you can do is assess the cancer from the Lumen side and maybe take biopsies I.E you can make a diagnosis of the esophageal cancer with the regular endoscope you cannot see the depth of spread of cancer uh into the wall that is the t- stage you cannot see what is happening outside the esophagus especially the lymph nodes the nodal stage however when you use a radial endoscope or radial e you can scan and figure out the chumo staging that is the spread of the cancer uh through the ples of the esophagus whether the chor is limited to the mucosa sub mucosa muscularis proia advantia lymph nodes and involvement of the iota you can also see the same findings with a linear us again linear us can figure out the Tuma staging and the noal staging one other additional advantage of a linear us scope is the ability to do fine needle aspiration otherwise known as FNA and in this you passin needle and Sample the lymph nodes in other words you do bsy of those lymph nodes and it's important uh to take a the fine needle aspiration from lymph nodes that look cancerous I mean lymph nodes that look round and shorty and one should take the lymph nodes from a normal uh looking uh area of the esophagus the needle should go from a normal looking esophagus if it goes through the cancerous wall of the esophagus then it may give a false positive result so when we are staging the lymph nodes in esophagal cancer we try to find the highest lymph node that is closer to the mouth and that looks cancerous to figure out how far the cancer has spread so that the radiotherapist could use that uh as the top extent of radiation so now we've learned a lot about uh the role of us uh radial us linear us final aspiration we could also use e to evaluate the pancreas either with the help of a radial echoendoscope in which case you can see the pancreas the pancreatic duct uh the normal pancreas surrounding the duct the commonest reason for pancreatic us is to establish the diagnosis of pancreatic cancer in that case we need to use a linear echoendoscope uh pass it into the antrum or the or the dadum and find that cancer under ultrasound and use a needle to do FNA and Sample the pancreatic cancer and thus establishing the diagnosis in addition to establishing the pancreatic cancer diagnosis us could also help in nodal staging and also figure out whether there is superior mric artery Superior mric vein or Celiac artery involvement by the cancer in which case the cancer is not amenable to surgery another reason for use of us is to evaluate uh cystic lesions of the pancreas to figure out whether it is a pseudocyst or a mucinous cystic neoplasm cystoma uh ipmn ilas Etc uh we could also consider taking uh fluid aspiration from the cyst and bses from the cyst wall especially if they look suspicious and nowadays people are exploring the role of either introducing chemo therapy or or also using radio frequency to ablade these small tumors in summary there are lots of indications for us one is to Stage the tumor uh establish the noal spread by taking a biopsy or final aspiration evaluating and treating pancreatic CIS mass and pseudois and in the last few years us guided anastomosis either gastrostomy or hepatic or gastrostomy or vno colostomy uh these are different techniques that are being used uh to create anastomosis and relieve obstruction coming to the complications of uh eus uh one complication is perforation uh this tends to happen when there is an esophagal cancer that looks obstructed and then we try to push this endoscope through uh it can result in perforation it's important to keep in mind the outer diameter of an echoendoscope is much larger than a regular EGD scope and also much stiffer another complication is bleeding and if you do fin needle aspiration of cyst especially pancreatic cyst there is a risk of infection so they need to be pre-treated with antibiotics and in some cases pancreatitis can happen especially after final aspiration or bsy of the pancreas although rare and these procedures are done under sedation one should keep in mind reaction to sedation as another complication I hope this is useful thank you