all right everybody Welcome to day two my name is Dave nagger and I'm a chest radiologist at UCSF we're going to start off the day with the bread and butter of Chester Radiology pulmonary nodules and the reason I put together this talk is because pulmonary nodules are actually pretty variable right every one of these is a nodule and I'm fear that sometimes we just say oh they're nonspecific could be bad could be okay so how can we be helpful how do we become more specific the path I'm going to go through is to first we can find definitely benign features then they don't need followup if that's not there we can give follow-up recommendations as Radiologists and if they're not small enough to fall into our follow-up recommendations then we can assess how bad is this nodule because then as a collaborative team we can figure out what should be done next so that's what we're going to go through definitely benign features followup of small nodules and then how we can assess the risk including pet so what are our definitely benign features people usually say three I'm going to have four here there's benign calcification fat long-term stability we'll talk about what that means and then one that I sort of realized is true small nodules and young people also are benign so let's go through each one of those benign calcifications here's the classic one of totally calcified granuloma essentially calcified nodules usually also from granulous disease concentric or the classic popcorn of a hamartoma and I'll give you a tip that thins can really help here with the small nodules so for example on this medium thickness slice I don't really know if this one's calcified but on thins it's pretty clearly calcified on the soft tissue Windows there so what are the other calcifications then the stippled or small calcifications that's a indeterminant eccentric very irregular calcifications and then this last sort of odd category which is if the calcification is Central and maybe you'd be okay with it if it's in a really ugly looking nodule then that ugly looking nodule Park trumps all right our second benign feature is fat here's a nice nodule soft tissue windows I have no idea what it is I'm sorry in Long windows but on soft tissue Windows you sort of get a sense that it's fat we could actually measure it as long as it is fat density that is a benign feature next is long-term stability so the classic definition here is two years for solid nodules the problem problem and where everything is in flux right now is ground glass nodules we have a whole talk on this together later in the morning but how long you have to follow these up is not totally clear it's probably at least three years or more and the reason why they say or more is because late sometimes these nodules can really get bad here's two ground glass nodules we saw at our institution and each exploded into an invasive adnoc carcinoma but at eight years so how long do these really need to be followed still being worked out and then the last one that I sort of add is small nodules and young patients that requires some definition so small we'll just say whatever is in the fler society guidelines so 8 millimeters are smaller and then young is defined as my age or younger I'm joking I wish that were true but it's not so it's 35 and I got that number from the Flasher Society guid lines it's actually at the bottom saying that this does not apply to young people okay so if it is not one of those features I mean those who are get out of jail free card then we can provide followup of it's small that's the next way we're helpful so the way we do that is with this big table um you've probably all seen this it's classic it's now 10 years old this year um and this is our follow-up recommendation table there's lots and lots of words and lots of numbers so I can't memorize this so I have a simplified version and this I can actually get into my brain I just think about it low risk and high risk so in low risk four millimeters and smaller no followup at all if you're at a mediumsized nodule and low risk you just get one followup at a year and a large nodule is two follow-ups in two years right so roughly at the oneyear Mark there's actually ranges but I just find that really hard to uh memorize so this is how I do it and then if it's a highrisk patient all these recommendations move up one okay so the smallest nodule now does need to be followed but it's just the one followup at a year medium nodules now get the two follow-ups in two years so roughly one a year and the biggest nodules now get this three CTS in two years and I just memorize that that first CT is in the 3 to six month range and then if you look at those guidelines what does it say we should do if it's over 8 millimeters it says okay well you have any one of these four options so let's see if I can break them down how many people are doing Dynamic contrast enhanced CT nobody never done so this was all the rage 10 years ago which is why it's in our official recommendations and Nobody Does it um and particularly now with concerns of radiation uh it's just not going to happen so if we have three options we have the most conservative which is just follow it like the 7 mm nodules we can do pet which is still fairly conservative but has a lot of radiation it's pretty costly or we can do something invasive so we have this range from the same thing we do with a small nodule down to an invasive test so that's where we can come in because we can help assess how bad is this nodule and in consultation with the other doctors and the patient often then figure out what the best plan is for these bigger nodules so let's talk about how we can help assess we'll do it with CT and pet by CT the first criteria we'll talk about is size now we're concerned about these 8 millimeters and bigger but still I thought it'd be interesting to say how risky really are these nodules you know we just went through a table talking about falling up four to 7 mm what is the chance that these things turn out to be cancer it's like nothing right that's what we're doing all this fall that whole table is about 1% so that's something I keep at the back of my mind risk here pretty low once it starts getting bigger though the risk does actually start going up quite a bit and you can see the 2 cm Mark it's really risky so what should we be thinking about with these nodules that middle nodule that's 1.3 cm it's sort of indeterminate that turned out to be a scam Miss that little tiny dot we should assume is benign you know it get a follow-up based on recommendations turn out that was actually cancer there's always exceptions I'll tell you when there are exceptions it does tend to be Mets in my experience the little tiny dots that uh grow and then that big huge one we should assume that's cancer of course there are exceptions that one was TB but that's how we're supposed to be thinking until we're proven wrong the next feature is growth and the key here is that slow or moderate continued growth is really concerning so this is only a 6 mm nodule that is not that concerning except that 6 months prior it was smaller it was still smaller a year prior two years even tinier this thing has done nothing but grown that is now concerning it turned out to be the smallest Ado you're ever going to find or this this one this is a very scary looking nodule that just speculated I mean that is screaming cancer except 3 months earlier there is nothing there that is too fast of a growth to be in the normal range of cancers I mean it technically could be it deserves a followup but this is now less concerning than I thought we gave them the benefit of the doubt and it started going away so it was an infection I want to talk about with the growth the opposite a very slight decrease in size it turns out that if a nodule gets slightly smaller that's really helpful right it's usually benign small decreases transiently do happen with cancer even if not treated okay so if you have a single followup and a slight decrease in size you can say that that's helpful suggests it's not malignancy but still needs followup so let me give you an example this patient had lots of cysts and empyema and that small nodule right there and then eventually it grew and that looked it was over a Time course it looked like cancer they asked for a biopsy we said sure no problem put them in the canc in the scanner a couple weeks later and it got smaller no treatment so we canceled the biopsy that suggests it's not malignancy because it got smaller by itself but the person needs a followup they got a follow up and it continued to grow again then it was finally biopsied and it was proven to be an Ado the whole time no treatment so it happens you can't let these people fall off the face of the planet okay next characteristic is the border so speculation here is of course the bad characteristic if you're speculated High chance of being cancer is some combination of causing fibrosis or the cancer spreading along the lymphatics the problem is as I showed with that big example granul ominous disease can do it too but that is a concerning feature the next is cavitation so the classic teaching here is cavitation with a really thin wall tends to be benign so here it's in the 90s per chance really thick walled nodules of cavitation tend to be malignant somewhere in the 80s per chance what that means is there's somewhere in the middle that's not so a okay so this is the unhelpful thickness of the wall and I'll tell you the extremes are even more true so if you have a tiny tiny thin wall like here it's a millimeter the chance of that being benign is exceedingly High close to 100% for example this one was coxy in the rare cases that it is actually cancer it does tend to be gine cancers like this uterine that was a met but it's very uncommon to be like that the next feature is density this is the classic pimp question in all of chest Radiology if you have two different patients and they have nodules about the same size and one is solid and one is ground glass who is more likely to have a neoplastic nodule what do you think so it's the ground glass right counterintuitive so the risk is actually much higher for ground glass uh probably greater than 50% and the reason is that it's counterintuitive is there are so many more solid pulmon nodules in the world that the really bad ones that we've seen that turn into cancers tend to be solid we see more solid ones in these smaller number of ground glass nodules in the world though more of them are these very indolent level adenocarcinomas and we're going to talk about those later in the morning morning so when you see ground glass like this here in a patient with lots of empyema the risk of neoplasma is actually surprisingly high so they cannot be ignored the good thing is these ones tend to be less aggressive so these are the ones that won't really show up on pet they grow slowly and that's why sometimes we follow them and the prognosis is not so bad so these tend not to be the cancers that are horrible uh and then really destroy people's lives but but uh they still need to be followed because they're risky and they're less smoking related all right and the last part is how can we use pet to really assess risk and I noticed as I try to put this together that this is the part of pet reading that I find has tons and tons of artifacts and that they actually affect how I read the pet for nodle cases in fact more than any other use for pet so I thought we would run through a couple only clinically relevant artifacts that can help us assess pet so here are the four but I'm just going to go through them the first is misregistration so the CT and the pet are acquired at different times here you can see in that person's head the images don't always overlap and that's because the person moved their head well fine who cares about the head nothing important up there we're all about the chest the problem in the chest is the diaphragm moves as well so you can get lots of misregistration around there so for example this patient had a known metastasis in the liver and in our follow-up pet we see this it looks like a palmary nodule so there it is in the chest we go to find it and there is no nodule I even put the overlay I could not find the nodule where is it down here in the liver it's actually another liver met so misregistration around the diaphragm can happen it's very common so that means is if we actually found the nodule in the liver first the metabolism is not going to be there you actually have to look somewhere else in this case higher to find out that it was hyper metabolic what that also means is that nodule or I'm sorry that liver metastasis that looks like it's in the dome that actually was much lower at liver it's not even in the dome so things really can move around in that area and be misregistered so the take on point is look high and low and it can even fake you out to look like it's in the lung or the liver if it's the opposite the next uh artifact that's clinically relevant it's attenuation correction errors so the CT actually has two purposes here one is so you can actually find the lesions that are uh glowing on pet but also it corrects the picture so what I mean by that this is actually what a pet looks like when it comes off the scanner lots of activ up here in the head because the saler glands and the Brain not much blocking the photons whereas the pelvis for example lots of muscles and Bones everything's blocked so you can't really read that so what does a scanner do it looks at the CT figures out how much soft tissue and bone is here and there Etc and then back calculates and says this must be how much FDD is actually distributed throughout the body that is actually the Pet Scan that's red and you see in packs and it's overlaid over CT so that's fine when things work well so for example lesions in the lung and the liver notice that you can't actually tell much of a difference between those two organs an uncorrected pet this the scanner actually needs to go to the CT and figure out where the lung is which is low density where's the liver which is high density and then it corrects that entire region to give you the right answer at the end and that's fine unless the person's diaphragm moved a lot between the two then it's going to correct assuming that the lung volume is this big or that big and it can be wrong and then you'll get the wrong correction so the take on point here and it's you know you can sort of play it in your head it actually takes a couple minutes to figure out the math but the really the the summary here is near the diaphragm the SUVs can be wrong and if you see misregistration on the pet and the CT of the diaphragm probably the SUVs are incorrect in that region the next is motion this is the same patient inspiration expiration the exact same day so you can imagine if a nodule is there that's a lot of motion and the problem is on pet we're actually taking the picture while they're breathing so if they breathe that much on pet it's going to create this big blurry hot spot so the motion particularly around the diaphragm will blur out our nodules and then usually make the SUV really low and then the last sort of artifact I want to talk about was size so if these seven nodules that say we inside a patient's lung when we actually take the Pet Scan they start getting bigger and blurrier and that's fine in the big nodules right we can still see how hot the center is but the nodule gets smaller and smaller and smaller it starts getting blurred out and by the time we get to Tiny nodules we might not even see them so the take home is Pets not so great with small things so small lesions tend to be really blurry and the SUVs incorrectly low okay so that was it for the artifacts so what were they we know that we should be looking for them we saw that lots of them really make the measured SUV too low and then here's the key point which we'll talk about in a second accurately saying that a nodule has low activity is where pet is valuable okay so if it's in if it's artifactually low that's not helpful if it is for real low that is when pet helps so if you don't believe in SUV you can say that doubt in your report or sometimes I won't even put the number if I know the number is wrong that I don't measure it okay so let's say that we now assessed if we can actually trust the measurement how do we use it the take the simple version is hot nodules are more risky nodules with no activity are less risky but of course it's more complicated right so where does the pet not work for nodules these ground glass nodules almost never are hot really indolent cancers like this carcinoid in the airway is not and finally nodules that are full of air they are not going to have much metabolism there's not enough cells okay how about the flip when is it incorrectly positive usually it's infections particularly granulous infections and the big problem here is that infections can be screaming hot which is the same category of metabolism as cancers lots of overlap so here is the secret sauce of using pet for nodules when do we start calling it positive and if you look through all the papers people say ah we should compare it to the lung or the medius stum or this or that lots of people actually said we should use a number 2.5 has actually been published a lot so where do I call it positive well it's all about where do you want to be in this little seesaw here should we have a low threshold for calling it which means we won't miss cancers but we're definitely going to start overcalling some or do we want to say no it needs to be a little bit hotter before I call a positive that's going to confirm cancer better but then we're going to start missing cancers that aren't so uh hyper metabolic so which side do we want to be on here's the thing we don't need to confirm cancer well that is what needles are for what we actually can do to be helpful is to take a nodule that otherwise is going to be biopsied or causes anxiety to a patient or needs to be followed really closely if we can take that nodule and suggest with certainty or strong suggestion that it's a lowrisk nodule that they can avoid a biopsy that is how pet is helpful and the only way you do that is if you have a really low threshold so if you're below that low threshold we're pretty sure this is not an aggressive lesion so I use in these cases anything above background and that gives me this test characteristic so how does it work out let's say we have a mediumsized nodule starts at 40% risk in a world without pet what would that get a needle right so let's say that they decide to do a pet if it's positive okay anything above DET uh above background the risk is now higher what are they going to get though the same biopsy they are going to get anyway but with that kind of threshold if it is negative the chance that lesion is now something bad is 2% or less okay that I think is a risk most people are comfortable at least following okay no needles much more reassuring so this this test does work in fact it one of the first approved indications for pet believe it or not the thing is these days with great CTS uh it's just not that helpful at all patients so people do not get pet CS in all nodules and in fact I usually only see them in pie uh these sort of troubleshooting cases where the person's a bad surgical risk and they don't know what to do and everyone's Heming and haing this helps push one direction or another people ask how small can I measure because I told you small nodules are a problem the simple version they say oh a centimeter the real answer is of course it depends so if it's a very aggressive tumor like let's say a melanoma mat and it's in the Apex where things don't move you you can see tiny little nodules they'll glow but if it's a medium or low aggressive tumor and it's near the base and it's moving uh you know we probably won't even see one in a half or 2 cim nodules with activity it just all depends on how big where it is and how much motion okay so in this quick run through of nodules we talked about definitely benign features followup of small nodules and then how to assess bigger nodules uh if that's where we are okay we have our Sam questions so you have them in your booklet uh Sams as you know for people doing are required