So, the last speaker, who's my mentor, Dr. Linda Lee, she's the medical director of endoscopy at Brigham and Women's Hospital in Boston, and she's the queen of EUS, so she's going to be speaking on basically all the pearls, tips, and tricks on how to do diagnostic EUS. You heard a wonderful talk from Amy Tiberk already on interventional EUS, it's as important to be good at diagnostic EUS. Thank you, Dr. Lee. Thank you so much, Sai, and thank you and Mo again for inviting me to be part of this fun course this weekend. You know, so diagnostic EUS is not nearly as sexy as putting lambs everywhere, but unlike ERCP, diagnostic EUS is not dead and it's not going anywhere, so it's vitally important to know how to do diagnostic EUS well, and in fact, not all of us do it well, because when you look at inter-observer variability, even amongst expert endoscenographers, it's not great, so important to know how to do this well. I will talk about visualizing structures, sampling, artifacts, and a quick word of adverse events, of which there really are not that much with diagnostic EUS. So stomach, liver, right, so you can obviously see the liver well, gastropathic ligament here, here's the pancreas tucked behind the stomach and into the C-curve or the duodenum spleen you don't see there, but obviously is over there. And I'm going to first talk about looking at the liver, which is usually the easiest to find once you're in the stomach, usually start at about 50 centimeters and then torque with your right hand, clockwise, counterclockwise, just pulling back gradually until you see the liver. I like to find the corner of the liver, this triangular corner, and then I just torque through the depth of it, clockwise, counterclockwise, pulling back a centimeter at a time until I've seen the entire left lobe of the liver as best as I can. When I'm demonstrating here, notice how it's so dark on the far side of the liver, you can't see, right? And so I'm, and also there's actually air in my balloon. But the reason I'm demonstrating this to you is it's also very important for you to know how to use your EUS processor, right? And I'm going to ask you guys, so in order to see further away, what do you do with your frequency? What was that? Go down. Exactly. So the higher the frequency, the higher the depth of penetration, but decrease resolution. I don't need great resolution for the liver, I just need better depth of penetration, so totally reasonable to decrease the frequency. But if you're doing esophageal cancer staging of like a small lesion, there you want to turn up the frequency because you really want to get good resolution there. So continuing with this video, again, I'm just kind of slowly pulling back, torquing. These are big movements. Times when you do big movements in EUS and times where you do small. This is big. I reach the other corner of the liver, right next to the heart. And at this point is when I torque about 180 degrees to find the, first you're going to see the hepatic vein outflow tract. And then you'll see the aorta right here. And then you just gently push in, torquing a little bit. And you'll see the first branch is your celiac artery, followed by the SMA below. So now, finding the pancreas. What are some ways to find the pancreas? Oh, okay. All right. You can do that. Yeah. Trace the portal vein. Trace the portal vein, okay. You guys like vessels, huh? So the ways that I like to think about doing it is you follow the SMA and you'll get to the pancreas. Also, the fattest part of the liver, torque 180 degrees, you'll find the pancreas. If you're in the duodenum, then you can slowly pull back. This is a little harder technique, but eventually you should master the technique of slowly pulling back from the duodenum, keeping your eye on the pancreas so you can see the rest of it. So this is the same video, continuation of the video I showed you before, where here's the aorta, celiac artery, and then here's the SMA right below that. I'm going to push the scope in a little big knob away and boom, right there is the pancreas. Very easy to find the pancreas that way. And then this is the fattest part of the liver, right? And so again, from here, torque about 180 degrees, sometimes deflect the big knob a little bit away, and then you can already see some pancreas over here. And again, boom, right there, pancreas. We're seeing kind of the body tail because you see the kidney there. And you know, it's not just about how you handle the scope, but it's also about recognizing the structures, right? Because I'll tell you, you know, my fellow looking for the pancreas, I've seen it several times and he's, you know, clearly hasn't seen it because he keeps like looking around. So you have to kind of get used to, right, what normal structures look like so you can identify. Now, tail of the pancreas. So here is some pancreas right there, splenic artery, splenic vein. And I like to, again, this is magnifying in, right, so you can get a closer view of the pancreas. You don't need, you don't want to be so far away. Here's the tail, the duct. We know we're looking at part of the tail because we see the kidney there. And you see some hyperechoic duct wall in the tail. You haven't seen the entire tail until you've seen the spleen as well. And it's important, the technique is you're pulling back slowly, twerking clockwise and following the PD typically. And here's more tail of the pancreas. And then I think in a second, you're going to see some of the spleen starting to come in view right there. And here's tail of the pancreas. I'm twerking all the way through it, right? You don't just want to be like, oh, boom, I saw it. That's fine. You want to get a nice view, especially if you're doing screening, right, in high risk pancreatic cancer patients that we do a lot of, twerk all the way through the depth of the pancreas clockwise and then counterclockwise, pushing the scope in to go back the other way to start seeing more upstream tail. And then I keep pushing the scope in, twerking counterclockwise to see the body of the pancreas now. And you see the splenic vessels underneath. And then you're going to see here's the pancreas duct right there. Now which part of the pancreas am I looking at right now in this view? Neck. Exactly. Because the PD is diving down. So it's a good clue that you're looking at the neck of the pancreas there. And then, let's see, when this, oh, shoot, I wanted to stop right there. Let me try to go back. Just around here and see if I can stop because I want to show you guys one other thing about the, hmm. Okay, there we go. So the PD, again, diving down. And there we go. Okay. All right. So this is actually, I think I moved past the previous video, but what I'm going to talk about right now, if I can pause it a little here and rewind a little, ah, here we go. So what are we seeing here? What is this? Oh, well, um, no, but, uh, what, what are we, this is pancreas though. So what is it that we're seeing here? Concentrating on parenchyma. Yeah, so what's that called, do you all know? That's the ventral-dorsal split, okay? And the ventral part of the pancreas typically looks darker, more hypoechoic than the dorsal part. So this is very important to recognize because you don't want to call this a mass, okay? This is normal. And then if the PD is crossing the ventral-dorsal split, what does the patient not have? Exactly, right? So very important to understand that. And then here we saw the splenic, I'm sorry, the portal, splenic-portal confluence. And you can actually, I was able to actually follow the PD from sitting in the stomach all the way almost to the ampulla, and you see the bile duct there as well. All right, so now we talked about this already, the interplay between frequency, resolution, and depth of penetration, very important to remember. And now let's look at the head of the pancreas, which we typically see from the duodenal bulb. Here you see the portal vein parallel to it, you see the common bile duct. And then here's some pancreatic parenchyma, here's pancreatic duct right there. And then to look at the, this is again pancreatic parenchyma right here, looking pretty unremarkable. And at this, oh, actually, what is, what vessel is this? Nope, not SMV. This is SMV. Yeah, this is SMV, this is splenic, meets to form the portal vein, exactly. So this is splenic-portal confluence, so-called whale tail sign, because it looks like the tail of a whale there, classic appearance there. And then now, what you can also do, if you want to look at the ampulla, you can kind of slowly push the scope in carefully, torque a little bit, follow the bile duct and the pancreatic duct towards the ampulla. And I think we'll see that, let me move fast forward through this, ah, there we go. So this is the bile duct, there's the pancreatic duct, they're coming together in the region of the ampulla there. And the other way to find the ampulla is from the second portion of the duodenum, where you pull back slowly, find the pancreatic parenchyma, here's the uncinnate here, and then you're usually torquing clockwise to find the uncinnate, and then counterclockwise to find the PD right there, and then the bile duct right above. And then here we go, that's the PD entering into the duodenal wall there, this is the duodenal wall, the muscular is propria, and above it is the bile duct, so that's the other way to look at the ampulla. And so for the sake of time, because we've talked about it, I'm going to skip over that. Now this is an image of what kind of EUS scope? Exactly. I know most of us don't use a radial when we're doing pancreatic work, because usually we're biopsying or doing something. But the radial scope is a beautiful way to look at the pancreas, this is obviously linear. And let me just play this quick video of the radial view of the pancreas here. So you see the parenchyma there, right, the PD there, this is the tail, and then you'll see going back the other way, this is a kidney actually underneath there, this is the tail of the pancreas, and now you see this beautiful image of the pancreas, it's ducked all the way down to the neck, like in one view, right, so you can get really beautiful imaging. This radial image again, I just want to demonstrate how this is the liver, and then this is pancreas underneath, which is why again, that technique of finding the fat part of the liver and torquing a hundred degrees lets you find the pancreas, so liver, and then down below right there is pancreas. And again, you can get this beautiful view of the pancreas using a radial scope, which you know, totally fine to use if you're not planning on biopsying or anything. If you are going to biopsy, obviously you need a linear scope, and here's the mass here in the tail of the pancreas. Again, you need to understand how to manipulate the image quality to make it better for you. I'm magnifying in, and then I also changed the frequency. I decreased the frequency so I had increased depth of penetration so I could see the entire mass better. And then as far as the technique of biopsying, you usually advance a little bit of sheath out, which you'll see coming out at about five o'clock. And then once you see a little bit of sheath coming out, lock the sheath in place. Here's the sheath, and then you'll see me advancing the needle out slowly. And then once the needle is out, then usually you have to pull the silate back a little bit to sharpen these needles, and then Doppler, of course, and quick jab in. And then the technique of doing the biopsy, I like to traverse through the entire lesion. Quick jab in, slow pull back is what I typically do, and fanning. So you're going to see me fanning here, which you can do by changing your big knob and or your elevator. And it's important to fan because, you know, especially in pancreatic masses, the center can be necrotic, the edge can have desmoplastic reaction, so it's important to try to sample different parts of the lesion. Now, optimizing technique, anesthesia, it appears to increase diagnostic yield. I think most of us are doing these cases with anesthesia nowadays. We talked about this at length, how important it is to review radiology imaging. And it can also, especially for weird things in weird areas, I always go to my radiologist and say, where should my scope be so I can see this lymph node or whatever. And then the technique, a million different needles, FNA versus FMB, fewer passes overall needed with FMB. Diagnostic yield doesn't seem all that different except for subepithelial lesions, FMB is superior. Probably for pancreatic masses as well, some studies suggest that. And certainly increased adequacy of the histologic sample because you see this beautiful core from a fine needle biopsy compared to this amorphous collection of cells with cytology. Bigger, not necessarily better with FNA needle, 22 and 25 seem to have similar diagnostic yield. 19 gauge, better core sample as you might imagine, but similar diagnostic yield. Some people talk about using 25 gauge in the unsnip or head because it may be harder to push out bigger needles in that area because you have loops in the scope and everything. And then 22 elsewhere. If you don't have FMB needle, you can think about using a 19 gauge FNA. And then certainly for lymph nodes, some people talk about using a 25 gauge because they feel there's maybe less blood contamination. I use 22 for most everything. But again, for subepithelial lesions, you really need to use an FMB needle or perhaps a 19 gauge FNA if you don't have that. The technique of you don't, stylet doesn't matter, suction, you probably should apply some kind of suction. The type of suction doesn't really seem to matter. You can use vacuum, capillary pull, you know, the suction pulling the stylet, slow pull technique or wet suction. Number of actuations, probably about 20. Fanning, absolutely yes. Rows, we did one of the studies comparing 7-FNA with no rows, two rows and found 7-FNA was not inferior. But of course, nowadays, we're mainly using FMB. Similar results with FMB. For FMB, about two or three passes. Mows, you should absolutely do. That's just macroscopic on-site evaluation. You're looking for tan tissue, not the red. And if the needle doesn't come out, don't force it out of the scope because you'll damage the scope. You might bend the needle. You may need to unlock your knobs, make sure the elevator is open. You might even need to get out of position in order to get the needle come out. There's a newer cook needle that's made of chromium cobalt that seems actually easier to come out. So just think about all those things. Stent, plastic stents are fine if you're trying to biopsy pancreatic masses, but metal stents not as fine because of all the shadowing it causes, right? So if at all possible, try to biopsy pancreatic masses before metal stent goes in. One word about post-surgical anatomy, obviously, if somebody was roomwide gastric bypass, you're not going to be able to see the head of the pancreas. If there's a lesion there, you can't do it unless you're doing some kind of gait or edge procedure or something like that to access the excluded stomach. And then obviously, do EGD in these patients so you know what the anatomy is. And then alert the patient. You may not be able to see everything. I'm going to skip over this for the sake of time. Now artifacts, I think, are important to understand because these are echoes seen on the screen that actually don't represent real structure, and it can help you identify things. And what is this? What kind of artifact are we seeing here? Excellent. The reason is because this is a calcified stone in the gallbladder where most of the sound waves are reflecting back to the transducer. So there's very few sound waves going beyond the stone, so hence black or shadowing behind the stone. So this helps you identify that this is a calcified stone compared to this sludge right next to it that's not calcified and not shadowing. Now this I'm going to show you. This is pancreas, body of the pancreas, the pancreatic duct. And then what is this right here that we're seeing? Yeah, looks like a cyst in the pancreas. Notice how bright it is on the opposite side of the cyst? That's called through transmission artifact. That's because this is the opposite of what's happening with shadowing. Most of the sound waves actually go through, are absorbed by fluid. And then there's a lot of sound waves bouncing off on the opposite tissue, so that's why it looks brighter here. And this can help you. If you see this, if you're not sure if something is fluid-filled, but you see this, this helps you to say, okay, this is a fluid-filled structure. Now this is side lobe artifact. This is not sludge in the gallbladder. This is because ideally what you want to be doing when you're imaging is have the transducer perpendicular to whatever you're imaging, not tangential. When you do tangential imaging, you can get these weird artifacts here. And the way you know these are artifacts is like with most of diagnostic EOS, go over the area again and again, like in different positions. If you only see this like once, you know it's an artifact, but if you keep seeing it over and over again, then you start thinking that it's a real lesion. And then this is just a scope, again, not having perpendicular imaging. This is the scope, radial scope, not centered in the lumen and kind of pulling on one side of the lumen. And so therefore the wall layers appear artificially thickened here when they're not. So again, important to center yourself and have good perpendicular imaging. You can, this is particularly for the bile duct, you can compress it, right, if your scope is really pushing up against and pushing the bile duct, you can make it look artificially small. So you want to deflect the tip away so you can get a better view of it. And then what is this? What are these artifacts? Air. Air, exactly. Air is the enemy of EOS. And oftentimes I'll do my linear EOS even without a balloon. With radial, you really should use a balloon, but now adverse events, again, overall very safe, except if you're using microbiopsy forceps or pancreatic cysts, which I'm not going to go into in detail here, but pancreatitis can happen one to 3% of the time. How do you minimize adverse events? Traverse minimal amount of normal pancreas tissue to get to the lesion. You don't want to go through like three, four centimeters of normal pancreas to get to something. Doppler, of course, before you stick the needle in, be sure you're not going through bile duct or gallbladder. This is different from therapeutic EOS. You do not want to do that because you will give the patient a bile leak. And then I would recommend setting how far the needle is going to extend, you know, lock that knob in place because you guys just aren't very experienced at being able to control how far the needle is going to come out. Always see the tip of the needle before you start doing anything, right? You stick it in, you can't see it, pull it back a little and look for it, torque, look for it. And while you're doing the actuations, if you can't see the tip, again, stop, look for it and then continue. You should stop if there's blood in the vacuum syringe, if that's what you're using for suction. I'll tell my nurse and tech to be looking at it because I'm usually looking at the EOS image. And for pancreas cyst, we usually say to try to completely aspirate in one pass and maybe use antibiotics. I say maybe because there's more recent studies suggesting it may be safe not to use antibiotics. Now this is a cyst with an, you know, FNA needle in it. What is this? Yeah, intracystic hemorrhage can happen. Don't worry. Most of the times, almost all the time, there's no, there's no consequence. I would pull the needle out. I would sit there and watch, Doppler watch, make sure it's not like ballooning bigger and bigger. I would give antibiotics in this situation because blood is a good medium. But almost never does this actually cause significant clinical issues. So take-home points, practice a systematic approach to evaluating the pancreatic ovulary system. By systematic, I mean, people talk about stations. You know, I don't really care about the stations. I just do it systematically. Whether you start from the D2, pull back, or whether you start from the stomach and go down the D2. Optimize your biopsy technique by carefully looking at radiology, FMB needles, what I recommend almost all the time with suction, fanning, and Mohs. Be aware of artifacts, although they can help you diagnosing, and use careful technique to minimize adverse events. So thank you very much.

endoscopic ultrasound

diagnostic EUS

inter-observer variability

fine needle biopsy

anatomical visualization

biopsy techniques