Let me introduce our next speaker. Unfortunately, Dr. David Brony is not available live, but he was able to pre-record his excellent presentation. In the abdominal imaging, before you do anything, evaluation for the structure, fistula, and epithelium. And then Dr. David Brony is Associate Professor in Medicine in the Mayo Clinic. Yes, Dr. Brony is recording. Please. Hi, I'm Dave Brony, gastroenterologist at the Mayo Clinic in Rochester, Minnesota. It's a great honor to be asked to present on a topic that's near and dear to me, and that's abdominal imaging before endoscopic intervention. I wanted to thank the ASG, Dr. Bo Shen, for the invitation, and to give my sincerest apologies for not being able to attend live to the meeting. I'd be happy to address any questions or concerns as well by email. I do have a few disclosures as far as consulting and research support. Over the next 15 to 20 minutes, what I'd like to do is talk about what is the role of imaging, particularly in the peri-endoscopic period, and really to kind of set what I think is the groundwork for future talks, both today and tomorrow, about why radiologic imaging is potentially very important in your practice. We'll then segue into the different imaging modalities, talk a little bit about nomenclature, and then really come full circle with how to implement or how to use radiologic imaging in your practice prior to endoscopic intervention. I think the first real tenet here about why to consider or why to make the case for imaging prior to endoscopic intervention is the notion that symptoms aren't enough. And I think that everybody who's attending is well aware of this principle, the notion that what we hear and see from patients in the clinic doesn't necessarily match disease activity. This is an older study, but a really nice example of a comparison between the Crohn's Disease Activity Index, a subjective patient-reported or patient-driven scoring system, and the Crohn's Disease Endoscopic Index of Severity, an endoscopic scoring tool. And really the take-home here is absolutely no correlation between what you might be seeing, what you might be hearing in the clinic, and what you may find when you perform the endoscopy. Well how about taking that further? Jennifer Jones looked at various serologic stool markers and again, CDAI, SESCD, another endoscopic scoring system. And really here if you follow the last row and the last column across, you'll see absolutely no correlation again between the endoscopy and the Crohn's Disease Activity Index. So if you agree, that makes a lot of sense. But the next part of that argument then is, well what do I do then if I can't use symptoms to determine the next step or to guide my management? And as gastroenterologists, you know what comes natural to us is endoscopy. But here's the argument that endoscopy is also very important, but imaging adds kind of an additional component to our assessment of these patients. So Neil Samuel published this and I'm going to show two very nice examples of what imaging brings to these patients. This is a patient with active Crohn's disease and what this demonstrates is skipping so-called active disease beyond the terminal ileum. This is a patient who had a normal ileoscopy, but quite clearly this is a patient that had active disease just proximal to where the endoscope was able to interrogate. This is an example and a little bit more unsettling I think to a lot of us. This is an example of so-called intramural disease. This is a patient with Crohn's disease who I think clearly noted by the arrows to all of us who are not radiologists, this is an abnormal segment. There's mural enhancement, there's thickening. You can see in figure B what looks like evidence of comb sign or dilation of the vasorecta. It almost looks like fingers to the comb. This is an abnormal segment of bowel with a normal ileoscopy, had normal images and even had normal biopsies. So the notion that radiologic imaging does add both for more proximal disease, the so-called intramural disease, and may help with the planning and I'll come back to that in a little bit. Now how about penetrating the disease? This is important knowing that what are the risks, what are the contraindications to potential interventions, including dilation of strictures, one of which would be penetrating disease. This was a study that looked at more than 350 consecutive patients undergoing CT neurography at a tertiary care center and found about one in five, 20% had penetrating disease, a new finding in more than 50%. And I included this here because the numbers are almost identical. More than 50% had, or more than 20%, close to 20% had extra intestinal manifestations. Note on CT neurography, a new finding of more than 50%. So again, it's the 20%, 50% you see in the data. Why I think that's important is it's a potential alternate explanation for maybe a patient's symptoms when they come into clinic. Maybe it's another thing to consider prior to endoscopic intervention, prior to assuming that all the symptoms are driven by a stricture. Maybe we need to consider some of the other things that may be driving much of what we see from the patient's symptoms while they're in our clinic. Now, many of us consider this kind of the study that took us down the pathway to enterography. This was by Craig Solem. This was a four-way comparison trial of CT enterography, capsule endoscopy, ileoscopy, and small bowel follow-through. And if you look at sensitivity, one notice that both CT and capsule endoscopy have excellent sensitivity, but really it's the specificity that sets apart enterography, either CT or MR, from some of the other modalities. Now, what's the so-called secret in the sauce, right? What is it about enterography that makes it special? On the left, we see an example of a routine CT, and the contrast we use typically provides or generates a bright lumen on imaging. It certainly can be helpful when looking for things like polypoid lesions, patients that have polyposis, other conditions, but it may not be ideal when looking for active inflammation in patients with Crohn's disease. On the right is an example of CT enterography. We tend to use a neutral or a negative oral contrast agents generating a dark lumen. And why that's important is it allows enhanced mucosal assessments. We can look for mucosal enhancement, some mucosal edema, some of these other findings which might be subtle and might be missed if we have a bright lumen from traditional CT enterography. Now, I wanted to highlight this because I think that this is where we're going. We're going to hear a lot more about this. And this is some of the new oral contrast agents which are taking what are already phenomenal imaging and just pushing them to a whole nother level. This is conventional imaging on the right, and a patient underwent CT enterography with that new contrast agent called Nextrast. Both of these produce phenomenal imaging, but if you really focus on stomach or the duodenum, you notice with the Nextrast just how crisp the wall is of the intestinal tract. You notice how you can see subtle enhancement, really just phenomenal imaging. Similar, this is almost reversed here. We have current CT enterography, our current techniques on the image to your left. On the right here is Nextrast CT enterography. And again, the only thing I wanted to highlight is just how crisp, how we keep pushing the envelope for the detail that we're able to see in these patients as far as inspection of the intestinal wall. What are some of the typical parameters we look for, we talk about when looking for active disease? I think length is certainly an important marker. It's particularly important for planning endoscopic interventions that we'll talk about more here in a minute. We talk about thickness in millimeters. Typically, I think of a rule of three. More than three millimeters on CT or MRE, three millimeters is considered kind of the threshold for defining things as being thick and if it's greater than three millimeters. Three centimeters is considered dilation of the bowel. So rule of three, three millimeters for thickness, three centimeters for pre-stenotic dilatation. We have also examples of what hyper enhancement may look like. And again, the so-called on the right comb sign, which is dilation of the basal rectum. What are the advantages as well as limitations of the various modalities? The resolution may still be slightly higher with CT enterography. I think the main one here is knowing that CT image acquisition is typically two to three minutes. I normally tell patients about five minutes versus 35 to 40 minutes for MR enterography. So many times with the sicker patients, we'll consider CT enterography knowing it can be very difficult for them to tolerate multiple breath holds being inside an MR scanner for up to 40, 45 minutes. Certainly, MR is more expensive, but it also, you avoid any potential concerns about radiation. This is a really nice example of dynamic imaging with MR enterography. If you're able to see my cursor here, this is a segment where there was question about an intestinal stretcher. With dynamic imaging, one can follow the wave of peristalsis, and this was really just a contractive bowel. This was not an intestinal stretcher. How about ultrasound? Well, I certainly think it has a role in our practice for looking for disease activity, possibly response to therapy. It's unclear about predicting response. We avoid radiation. It's low cost. You may be able to do this without oral contrast. I think some of the limitations, however, include the fact that IV contrast is not widely available in the U.S., but more so to me, I think the data for penetrating disease, really mapping out the entire intestinal tract is less robust for ultrasound. For me, if I really want to make sure I have length of disease, I don't have to worry about possibly a loop going into the pelvis that I don't get full visualization. I really want to define, make sure there's not penetrating complications associated with the stretcher. CT and MRE are still the workhorses in my practice for that. How about nomenclature? This is a different part of the talk here, but I wanted to mention it because I think this is very important. If we're going to go forward, we're going to define treatment strategies, whether it's endoscopic, clinical trials, antifibrotic agents. We have to make sure apples are apples, oranges are oranges, that we're talking about the same thing. This was a joint publication by the AGA, the Society of Abdominal Radiology, SARB, which did the first step of this looking at, well, how do you find a fistula? You can see the definitions for sinus tract. Typically, these are a defect that doesn't extend to another organ or the skin. Inflammatory mass has replaced what we used to call a phlegma, and then an abscess, I think as everyone's aware, a fluid collection with rib enhancement, with or without internal air. This is a nice example of a patient with Crohn's, iliitis. The white arrows denote the abnormal segment, and the red arrows highlight an adjacent abscess. You can actually see air within those fluid-filled cavities. Now, the AGA SAR also talked about how we should describe, how we should report, how we should see strictures reported in radiologic interpretations, and that's one where you have luminal narrowing being a stricture without upstream dilation, with mild upstream dilation, with moderate upstream dilation. And again, you see the rule of three, greater than three centimeters and considered dilation. And then a really nice publication by Dr. Ryder, further defining exactly what we're going to call a stricture, and this has become known as the constrict criterion, with a 25% increase wall thickness. There's a little bit of uncertainty about whether that's going to hold true with anastomotic lesions or anastomosis. 50% luminal reduction and preskinotic dilation greater than, again, three centimeters. There's a caveat, however, that many studies going forward will also accept endoscopy unable to pass the colonoscope, and some of them require inability to pass the colonoscope with dilation greater than 2.5 centimeters. So there's a few caveats to the constrict criteria. There's also criteria, and I think this will be important going forward with upcoming trials, looking at various treatment strategies. Well, how do we define response and cross-sectional imaging? Reduction of thickening 50%, improving luminal narrowing by 50%, and a bowel wall diameter less than 2.5 centimeters. Now talking a little bit about stricture types and subtypes, and I think this is a little bit important when thinking about how you're going to endoscopically approach these lesions, which ones should or shouldn't be interrogated and addressed endoscopically. Typically, those with the short waist, diaphragm-like, often we see those words, we see that appearance where we tend to think more NSAID-related strictures. Long typically is defined as greater than 4.5 centimeters, and what's become new in the last couple of years is typically, at least in many imaging reports, including studies, if you have multiple strictures but they're separated by less than three centimeters, that's now being defined as being the same stricture. So that's a little bit of nomenclature, but I think it's important to keep in mind. These may be single or multifocal, and we'll talk a little bit more, we're realizing kind of these different subtypes, extreme overlap between inflammatory fibrotic, or what may have smooth muscle hypertrophy, and so-called mixed lesions, which actually have components of both. And there's ongoing studies looking at how we can better characterize the pathologic features, possibly with delayed enhancement, MR, MAG transfer, ultrasound elastography. And then I think some other important features that imaging can tell us when we're planning how to address these lesions is whether or not the area is angulated fixed. Certainly, we want to know if there's associated fistula or penetrating disease. This is a nice example of the left of a patient who has multifocal iliitis. You can see lower down, there's areas of enhancement, collapsed lumen, with high-grade obstruction, see the dilated loops. On the right, we see patients with chronic obstruction, we see a large burden of feces, a so-called feces sign. And then the lower part of the images, we'll see examples of active Crohn's iliitis, and the blue highlights an example of an enterolith. So more good examples of a complex enteroenteric fistula noted by the green arrows, as well as a penetrating ileal ulcer by the red arrow. A lot of times to pick up on the enteroenteric fistulas, look for areas of tethering. It almost looks like a star lesion, where the bowel looks almost stuck together. If you see that, the so-called star sign really becomes suspicious that there might be an enteroenteric fistula. This is another nice example of various subtypes. All the way to the left, you see this enhancing, angulated lesion. The middle image, it almost looks like a dumbbell. We see kind of a short-waisted stricture. There's really not that much or any enhancement there. And on the right, you see this long, thickened segment of bowel. Now, talking further about various phenotypes, when we think about what are features of inflammatory components, a mural enhancement noted with the red arrow. We have, again, coming back to the comb sign with the yellow arrow. And they're layered enhancement on delayed imaging. We tend to think that's more of this mixed inflammatory fibrostenotics. Well, how about ones that really lack a lot of inflammatory signature features? All the way to the left, you'll see, and it looks dark on T2. We don't see a lot of enhancement in this thickened area of bowel. Over here, we see this homogenous enhancement on the delayed images. And some of the tip-offs you may see on portal or delayed, you see this nodularity, this irregularity to the external surface or the cirrhosis surface without the so-called comb sign, without dilated vasorecta. And those all might be features of more fibrostenotic disease. So getting back, kind of coming full circle about imaging pre- and intraprocedural when talking about endoscopic interventions. Often, we think about MR in patients, certainly, who are young, who need serial imaging. CT or MR have the ability to give us a roadmap, how to best approach, whether it's integrate, retrograde, are there multiple lesions, what tools are needed. And that's also very helpful when talking to the patients, getting consent about exactly what we expect we might need to do and what the risk is going to be. It helps us to find really high-risk patients who have multiple strictures in a short segment, have the so-called long, greater than four to five centimeter strictures, or patients who have deep ulcerations and penetrating disease. Predict likelihood of response to medical therapy. I think there's still some question about that. And not to be forgotten, even though it's uncommon, but assess for features that suggest malignancy within small bowel strictures. Intraprocedural imaging, I'd like to have fluoroscopy available when I'm addressing the angulated area, whether that's pylorus, duodenum, anastomosis, or elastical valve. My preference is for shorter balloons with the guide wire. I'd like to advance the wire from the balloon to try and control the tip as much as possible. And there's some who prefer contrast in the balloon to look for elimination of the waves. In summary, I hope over the last 10 to 15 minutes, we've really highlighted the critical role and the value that cross-sectional imaging brings to your practice when planning endoscopic interventions. Please keep in mind the high-risk features, multiple strictures in the short segment, deep ulcerations, increased complications with long strictures greater than four to five centimeters. And noting that if you look at the guidelines, the recommendation to avoid endoscopic balloon dilation if there's penetrating disease associated with the strictured segment. And again, that can be difficult to diagnose or identify intraprocedurally. So again, one of the critical roles that imaging can provide for gastroenterologists. With that, I thank you for your time. And I welcome any questions if you'd like to send them to me. And I hope you really enjoy what I'm sure is an excellent course. Thank you again.

abdominal imaging

endoscopic intervention

disease activity

radiologic imaging

imaging modalities

cross-sectional imaging