I thought we finish up with a little general GI imaging with large bowel obstruction, and then talk a little bit about diverticulitis and colon mass. There we go. No disclosures. Objectives, we'll discuss a case, and then after the case, we'll talk a little bit about large bowel obstruction and the clinical aspects of diverticulitis and colon cancer as well. These will be very brief. As we think about radiology, in order to understand imaging, the reports, and if you read images, we really need to understand the clinical context that we're working in, as was well pointed out in the first two case studies. And then we'll end with about five or six images and see if we can learn some of the basics of some imaging of general GI and large bowel obstruction, diverticulitis, and colon cancer. First question, I guess I'd like to be 100% person like Vivek and Samit, so the first question is, colon cancer is the most common cause of large bowel obstruction, true or false? See if you can make me 100% with this one. The answer is true, and we'll come back around to discuss that in a moment. Next question, please. Bindings on CT of the abdomen and pelvis consistent with acute diverticulitis could include which of the following? Bowel wall thickening at the site of the inflammation, appearance of a soft tissue density, fat stranding or inflammation of the fat surrounding the area of diverticulitis, abscess, or all of the above? Very good. The answer is E. You could see any of these or a combination of these in diverticulitis. Let's take a brief look at a brief case. The patient is a 72-year-old male who presents to the ER with a four to five-day history of abdominal bloating, abdominal pain, and no bowel movement for three days. He denies nausea, vomiting, fever, bleeding, or weight loss. He's had little to no appetite. He recalls colonoscopy about eight years ago. There was minimal sigmoid diverticulosis, but no other findings. In the ER, labs and imaging tests were ordered. At least my brief thought as I look at this is some type of obstruction and maybe based on the symptoms, a large bowel obstruction. Let's take a look at some pearls on large bowel obstruction. Seventy-five percent of large bowel obstructions occur at or distal to the transverse colon, so certainly areas where we see colon cancers and the majority of colon cancers as well as diverticulitis. Malignancy causes a large bowel obstruction in 60 percent of the cases, and the overwhelming cause of the malignancy is colon cancer. So colon cancer is the most common cause of large bowel obstruction. Some benign causes are valvulose, which makes up the largest portion of non-malignant obstruction. That's 15 to 20 percent, and you can see a sigmoid valvulose or a sequel valvulose. You can see hernias, including internal hernias, adhesions, and benign strictures, whether these are from perhaps radiation or recurrent diverticulitis leading to a chronic stricture. Some other pearls. Average duration of symptoms is about five days, so this person had symptoms for three to five days. Bloating, abdominal pain, and obstipation. The patient had these symptoms, and on physical exam we can see abdominal distension, abdominal tenderness, and tympani or percussion. So some clinical pearls for diverticulitis. The pain tends to be sudden and onset. Left lower quadrant is typically the location. The pain is typically constant, and we usually see associated change in bowel habits. Constipation, diarrhea, either one can occur, and although it doesn't happen in the majority of patients, we can see fever. This is, I think, a really important set of symptoms to think about. 10 to 15 percent of patients with diverticulitis will have urinary urgency, frequency, or dysuria. So these patients may end up seeing their primary care provider and be diagnosed with a urinary tract infection, yet their symptoms maybe get a little better, don't get better, and end up seeing you because of abdominal pain. So don't get fooled by a history of urinary symptoms and think it's not GI-related. Palpable masses are uncommon. Some colon cancer clinical pearls. Most, about 70 to 90 percent, are diagnosed at the onset of symptoms, which is unfortunate because that puts us later in the stage of the disease typically, and the symptoms are secondary to the growth of tumor into the lumen or adjacent structure. Structures, again, point to later disease when we have the onset of symptoms. You're all familiar with the symptoms of hematochesia, abdominal pain, unexplained anemia, change of bowel habits and weight loss, and again, a palpable mass is uncommon. So as I said earlier, in order to become proficient, or if you wish to become an expert at reports and imaging, we really need to understand the clinical context of these diseases to understand GI radiology. And I would say that all of us need to become experts at reading reports, and at first glance that may sound silly, but I'll point out some reasons why that is not silly. So we all should have an interest in GI radiology because it's an important part of making the right diagnosis. We need to learn GI radiology terms, anterior, posterior, cross-sectional, sagittal, hyperdense, hypodense. These are just some of the terms we need to become familiar with. I think the most important takeaway from this report, and I'll point out some examples in a moment, is to read the entire report. Read the indication. Read the body of the findings. Read the impression and plan. And make sure you compare the comments in the findings and body of the report to the final conclusion or impression and plan, because as scary as it sounds, they're not always the same. And I can tell you a number of times over the years our APPs have picked up some important findings, including malignancies that appeared in the body but did not appear in the impression or plan, and vice versa. And this is important because these APPs may have saved the patient's life from having a missed interpretation or a missed malignancy, and it has medical legal implications. So the most important point, if you only wish to read reports and have your GI interest stop there, make sure you read the entire report and compare the findings in the body to the impression and plan to make sure everything makes sense. However, if you wish to develop a further interest in GI radiology, like a couple of our hospitalist-based GI APPs have done, then the next step is to figure out how you're going to become good at it and how you can review images and learn from good teachers. Again, develop an interest beyond just reading the reports. You'll need to seek support from your APP and or physician mentor, and if your organization has good leadership, they will allow this part of career development to take place, because you can really become an asset to the organization by developing expertise in GI radiology. Like everything else in life, it takes practice, practice, and more practice. That means the organization needs to provide dedicated time for you with a GI radiologist, with a GI physician, or a combination of both, so you can read images and learn how to read images. Read the reports like we talked about, compare those reports to the images as you review them. In some ways, it might be a little bit easier for a hospitalist-based APP to become proficient or an expert at GI radiology compared to the clinic, because they are in the hospital and they have easy access to the radiologist. I always encourage our APPs to review all their images with the radiologist, specifically the hospital APPs, but I also encourage our clinic APPs to look at images when they had time. And if you choose to become an expert at radiology and make this a career development path within your organization, patience, patience, and more patience. It will pay off over time to learn a new skill set, to diversify your skill set, and to really make your practice and professional life more happy. All right, let's take a look at some films. We'll start with an imaging of a plane film that's normal. Sam, if you could just put the pointer to the right side of the image over what appears to be the fluffy stuff a little above where you are right now. That's perfect. Right there. If you could just leave it right there. Some normal structures. Dead center, we have the vertebral column, the vertebral bodies. We see some ribs coming off of those in the top portion of the film. We see the pelvic structures and including bilateral ephemeral head. Where Sam has put the pointer, we see some stool within a non-dilated colon. Some of the fluffy cotton appearance that is the stool is surrounded by some blacker material or air. So this is a very normal plane film. Pretty easy to read. Nothing scary or special. Here, and you can leave your cursor right there, Sam. That looks great. In this film, we see a large bowel obstruction. We see that the colon is dilated. Typically, it's when we look at plane films, we're looking at more than six centimeters. And so Sam is pointing to an area of dilated colon. We see, especially Sam, if you could bring that to the top of the left portion of the slide over just to the little bit right there, a little more to the left, please. A little bit more. Right there. Just leave it right there. There's an area of dilated colon, and we're losing the haustral folds. If you look just to the right of that, there may be some haustral folds. Those are some of the more hyperdense markings. So you tend to lose haustral folds. And as the colon dilates, you might see some thinning of the wall, which we'll see on a CT. And you can see air fluid levels on plane films and obstructions. However, there's a really nice example and easier to understand when we look at the CT. So I'll use that as a teaching point. So this image shows dilated colon. This is a normal CT of the abdomen and pelvis. Right where the cursor is just below that is a normal liver. Sam, just to the right, if you could slide it to our right. And a little bit more. Stop it right there. There we see normal colon with air as represented by the black within the colon. And if we just look to the right of where the cursor is, we see some faint lines right about there. Those are some haustral markings, which is normal colon. And just to the right of that, we have a saccular appearance of the colon, which is also normal. To the bottom, just for reference, excuse me, we have bilaterally the kidneys as some reference as well. So right there, we see the kidneys. All right, let's go to our next slide. Sam, could you bring it up to that area just to your left right there? Stop a little bit there. Stop right there. Here's a CT of the abdomen and pelvis that shows dilation of the colon. Typically, we talk about greater than five centimeters on a CT. And just below where Sam is at about nine o'clock and eight o'clock position on the left, we see air fluid levels within the colon. So Sam, if you could just slide that down to your left right there, where he's got the cursor is air and the gray material below is fluid and debris. So that's a good example of an air fluid level within dilated colon. Much easier to see on CAT scan. And frankly, you're going to see it more on CAT scans because we tend to see a lot of CAT scans ordered and many times overuse. But you'll tend to see more of this on CT imaging as it's a little bit easier to see on CT imaging than plain film. So again, dilated colon, some air fluid levels, and actually some houstra just off to the right of the midline. You see some faint houstra markings. All right, we'll go to the next one. This is a cartoon. And I just want to look at part B of the cartoon. This shows a transition point. We don't typically see transition points in large bowel obstructions, but when we do, it looks something like this. This is a colon cancer in the left side of the colon where the cursor is. We see a dilated colon above it. And below the cancer, we see some collapsed and normal colon. So that is a good example of a transition point. Pretty hard to identify on plain film. A little bit easier to identify on CT. All right, I don't need the cursor on this one, Sam. Thank you. This is a CT image of a mass, and we'll just call it a mass. And the mass is represented by the red arrow. We see some soft tissue density with thickening of the wall. There's some debris and probably some mild narrowing within the wall. All we know at this point is it's a soft tissue density and probably causing some degree of obstruction. If you take a look at the green arrows, we can see what looks like to be some dilated colon with stool and maybe a component of air fluid level, although I think it's more stool. So again, the red arrow is a soft tissue density. Generically, we're calling it a mass. There may be some luminal narrowing. And then we'll go to the next slide and see where that takes us. So before we get into specifics of diverticulitis and then end with a CT image on colon cancer, this is a nice CT image of diverticulosis. Menine, no diverticulitis. The arrows are pointing out those small circles with some black representing air-filled sacs, so diverticulosis. Acute diverticulitis. Sam, can I have you back, please? And I'll slide it directly to your right. Keep going, keep going, keep going a little bit more, and you'll see that right there, that hazy area. So this is a soft tissue density. It has some wall thickening that's mild. It looks like there may be some debris within the lumen of this. And if you slide the cursor just to the left, Sam, right there, right there, we see that haziness surrounding that portion of the left colon, and that's fat stranding or inflammation of the fat and surrounding tissue. So these are classic findings of diverticulitis. Soft tissue density surrounded by some fat stranding. Less discrete in its surroundings, especially at the six o'clock position, and you'll see a more discrete mass when we look at a colon cancer. So this is very consistent with acute diverticulitis. And here we'll finish up with our last image. We see the red arrow pointing to a colon cancer, a very thickened colon wall with, you could see, a very narrow lumen represented by that black space, which has air. The hyper intense, that white hyper intense coloration is probably representing, represents some contrast. Don't really think the bowel behind it is dilated, but if we took some different sections, we may find some dilated bowel. So here's a classic colon cancer, really thickened wall, luminal narrowing with a concentric lumen that is very, very suspicious for colon cancer. I'll end with just a couple slides to summarize, but I do want to again say, if you take away nothing else from this lecture, read the reports carefully, compare the indication to what's in the body of the report, to what's in the impression of implant, to make sure it all makes sense. And if it doesn't, I would always encourage our APPs to call the radiologist, to point this out to the radiologist, because they definitely would want to know if there are some inconsistencies. On plain films for a large bowel obstruction, dilated colon greater than six centimeters, with or without air fluid levels. On CT of the abdomen and pelvis, dilated colon is about five centimeters or more. Definitely easier to see air fluid levels, as I pointed out, definitely easier to see transition points. We can see collapsed or normal caliber distal to the transition point. And at the area where there is, whether it's an obstruction from a malignant mass or from diverticulitis, you could see some bowel wall thickening locally, but proximally, especially if there's significant distention of the colon, you can see some bowel wall thinning. It's almost like a balloon as it gets bigger and bigger, the wall becomes thinner. Diverticulitis, localized bowel wall thickening, typically greater than four millimeters, may not be well-defined thickening or as circumferential as we saw in that colon cancer. There's soft tissue density and a haziness to it with periclonic fat stranding or inflammation of the fat surrounding tissue. Usually, you will see the presence of diverticuli. I didn't point those out, but you can see the presence of diverticuli in the area, and you could see complications of abscess and large bowel obstruction. And finally, colon cancer, soft tissue density, significant wall thickening, lumen tends to narrow. We didn't see any, I didn't point out any lymph nodes because I don't believe there are any on that image, and it's rare that you would see fat stranding, but definitely a discrete mass with a narrow concentric lumen and wall thickening and possibly a large bowel obstruction. I hope you enjoyed all of the cases, and hopefully this can spur some interest for you in pursuing perhaps a career path and becoming an expert for your group in GI radiology. I will now turn it back to Sumit and Caitlin.

gastrointestinal imaging

large bowel obstruction

diverticulitis

colon cancer

radiology interpretation