Hi, this is Elliot Fishman, and here's our newest talk. This is going to be on the role of cinematic rendering in the evaluation of small bowel tumors. This is based on an article we recently published by Zahra, Satomi, and myself.

And what I'm going to go through is some of the basic points in this article, and how cinematic rendering can help you detecting and evaluating small bowel tumors. Now, we know that primary small bowel tumors are rare, symptoms will vary, and diagnosis is often delayed. People talk about 18 months from presentation to diagnosis.

The question is, how can we make it easier to see tumors? And one thought is cinematic rendering. Can you accentuate bowel that you can pick up smaller tumors? We've talked about that in pancreas, we've talked about that in liver, we've talked about kidney. And what we'll do in this article and in this talk is basically show you a range of small bowel tumors, from adenocarcinoma, to carcinoid, to GIST tumors, and lymphoma, and show you how we think that cinematic rendering may be helpful for us.

Again, the challenge of small bowel tumors, even malignant tumors, symptoms are non-specific: abdominal pain, nausea, vomiting, and weight loss. And when patients get scans, people look at pancreas, they look at liver, but maybe they don't look as carefully at the small bowel as they should. But also, the problem is small bowel tumors are often difficult to see if they're not causing obstruction or GI bleeding, particularly when they're small.

So, what is it that we can do? Well, we can look for transition points, we can look at the vasculature, we can look for changes in perfusion. There are a number of things we can do.

Now, of course, one of the issues we go back to is, in the big picture of things, small bowel malignant tumors are rare, only about 0.6% of all cancers, and only 3% of GI malignancies. Now, the rate of small bowel tumors has increased, particularly carcinoid and GIST tumors in our experience, but they're still going to be small numbers. So, again, the question is, how do we do better?

Well, we've talked about using cinematic rendering before as I mentioned. And in this last series of talks on CTisus, you have seen a number of different applications. We're going to talk about musculoskeletal applications, we've spoken about adrenal, we've spoken about kidney, we've spoken about pancreas, but let's look at the small bowel.

So, let's start with small bowel adenocarcinoma. It's most commonly proximal, proximal duodenum or distal duodenum and jejunum. We always talk about how in the ileum, yes, you can get small bowel cancer, but you're typically thinking about lymphoma, and also distally you think about carcinoid, and carcinoid typically have a mass in the mesentery and desmoplastic reaction.

The challenge with small bowel adenocarcinoma, initially the lesions are flat and they're small. They may not cause obstruction, they may not enhance, and so if the bowel is not well distended, and if you're not very careful, it's very, very easy to miss. So, again, you need to be really, really careful.

With cinematic rendering, we enhance the difference between normal bowel and any potential abnormal bowel. We also try to enhance the interfaces, and this hopefully will help accentuate the definition of both vessels, normal structures, and abnormal structures. And here's just a good example. You can see that when you look at the axials, is this under distention? No, this is a mass around the fourth portion of duodenum. You can see on the coronals that it's really from the second portion of duodenum, really to jejunum.

But that's better seen on the cinematic. You see the lumen, the eccentric mass, very nicely defined, and the bulky component going from the third and fourth portion of duodenum into jejunum. And this was biopsy-proven adenocarcinoma, but you can see it's bulky, but it's not causing obstruction, and of course it's very, very easy to miss.

Here's another example of a small bowel adenocarcinoma. It's a bulkier tumor shown nicely here, but maybe you're going to walk by it. But on the cinematic, it really stands out well: a large, ulcerating mass. If you mentioned lymphoma, I would have a hard time saying no. If you thought about metastatic disease, that would also be a possibility. But at the end of the day, the key is recognizing it. It also shows very nicely that even when you have a reasonably large small bowel tumor, it may not cause obstruction because in this case you don't see any dilated bowel loops, but it's easy to see the tumor.

Now, again, talking about the whole area of looking at small bowel tumors, again, we emphasize you need axials and coronals, but then 3D mapping using both MIP looking at vessels and cinematic rendering or volume rendering for enhancing the interface between normal and abnormal tissue becomes very important.

Now, we spoke about the adenocarcinomas being proximal. I mentioned distally we think about carcinoid, though carcinoids can occur in the first and second portion of duodenum, and there they're just simply polypoid vascular lesions. When you have distal tumors like in the classic in the ileum, you'll often see a mass in the mesentery, and the mass in the mesentery has desmoplastic reaction, and in 60 to 70% of the cases, it will also have calcification.

Here's a nice example of a patient with abdominal pain. There's a vascular lesion here. It's not in the terminal ileum, it's higher up, it's more proximal jejunum to mid-jejunum. More distally, there is something going on in the bowel mesentery, right? There is a mass here with desmoplastic reaction. Put both of them together, and now you're dealing with a carcinoid tumor.

Another example: mass in the mesentery with calcification. 70% of carcinoids do calcify. There's a second mass here. Desmoplastic reaction best seen on the cinematic rendering views, where you see the masses and you see the irregularity of the vessels, the so-called desmoplastic reaction, which is classic for carcinoid tumor. Now, you can get mesenteric masses like from sclerosing mesenteritis that calcify also in the 60 to 70% range, but with sclerosing mesenteritis, you don't have that desmoplastic reaction that you have with a carcinoid tumor.

Now we talk about GIST tumor. When I speak about GIST, usually I'm speaking about the stomach, but they can occur in the esophagus, the stomach, the small bowel, or the large bowel. When they occur in the small bowel, sometimes they occur in the duodenum, and it's hard to distinguish them from pancreatic cancer at times because they can be vascular, and you have to differential of pancreatic adenocarcinoma or even sometimes a neuroendocrine tumor, carcinoid tumor, and a GIST tumor.

GIST tumors can be multiple, they can be necrotic, they can ulcerate, and they can bleed. And again, cinematic rendering is helpful detecting them.

Here's a nice example of a mass coming off the duodenum, second portion. Polypoid. You can consider a carcinoid, but carcinoids are usually more vascular and intraluminal. Adenocarcinomas usually more infiltrative, not a mass that's so exophytic, which is nicely shown on the cinematic coronal rendered images, very nicely shown. And you can see there's no obstruction. One other thing with GIST tumors, they can bleed, but they often do not obstruct, unless they really have some sort of desmoplastic reaction.

Another example: here's a large mass, and if you said this was lymphoma, a big polypoid, ulcerating mass, to me, my first thought would have been lymphoma. I could have thought about metastatic disease. I could have thought about a carcinoid tumor, but carcinoids usually don't become necrotic and they're more vascular, so I don't really like that. But a GIST tumor, often it's exophytic, it's bulky, it ulcerates, and this was a GIST tumor that actually perforated and the patient has carcinomatosis.

Finally, lymphoma is the most common extranodal site of disease in the GI tract. One of the things with lymphoma, it's usually in the terminal ileum. It can be polypoid, it can be infiltrating. Even when it's bulky at times, it doesn't obstruct. That's one of the hallmarks of lymphoma, that it's a very unusual kind of like a soft tumor that it's bulky, it's large, it can be ulcerating, but it may not obstruct. Now, with lymphoma, we see it more commonly in patients who are organ transplant recipients, patients who are immunosuppressed, amongst other factors.

And here's a nice example of a mass in the right lower quadrant. If you only look at the mass, you could have thought about an ulcerating GIST tumor, you could have thought about metastasis. You see the bulky components into the mesentery. When I see this, I'm going to think about lymphoma, particularly when I see that. So this is a nice example of a bulky mass with ulceration, with extension down the root of the mesentery, very nicely appreciated on the cinematic rendering as well.

Now, we also mentioned that key indicators of primary small bowel lymphoma include wall thickening, enlarged nodes without necrosis. And again, the challenge is that the very ability in appearance. Now, at the end of the day, often you can make the diagnosis. Lymphoma will typically have more bulky nodes than any of the other processes. Desmoplastic reaction is something in carcinoid, but it's not something you see in lymphoma. You can see lymphomatous involvement of multiple bowel loops, you can see lymphomatous involvement of nodes, obviously, but it's not that desmoplastic reaction, so again, we're able to make the distinction.

We also mentioned sarcomas, which are rare, but they do occur, most commonly in jejunum. They're typically large and ulcerating, could look identical to a GIST, can look identical to lymphoma.

So, I've shown you a number of examples, and I'll go through a few more. But again, you can see how the cinematic rendering, I would say at this point doesn't replace classic axial or coronal imaging, but it does enhance it, because CR can sharply define the mass, highlight its consistency, and provide superior visualization of mucosal involvement, but also vascular involvement, and can be used very well for pre-operative planning.

In summary, small bowel neoplasms are rare and often present with either non-specific symptoms or acute emergencies. It's often a challenging diagnosis. Tumors are often missed because they can be small or because they may be hard to see, or you may have some dilated bowel loops and you don't appreciate it. But again, careful analysis of the dataset, both on axial and coronal, and with 3D mapping, can prove to be very helpful.

Now, again, I ask the question about what about small bowel tumors to Gemini, and it actually summarized this article: "The study investigates how cinematic rendering, a sophisticated 3D reconstruction technique, improves the visualization and diagnosis of primary small bowel malignancies compared to standard CT."

It mentions the advantages which I've covered with you: photorealistic depth, texture detail, and can be used for surgical planning. Again, beyond just making the diagnosis, staging correctly, staging and thinking about pre-operative planning, whether it's surgery or other therapies, and then as part of the follow-up process.

And with that, I'll stop there, and thank you for your attention.