Dr St Pierre discusses the award-winning poster she presented at Digestive Disease Week on the Chicago Mesenteric Fat Index, which proved a reliable measure that can be incorporated in point-of-care intestinal ultrasound in the care of IBD patients.

Joelle St Pierre, MD, is an advanced IBD fellow at the University of Chicago. 

TRANSCRIPT:

Hi, my name is Joelle Saint -Pierre. I'm one of the Advanced IBD Fellows at the University of Chicago. I'm currently at DDW 2024, and I'm here to talk about a poster that we presented here that got a poster of distinction award. Our poster is basically coming up with an index to look at mesenteric fat.

It's called the Chicago Mesenteric Fat index and we basically show it's a reliable indicator of mesenteric fat wrapping. I'll talk about this in a little bit. So the background is that mesenteric fat is an inflammatory organ and there's increasing interest in its role in the pathophysiology of Crohn's disease. It's obviously better assessed through cross-sectional imaging or other imaging modalities. And more and more, with this interest, there's been a few scoring systems proposed by CT or MRI to assess mesenteric fat wrapping, which is the process of that creeping fat or inflammatory fat engulfing the exterior of the bowel, most notably in the ileum of patients with Crohn's disease.

Now these are great imaging modalities, but more and more point-of-care intestinal ultrasound is used in clinical care of patients with IBD. And certainly it's a finding that we see routinely on ultrasound when we do image our patients. Point-of-care intestinal ultrasound is inexpensive. We don't need our patients to prepare for these tests. They're done pretty fast and again we can get answers very quickly and so it has many advantages.

The point of our mesenteric fat index here is to provide a reliable way to grade the degree of mesenteric fat wrapping. Currently the recommendations are to report it as either absent or present and so we wanted to a little bit expand on that and provide a graded system. Our graded system is based on 3 stages. So on one end of the spectrum we have no mesenteric fat wrapping. On the other end we have complete mesenteric fat wrapping and that's where the mesenteric fat completely engulfs that segment of the bowel. And in the middle, we propose an incomplete wrapping. So where we see about half of the bowel or less than 75% to 50% of the bowel that is associated with mesenteric fat. And that provides a little bit more nuance in that degree of mesenteric fat wrapping.

Even though we go from 2 to 3, there's a lot of thought that goes into this. We already know that even by grading it as absent or present, there's moderate to substantial reliability, but certainly not perfect. And so we wanted to keep it simple, we also wanted to keep it simple because as we're doing point-of-care intestinal ultrasound, it needs to be something that we can quickly assess and integrate in our clinical decision making, and hence our proposed index.

We used images from a database, and this is a real-world database. We just took images that we had. They weren't specifically taken to look at a mesenteric fat index so to have a better representation of what it would look like in the real world.

So we had 64 patients and images from 95 scans and we basically graded those images by 3 independent readers that had extensive knowledge in point of care intestinal ultrasound and we had their grading of the Chicago Mesenteric Fat Index as well as through our binary assessment so is it absent or present, and then we repeated that 6 months later to look at intra-rater reliability and so we compiled those and what we showed in a nutshell is that even though we go from a 2 point to 3 point grading system we don't lose much in terms of inter- or intra-rater reliability. We show that we still have moderate to substantial inter- and intra-rater reliability, but yet it tells us a little bit more about how that mesenteric fat associates with some of the parameters with both markers of inflammation as well as clinical disease and patient findings. So what we're able to do is also show that it correlates as well.

The presence of mesenteric fat wrapping correlates with other markers of inflammation on point of care intestinal ultrasound. So it correlates with increased bowel wall thickness and with the degree of hyperemia, which is a marker of increased vascularity, as well as other markers that we routinely look at for the presence of inflammation. And interestingly, we also see that it's associated with the presence of ileal strictures, which is very interesting, and more and more studies are looking into the association of fibrosis in the ileum as well as the presence of mesenteric fat.

So all in all we show that this is a nice index with good inter- and intra-rater reliability that we hopefully can incorporate in point-of-care intestinal ultrasound in the care of IBD patients. And our further steps are going to be to see whether we can even integrate it in some of the validated scores that we use for research and clinical applications such as the international bowel ultrasound score and other scores that we look for in Crohn's disease.