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MRI features of perianal fistulas: is there a difference between Crohn's and non-Crohn's patients?
Irai S Oliveira1, Aoife Kilcoyne2, Melissa C Price3
1Division of Abdominal Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, 55 Fruit St., White Building 270, Boston, MA, 02114, USA. isantanadeoliveira@mgh.harvard.edu.
Purpose:
Though perianal fistulas are commonly seen in patients with Crohn's disease, they can also be seen in patients without inflammatory bowel disease. The purpose of this study was to evaluate MR imaging differences of perianal fistulas in patients with and without Crohn's disease.
Methods:
Our retrospective search from January 2012 to December 2015 of the Radiology database for perianal fistula yielded 207 patients. Only patients with dedicated MR fistula protocol studies were included, whereas patients with previous anal surgery or anastomosis, anorectal tumors, and equivocal findings that could not be definitely assessed as a fistula were excluded. The following features were assessed: anatomic type of fistula (Parks Classification), luminal origin (hour clock position), anal verge distance, signs of acute inflammation, circumference of anus involved by inflammation, presence of rectal inflammation. and abscess.
Results:
One hundred and twenty six of 207 patients met inclusion criteria. Of these, 96 (76.2%) had Crohn's disease and 30 (23.8%) did not. The most common fistulas identified were transphincteric (38.5% of Crohn's and 50% of non-Crohn's) and intersphincteric (33.3% of Crohn's and 35.4% of non-Crohn's). An abscess was associated in 41 cases, 32 (33.3%) in the Crohn's group and 9 (30.0%) in the non-Crohn's group. Rectal inflammation was present in 29 patients with Crohn's disease (29.2%) and in 2 without Crohn's (6.7%). This finding was statistically significant (p = 0.0009).
Conclusions:
Our study demonstrates that while both groups can have similar MR imaging features, accompanying rectal inflammation was more commonly seen in Crohn's disease.
Insights
Magnetic resonance (MR) imaging can identify perianal fistulas in patients with and without Crohn's disease. Rectal inflammation on MR imaging was significantly more common in patients with Crohn's disease.
Area of Science:
- Radiology
- Gastroenterology
- Medical Imaging
Background:
- Perianal fistulas are a common complication of Crohn's disease.
- However, they can also occur in individuals without inflammatory bowel disease.
- Differentiating these causes using imaging is crucial for appropriate management.
Purpose of the Study:
- To compare the magnetic resonance (MR) imaging features of perianal fistulas in patients with Crohn's disease versus those without.
- To identify potential imaging biomarkers that distinguish between the two groups.
Main Methods:
- Retrospective analysis of 207 patients with perianal fistulas who underwent dedicated MR imaging.
- Exclusion of patients with prior anal surgery, tumors, or equivocal findings.
- Assessment of fistula anatomy (Parks Classification), location, associated abscess, and rectal inflammation.
Main Results:
- 126 patients met inclusion criteria (96 with Crohn's, 30 without).
- Transphincteric and intersphincteric fistulas were most common in both groups.
- Rectal inflammation was significantly more prevalent in Crohn's disease patients (29.2%) compared to non-Crohn's patients (6.7%), p=0.0009.
Conclusions:
- MR imaging features of perianal fistulas can overlap between Crohn's disease and other causes.
- The presence of associated rectal inflammation on MR imaging is a key differentiator, being more common in Crohn's disease.
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