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Updated: Feb 6, 2026
Contrast Enhanced Vessel Imaging using MicroCT
Published on: January 27, 2011
Contrast- vs. non-contrast enhanced MR data sets for characterization of perianal fistulas
Kamonwon Cattapan1,2, Thitinan Chulroek1,3, Hamed Kordbacheh1
1Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, White 270, Boston, MA, 02114, USA.
Purpose:
To evaluate the diagnostic efficacy between pre- and post-contrast MRI sequences in perianal fistulas using intra-operative findings as the gold standard.
Materials And Methods:
Retrospective analysis of 50 patients with a history of perianal fistula and MRI performed between January 2006 and January 2018 was performed. The inclusion criteria were patients who underwent MRI prior to surgery and had a detailed surgical report available. Pre- and post-contrast MR data sets were evaluated by two radiologists at two-week-intervals, assessed fistula type, internal/external opening, presence of abscess/secondary tracts, and confidence scores. The area under the curve (AUC) was used for comparison the diagnostic ability. The sensitivity and specificity were compared using the McNemar's test.
Results:
The confidence scores in detecting perianal fistulas were significantly higher in the post-contrast MR data set (p < 0.003). The post-contrast MR data set had similar ability to classify perianal fistulas as combined T2-DWI and isolated T2 data sets in 49/50 cases. For internal/external opening, the post-contrast MR, combined T2-DWI, and isolated T2 data sets had 100% concordance with intra-operative reports. For perianal abscess, there was no significant difference in sensitivity or AUC value between the isolated T2 or combined T2-DWI data sets and post-contrast MR data set (p > 0.05). All MR data sets correctly identified secondary tracts in all 50 cases.
Conclusions:
Although contrast-enhanced MR studies can improve a radiologist's confidence, non-contrast MR studies had similar diagnostic efficacy in identifying perianal fistulas and their complications. Therefore, a non-contrast study may suffice in selected patients such as those with renal impairment.
Insights
Non-contrast MRI demonstrates comparable diagnostic efficacy to contrast-enhanced MRI for perianal fistulas. This finding supports using non-contrast MRI in select patients, particularly those with renal impairment, for accurate fistula evaluation.
Area of Science:
- Radiology
- Gastroenterology
- Surgical Imaging
Background:
- Perianal fistulas are complex anorectal conditions requiring accurate imaging for diagnosis and management.
- Magnetic Resonance Imaging (MRI) is a key modality for evaluating perianal fistulas, with both pre- and post-contrast sequences utilized.
Purpose of the Study:
- To compare the diagnostic efficacy of pre- and post-contrast MRI sequences in identifying perianal fistulas.
- To determine if non-contrast MRI can achieve similar diagnostic accuracy to contrast-enhanced MRI for perianal fistula evaluation.
Main Methods:
- Retrospective analysis of 50 patients with perianal fistulas who underwent MRI prior to surgery.
- Evaluation of pre- and post-contrast MR datasets by two radiologists for fistula type, openings, abscesses, and secondary tracts.
- Comparison of diagnostic abilities using Area Under the Curve (AUC) and McNemar's test for sensitivity and specificity.
Main Results:
- Post-contrast MRI significantly increased radiologist confidence (p < 0.003).
- Non-contrast MRI (isolated T2 and T2-DWI) showed similar diagnostic ability to post-contrast MRI for fistula classification (49/50 cases).
- All MRI sequences achieved 100% concordance with intra-operative findings for internal/external openings and secondary tracts; no significant difference in perianal abscess detection.
Conclusions:
- Non-contrast MRI sequences exhibit comparable diagnostic efficacy to contrast-enhanced MRI for perianal fistulas and their complications.
- Non-contrast MRI may be sufficient for selected patients, including those with renal impairment, potentially avoiding contrast-related risks.
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