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P178. Assessment of perianal Crohn's disease by diffusion-weighted MRI compared with conventional MRI


A. Avgerinos1, A. Xyda2, L. Bourikas1, A. Karantanas2, E. Kouroumalis1, I. Koutroubakis1

1University Hospital of Heraklion, Gastroenterology Department, Heraklion, Greece; 2University Hospital of Heraklion, Radiology Department, Heraklion, Greece



Background: Perianal fistulas occur in up to 45% of patients with Crohn's disease (CD). MRI is the method of choice in imaging and classifying perianal fistulas. Diffusion-weighted image (DWI) constitutes an innovative MR technique relying on restricted diffusion of protons in neoplastic or inflammmatory tissues. The purpose of the present study was to asses in CD patients any additional information provided by DWI MRI, in comparison with conventional MRI, with regard to depiction and staging of fistulas.

Methods: Thirty two CD patients, 22 males and 10 females (age 23–61 y, mean 41.2), with clinical suspicion of perianal fistulas, underwent perineal MRI. The location of the disease according to the Montreal classification was mainly L2 (12/32), L3 (12/32) and L1 (5/32). Conventional MRI sequences (T1‑w before and after intravenous contrast, fat suppressed T2‑w TSE, STIR) and DWI technique were applied in coronal and axial planes in all patients. Fistulas were assessed for presence and enhancement, which is an index of inflammation. Apparent Diffusion Coefficient (ADC) maps were created and measured in the abnormal area. The activity of perianal CD was scored clinically using the Perianal Crohn's Disease Activity Index (PDAI).

Results: In 30 out of 32 patients (93.9%) there was accordance in findings between conventional MRI sequences and DWI MRI. In two patients fistulas were detected only on STIR, contrast enhanced T‑1w and DWI technique. Linear regression analysis between ADC values and PDAI did not show any significant correlation (p > 0.05).

Conclusions: DWI seems to offer no significant additional information in detecting and staging of perianal fistulas in CD patients, compared with standard MRI techniques.