Fistulizing perianal Crohn's disease: contrast-enhanced magnetic resonance imaging assessment at 1 year on maintenance anti-TNF-alpha therapy.

Background: The aim of the study was to assess perianal fistulas by magnetic resonance imaging (MRI) in patients with severe fistulizing Crohn's disease (CD) using maintenance antitumor necrosis factor alpha (TNF-α) therapy and to correlate MRI changes with clinical outcome.

Methods: Perineal MRI before and after a 1-year scheduled anti-TNF-α maintenance therapy was performed in 20 patients (14 females; mean age = 33.7). The Van Assche score (i.e., number of fistulas, localization, and extension, importance of T2 hyperintensity, presence of abscess) was calculated. Fistula track contrast enhancement was also used. Clinical outcome was defined as no response, response, or remission.

Results: Response and remission were observed in respectively 40% and 35% of cases. The Van Assche score varied from 13.8 (7-20) to 6.13 (0-12) in patients with a response or remission (P < 0.05). The T2 hyperintensity follow-up value decreased in patients in response or remission (P < 0.01). T2 hyperintensity disappeared or decreased in 14 out of 15 patients in clinical response or remission as compared to one among the five nonresponding patients (P < 0.01). The decrease in Van Assche score and hyperintensity value was not significantly different in patients in remission compared to those with response. Only one patient in clinical remission had a persisting contrast enhancement on MRI, whereas contrast enhancement persisted in all other patients not in remission (P = 0.002).

Conclusions: The clinical benefit of maintenance anti-TNF-α therapy in perianal CD is associated with a significant improvement of the Van Assche score, particularly T2 hyperintensity. The disappearance of contrast enhancement was the only semiological MR feature associated with remission.