Abstracts
1997 Digestive Disease Week

Assessment of perianal Crohn's disease by magnetic resonance imaging - a 5-year follow-up study.

F Makowiec, J Loichat, M Laniado, HD Becker, M Starlinger. Departments of Surgery and Radiology, University of Tubingen, Germany.

Perianal Crohn's disease (CD) is characterized by a chronic recurrent course. Magnetic resonance imaging (MRI) has a very high accuracy in correctly describing these lesions. In this study we evaluated the changes of perianal CD visualised by MRI in 22 patients who had an initial MRI (MRI1) between 1989 and 1991 for extensive and symptomatic perianal disease. They were treated through 1995 with prospective follow-up. None of them had undergone proctectomy. METHODS: In 1996 a second MRI (MRI2) was performed a mean of 5.2±1.1 years after MRI1. Mean duration of perianal CD in 1996 was 10.8±5 years. During follow-up treatment of active fistulas or abscesses consisted of drainage procedures (incision, seton, catheter). At the proctological examination before MRI2 19 of 22 patients were asymptomatic. The MR images were analyzed by two radiologists and one surgeon unaware of the clinical findings. Anatomical progress of disease was defined as occurence of new fistulas/abscesses, progress of severity as enlargement of fistulas/abscesses. Healing was defined as scar formation without new fistulas or abscesses. RESULTS: Progress, changes in severity and healing of abscesses (MRI2 versus MRI1) are shown (table):

     initial abscess    n   anatomical   progress of     healed at
     location                progress     severity        MRI 2
     subcutaneous/     11       3           5              5
     intersphincteric
     para-anal          4       0            0             1
     ischiorectal       7       3            2             0
                  all  22       6            7             6

At MRI1 (MRI2) 35 (17) abscesses, 24 (24) fistulas and 16 (25) scars were demonstrated. Ten abscesses found at MRI2 in asymptomatic patients were not adequately drained. One third (n=8) of the fistulas seen at MRI1 were healed but the same number of new fistulas was documented at MRI2. CONCLUSIONS: 1. In one third of the patients abscesses were healed after 5 years, but another third had progressive disease. Healing rate is lowest in ischiorectal fistulas/ abscesses. 2. MRI identifies a relevant number of clinically asymptomatic abscesses in patients with extensive perianal CD. 3. To prevent septic complications MR examination should be performed in patients with a history of extensive perianal disease prior to immunosuppressive therapy for active intestinal disease.