[Magnetic resonance study of complex anal fistulae. Preliminary results apropos of 28 cases].
OBJECTIVE
To evaluate the use of Magnetic Resonance Imaging (MRI) for the treatment of problematical anal fistulas and follow-up of cases treated by long-term seton drainage with two or three-stage fistulotomy.


METHODS
prospective study on 24 patients with surgical treatment between July 1993 and March 1995 selected for MRI among 100 anal suppurations according to following criteria: high trans-sphincteric or supra-sphincteric fistula with one or more previous definitive attempts at treatment (15), and/or severe anal or rectal fibrosis (11). Patients with Crohn's disease were not included. For 14 of these patients who had a long-term seton drainage, MRI tried to assess the quality of the surgical drainage and the course of residual abscess.


RESULTS
the overall accuracy of MRI for visualization of internal opening, primary and secondary tract was 84% when compared with surgical data. The sensitivity and specificity were 100% for the detection of horse shoe fistulous tracts (8). For the 14 patients followed by MRI, only one false positive was noted and in 5 cases the results of MRI modified the previous staged procedure (prolonged seton drainage or new excision). For the 20 patients treated for more than 6 months, the mean follow-up was 18 months and median was 14 months. Only one recurrence was noted with no loss of follow-up.


CONCLUSIONS
this study confirms the high degree of accuracy of MRI for mapping of high complex fistula in ano. MRI is very helpful for the survey of healing in cases treated with seton drainage and two or three stage fistulotomy to preserve continence.
Grandjean
J P
JP
Centre Lyonnais de Colo-Proctologie, Lyon.
Daville
O
O
Henry
L
L
Milox
B
B
Tissot
O
O
Valette
P J
PJ
D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D012003:Rectal Fistula / Q000175:diagnosis* / Q000601:surgery; D013997:Time Factors