A pilot assessment of whether external coil MRI is useful to assess evacuatory disorders

This study assessed the value of common surface coil magnetic resonance ima ging (MRI) in patients with evacuatory disorders including fecal incontinen ce and constipation. These findings were then compared with those from othe r standard physiological examinations and/or surgical findings. From July 1 996 to June 1997, 14 consecutive patients underwent surface coil MRI for ev aluation of either fecal incontinence (n=5) or constipation (n=9). In patie nts with incontinence we compared the findings from endoanal ultrasound (EA US), anal MRI, and surgery regarding morphopathological findings of the int ernal and external anal sphincter components. In constipated patients the f indings of videoprography and dynamic pelvic MRI were compared regarding th e presence of rectocele, rectoanal intussusception, and sigmoidocele as wel l as the measurements of anorectal angle and perineal descent. The five inc ontinent patients were all women, with a median age of 67 years (range 43-7 7). EAUS revealed an anterior sphincter defect in two patients, a posterior defect in one, and normal anal sphincter images in two. Surgical findings confirmed an anterior external anal sphincter scar in two patients, an inte rnal anal sphincter defect in one, and an anatomically normal anal sphincte r in two. In one patient, although anal MRI showed posterior external anal sphincter defect, EAUS and surgery revealed normal external anal sphincter appearance. The accuracy rate between EAUS and anal MRI was only 20%, that between surgery and anal MRI 40%, and that between surgery and EAUS 80%. Th us EAUS was more accurate than anal MRT in incontinent patients. The nine c onstipated patients were all women, with a mean age of 59 years (range 40-7 8). Videoproctography revealed an anterior rectocele in six patients, recto anal intussusception in three, and sigmoidocele in five; no abnormalities w ere identified in two patients. On dynamic pelvic MRI anterior rectocele wa s seen in three patients and sigmoidocele in two, and five studies were int erpreted as normal. One of the patients underwent sigmoidectomy for sigmoid ocele, and five patients were treated by biofeedback. Thus the accuracy rat e of dynamic pelvic MRT against videoproctography was 60% for anterior rect ocele, 40% for sigmoidocele, and zero for rectoanal intussusception. In con clusion, neither MRI for the evaluation of patients with fecal incontinence nor for the evaluation of patients with constipation added any significant information that would warrant its continued use in these patient groups. Perhaps the more widespread availability of an endoanal coil will alter thi s conclusion; however, at the present time we cannot routinely endorse the expense, time, or inconvenience of these MRI investigations in patients wit h these diagnoses. Larger prospective comparative studies are required prio r to endorsing the technique.