MR-IMAGING OF FISTULA IN ANO - ARE ENDOANAL COILS THE GOLD STANDARD

OBJECTIVE. It has been suggested that fistula in ano is most accuratel y assessed using endoanal receiver coils because they provide superior spatial resolution. We aimed to determine their advantage by prospect ive comparison with conventional body coil imaging, SUBJECTS AND METHO DS. Thirty consecutive unselected patients with a diagnosis of anorect al sepsis were examined by MR imaging with an endoanal coil. Imaging w ith a body coil followed, Imaging was independently evaluated by two r adiologists who classified fistulas according to the coil used and the n compared their findings, which were validated surgically, RESULTS. F ive patients could not tolerate coil insertion. In the remaining 25 pa tients, endoanal imaging revealed no abnormalities in three patients i n whom the body coil image correctly showed Crohn's disease, a sinus, and a transsphincteric fistula. Imaging with both coils revealed sepsi s in 16 patients, allowing radiologists to make correct primary track classification in 13 patients on endoanal imaging compared with 15 pat ients on body coil imaging. Endoanal imaging revealed 10 secondary ext ensions in eight patients, but further extensions in two of these pati ents and in a third patient were undetected. All these extensions were seen on body coil imaging. Overall, surgical concordance was 68% for endoanal imaging compared with 96% for conventional body coil imaging. CONCLUSION, Due to field-of-view limitations, endoanal imaging is less accurate than conventional body coil imaging for preoperative assessm ent of complex anal fistulas.