MRI of fistula-in-ano: a comparison of endoanal coil with external phased array coil techniques.
OBJECTIVE
The objective of our study was to compare MRI of fistulas-in-ano using an endoanal coil with that using a pelvic phased array coil and to assess the value of a combined approach by correlating the findings with those at surgery.


METHODS
Twenty consecutive patients with clinical suspicion of perianal sepsis were studied using an endoanal coil immediately followed by a phased array coil. T1 weighted and STIR images in transverse and coronal planes were made with each coil and analysed by noting the presence and site of a collection and primary track, the position of any internal opening, and subcutaneous or supralevator extension. Operative findings were similarly recorded.


RESULTS
Of 20 patients with suspected fistulas, 8 had simple fistulas, 8 had complex fistulas, and 4 had no current evidence of infection. The concordance between MR and surgery for identifying the presence and site of the collection, the primary track, and the internal opening in both simple and complex cases was superior using the endoanal coil as compared with the phased array. Both coils together reflected the findings of the endoanal coil used alone. However, for supralevator/subcutaneous extension, concordance was superior using the phased array compared with the endoanal coil, and a combined approach reflected the values of the phased array coil used alone.


CONCLUSIONS
Endoanal MRI is highly sensitive in the delineation of fistulas-in-ano. In combination with phased array techniques, it provides valuable preoperative assessment in both simple and complex cases.
deSouza
N M
NM
Robert Steiner Magnetic Resonance Unit, Royal Post-graduate Medical School, Hammersmith Hospital, London, England.
Gilderdale
D J
DJ
Coutts
G A
GA
Puni
R
R
Steiner
R E
RE
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001003:Anal Canal / Q000473:pathology; D001004:Anus Diseases / Q000175:diagnosis / Q000382:microbiology; D001424:Bacterial Infections / Q000175:diagnosis; D003287:Contrast Media; D003424:Crohn Disease / Q000175:diagnosis; D004867:Equipment Design; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008875:Middle Aged; D009130:Muscle, Smooth / Q000473:pathology; D012003:Rectal Fistula / Q000175:diagnosis* / Q000382:microbiology / Q000601:surgery
D003287:Contrast Media