[High-resolution Magnetic Resonance Tomography of the Anal Sphincter Using an Intravaginal Surface Coil]

Purpose: To assess the visualisation of the anal sphincter by means of an intravaginal surface coil.

Methods: MR imaging was performed using a 1.0 T unit. In 10 females (6 nullipara, one primipara without and three primipara with postpartum faecal incontinence) a surface coil, originally designed for endorectal use, was placed into the vagina. Transverse oblique T1-weighted spin echo and double echo turbo spin echo sequences with T2- and proton density-weighting were acquired parallel to the puborectal, rectococcygeal and anorectal planes. Three readers analysed the images in consensus.

Results: The anatomic structures of the external and internal sphincter as well as the mucosa were differentiated in all cases with a good contrast. The best results were yielded by the proton density weighting. In one case of faecal incontinence a sphincter defect after repair of a complete rupture of the anal sphincter was shown. In another case irregularities in the structure of the external sphincter and perineum were visualised.

Conclusion: Intravaginal surface coil imaging seems a well-tolerated novel method for the evaluation of the anal sphincter tissues in truly anatomical states. Due to its capability to depict subtle tissue structures as well as pathologic irregularities, it might become a potential tool in the diagnosis and operation planning of postpartal faecal incontinence.