Transanal MR imaging after repair of anorectal anomalies in children: Appearances in pull-through versus posterior sagittal reconstructions

OBJECTIVE. Our objective was to use transanal MR imaging to compare the ana tomic appearance of the components of the anal sphincter and the pattern of scarring after a pull-through perineoplasty versus a posterior sagittal an orectoplasty. SUBJECTS AND METHODS. Sixteen children ranging in age from 10 months to 15 years (mean, 10 years) were imaged using transanal receiver coils appropria te to the size of the child. Five had low, four intermediate, and seven hig h anomalies. Seven had undergone a transanal pull-through procedure, and ni ne had undergone posterior sagittal reconstruction. The integrity of the mu scles was assessed on TI-weighted and short inversion time inversion recove ry transverse and coronal images using a qualitative MR imaging score. The pattern of scarring was also assessed. RESULTS. In the transanal pull-through group, four of seven patients showed external sphincter deficiency. A circumferential low-signal-intensity band was seen inferior to the sphincter in six patients. All posterior sagittal reconstructions had a long posterior midline scar. Five of nine patients s howed external sphincter deficiency, whereas a further two had internal sph incter deficiency. No differences were seen in MR imaging scores for each o perative procedure for all grades of severity of anorectal anomaly. However , a comparison between high and intermediate anomalies showed a small impro vement in MR imaging score using the transanal pull-through procedure (Mann -Whitney U test = 3, p < .03). Manometric pressures obtained in 13 patients were poor. CONCLUSION. Transanal MR imaging identifies focal defects and patterns of s caring of the anal sphincter complex in infants and children and provides v aluable information about individual muscle components.