Purpose: Assessment of sphincter integrity is important as patients with an external anal sphincter (EAS) defect may benefit from surgery. The purpose of this study is to compare endoanal MR imaging and body phased array MR imaging in the detection of EAS defects in patients with fecal incontinence and to evaluate the reproducibility of both techniques.
Methods and Materials: Patients with fecal incontinence were included. The degree of incontinence was assessed according to the grading system of Vaizey (0=normal continence; 24=total incontinence). All patients underwent MR imaging with an endoanal coil and with a body phased array coil; axial and coronal T2FSE images were performed with both coils separately. 30 endoanal MRI and 30 phased array MRI examinations were independently evaluated for EAS defect by two radiologists (observer 1 and 2), experienced in pelvic floor MR imaging. Observer 1 was more experienced in evaluating endoanal MRI and observer 2 in phased array MRI. After an interval 15 endoanal MRIs were again evaluated by observer 1 and 15 phased array MRIs by observer 2. Both observers were blinded for their own and each other's results.
Results: 30 patients (mean age 59 years, range 38-79; 23 women and 7 men) with a mean Vaizey incontinence score of 18 (range 7-23) were included. Obs.1 detected 8 EAS defects on endoanal MRI and 7 EAS defects on phased array MRI (kappa 0.38). Obs.2 identified 13 EAS defects on endoanal MR and 11 EAS defects on phased array MRI (kappa 0.45). The interobserver agreement was moderate for endoanal MRI (kappa 0.50) and fair for phased array MRI (kappa 0.22). The intraobserver agreement was very good for endoanal MRI (kappa 1.00) and good for phased array MRI (kappa 0.61).
Conclusion: Detection of EAS defects is feasible with both endoanal MRI and body phased array MRI. The reproducibility for both techniques was fair to moderate between the observers with different experience in specific techniques, while it was (very) good for each observer when evaluating their own specific technique.
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