Pelvic floor dynamic imaging: MR versus conventional defecography

Purpose: to evaluate diagnostic capabilities of Magnetic Resonance Imaging (MRI) in functional pelvic floor abnormalities and to compare them with conventional defecography (CD). Materials and methods: 15 consecutive patients with clinical symptoms of pelvic floor dysfunction underwent dynamic pelvic examination with a closed-configuration MR system. After rectal distension with ultrasound gel, midsagittal T2-weighted single-shot fast spin-echo and FIESTA-cine MR images were obtained, with the patient at rest, straining, maximally contracting the sphincter and defecating. MR images were blindly evaluated by two radiologists and compared with CD and clinical examination available in all patients and considered as the gold standard. Results: disease prevalence was 66,7%. MRI showed accuracy of 86,7%, sensitivity of 90% (95% CI: 0,71-1,08), specificity of 80% (95% CI: 0,44-1,15), predictive positive value (PPV) of 90%, predictive negative value (NPV) of 80%. MRI permitted analysis of anorectal angle, the function of the puborectal muscle, and the descent of the pelvic floor during defecation. Good demonstration of the rectal wall permitted visualization of rectoceles. Excellent demonstration of the perirectal soft tissues allowed assessment of spastic pelvic floor syndrome, descending perineum syndrome and visualization of enteroceles. Conclusion: MRI can replace CD in the diagnosis of the pelvic floor disorders, providing useful information for the therapeutic planning. The lack of radiation exposure makes MRI the preferred method for post-treatment follow-up.