MR-IMAGING OF TRAUMATIC POSTERIOR URETHRAL INJURY

To assess the role of magnetic resonance (MR) imaging in defining the surgical approach and in predicting permanent erectile dysfunction in patients with traumatic posterior urethral injury, 27 patients underwe nt MR imaging before open urethral reconstruction. MR findings were co rrelated with surgical findings, surgical approach, and sexual potency at 12,month follow-up. MR imaging correctly reveal ed the length of t he urethral injury (allowing for 0.5-cm discrepancy) in 23 of 27 (85%) patients and displacement of the prostatic apex in 19 of 21 (90%) pat ients. MR findings prompted a change in the clinically planned surgica l approach from perineal to combined perineal and transpubic in seven (26%) cases. Significant variables affecting permanent impotence were avulsion of the corpus cavernosum (P <.001), separation of the corpore al body (P < .05), and superior and/or lateral prostatic displacement (P <.05). When MR imaging findings of both cavernous avolsion and supe rior and/or lateral prostatic displacement were present, the probabili ty of permanent impotence was 95%. In the absence of these findings, t he probability of normal potency was 83%. MR imaging can be performed to help select the most effective surgical approach and to assess perm anent erectile dysfunction.