Magnetic resonance imaging of traumatic posterior urethral defects and pelvic crush injuries.

A total of 18 patients 4 to 71 years old with complete occlusion of the prostatomembranous urethra from pelvic crush injury underwent magnetic resonance imaging (MRI) of the pelvis just before open urethroplasty. MRI studies included T2-weighted sagittal and coronal images as well as transaxial T1 and T2-weighted spin-echo images. Operative findings and erectile function were correlated with MRI findings. All patients underwent conventional cystography and retrograde urethrography. The mean interval from injury to operation was 5.5 months (range 3 to 12 months) and followup averaged 12 months (range 3 to 40 months). Posttraumatic pelvic anatomy can be distorted and imaging in all 3 planes was needed. The severity and direction of prostatourethral dislocation, and the length of the urethral defect could be accurately determined, which often is not possible with conventional radiographic studies. MRI also demonstrated injuries at many locations along the erectile pathway, including sacral and ischial fractures as well as fractures and avulsions of the cavernous bodies. Pelvic MRI can accurately define the pelvic anatomy after crush injury and, therefore, it can provide useful preoperative information that cannot be obtained by conventional radiographic studies. Our results correlating MRI findings of cavernous avulsion with clinical impotence require further study.