Injected periurethral collagen for postprostatectomy urinary incontinence: MR and CT appearance

Background: Urinary incontinence, a disturbing complication of radical prostatectomy, is often treated with periurethral collagen injections to increase urethral closure and resistance to urinary outflow. Methods: Using magnetic resonance imaging and computed tomography, we studied the appearance of glutaraldehyde cross-lined bovine collagen endoscopically injected into the periurethral tissues in four men who developed urinary incontinence after radical prostatectomy. Collagen was also scanned in vitro to verify its magnetic resonance appearance, Results: Collagen deposits appear as well-circumscribed nodules of low to intermediate signal intensity on both T1- and T2-weighted images in the periurethral tissues or in the base of the subjacent penile bulb (base of corpus spongiosum). On contrast-enhanced computed tomography, collagen appears as a hypoattenuating nodular-filling defect within the penile bulb. Conclusion. These imaging characteristics should allow differentiation of collagen from locally recurrent prostate carcinoma and avoid inappropriate work-up of benign findings.