Laser ablation-induced changes in the prostate: findings at endorectal MR imaging with histologic correlation

To correlate laser ablation-induced changes in the prostate as depicted at endorectal magnetic resonance (MR) imaging with results at histologic examination.

In eight patients with prostate carcinoma, visually guided laser ablation was performed during lymphadenectomy. Radical prostate resection was performed 4-9 days (mean, 6.9 days) after ablation in seven patients and at 70 days in one patient. The study protocol consisted of (a) endorectal T2-weighted fast spin-echo imaging, (b) dynamic T1-weighted spoiled gradient-echo imaging prior to and after injection of contrast material, and (c) gadolinium-enhanced T1-weighted spin-echo imaging. Imaging findings were correlated with macroscopic and histologic findings.

Histologic examination revealed periurethral necrosis with a marginal zone that consisted of partially necrotic tissue, dilated vessels, and hemorrhagic areas. Considerable interindividual difference was observed in the extent of morphologic alterations (area, 0-18.0 cm3). Gadolinium-enhanced images were best suited for assessment of laser ablation-induced changes. The correlation between the volume of altered tissue measured on MR images and in macroscopic specimens was excellent (r2 = .96).

MR imaging helped monitor changes induced with laser ablation (which differed greatly among individuals). MR monitoring may thus be useful in patients with obstructive benign prostatic hyperplasia after laser ablation.