LASER ABLATION-INDUCED CHANGES IN THE PROSTATE - FINDINGS AT ENDORECTAL MR-IMAGING WITH HISTOLOGIC CORRELATION

PURPOSE: To correlate laser ablation-induced changes in the prostate a s depicted at endorectal magnetic resonance (MR) imaging with results at histologic examination. MATERIALS AND METHODS: In eight patients wi th prostate carcinoma, visually guided laser ablation was performed du ring lymphadenectomy. Radical prostate resection was performed 4-9 day s (mean, 6.9 days) after ablation in seven patients and at 70 days in one patient. The study protocol consisted of (a) endorectal T2-weighte d fast spin-echo imaging, (b) dynamic T1-weighted spoiled gradient-ech o imaging prior to and after injection of contrast material, and (c) g adolinium-enhanced T1-weighted spin-echo imaging. Imaging findings wer e correlated with macroscopic and histologic findings. RESULTS: Histol ogic examination revealed periurethral necrosis with a marginal zone t hat consisted of partially necrotic tissue, dilated vessels, and hemor rhagic areas. Considerable interindividual difference was observed in the extent of morphologic alterations (area, 0-18.0 cm(3)). Gadolinium -enhanced images were best suited for assessment of laser ablation-ind uced changes. The correlation between the volume of altered tissue mea sured on MR images and in macroscopic specimens was excellent (r(2) = .96). CONCLUSION: MR imaging helped monitor changes induced with laser ablation (which differed greatly among individuals). MR monitoring ma y thus be useful in patients with obstructive benign prostatic hyperpl asia after laser ablation.