Perioperative prediction by MRI of prostate volume six to twelve months after laser-induced thermotherapy of benign prostatic hyperplasia

The purpose of this study was to predict prostate volume outcome 6-12 month s after Interstitial, laser-induced thermotherapy (LITT) for benign prostat ic hyperplasia (BPH) on the basis of prostate magnetic resonance (MR) image s obtained within 48 hours before and after LITT. Twenty patients (age, 64. 2 +/- 7.4 years) with symptomatic BPH had LITT of the transitional zone of the prostate. NM was performed within 48 hours before and after LITT, and 6 -12 months after LITT (late follow-up). MM included axial and sagittal T2-w eighted fast spin-echo (PSE) images and contrast-enhanced, axial TI-weighte d images. Volumes of different prostatic compartments (total prostate, tran sitional zone, peripheral zone, LITT lesions) were measured by planimetry. Subtraction of LITT lesion volume less than 48 hours after LITT from total and transitional zone vol,,me before LITT, respectively, predicted respecti ve prostatic volumes at late follow-up. Pearson correlations of predicted a nd measured total prostate and transitional zone volumes were 0.972 and 0.9 75, respectively. Total prostate volume at late follow-up was accurately pr edicted (difference, -0.5 +/- 5.7 cc; P = 0.6981, two-tailed paired t-test) . Transitional zone volume was underestimated (difference, -3.1 +/- 4.7 cc; P = 0.0075). Peripheral zone volume was overestimated (difference, 2.6 +/- 3.5 cc; P = 0.0034). Perioperative MRI allows accurate prediction of prost ate volume 6-12 months after LITT for BPH. Underestimation of transitional zone volume may be due to ongoing growth of BPH. LITT appears to affect per ipheral zone tissue outside the target region. (C) 2001 Wiley-Liss, Inc.