Utility of Restriction Spectrum Imaging Among Men Undergoing First-Time Biopsy for Suspected Prostate Cancer.

Abstract

<b>OBJECTIVE.</b> The purpose of this article is to evaluate restriction spectrum imaging (RSI) in men undergoing MRI-ultrasound fusion biopsy for suspected prostate cancer (PCa) and to compare the performance of RSI with that of conventional DWI. <b>MATERIALS AND METHODS.</b> One hundred ninety-eight biopsy-naïve men enrolled in a concurrent prospective clinical trial evaluating MRI-targeted prostate biopsy underwent multiparametric MRI with RSI. Clinical and imaging features were compared between men with and without clinically significant (CS) PCa (MRI-ultrasound fusion biopsy Gleason score ≥ 3 + 4). RSI <i>z</i> score and apparent diffusion coefficient (ADC) were correlated, and their diagnostic performances were compared. <b>RESULTS.</b> CS PCa was detected in 109 of 198 men (55%). Using predefined thresholds of ADC less than or equal to 1000 μm²/s and RSI <i>z</i> score greater than or equal to 3, sensitivity and specificity for CS PCa were 86% and 38%, respectively, for ADC and 61% and 70%, respectively, for RSI. In the transition zone (<i>n</i> = 69), the sensitivity and specificity were 94% and 17%, respectively, for ADC and 59% and 69%, respectively, for RSI. Among lesions with CS PCa, RSI <i>z</i> score and ADC were significantly inversely correlated in the peripheral zone (ρ = -0.4852; <i>p</i> < 0.01) but not the transition zone (ρ = -0.2412; <i>p</i> = 0.17). Overall diagnostic accuracies of RSI and DWI were 0.70 and 0.68, respectively (<i>p</i> = 0.74). <b>CONCLUSION.</b> RSI and DWI achieved equivalent diagnostic performance for PCa detection in a large population of men undergoing first-time prostate biopsy for suspected PCa, but RSI had superior specificity for transition zone lesions.