Patient-level detection of grade group ≥2 prostate cancer using quantitative diffusion MRI

Purpose Multiparametric MRI (mpMRI) improves detection of clinically significant prostate cancer (csPCa), but the qualitative PI-RADS system and quantitative apparent diffusion coefficient (ADC) yield inconsistent results. An advanced Restrictrion Spectrum Imaging (RSI) model may yield a better quantitative marker for csPCa, the RSI restriction score (RSI rs ). We evaluated RSI rs for patient-level detection of csPCa. Materials and Methods Retrospective analysis of men who underwent mpMRI with RSI and prostate biopsy for suspected prostate cancer from 2017-2019. Maximum RSI rs within the prostate was assessed by area under the receiver operating characteristic curve (AUC) for discriminating csPCa (grade group ≥2) from benign or grade group 1 biopsies. Performance of RSI rs was compared to minimum ADC and PI-RADS v2-2.1via bootstrap confidence intervals and bootstrap difference (two-tailed α=0.05). We also tested whether the combination of PI-RADS and RSI rs (PI-RADS+RSI rs ) was superior to PI-RADS, alone. Results 151 patients met criteria for inclusion. AUC values for ADC, RSI rs , and PI-RADS were 0.50 [95% confidence interval: 0.41, 0.60], 0.76 [0.68, 0.84], and 0.78 [0.71, 0.85], respectively. RSI rs ( p =0.0002) and PI-RADS ( p <0.0001) were superior to ADC for patient-level detection of csPCa. The performance of RSI rs was comparable to that of PI-RADS ( p =0.6). AUC for PI-RADS+RSI rs was 0.84 [0.77, 0.90], superior to PI-RADS or RSI rs , alone ( p =0.008, p =0.009). Conclusions RSI rs was superior to conventional ADC and comparable to (routine, clinical) PI-RADS for patient-level detection of csPCa. The combination of PI-RADS and RSI rs was superior to either alone. RSI rs is a promising quantitative marker worthy of prospective study in the setting of csPCa detection. Disclosures MEH reports honoraria from Multimodal Imaging Services Corporation and research funding from General Electric Healthcare. AMD is a Founder of and holds equity in CorTechs Labs, Inc, and serves on its Scientific Advisory Board. He is a member of the Scientific Advisory Board of Human Longevity, Inc. and receives funding through research agreements with General Electric Healthcare. The terms of these arrangements have been reviewed and approved by the University of California San Diego in accordance with its conflict-of-interest policies. TMS reports honoraria from Multimodal Imaging Services Corporation, Varian Medical Systems, and WebMD; he has an equity interest in CorTechs Labs, Inc. and also serves on its Scientific Advisory Board. These companies might potentially benefit from the research results. The terms of this arrangement have been reviewed and approved by the University of California San Diego in accordance with its conflict-of-interest policies.