Restriction Spectrum Imaging-Magnetic Resonance Imaging to Improve Prostate Cancer Imaging in Men on Active...

Restriction spectrum imaging-magnetic resonance imaging is a short duration enhanced diffusion-weighted technique that seeks to standardize sequences and predict upgrading. We test this technology for active surveillance biopsies. Our objective is to investigate the utility of restriction spectrum imaging-magnetic resonance imaging to improve upgrading detection in a prostate cancer active surveillance cohort.

We prospectively enrolled men on active surveillance undergoing repeat biopsy from January 2016 to June 2019. Subjects underwent prostate multiparametric magnetic resonance imaging and restriction spectrum imaging-magnetic resonance imaging reviewed by a urological radiologist for PI-RADS® scored lesions, followed by magnetic resonance imaging-guided prostate biopsy by a urologist. Restriction spectrum imaging-magnetic resonance imaging analysis with proprietary research software (CorTechs Labs, San Diego, California) generated a restricted signal map. We compared the restricted signal map and apparent diffusion coefficient values using T-test, ANOVA, and logistic regression analyses for prediction of upgrading.

Of 123 enrolled men we identified 74 restriction spectrum imaging-magnetic resonance imaging regions of interest (targeted lesions) in 110 subjects, with 105 subjects completing biopsy. The restricted signal map was significant per PI-RADS score for true-positive lesion detection (mean difference 28, SD 0.7, p=0.001), and better than apparent diffusion coefficient (mean difference -15, SD 55, p=0.6). Restriction spectrum imaging generated restricted signal map values >50 improved sensitivity, specificity, positive predictive value and negative predictive value (81.0%, 81.8%, 54.2% and 94.2%) over PI-RADS ≥3 (71.4%, 38.9%, 23.7% and 83.7%, respectively) for Gleason upgrading. Overall restriction spectrum imaging is able to improve the AUC of 0.70 (95% CI 0.49-0.92, p=0.03) to 0.90 (95% CI 0.82-0.98, p <0.001).

Restriction spectrum imaging-magnetic resonance imaging enhances the standard PI-RADS system by providing a noninvasive radiological biomarker to predict upgrading in active surveillance.