Participants will undergo RSI at three time points: before therapy (MRI #1), after neoadjuvant ADT (MRI #2), and after radiotherapy (MRI #3). Treatment response will be assessed primarily by absence of biochemical recurrence (PSA ≥2 ng/mL greater than nadir) within 3 years of completing radiotherapy. Change in RSI cellularity index from MRI #1 to MRI #2 will be evaluated for prediction of participants who will experience biochemical recurrence within 3 years, using area under the receiver operating characteristic curve. We hypothesize that RSI cellularity index will be an early biomarker for treatment effectiveness in prostate cancer treated with ADT and radiotherapy.
