Serial mpMRI (Multi Parametric Magnetic Resonance Imaging) Scanning in Prostate Cancer After Androgen Deprivation Therapy and RadioTherapy

External beam radiotherapy (EBRT) fails to eradicate prostate cancer in 24-33% of cases. Response is monitored solely by testing serum prostate specific antigen (PSA), with biochemical failure following radiotherapy defined as a prostate specific antigen (PSA) level of 2 ng/ml above the nadir. T2 and Dynamic Contrast Enhanced (DCE) MRI have been shown to be able to detect the recurrence of prostate cancer following radiotherapy. Changes seen in Apparent Diffusion Coefficient (ADC) variables post-treatment have potential use in monitoring disease response to radiotherapy but the natural history of these changes during and after treatment remains uncertain and warrants further investigation. This study investigates the feasibility of using multi-parametric MRI (mpMRI) and novel diffusion-weighted sequences called VERDICT (Vascular, Extracellular and Restricted Diffusion for Cytometry in Tumours) at various stages during the treatment of prostate cancer with radiotherapy. Patients will be first scanned before androgen deprivation therapy (ADT) starts, then 3 weeks before the start of radiotherapy, again in week 6 of radiotherapy and once more 6 months after the end of radiotherapy. In addition, all patients entered into the study will already have had a mpMRI scan prior to prostate biopsy as part of their standard care. Multi-parametric MRI and VERDICT sequences may reveal changes in the tumour and normal prostate before a detectable PSA increase. This could allow for their use in response assessment following radiotherapy and androgen deprivation treatment. If such clinical utility is proven, referral for salvage treatment using High Intensity Focussed Ultrasound (HIFU), cryotherapy or salvage radical prostatectomy may be expedited.