Candidate selection for quadrant-based focal ablation through a combination of diffusion-weighted magnetic resonance imaging and prostate biopsy.

Abstract

To identify prostatic quadrants that could be preserved without intervention, using diffusion-weighted magnetic resonance imaging (DWI) and extended core biopsy, as a step toward implementation of quadrant-based focal ablation with potential preservation of erectile and ejaculatory functions, based on comparisons with unilateral hemi-gland ablation. We conducted a prebiopsy DWI study including 648 quadrants in 162 men who underwent 14-core biopsy including anterior sampling and radical prostatectomy (RP) for localised cancer. Imaging and pathology were analysed on a quadrant basis. Each quadrant was assessed through four-core sampling. Predictive performance of DWI and biopsy for quadrant status was analysed. On RP specimens, 170 anterior (52.5%) and 172 posterior quadrants (53.1%) harboured significant cancer. Negative predictive values of DWI, biopsy, and their combination for significant cancer were 79.7%, 70.6%, and 91.1%, respectively, in anterior quadrants, and 78.5%, 81.3%, and 91.7%, respectively, in posterior quadrants. DWI incrementally improved the negative predictive values of biopsy in anterior (P < 0.001) and posterior quadrants (P = 0.025), without untoward impacts on positive predictive values. Negative findings on both DWI and biopsy were identified in posterior quadrants of 109 sides (33.6%), but in entire hemi-glands of 54 sides (16.7%). The combination of DWI and 14-core biopsy including anterior sampling efficiently identifies quadrants without significant cancer in men with localised prostate cancer; the remaining quadrants, therefore, could be potential candidate areas for focal ablation. Focal therapy designed based on quadrant-based assessment could be superior to unilateral hemi-gland ablation for preservation of posterior quadrants and retaining of sexual function in more sides.