Imaging for the selection and monitoring of men on active surveillance for prostate cancer.

Traditional prostate imaging is fairly limited, and only a few imaging modalities have been used for this purpose. Until today, grey scale ultrasound was the most widely used method for the characterization of the prostatic gland, however its limitations for prostate cancer (PCa) detection are well known and hence ultrasound is primarily used to localize the prostate and facilitate template prostate biopsies. In the past decade, multiparametric magnetic resonance imaging (mpMRI) of the prostate has emerged as a promising tool for the detection of PCa. Evidence has shown the value of mpMRI in the active surveillance (AS) population, given its ability to detect more aggressive disease, with data building up and supporting its use for the selection of patients suitable for surveillance. Additionally, mpMRI targeted biopsies have shown an improved detection rate of aggressive PCa when compared to regular transrectal ultrasound (TRUS) guided biopsies. Current data supports the use of mpMRI in patients considered for AS for reclassification purposes; with a negative mpMRI indicating a decreased risk of reclassification. However, a percentage of patients with negative imaging or low suspicion lesions can experience reclassification, highlighting the importance of repeat confirmatory biopsy regardless of mpMRI findings. At present, no robust data is available to recommend the substitution of regular biopsies with mpMRI in the follow-up of patients on AS and efforts are being made to determine the role of integrating genomic markers with imaging with the objective of minimizing the need of biopsies during the follow up period.