From Detection to Surveillance: The Evolving Role of Micro-Ultrasound in Prostate Cancer.

High-resolution micro-ultrasound (microUS) is a 29 MHz imaging modality that allows visualisation of prostatic ductal architecture at 70 µm resolution, enabling real-time recognition of architectural disruption associated with clinically significant prostate cancer (csPCa). This review summarises the current evidence for microUS in the diagnosis and management of prostate cancer, with emphasis on developments since the pivotal OPTIMUM phase-3 randomised controlled trial. OPTIMUM provided level 1 evidence for microUS-guided biopsy as non-inferior to MRI-guided biopsy for csPCa detection. We examine the PRI-MUS risk identification protocol, the pre- and post-OPTIMUM evidence base, biopsy targeting and core number, inter-observer reliability and the learning curve, and emerging applications in active surveillance, restaging biopsy, local staging and tumour characterisation, and post-treatment surveillance for local recurrence. We also review the growing body of work on artificial intelligence-enhanced microUS, alongside workflow, cost, and environmental considerations. Whilst inter-reader variability and the learning curve remain barriers, microUS offers comparable sensitivity to multiparametric MRI with practical advantages in cost, accessibility, and workflow. In our view, microUS warrants acceptance as a primary imaging modality for the work-up of suspected prostate cancer.