Micro-Ultrasound: Current Role in Prostate Cancer Diagnosis and Future Possibilities

SIMPLE SUMMARY: Prostate cancer (PCa) is the second most common cancer in males, and ranks second for cancer death in men. Magnetic resonance imaging (MRI) can detect PCa more accurately than biopsy alone and is now the recommended initial test in men at risk for PCa. MRI however requires additional resources and cost. Micro-ultrasound (microUS) is a new high resolution ultrasound technology that can be used to image the prostate. It integrates into the standard clinical workflow of prostate biopsy. In this review, 13 relevant publications comparing detection of clinically significant PCa between MRI and microUS were selected. The studies conclude that prostate cancer detection by microUS and MRI are comparable. ABSTRACT: Prostate Cancer (PCa) is the second most common cancer in men. Population screening using prostate specific antigen (PSA) blood test and digital rectal exam (DRE) is recommended by the NCCN, EAU and other prominent clinical guidelines. While MRI is the recommended initial test in men at risk for PCa, micro-Ultrasound (MicroUS) is a novel high resolution ultrasound technology that has shown promise in PCa detection. This article provides a narrative review of the studies to date which have been conducted to evaluate the functionality and efficacy of MicroUS within the patient care pathway for prostate cancer. A total of 13 relevant publications comparing detection of csPCa between MicroUS and mpMRI were selected. An amount of 4 publications referring to use of MicroUS for other indications were found. Each publication was evaluated for risk of bias and applicability using the Quality Assessment of Diagnostic Accuracy (QUADAS-2) tool. The studies reviewed conclude that MicroUS detection rates for clinically significant prostate cancer diagnosis are comparable to the detection rates of mpMRI guided biopsy procedures. While the existing literature indicates that MicroUS should replace conventional TRUS for prostate imaging and biopsy, it is not yet clear whether MicroUS should be used on its own or in conjunction with mpMRI for augmenting prostate cancer detection. The ongoing OPTIMUM trial will provide evidence on how best to utilize this new technology. Early data also suggest this flexible new imaging modality has a place in local staging and active surveillance of prostate cancer as well as in bladder cancer staging.