Magnetic resonance-ultrasound fusion prostate biopsy in the diagnosis of prostate cancer

• Multiparametric MRI is an excellent imaging method to identify clinical relevant prostate cancers. T2WI provides the best anatomic image of the prostate, but functional parameters like DWI and DCE offer insight into the grade and aggressiveness of the index tumor.
• Targeted biopsy, using MRI fused with real-time ultrasound, can be routinely performed in an office-based setting using one of several commercially-available fusion devices equipped with advanced image registration software.
• Targeted prostate biopsy has the potential to improve prostate cancer diagnosis and management through the accurate localization of prostate cancers and preferential identification of significant cancers over indolent cancers. However, changes to the current prostate cancer risk classification systems may be needed to prevent the overtreatment of clinically indolent prostate cancers.
• Men with persistently elevated PSAs in the setting of a previous negative biopsy as well as men considering active surveillance may be the best candidates for targeted prostate biopsies.

The advent of multiparametric magnetic resonance imaging (MRI) has ushered in a new era for urologists who perform prostate needle biopsies. The fusion of MRI with transrectal ultrasound (US) allows the direct targeting of suspicious lesions, which has been shown to improve the performance of conventional random biopsy techniques by increasing detection of clinically relevant disease while also decreasing detection of low-risk cancer. However, as with any new technology, many questions regarding effectiveness, reproducibility, and generalizability still remain. In this review, we (1) provide a summary of the various sequences that comprise a MRI of the prostate; (2) evaluate the 3 different ways of incorporating MRI into targeted biopsies of the prostate including in-bore MRI-guided biopsy, cognitive fusion, and device-mediated fusion; (3) review the sensitivity of MR-US fusion in the detection of clinically significant and clinically insignificant disease; and (4) review the barriers to the widespread implementation of MR-US fusion into everyday practice. Whereas other articles in this issue of Urologic Oncology Seminars will discuss other aspects of MRI in the management of prostate cancer, the purpose of this article is to provide an overview of MR-US fusion biopsies in the diagnosis of prostate cancer.