Integrated US-MR fusion images and MR targeted biopsies. What are their role and value in the detection and follow-up of prostate cancer.

Accuracy of multiparametric MRI has greatly improved the ability of localizing tumor foci of prostate cancer. This property can be used to perform a TRUS-MR image registration, new technological advance, which allows for an overlay of an MRI onto a TRUS image to target a prostate biopsy toward a suspicious area Three types of registration have been developed: cognitive-based, sensor-based, and organ-based registration. Cognitive registration consists of aiming a suspicious area during biopsy with the knowledge of the lesion location identified on multiparametric MRI. Sensor-based registration consists of tracking in real time the TRUS probe with a magnetic device, achieving a global positioning system which overlays in real-time prostate image on both modalities. Organ based registration does not aim to track the TRUS probe, but the prostate itself to compute in a 3D acquisition the TRUS prostate shape, allowing for a registration with the corresponding 3D MRI shape. The concept of an MR-US fusion TB strategy only is gaining more and more widespread acceptance. In a TB only strategy, fewer men could be biopsied overall, with a greater proportion of men diagnosed with clinically significant prostate, as well as fewer men"over diagnosed" with clinically insignificant cancer. However, more clinical research is required before this strategy is ready for widespread adoption.