MRI of the prostate: potential role of robots

Prostate cancer is the most frequently diagnosed malignancy in the male population. Transrectal ultrasound- guided biopsy is still the imaging modality of choice in detecting prostate cancer. However, with prostate cancer being detected at an earlier stage, most prostate cancers tend to be isoechoic to the surrounding healthy prostatic tissue and, therefore invisible, resulting in transrectal ultrasound-guided biopsy having a positive predictive value of only 15.2%. MRI of the prostate has a superior soft-tissue contrast resolution, high spatial resolution and multiplanar capability. The ability to localize prostate cancer with MRI provides an opportunity to utilize magnetic resonance (MR) guidance for prostate biopsy. A number of MR-compatible robots, ranging from a simple manipulator to a fully automated system, have been developed to biopsy suspicious prostate cancer areas. When combining MRI with fast imaging sequences, it is possible to track the needle or organ deformation in real time. As technology matures, precise image guidance for prostate interventions performed or assisted by specialized MR-compatible robotic devices may provide a uniquely accurate solution for guiding the intervention, directly based on MR findings and feedback. Such an instrument would become a valuable clinical tool for biopsies directly targeting imaged tumor foci and for delivering tumor-centered focal therapy.