Prostate cancer is the most common male cancer in the United States with an estimated 181,000 new cases and 26,000 deaths in 2016 . Transrectal ultrasound (TRUS) guided biopsy is the gold standard for definitive diagnosis in which the imaging and needle insertion are both done transrectally. Since ultrasound guidance results in insufficient sensitivity of prostate cancer diagnosis (40–60%), fusion of preoperative MRI with real-time US has been proposed to increase the sensitivity (∼ 90%). Transperineal biopsies have recently gained attention using a brachytherapy grid to biopsy through the perineum rather than the rectum, practically eliminating the possibility of infection.
To enable MR-US fusion, electromagnetic tracking system is commonly used to make a 3D volume out of a stack of 2D US images acquired during an initial sweep of prostate. The EM tracking however is somewhat undesirable as it adds to the cost of the procedure and is prone to inaccuracies. Therefore, in this study, we propose a method that eliminates the need for such external tracking devices and inserts the needle transperineally thus reducing infection risks. Also, the procedure is more comfortable to the patient since the TRUS probe is eliminated. A patient specific grid template is designed based on the MR image of the patient.