For the laser ablation, you will lie on your back on a cushioned table in the MRI scanner. An endorectal MRI coil will be gently placed to your rectum similar to the diagnostic MRI examination. After starting intravenous sedation and injecting a local anesthetic, physicians will insert a small catheter to deliver a tiny optical fiber, the laser and a cooling device into the prostate. MR images will be used to change the orientation of the laser fiber to best target the lesion in the prostate. Under real-time MRI guidance, the laser fiber will be positioned within the tumor and used to heat the area to a temperature that kills cancer cells. The physicians will monitor the temperature within and around the treatment region to protect healthy tissue, especially areas near critical structures such as the urethra, erectile function nerves, and the rectal wall. After all of the targets are ablated, the coil will be removed. You will be helped up and shown to the restroom or to your dressing room to change back into your clothing.