In the current pilot safety and feasibility (S&F) study for ultrasound-guided PVP (UG-PVP), we propose to use TRUS and the TRUS-Robot to record ultrasound images during PVP in 10 patients. The PVP procedure will be conducted as usual, without using the ultrasound for guiding the intervention. TRUS images of the prostate gland and the intraprostatic cavity formed during the PVP procedure will be recorded. These will include three dimensional (3-D) images acquired at the beginning and end of the operation. In addition, real-time 2-D images will be recorded during the case. Recorded images will then be analyzed offline to observe the extent of the vaporization or enucleation of the prostate gland.