Four types of transurethral applicators were devised for thermal ablation of prostate combined with MR thermal
monitoring: sectored tubular transducer devices with directional heating patterns; planar and curvilinear devices with
narrow heating patterns; and multi-sectored tubular devices capable of dynamic angular control without applicator
movement. These devices are integrated with a 4 mm delivery catheter, incorporate an inflatable cooling balloon (10
mm OD) for positioning within the prostate and capable of rotation via an MR-compatible motor. Interstitial devices
(2.4 mm OD) have been developed for percutaneous implantation with directional or dynamic angular control. In vivo
experiments in canine prostate under MR temperature imaging were used to evaluate the heating technology and develop
treatment control strategies. MR thermal imaging in a 0.5 T interventional MRI was used to monitor temperature and
thermal dose in multiple slices through the target volume. Sectored tubular, planar, and curvilinear transurethral
devices produce directional coagulation zones, extending 15-20 mm radial distance to the outer prostate capsule.
Sequential rotation and modulated dwell time can conform thermal ablation to selected regions. Multi-sectored
transurethral applicators can dynamically control the angular heating profile and target large regions of the gland in short
treatment times without applicator manipulation. Interstitial implants with directional devices can be used to effectively
ablate the posterior peripheral zone of the gland while protecting the rectum. The MR derived 52 °C and lethal thermal
dose contours (t43=240 min) allowed for real-time control of the applicators and effectively defined the extent of thermal
damage. Catheter-based ultrasound devices, combined with MR thermal monitoring, can produce relatively fast and
precise thermal ablation of prostate, with potential for treatment of cancer or BPH.
The purpose of this study is to further investigate the approach of DWI to estimate the cell viability immediately after treatment. In this work, we reported the result from 12 canine prostate experiments underwent cryoablation or hyperthermic therapy. The lesion detected by diffusion-weighted imaging was evaluated through apparent diffusion coefficient (ADC) value, image contrast, and lesion contour compared to contrast enhanced imaging and histology.