A Feasibility Study to Evaluate Safety and Initial Effectiveness of ExAblate Transcranial MR Guided Focused Ultrasound for Unilateral Pallidotomy in the Treatment of Dyskinesia of Parkinson's Disease

Focused ultrasound is an attractive method for non-invasive thermal ablation of soft tissue, including functional brain targets. Treatment begins by acquiring a series of MR images of the target organ. The physician then identifies a target volume in the MR images, and delineates the treatment contours on the images. Therapy planning software calculates the parameters required to effectively treat the defined target volume. During the treatment, an ultrasound transducer generates a point of focused ultrasound energy, called a sonication. The sonication raises the tissue temperature within a well-defined region, enabling neurophysiological assessment in the low range, and thermal coagulation at higher ranges. MR images acquired during sonication provide a quantitative, real-time temperature map of the target area to confirm the location of the sonication and the size of the affected region.