Intraprocedural Three-Dimensional Imaging Registration Optimizes Magnetic Resonance Imaging–Guided Focused Ultrasound and Facilitates Novel Applications

Transcranial magnetic resonance-guided focused ultrasound (MRgFUS) has revolutionized ablative treatment of essential tremor in recent years. However, limitations in precision targeting may account for suboptimal efficacy and significant side effects. We describe a simple intraprocedural three-dimensional image-guided lesion shaping technique that can improve overall outcomes of MRgFUS for essential tremor and facilitate expansion to novel indications. A retrospective review of 84 consecutive MRgFUS procedures performed at Pennsylvania Hospital was performed. Comparison of patient demographics, treatment parameters, and clinical outcomes before and after implementation of this protocol was conducted. Further application of this technique in pallidotomy treatments and ablative disconnection of hypothalamic hamartoma are described. After implementation, the median of total number of sonications (7 vs 9, P = .001), number of therapeutic sonications (3 vs 4, P < .0001), and interval time between the first and last sonication (46:10 vs 68:53 minutes, P = .0004) were significantly reduced. Patients expressed greater satisfaction of treatment (94.1% vs 82.4%, P = .018), greater global impression of change (CGI) (7 vs 6, P = .033), and reduced median number of side effects at 6 months (0 vs 1, P = .026). We also successfully implemented this protocol for novel indications. Intraprocedural lesion shaping for MRgFUS is a simple and versatile imaging protocol augmentation that improves ablation precision and can improve treatment efficacy and broader neurological application.