BACKGROUND AND PURPOSE: MR imaging-guided focused sonography surgery is a new stereotactic technique that uses high-intensity focused sonography to heat and ablate tissue. The goal of this study was to describe MR imaging findings pre-and post-ventralis intermedius nucleus lesioning by MR imaging-guided focused sonography as a treatment for essential tremor and to determine whether there was an association between these imaging features and the clinical response to MR imaging-guided focused sonography.

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) has the potential to create a shift in the treatment paradigm of several intracranial disorders. High-resolution MRI guidance combined with an accurate method of delivering high doses of transcranial ultrasound energy to a discrete focal point has led to the exploration of noninvasive treatments for diseases traditionally treated by invasive surgical procedures. In this review, the authors examine the current intracranial applications under investigation and explore other potential uses for MRgFUS in the intracranial space based on their initial cadaveric studies. 215Abbreviations used in this paper: ICH = intracerebral hemorrhage; MRgFUS = magnetic resonance-guided focused ultrasound surgery; TCCD = transcranial color-coded duplex; TCD = transcranial Doppler; tPA = tissue plasminogen activator.

The authors have demonstrated that transcranial focal heating can be significantly improved in vitro by using UTE MRI to compute skull-induced ultrasound aberration corrections. Their results suggest that UTE MRI could be used instead of CT to implement such corrections on current 0.7 MHz clinical TcMRgFUS devices. The MR image acquisition and segmentation procedure demonstrated here would add less than 15 min to a clinical MRgFUS treatment session.

Magnetic Resonance guided Focused Ultrasound Surgery (MRgFUS) represents a novel combination of technologies that is actively being realized as a non-invasive therapeutic tool for a myriad of conditions. These applications are reviewed with a focus on neurological utilization. A combined search of Pubmed and Medline was performed to identify the key events and current status of MRgFUS, with a focus on neurological applications. MRgFUS signifies a potentially ideal device for the treatment of neurological diseases. As it is nearly real-time, it allows monitored provision of treatment location and energy deposition, is noninvasive, thereby limiting or eliminating disruption of normal tissue, provides focal delivery of therapeutic agents, enhances radiation delivery, and permits modulation of neural function. Multiple clinical applications are currently in clinical use and many more are under active preclinical investigation. The therapeutic potential of MRgFUS is expanding rapidly. Although clinically in its infancy, preclinical and early phase I clinical trials in neurosurgery suggest a promising future for MRgFUS. Further investigation is necessary to define its true potential and impact.

The feasibility of transcranial MRgFUS sonothrombolysis was demonstrated in in vitro and cadaveric models of ICH. Initial in vivo safety data in a swine model of ICH suggest the process to be safe. Minimally invasive treatment of ICH with MRgFUS warrants evaluation in the setting of a clinical trial.