Brain-focussed ultrasound: what's the "FUS" all about? A review of current and emerging neurological applications

Abstract

MR-guided focussed ultrasound surgery (MRgFUS) allows for precise non-invasive thermal ablation of target tissues for a wide range of clinical applications. It is an innovative and rapidly expanding technology, which has already established itself as an effective and safe incisionless alternative in the treatment of various soft tissue tumours, with many more research studies underway to extend its therapeutic envelope. The non-invasiveness of the procedure makes FUS particularly attractive in functional neurosurgery, where existing treatment options are not suitable for all patients. Several clinical trials have demonstrated the feasibility and favourable safety profile of MR-guided focused ultrasound surgery in essential tremor, Parkinson's disease and other neurological conditions. This article reviews the existing evidence base for the neurological applications of FUS and the evidence for its emerging roles in the treatment of a range of brain disorders.

Figure 1.

Sagittal T₂ weighted image of the brain, showing the depth of brain targets amenable to modern MRgFUS techniques. The lines indicate the multiple possible ultrasound beam trajectories to reach a target in the thalamus. MRgFUS involves incisionless deep brain focal ablation, without the trajectory planning constraints associated with the more traditional neurosurgical alternatives. MRgFUS, MR-guided focussed ultrasound surgery.