Transcranial magnetic resonance imaging- guided focused ultrasound surgery of brain tumors: initial findings in 3 patients

The Objective of this study was to evaluate the clinical feasibility of transcranial MRgFUS of brain tumors. Transcranial MRgFUS for brain tumors offers a potential noninvasive alternative to a surgical procedure. The method combines a hemispherical phased-array transducer and patient-specific treatment planning based on acoustic models with feedback control based on magnetic resonance temperature imaging to overcome the effects of the cranium and allow for controlled and precise thermal ablation in the brain.
In initial trials in 3 glioblastoma patients, multiple focused ultrasound exposures were applied up to the maximum acoustic power available. Offline analysis of the magnetic resonance temperature images evaluated the temperature changes at the focus and brain surface. It was found that it was possible to focus an ultrasound beam transcranially into the brain and to visualize the heating with magnetic resonance temperature imaging. Although the limitations by the device power available at the time, extrapolation of the temperature measurements at the focus and on the brain surface suggests that thermal ablation will be possible with this device without overheating the brain surface, with some possible limitation on the treatment envelope. These findings are a major step forward in producing a completely noninvasive alternative to surgical resection for brain tumors and brain disorders.