MRI Guided Transcranial Acoustoelectric Imaging for Safe and Accurate Electrical Brain Mapping

Transcranial acoustoelectric brain imaging (tABI) is a new modality that combines ultrasound (US) delivery through the skull with radiofrequency sensing to produce electrical maps of the brain at high resolution. Whereas noninvasive EEG suffers from poor spatial resolution and inaccuracies for estimating current source densities, tABI takes advantage of an acoustoelectric (AE) interaction signal, which confines the current measurement to the focal region of the US beam on the millimeter scale. To safely and accurately deliver US pulses to the brain and co-register tABI maps with structure, a feedback and guidance system is required. The goal of this study is to demonstrate and determine the accuracy of neuronavigated tABI with real-time feedback for optimally placing the US array and directing the beam to the selected target location in the head. This will facilitate co-registration of the human head model, structural MRI, and tABI current density maps. The integrated system allows for a prediction of the US beam trajectory through the human skull with registration to clinical images for guidance and improving accuracy of real-time tABI. The guided system protocol adds only minutes to the process and results in easy localization of the target in the brain. The guided tABI has a resolution of 3 mm and a targetting accuracy of 5.1 mm.