Image Guidance of a Phased Array Transducer for Neuromodulation with a Small Focal Volume

Transcranial focused ultrasound (tFUS) can modulate the brain using neuronavigation systems that guide where tFUS is delivered. However, neuronavigation systems can have up to 3-mm of targeting error. Previous tFUS systems have circumvented these targeting errors by using transducers with large focal volumes. However, these large focal volumes also deliver large amounts of pressure to off-target brain regions. Here, we describe a method that integrates a phased array into a neuronavigation system with a broadened focus that ensures sonication at the selected target while minimizing off-target effects. We show the broadened focus delivers significantly less energy off-target and has a focal volume of 189.07mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> which is more than 8 times smaller than the focus created by other common single element transducers.