Safe and Accurate Targeting for Transcranial Focused Ultrasound

Abstract

Transcranial focused ultrasound (FUS) is being studied for a number of research and clinical applications in the brain. Transcranial FUS is able to generate bioeffects with minimal invasiveness on a millimeter-scale. It is important that the FUS is applied to the brain region of interest. Image guidance with optical tracking provides the ability to target brain regions and magnetic resonance acoustic radiation force image (MR-ARFI) provides the ability to localize the FUS beam by measuring its effects on tissue. Localization of the FUS beam with MR-ARFI requires application of FUS energy which has potential to cause damage. By reducing the energy and number of sonications needed to localize the beam the risk of damage can be reduced. Simulations and in vivo measurements of the expected pressure and temperature during ARFI sonications can provide exposure estimates. Altering the geometry of the FUS transducer allows less pressure to be used for MR-ARFI localization. Combining optical tracking and phased array transducers allows multiple brain regions to be accurately targeted with a single localization scan. By reducing the potential for damage during localization and ensuring accurate targeting FUS can applied for many applications in neuroscience including blood brain barrier opening and neuromodulation.