Abstract

Transcranial magnetic resonance (MR) guided focused ultrasound (tcMRgFUS) enables the non-invasive treatment of the deep brain. This capacity relies on the ability to focus acoustic energy through the in-tact skull, a feat that requires accurate estimates of the acoustic velocity in individual patient skulls. In current practice, these estimates are generated using a pre-treatment CT scan and then registered to an MR dataset on the day of the treatment. Treatment safety and efficacy can be improved by eliminating the need to register the CT data to the MR images and by improving the accuracy of acoustic velocity measurements. In this study we examine the capacity of MR to supplement or replace CT as a means of estimating velocity in the skull. We find that MR can predict velocity with less but comparable accuracy to CT. We then use micro CT imaging to better understand the limitations of Hounsfield Unit (HU) based estimates of velocity, demonstrating that the macrostructure of pores in the skull contributes to the acoustic velocity of the bone. We find evidence that detailed T2 measurements provide information about pore macrostructure similar to the information obtained with micro CT, offering a potential clinical mechanism for improving patient specific estimates of acoustic velocity in the human skull.

View details for DOI 10.1109/TUFFC.2022.3192224

View details for PubMedID 35853046