Applications of focused ultrasound to the brain rely on the knowledge of acoustic parameters of bone, including the speed of sound, absorption, scattering, and heat capacity. The speed of sound is needed for phase aberration correction. The other parameters are needed for modeling of the loss when the beam crosses the skull, as well as modeling of heating in the skull. Phase aberration correction and accurate modeling are needed for all brain studies including ablation studies, BBB opening studies, and neuromodulation.
Unfortunately, the literature on these values is scarce. They are sometimes given as a function of density and/or CT Hounsfield units, but this literature is not robust. They are never given as a function of MRI T2. This is needed for applications such as neuromodulation, as these studies need to rely on the less invasive MRI for phase aberration correction, rather than the more invasive CT.
In this work, we propose to measure the acoustic parameters of bone as a function of CT HU and MRI UTE parameters and do a comparison with experimental effeciency of the skull in patients treated with ET.