# Acoustic Modeling of skull bone for improved transcranial MR-guided focused ultrasound therapy

> **NIH NIH F31** · UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH · 2024 · $43,374

## Abstract

Project Summary/Abstract (Limit 30 lines)
This proposal aims to improve the patient-specific Computed Tomography (CT)-derived modeling of
transcranial focused ultrasound by comparing acoustic and thermal simulations to hydrophone scans of
excised skull flaps and clinical magnetic resonance thermometry (MRTI) from Essential Tremor (ET)
thalamotomy treatments. Magnetic resonance-guided transcranial focused ultrasound (tMRgFUS) is a non-
invasive therapeutic modality used to treat a wide variety of neurological disorders. tMRgFUS relies on tightly
focusing the ultrasound beam through the inhomogeneous human skull. A fundamental challenge is accurately
determining the acoustic properties of the skull to phase-compensate for the inhomogeneities. Furthermore,
acoustic parameters such as speed of sound c and attenuation α may change with increased temperature,
causing further defocusing. Inaccurate acoustic parameters can result in off-target heating, longer treatment
times, and failed treatments.
This project will improve the focusing of ultrasound through the human skull by accurately determining
individual skull acoustic parameters. The Hybrid Angular Spectrum (HAS) beam simulation method and the
Pennes bioheat equation can simulate pressure fields and thermal rises by mapping acoustic and thermal
parameters to CT Hounsfield Units. The results of these simulations may be compared to experimental data to
determine the accuracy of tFUS acoustic and thermal modeling. Applying this method in reverse, a surrogate
optimization algorithm, which excels at black-box expensive optimization problems, will be used to iteratively
adjust simulation parameters to fit experimental data using a cost function. Aim I will determine the relationship
of the acoustic properties of bone to CT Hounsfield Units. An optimization algorithm will iteratively adjust the
acoustic parameter mapping such that a cost function comparing simulated and measured transmitted acoustic
pressures is minimized. The resulting optimal acoustic parameters accurately model transcranial acoustic
transmission. Aim II will determine the cause of reduced treatment efficiency with high acoustic powers during
tMRgFUS. An optimization algorithm will iteratively adjust the acoustic and thermal parameters to minimize a
cost function comparing simulation to MRTI data from clinical ET Thalamotomy patients.
This work will improve acoustic modeling through the human skull, which is the first step in improving
transcranial focused ultrasound therapy. According to the Focused Ultrasound Foundation, tMRgFUS could be
applied to at least 34 neurological disorders. Thus, this work could have a magnified effect, significantly
reducing morbidity and mortality across the field of neurology.

## Key facts

- **NIH application ID:** 11015757
- **Project number:** 5F31DE032916-02
- **Recipient organization:** UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH
- **Principal Investigator:** Sam Clinard
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $43,374
- **Award type:** 5
- **Project period:** 2023-07-20 → 2025-07-19

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11015757

## Citation

> US National Institutes of Health, RePORTER application 11015757, Acoustic Modeling of skull bone for improved transcranial MR-guided focused ultrasound therapy (5F31DE032916-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/11015757. Licensed CC0.

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