A Time-Resolved Forward Model for MR-ARFI: Towards Acoustic Dosimetry for FUS Neuromodulation

Motivation: MR-ARFI is currently used to target focused ultrasound in the brain, but as a quantitative imaging method it has the potential to provide acoustic dosimetry if the measured tissue displacement can be related back to acoustic intensity or pressure. Goal(s): Develop a method to calculate MR-ARFI images based on high-intensity acoustic simulations of focused ultrasound and finite element modeling. Approach: We converted acoustic beam simulations to acoustic force, which was input to an FEM solver to calculate time-resolved tissue displacements, and subsequently MR-ARFI images. Results: The method enabled a lookup table calculation to recover acoustic intensity from MR-ARFI measurementsImpact: MR-ARFI is used to target focused ultrasound in the brain, but as a quantitative imaging method it could also provide dosimetry. We established the ability to relate simulated acoustic pressure fields to MR-ARFI images via finite element modeling.