Multi-resolution simulation of focused ultrasound propagation through ovine skull from a single-element transducer

Kyungho Yoon, Wonhye Lee, Phillip Croce, Amanda Cammalleri, Seung Schik Yoo

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Transcranial focused ultrasound (tFUS) is emerging as a non-invasive brain stimulation modality. Complicated interactions between acoustic pressure waves and osseous tissue introduce many challenges in the accurate targeting of an acoustic focus through the cranium. Image-guidance accompanied by a numerical simulation is desired to predict the intracranial acoustic propagation through the skull; however, such simulations typically demand heavy computation, which warrants an expedited processing method to provide on-site feedback for the user in guiding the acoustic focus to a particular brain region. In this paper, we present a multi-resolution simulation method based on the finite-difference time-domain formulation to model the transcranial propagation of acoustic waves from a single-element transducer (250 kHz). The multi-resolution approach improved computational efficiency by providing the flexibility in adjusting the spatial resolution. The simulation was also accelerated by utilizing parallelized computation through the graphic processing unit. To evaluate the accuracy of the method, we measured the actual acoustic fields through ex vivo sheep skulls with different sonication incident angles. The measured acoustic fields were compared to the simulation results in terms of focal location, dimensions, and pressure levels. The computational efficiency of the presented method was also assessed by comparing simulation speeds at various combinations of resolution grid settings. The multi-resolution grids consisting of 0.5 and 1.0 mm resolutions gave acceptable accuracy (under 3 mm in terms of focal position and dimension, less than 5% difference in peak pressure ratio) with a speed compatible with semi real-time user feedback (within 30 s). The proposed multi-resolution approach may serve as a novel tool for simulation-based guidance for tFUS applications.

Original languageEnglish
Article number105001
JournalPhysics in medicine and biology
Volume63
Issue number10
DOIs
Publication statusPublished - 2018 May 10

Bibliographical note

Funding Information:
This study was supported by NIH (RO1 MH111763,to SS Yoo).We would like to thank Dr Yongzhi Zhang and Ms Lori Foley for the skull extraction, and Dr Nathan J McDannold for the initial consultation regarding the project.

Publisher Copyright:
© 2018 Institute of Physics and Engineering in Medicine.

All Science Journal Classification (ASJC) codes

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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