Magnetic Resonance Imaging of Focused Ultrasound Radiation Force Strain Fields for Discrimination of Solid and Liquid Phases

William Ryan Willoughby; Henrik Odéen; Jesse Jones; Mark Bolding

doi:10.1016/j.ultrasmedbio.2023.05.004

Magnetic Resonance Imaging of Focused Ultrasound Radiation Force Strain Fields for Discrimination of Solid and Liquid Phases

Ultrasound Med Biol. 2023 Aug;49(8):1892-1900. doi: 10.1016/j.ultrasmedbio.2023.05.004. Epub 2023 Jun 2.

Authors

William Ryan Willoughby¹, Henrik Odéen², Jesse Jones³, Mark Bolding⁴

Affiliations

¹ Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA. Electronic address: wwilloughby@uab.edu.
² Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA.
³ Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, AL, USA.
⁴ Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA.

PMID: 37271680
DOI: 10.1016/j.ultrasmedbio.2023.05.004

Abstract

Objective: Focused ultrasound (FUS) has become a non-invasive option for some surgical procedures, including tumor ablation and thalamotomy. Extension of magnetic resonance (MR) imaging-guided focused ultrasound for ablation of slowly perfused cerebrovascular lesions requires a novel treatment monitoring method that does not rely on thermometry or high-frequency Doppler methods. The goal of this study was to evaluate the sensitivity and specificity of strain estimates based on MR acoustic radiation force imaging (MR-ARFI) for differentiation of solids and liquids.

Methods: Strain fields were estimated in gelatin-based tissue-mimicking focused ultrasound phantoms on the basis of apparent displacement fields measured by MR-ARFI. MR-ARFI and diffusion-weighted imaging (DWI) measurements were made before and after FUS-induced heating to evaluate the performance of displacement, strain and apparent diffusion coefficient (ADC) measurements for the discrimination of solid and liquid phases.

Results: As revealed by receiver operating characteristic analyses, axial normal strain and shear strain components performed significantly better than axial displacement measurements alone when predicting whether a gelatin had melted. Additional measurements must be made to estimate certain strain components, so this trade-off must be considered when developing clinical strategies. ADC had the best overall performance, but DWI is vulnerable to signal dropouts and susceptibility artifacts near cerebrovascular lesions, so this metric may have limited clinical applicability.

Conclusion: Strain components based on MR-ARFI apparent displacement measurements perform better than apparent displacement measurements alone at discriminating between solids and liquids. These methods are applicable to FUS treatment monitoring and evaluation of mechanical tissue properties in vivo.

Keywords: Cavernous malformation; Focused ultrasound; Magnetic resonance imaging; Strain; Venous malformation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Diffusion Magnetic Resonance Imaging
Gelatin*
High-Intensity Focused Ultrasound Ablation* / methods
Magnetic Resonance Imaging / methods
Ultrasonic Waves

Substances

Gelatin