Photoacoustic-guided ultrasound thermal imaging without prior knowledge of tissue composition

Jeungyoon Lee; Kelsey P Kubelick; Ayoung Choe; Stanislav Y Emelianov

doi:10.1016/j.pacs.2023.100554

Photoacoustic-guided ultrasound thermal imaging without prior knowledge of tissue composition

Photoacoustics. 2023 Sep 1:33:100554. doi: 10.1016/j.pacs.2023.100554. eCollection 2023 Oct.

Authors

Jeungyoon Lee¹, Kelsey P Kubelick^{1

2}, Ayoung Choe^{1

2}, Stanislav Y Emelianov^{1

2}

Affiliations

¹ School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
² Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA, USA.

Abstract

Thermal strain imaging (TSI) is a widely investigated ultrasound (US) thermometry technique that is based on the temperature-dependent change in speed of sound. However, a major challenge of TSI is a calibration process to account for material-dependent thermal strain. In this study, we leverage nanoparticle (NP)-mediated photoacoustic (PA) thermometry to calibrate thermal strain and guide US thermal imaging. By controlling the molecular composition of the sub-micrometer layer surrounding the NPs, PA thermometry becomes independent of the thermal characteristics of the overall background tissue where the NPs reside. Thus accurate temperature measurements are obtainable from sparse NP-mediated PA signals. These measurements are used to guide TSI, allowing US thermometry to produce an expanded temperature map over the entire region of interest without prior knowledge of tissue composition. Our feasibility study in tissue-mimicking phantoms demonstrates the potential to improve TSI by integrating a PA-based calibration method that complements and guides US thermometry.

Keywords: Hyperthermia; Nanoparticles; Photoacoustics; Thermal imaging; Thermal therapy; Ultrasound.