Chen Mengyue, Sheng Zhiyu, Wei Ran, Zhang Bohua, Kim Howuk, Wu Huaiyu, Chu Yu, Chen Qiyang, Breon Andrew, Li Sibo, Wielgat Matthew B, Shanmuganayagam Dhanansayan, Tzeng Edith, Geng Xuecang, Kim Kang, Jiang Xiaoning
Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA.
Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
Theranostics. 2025 Jan 1;15(3):815-827. doi: 10.7150/thno.95997. eCollection 2025.
Ultrasound-induced thermal strain imaging (US-TSI) is a promising ultrasound imaging modality that has been demonstrated in preclinical studies to identify a lipid-rich necrotic core of an atherosclerotic plaque. However, human physiological motion, e.g., cardiac pulsation, poses challenges in implementing US-TSI applications, where achieving a millisecond-level temperature rise by delivering acoustic energy from a compact US-TSI probe is a key requirement. This study aims to develop a transient ultrasound heating and thermocouple monitoring technique at the millisecond level for US-TSI applications. We designed, prototyped, and characterized a novel US-TSI probe that includes a high-power, 3.5 MHz heating transducer with symmetrical dual 1D concave array. Additionally, millisecond-level temperature monitoring was demonstrated with fast-response thermocouples in laser- and ultrasound- induced thermal tests. Subsequently, we demonstrated the prototyped US-TSI probe can produce a desired temperature rise in a millisecond-short time window phantom and animal tests. The prototyped US-TSI probe delivered zero-to-peak acoustic pressure up to 6.2 MPa with a 90 V input voltage. Both laser- and ultrasound- induced thermal tests verified that the selected thermocouples can monitor temperature change within 50 ms. The fast-response thermocouple confirmed the transient heating ability of the US-TSI probe, achieving a 3.9 °C temperature rise after a 25 ms heating duration (50% duty cycle) in the gel phantom and a 2.0 °C temperature rise after a 50 ms heating duration (50% duty cycle) in a pig model. We successfully demonstrated a millisecond-level transient heating and temperature monitoring technique utilizing the novel US-TSI probe and fast-response thermocouples. The reported transient ultrasound heating and thermocouple monitoring technique is promising for future human subject studies in US-TSI or other ultrasound-related thermal investigations.
超声诱导热应变成像（US - TSI）是一种很有前景的超声成像方式，临床前研究已证明其可识别动脉粥样硬化斑块中富含脂质的坏死核心。然而，人体生理运动，如心脏搏动，给US - TSI应用的实施带来了挑战，其中通过紧凑型US - TSI探头传递声能实现毫秒级的温度升高是一项关键要求。本研究旨在开发一种用于US - TSI应用的毫秒级瞬态超声加热和热电偶监测技术。我们设计、制作了原型并对一种新型US - TSI探头进行了特性表征，该探头包括一个高功率、3.5 MHz的加热换能器，具有对称的双一维凹面阵列。此外，在激光和超声诱导的热测试中，使用快速响应热电偶进行了毫秒级温度监测。随后，我们在毫秒级短时间窗口的体模和动物测试中证明了原型US - TSI探头能够产生所需的温度升高。该原型US - TSI探头在90 V输入电压下可产生高达6.2 MPa的零至峰值声压。激光和超声诱导的热测试均证实，所选热电偶能够在50 ms内监测温度变化。快速响应热电偶证实了US - TSI探头的瞬态加热能力，在凝胶体模中，经过25 ms加热持续时间（50%占空比）后温度升高3.9℃，在猪模型中，经过50 ms加热持续时间（50%占空比）后温度升高2.0℃。我们成功展示了一种利用新型US - TSI探头和快速响应热电偶的毫秒级瞬态加热和温度监测技术。所报道的瞬态超声加热和热电偶监测技术有望用于未来US - TSI或其他超声相关热研究中的人体研究。
