Thermal memory based photoacoustic imaging of temperature
Thermal memory based photoacoustic imaging of temperature
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DOI：
10.1364/optica.6.000198
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发表时间：
2019-02-20
期刊：
影响因子：
10.4
通讯作者：
Yao, Junjie
中科院分区：
文献类型：
--
作者：
Zhou, Yuan;Li, Mucong;Yao, Junjie
温度测绘在许多生物医学研究和干预中至关重要，可以精确控制组织的热条件，以获得最佳治疗效率和最小的副作用。基于Gruneisen参数的温度依赖性，光声（PA）成像可以提供相对温度测量，但传统上在不知道基线温度的情况下测量绝对温度具有挑战性，特别是在光学和声学特性未知的深层组织中。在这里，我们报告了一种新的基于热能记忆的光声测温（TEMPT）。通过用纳秒激光脉冲的脉冲串照射组织，TEMPT利用热能延迟的温度依赖性，其由在热约束内获取的相应PA信号探测。一个自归一化的比率测量抵消了温度无关的数量和估计的Gruneisen参数。然后可以评估温度，给定组织的温度依赖性Gruneisen参数、质量密度和比热容。与传统的PA测温法不同，TEMPT不需要了解组织的基线温度，也不需要了解光学特性。我们已经开发了一个数学模型来描述TEMPT的温度依赖性。我们已经证明了在临床相关温度范围内对1.5 cm深度的组织体模进行温度评价的可行性。最后，作为概念验证，我们在聚焦超声治疗小鼠体内2 mm深度时应用TEMPT进行温度标测。作为一种通用的温度映射方法，TEMPT有望在小动物模型上的癌症热疗中得到应用。(c)根据OSA开放获取出版协议的条款，2019年美国光学学会
Temperature mapping is essential in many biomedical studies and interventions to precisely control the tissue's thermal conditions for optimal treatment efficiency and minimal side effects. Based on the Gruneisen parameter's temperature dependence, photoacoustic (PA) imaging can provide relative temperature measurement, but it has been traditionally challenging to measure absolute temperatures without knowing the baseline temperature, particularly in deep tissues with unknown optical and acoustic properties. Here, we report a new thermal-energy-memory-based photoacoustic thermometry (TEMPT). By illuminating the tissue with a burst of nanosecond laser pulses, TEMPT exploits the temperature dependence of the thermal energy lingering, which is probed by the corresponding PA signals acquired within the thermal confinement. A self-normalized ratiometric measurement cancels out temperature-irrelevant quantities and estimates the Gruneisen parameter. The temperature can then be evaluated, given the tissue's temperature-dependent Gruneisen parameter, mass density, and specific heat capacity. Unlike conventional PA thermometry, TEMPT does not require knowledge of the tissue's baseline temperature, nor the optical properties. We have developed a mathematical model to describe the temperature dependence in TEMPT. We have demonstrated the feasibility of the temperature evaluation on tissue phantoms at 1.5 cm depth within a clinically relevant temperature range. Finally, as proof-of-concept, we applied TEMPT for temperature mapping during focused ultrasound treatment in mice in vivo at 2 mm depth. As a generic temperature mapping method, TEMPT is expected to find applications in thermotherapy of cancers on small animal models. (c) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement