Noninvasive Estimation of Temperature Change Using Pulse-Echo Ultrasound

描述(由申请人提供)：拟议研究的广泛的、长期的目标是开发一种用于监测和指导非侵入性和微创性热疗设备的集成系统。我们考虑使用脉冲高强度聚焦超声(PHIFU)在单次激发模式和栅格扫描模式下形成体积病变。根据治疗性和亚治疗性PHIFU注射的应用对组织温度的非侵入性估计是这些设备在临床上被广泛接受的关键。脉冲回波超声已被证明在原则上适合作为一种具有温度成像能力的图像制导方式。然而，使用脉冲回波超声的非侵入性温度成像仍然受到限制，阻碍了其在临床系统中的采用。本申请通过提出开发一种具有多种成像模式的集成成像系统来解决这些限制，该成像系统旨在捕捉组织变形的所有空间和时间动态，无论是自然的(例如，由于呼吸和心脏周期引起的)还是源诱导的。对于单次激发加热毫米体积的PHIFU源，由于辐射力效应对组织的机械应力可能需要高脉冲重复频率(PRF)的M型成像，以捕捉组织对治疗性和亚治疗性脉冲的全部动力学响应。在具有相对较大的非均匀加热场的光栅扫描模式中，可能需要在高PRF下采集多条A线，以捕捉响应于脉冲源的瞬时2D组织变形。对于这两种模式，我们提出了一种新的数据采集协议，该协议将全帧2D射频数据采集与M模式相结合，用于单次激发PHIFU，并将M2D模式用于光栅扫描体积加热模式。所谓M2D模式成像，我们指的是以尽可能高的PRF收集有限数量的相邻A线。这将允许在空间和时间上同时以高分辨率同时捕获组织变形，以捕获复杂温度场的动态。如果成功，这项研究将导致使用诊断性脉冲回波超声进行强大的实时温度成像。这将对临床接受PHIFU作为对肿瘤和其他组织异常进行热疗的经济有效和可靠的方式产生重大影响。 与公共健康相关：强健的温度成像被认为是微创和非侵入性热疗的“使能技术”。诊断性脉冲回波超声有可能对加热设备的温度变化进行成像，但存在显著的局限性，阻碍了其临床接受。拟议的研究从系统和信号处理设计的角度解决了这些限制。如果成功，将开发用于监测和指导热疗的可靠的实时温度估计，并为体内试验做好准备。

DESCRIPTION (provided by applicant): The broad, long-term objective of the proposed research is to develop an integrated system for monitoring and guidance of noninvasive and minimally-invasive thermotherapy devices. We consider the use of pulsed high intensity focused ultrasound (pHIFU) in single-shot mode and raster scanned mode to form volumetric lesions. Noninvasive estimation of tissue temperature in response to the application of therapeutic and sub-therapeutic pHIFU shots is a key to the wide spread acceptance of these devices in the clinic. Pulse-echo ultrasound has been shown to be suitable, in principle, as an image guidance modality with temperature imaging capability. However, noninvasive temperature imaging using pulse-echo ultrasound still suffers from limitations that hindered its adoption in clinical systems. This application addresses these limitations by proposing to develop an integrated imaging system with a variety of imaging modes designed to capture all the spatial and temporal dynamics of tissue deformations, whether native (e.g. due to breathing and cardiac cycle) or source induced. For a pHIFU source with single shots heating mm-size volumes, the mechanical stresses on the tissue due to radiation force effects may require M-mode imaging with high pulse repetition frequency (PRF) to capture the full dynamics of tissue deformation in response to therapeutic and subtherapeutic pulses. In raster-scan mode with relatively large heterogeneous heating field may require a number of A-lines to be acquired at high PRF to capture transient 2D tissue deformations in response to the pulsed source. For both of these modes, we propose new data acquisition protocols mixing full frame 2D RF data collection with M-mode for single-shot pHIFU and M2D-mode for raster-scan volumetric heating mode. By M2D-mode imaging we mean the collection of limited number of neighboring A-lines at the highest possible PRF. This will allow for simultaneous capture of tissue deformations with simultaneously high resolution in space and time to capture the dynamics of the complex temperature field. If successful, this research will lead to a robust real-time temperature imaging using diagnostic pulse-echo ultrasound. This will have significant impact on the clinical acceptance of pHIFU as a cost-effective and reliable modality for delivering thermal therapy to tumors and other tissue abnormalities. PUBLIC HEALTH RELEVANCE: Robust temperature imaging is considered an "enabling technology" for minimally-invasive and noninvasive thermal therapy. Diagnostic pulse-echo ultrasound has the potential for imaging temperature changes in response to heating devices, but suffers from significant limitations that hindered its clinical acceptance. The proposed research addresses these limitations from the system and signal processing design perspectives. If successful, robust real-time temperature estimation for monitoring and guidance of thermal therapy will be developed and be ready for in vivo testing.