High intensity focused ultrasound (HIFU) focal spot localization using harmonic motion imaging (HMI).
High intensity focused ultrasound (HIFU) focal spot localization using harmonic motion imaging (HMI).
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DOI：
10.1088/0031-9155/60/15/5911
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发表时间：
2015-08-07
影响因子：
3.5
通讯作者：
Konofagou E
中科院分区：
文献类型：
--
作者：
Han Y;Hou GY;Wang S;Konofagou E
已经提出了几种基于超声的成像模态用于高强度聚焦超声（HIFU）治疗的图像引导和监测。然而，在HIFU消融的临床实施中，治疗的有效区域（焦点）的准确定位和表征仍然是重要的障碍。聚焦超声谐波运动成像（HMIFU）是一种利用辐射力诱导的局部振荡位移的HIFU监测技术。已经证明，HIFU可以正确识别HIFU热消融损伤的形成和程度。然而，在识别治疗计划所必需的HIFU焦点的位置方面仍然存在显著的问题。在这项研究中，诱导位移被用来定位HIFU焦点内的组织治疗前。两个独立系统的可行性得到了证明。一维高强度聚焦超声系统由一个高强度聚焦超声换能器和一个共焦单元件脉冲回波换能器组成，前者发射一个用于机械激励的调幅高强度聚焦超声束，后者用于同步射频采集。2D HIFU系统由HIFU相控阵和用于同时成像的同轴成像相控阵组成。最初的可行性首先在仿组织明胶体模上进行，聚焦区定义为HMI位移的半峰处的−3 dB全宽对应的区域。使用相同的参数，在犬肝脏标本中进行体外实验，以比较所定义的聚焦区与病变。体外测量显示HMI预测的聚焦区和诱导的HIFU损伤位置之间具有良好的一致性。实验表明，高强度聚焦超声能够预测和跟踪体模和体外组织中的聚焦区域。通过与消融后组织中的病变位置进行比较来评价焦斑定位的准确性，在2D HMI系统中，R2 = 0.821，p<0.002。我们证明了使用这种基于HMI的技术来定位HIFU焦斑而不会在计划阶段引起热变化的可行性。焦斑定位方法也已应用于离体人类乳腺组织消融，并可完全集成到任何HMI系统中用于规划目的。
Several ultrasound-based imaging modalities have been proposed for image guidance and monitoring of High-Intensity Focused Ultrasound (HIFU) treatment. However, accurate localization and characterization of the effective region of treatment (focal spot) remain important obstacles in the clinical implementation of HIFU ablation. Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a HIFU monitoring technique that utilizes radiation-force-induced localized oscillatory displacement. HMIFU has been shown to correctly identify the formation and extent of HIFU thermal ablation lesions. However a significant problem remains in identifying the location of the HIFU focus, which is necessary for treatment planning. In this study, the induced displacement was employed to localize the HIFU focal spot inside the tissue prior to treatment. Feasibility was shown with two separate systems. The 1D HMIFU system consisted of a HIFU transducer emitting an amplitude-modulated HIFU beam for mechanical excitation and a confocal single-element, pulse-echo transducer for simultaneous RF acquisition. The 2D HIFU system consists of a HIFU phased array, and a co-axial imaging phased array for simultaneous imaging. Initial feasibility was first performed on tissue-mimicking gelatin phantoms and the focal zone was defined as the region corresponding to the −3 dB full width at half maximum of the HMI displacement. Using the same parameters, in vitro experiments were performed in canine liver specimens to compare the defined focal zone with the lesion. In vitro measurements showed good agreement between the HMI predicted focal zone and the induced HIFU lesion location. HMIFU was experimentally shown to be capable of predicting and tracking the focal region in both phantoms and in vitro tissues. The accuracy of focal spot localization was evaluated by comparing with the lesion location in post-ablative tissues, with a R2 = 0.821 at p<0.002 in the 2D HMI system. We demonstrated the feasibility of using this HMI-based technique to localize the HIFU focal spot without inducing thermal changes during the planning phase. The focal spot localization method has also been applied on ex vivo human breast tissue ablation and can be fully integrated into any HMI system for planning purposes.