Ultrasound Monitoring of In Vitro Radio Frequency Ablation by Echo Decorrelation Imaging
Ultrasound Monitoring of In Vitro Radio Frequency Ablation by Echo Decorrelation Imaging
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DOI：
10.7863/jum.2008.27.12.1685
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发表时间：
2008-12-01
影响因子：
2.3
通讯作者：
Buell, Joseph F.
中科院分区：
文献类型：
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作者：
Mast, T. Douglas;Pucke, Daniel P.;Buell, Joseph F.
Objective.本研究的目的是测试超声回波去相关成像，用于射频消融（RFA）引起的组织效应的标测和表征。方法.对新鲜离体牛肝组织（n = 9）进行射频消融术（持续时间6分钟，功率20 W），连续采集7 MHz线性阵列的波束形成超声回波数据。处理回波数据以形成B扫描图像、回波去相关图像（与回波波形的快速随机变化相关）和背向散射积分图像（与接收到的回波能量的局部变化相关）。回声去相关和集成的反向散射值在一个低噪声热电偶的位置进行了评估，作为温度的函数。回波去相关和背向散射积分图像直接与消融组织横截面进行比较，并作为组织消融和过度治疗的预测因子进行定量评价。结果回波去相关图对应于局部组织温度和消融效果。一致的回声去相关增加，观察温度高于75摄氏度，而集成的背向散射图显示出复杂的声学阴影，在大的温度升高的高方差的非单调的温度依赖性。在回波去相关和背向散射积分图作为局部组织消融预测因子的受试者工作特征曲线分析中，回波去相关表现良好（消融的受试者工作特征曲线下面积[AUROC] = 0.855，过度治疗的受试者工作特征曲线下面积[AUROC] = 0.913），而背向散射积分表现较差（AUROC < 0.6）。结论.回波去相关成像可以在体外映射由于RFA引起的组织变化，局部回波去相关强烈对应于局部组织温度升高和消融效应。随着进一步的发展和体内验证，回波去相关成像可能有助于改善临床RFA手术的图像引导。
Objective. The purpose of this study was to test ultrasound echo decorrelation imaging for mapping and characterization of tissue effects caused by radio frequency ablation (RFA). Methods. Radio frequency ablation procedures (6-minute duration, 20-W power) were performed on fresh ex vivo bovine liver tissue (n = 9) with continuous acquisition of beam-formed ultrasound echo data from a 7-MHz linear array. Echo data were processed to form B-scan images, echo decorrelation images (related to rapid random changes in echo waveforms), and integrated backscatter images (related to local changes in received echo energy). Echo decorrelation and integrated backscatter values at the location of a low-noise thermocouple were assessed as functions of temperature. Echo decorrelation and integrated backscatter images were directly compared with ablated tissue cross sections and quantitatively evaluated as predictors of tissue ablation and overtreatment. Results. Echo decorrelation maps corresponded with local tissue temperature and ablation effects. Consistent echo decorrelation increases were observed for temperatures above 75 degrees C, whereas integrated backscatter maps showed a nonmonotonic temperature dependence complicated by acoustic shadowing, with high variance at large temperature elevations. In receiver operating characteristic curve analysis of echo decorrelation and integrated backscatter maps as predictors of local tissue ablation, echo decorrelation performed well (area under the receiver operating characteristic curve [AUROC] = 0.855 for ablation and 0.913 for overtreatment), whereas integrated backscatter performed poorly (AUROC < 0.6). Conclusions. Echo decorrelation imaging can map tissue changes due to RFA in vitro, with local echo decorrelation corresponding strongly to local tissue temperature elevations and ablation effects. With further development and in vivo validation, echo decorrelation imaging is potentially useful for improved image guidance of clinical RFA procedures.