超声非线性频率复合方法的发展及其在组织测温中的应用。

Development of an ultrasonic nonlinear frequency compounding method with applications in tissue thermometry.

机构信息

Department of Physics, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada.

出版信息

J Acoust Soc Am. 2021 Oct;150(4):3192. doi: 10.1121/10.0006207.

Abstract

Frequency compounding is an ultrasound imaging technique used to improve signal-to-noise ratio (SNR). In this work, a nonlinear frequency compounding (NLFC) method was introduced, and its application in noninvasive tissue thermometry investigated. The NLFC method was used to produce two-dimensional maps of the temperature sensitive change in backscattered energy of acoustic harmonics (hCBE), during heating of ex vivo porcine tissue with a low intensity focused ultrasound transducer. A hCBE-to-temperature calibration was performed, and temperature maps produced and compared with a theoretical COMSOL based model. Last, a comparative study of the NLFC and previously used nonlinear single frequency (NLSF) methods was completed to quantify the improvement in SNR of the produced hCBE maps. When using the NLFC method, a SNR of 6.06 ± 1.28 was found. SNR values of 3.70 ± 0.53 and 4.38 ± 0.84 were found while using central frequencies of 4.31 and 5.43 MHz, respectively, with the NLSF method. This translates to an improvement of (64.13 ± 4.16)% over the 4.31 MHz NLSF, and (38.72 ± 2.97)% over the 5.43 MHz NLSF methods overall. It was concluded that the NLFC method can produce hCBE and temperature maps with superior image SNR over the NLSF method.

摘要

频率复合是一种用于提高信噪比（SNR）的超声成像技术。在这项工作中，引入了一种非线性频率复合（NLFC）方法，并研究了其在无创组织测温中的应用。NLFC 方法用于产生背向散射能量声谐波（hCBE）温度敏感变化的二维图，在使用低强度聚焦超声换能器加热离体猪组织期间。进行了 hCBE 到温度的校准，并生成了温度图，并与基于理论 COMSOL 的模型进行了比较。最后，完成了 NLFC 和以前使用的非线性单频（NLSF）方法的比较研究，以量化产生的 hCBE 图的 SNR 提高。当使用 NLFC 方法时，发现 SNR 为 6.06±1.28。使用 NLSF 方法时，分别使用中心频率为 4.31 和 5.43 MHz 时，发现 SNR 值为 3.70±0.53 和 4.38±0.84。这相当于与 4.31 MHz NLSF 相比提高了（64.13±4.16）%，与 5.43 MHz NLSF 方法相比提高了（38.72±2.97）%。得出的结论是，NLFC 方法可以产生具有比 NLSF 方法更高 SNR 的 hCBE 和温度图。