Qin Yexian, Li Qian, Ingram Pier, Witte Russell S
Department of Medical Imaging, University of Arizona, Tucson, AZ USA 85724.
IEEE Netw. 2012 Oct;2012:910-913. doi: 10.1109/ULTSYM.2012.0227.
Ultrasound current source density imaging (UCSDI) is a noninvasive technique for mapping electric current fields in 4D (space + time) with the resolution of ultrasound imaging. This approach can potentially overcome limitations of conventional electrical mapping procedures often used during treatment of cardiac arrhythmia or epilepsy. However, at physiologic currents, the detected acoustoelectric (AE) interaction signal in tissue is very weak. In this work, we evaluated coded ultrasound excitation (chirps) for improving the sensitivity of UCSDI for mapping the electrocardiogram (ECG) in a live rabbit heart preparation. Results confirmed that chirps improved detection of the AE signal by as much as 6.1 dB compared to a square pulse. We further demonstrated mapping the ECG using a clinical intracardiac catheter, 1 MHz ultrasound transducer and coded excitation. B-mode pulse echo and UCSDI revealed regions of high current flow in the heart wall during the peak of the ECG. These improvements to UCSDI are important steps towards translation of this new technology to the clinic for rapidly mapping the cardiac activation wave.
超声电流源密度成像（UCSDI）是一种无创技术，可在4D（空间+时间）中以超声成像分辨率绘制电流场。这种方法有可能克服在治疗心律失常或癫痫时常用的传统电标测程序的局限性。然而，在生理电流下，组织中检测到的声电（AE）相互作用信号非常微弱。在这项工作中，我们评估了编码超声激励（啁啾信号），以提高UCSDI在活体兔心脏标本中绘制心电图（ECG）的灵敏度。结果证实，与方波脉冲相比，啁啾信号将AE信号的检测灵敏度提高了6.1 dB。我们进一步展示了使用临床心内导管、1 MHz超声换能器和编码激励来绘制ECG。B型脉冲回波和UCSDI显示，在ECG峰值期间，心脏壁中有高电流流动区域。UCSDI的这些改进是将这项新技术转化为临床应用以快速绘制心脏激活波的重要步骤。
