ECG Triggering and Gating for Ultrasonic Small Animal Cardiac Flow Imaging

• Main Authors: Wan-Ya Chen, 陳婉雅
• Other Authors: 李百祺
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/96651016387243847271

碩士 === 國立臺灣大學 === 生醫電子與資訊學研究所 === 98 === Ultrasound has been used to image murine models noninvasively and longitudinally in real-time for cardiovascular disorder studies. To improve spatial resolution to 100μm or higher, high frequency ultrasound (>20MHz) has to be used. Because of the frame rate limitation due to the fact that mechanical scanning on single element transducers need to be applied, the temporal resolution up to hundreds fps is hard to achieve. ECG gating strategies which synchronize the image acquisition with the cardiac cycle, can retrospectively reconstruct a series of images at equivalent high frame rate and thus is of interest in this study. In previous research, B-mode in vivo images were retrospectively reconstructed, with the center frequency of 25MHz and the pulse repetition frequency at 2kHz, and the frame rate is equivalently raised to 2000frames/second. The current study is extended from ECG gated/triggered B-mode imaging to Color Doppler imaging. Firstly, phantom experiments under the center frequency of 3.5MHz and the pulse repetition frequency at 1kHz were performed. The series of Color Doppler images corresponding to an output flow cycle were reconstructed with emulated ECG output that gates data acquisition. Phantom experiments were conducted again on a single element transducer high frequency system, under the frequency of 30MHz and the pulse repetition frequency at 5kHz~10kHz. The reconstructed Color Doppler images were compared to PW Doppler velocity profile quantitatively. The two are temporally matched and the spatial information is provided only by the former, but the velocity in the former is lower than that in the latter. ECG gating/triggering Color Doppler is suitable for retrospective flow imaging, taking the frame rate up to 5000-10000fps equivalently. In vivo tests with ECG and flow turbulence are on-going.