Eyding Jens, Wilkening Wilko, Postert Thomas
Department of Neurology, Ruhr-University Bochum, D-44791, Bochum, Germany.
Eur J Ultrasound. 2002 Nov;16(1-2):91-104. doi: 10.1016/s0929-8266(02)00042-3.
Advances in neurosonology have generated several techniques of ultrasonic perfusion imaging employing ultrasound echo contrast agents (ECAs). Doppler imaging techniques cannot measure the low flow velocities that are associated with parenchymal perfusion. Ultrasonic perfusion imaging, therefore, is a combination of a contrast agent-specific ultrasound imaging technique (CAI) mode and a data acquisition and processing (DAP) technique that is suited to observe and evaluate the perfusion kinetics. The intensity in CAI images is a measure of ECA concentration but also depends on various other parameters, e.g. depth of examination. Moreover, ECAs can be destroyed by ultrasound, which is an artifact but can also be a feature. Thus, many different DAPs have been developed for certain CAI techniques, ECAs and target organs. Although substantial progress in ECA and CAI technology can be foreseen, ultrasound contrast imaging has yet to reliably differentiate between normal and pathological perfusion conditions. Destructive imaging techniques, such as contrast burst imaging (CBI) or time variance imaging (TVI), in combination with new DAP techniques provide sufficient signal-to-noise ratio (SNR) for transcranial applications, and consider contrast agent kinetics and destruction to eliminate depth dependency and to calculate semi-quantitative parameters. Since ultrasound machines are widely accessible and cost-effective, ultrasonic perfusion imaging techniques should become supplementary standard perfusion imaging techniques in acute stroke diagnosis and monitoring. This paper gives an overview on different CAI and DAP techniques with special focus on recent innovations and their clinical potential.
神经超声学的进展催生了几种利用超声造影剂（ECA）的超声灌注成像技术。多普勒成像技术无法测量与实质灌注相关的低血流速度。因此，超声灌注成像是一种特定造影剂的超声成像技术（CAI）模式与适合观察和评估灌注动力学的数据采集与处理（DAP）技术的结合。CAI图像中的强度是ECA浓度的一种度量，但也取决于各种其他参数，例如检查深度。此外，ECA会被超声破坏，这既是一种伪像，也可能是一个特征。因此，针对某些CAI技术、ECA和靶器官，已经开发了许多不同的DAP。尽管可以预见ECA和CAI技术会取得重大进展，但超声造影成像尚未可靠地区分正常和病理灌注情况。诸如对比脉冲成像（CBI）或时间方差成像（TVI）等破坏性成像技术，与新的DAP技术相结合，为经颅应用提供了足够的信噪比（SNR），并考虑了造影剂动力学和破坏情况，以消除深度依赖性并计算半定量参数。由于超声设备广泛可得且具有成本效益，超声灌注成像技术应成为急性卒中诊断和监测中的辅助标准灌注成像技术。本文概述了不同的CAI和DAP技术，特别关注近期的创新及其临床潜力。
