Korosec F R, Turski P A, Carroll T J, Mistretta C A, Grist T M
Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin.
J Magn Reson Imaging. 1999 Sep;10(3):317-25. doi: 10.1002/(sici)1522-2586(199909)10:3<317::aid-jmri14>3.0.co;2-m.
With contrast-enhanced MR angiographic techniques, a T1-shortening contrast agent is injected into the blood stream. Imaging during the first pass of the contrast agent permits acquisition of a high-contrast MR angiogram. Scan parameters such as flip angle, repetition time, echo time, and scan duration, and injection parameters, such as dose and rate, must be carefully chosen to achieve maximum contrast between blood vessels and stationary tissues. A critical parameter affecting image quality is the timing of the acquisition relative to the injection. If the collection of the center of k-space does not coincide with peak arterial concentration, artifacts, reduced SNR, and venous enhancement may result. Several techniques have been developed to address the timing issue. Post-processing techniques such as subtracting a pre-contrast image from a post-contrast angiogram can be used to improve image quality. Intravascular contrast agents that may also lead to improved image quality are currently being developed.
使用对比增强磁共振血管造影技术时，将一种T1缩短型对比剂注入血流。在对比剂首次通过期间进行成像可获取高对比度的磁共振血管造影图像。必须仔细选择诸如翻转角、重复时间、回波时间和扫描持续时间等扫描参数，以及诸如剂量和速率等注射参数，以实现血管与静止组织之间的最大对比度。影响图像质量的一个关键参数是采集相对于注射的时间。如果k空间中心的采集与动脉峰值浓度不一致，可能会导致伪影、信噪比降低和静脉强化。已经开发了几种技术来解决时间问题。诸如从对比增强血管造影图像中减去对比前图像的后处理技术可用于提高图像质量。目前正在开发也可能提高图像质量的血管内对比剂。
