MR Research Laboratory and Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
Magn Reson Med. 2013 Aug;70(2):348-57. doi: 10.1002/mrm.24466. Epub 2012 Aug 30.
Time-resolved three-dimensional contrast-enhanced MR angiography often relies on view sharing of peripheral k-space data to enable acquisition of angiograms with both high spatial resolution and a rapid frame rate. It is typically assumed that k-space will be fully sampled during passage of the contrast bolus arterial phase. However, this is not the case when view sharing is incomplete, for example, at the leading edge of an enhancing vessel or if acquisition time is limited as in fluoroscopic tracking for multistation bolus chase MR angiography. Incomplete view sharing will degrade image quality, for example, by reducing vessel signal and sharpness and increasing undersampling artifacts. In this work, the evolution of angiogram quality with view sharing is quantitatively assessed in phantom experiments and in vivo contrast-enhanced MR angiography calf studies. It is demonstrated that there are multiple sets of sequence parameters that can yield a target image update time, but the choice of parameters can profoundly affect how image quality evolves with view sharing. A fundamental tradeoff between vessel signal and sharpness and its relationship to the sequence temporal footprint is investigated and discussed.
时分辨三维对比增强磁共振血管造影术通常依赖于外周 K 空间数据的视图共享，以实现具有高空间分辨率和快速帧率的血管造影图的获取。通常假设在对比剂团注动脉期通过时，K 空间将被完全采样。然而，当视图共享不完整时，情况并非如此，例如在增强血管的前缘，或者如果采集时间有限，例如在透视跟踪多站团注追踪磁共振血管造影术中。视图共享不完整会降低图像质量，例如，降低血管信号和锐度，并增加欠采样伪影。在这项工作中，通过体模实验和体内对比增强磁共振血管造影小腿研究定量评估了视图共享时血管造影质量的演变。结果表明，有多种序列参数可以产生目标图像更新时间，但参数的选择可以极大地影响视图共享时图像质量的演变方式。研究并讨论了血管信号和锐度之间的基本权衡及其与序列时间足迹的关系。
