Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
Magn Reson Med. 2012 Mar;67(3):609-13. doi: 10.1002/mrm.23318. Epub 2011 Dec 21.
Current myocardial perfusion MRI acquisitions are performed with a saturation recovery sequence, in large part to minimize sensitivity to arrhythmia. A new approach is proposed here where the images are acquired ungated at steady state without use of a saturation pulse. The data are acquired continuously and reach steady state after the first few images. A confluence of advances has made this new paradigm of an ungated steady-state acquisition possible-very rapid undersampled readouts with new reconstruction technologies permit enough measurements that continuous acquisition becomes a feasible approach. Gating can be applied retrospectively from a logged electrocardiogram (ECG) or with self-gating methods. In this work, simulations and measurements in a concentration phantom are used to demonstrate that similar contrast and signal can be obtained with the standard saturation recovery and the proposed spoiled gradient echo (SPGR) acquisition. Specifically, for a flip angle of 14° and a saturation recovery time of 80 ms, similar signals are acquired over a range of T(1) s that reflect realistic myocardial tissue concentrations. Preliminary results in one subject are presented to show the potential of this new approach. The method may allow for cine cardiac perfusion and more signal-to-noise ratio-efficient acquisitions.
目前的心肌灌注 MRI 采集是使用饱和恢复序列进行的，在很大程度上是为了最大限度地减少对心律失常的敏感性。这里提出了一种新的方法，即在没有使用饱和脉冲的情况下在稳态下采集未门控图像。数据连续采集，在前几张图像后达到稳态。一系列进展使得这种无门控稳态采集的新范例成为可能——使用新的重建技术进行非常快速的欠采样读数，可以进行足够的测量，从而使连续采集成为一种可行的方法。门控可以从记录的心电图 (ECG) 或自门控方法中回顾性应用。在这项工作中，使用浓度体模中的模拟和测量来证明，标准饱和恢复和所提出的扰相梯度回波 (SPGR) 采集可以获得相似的对比度和信号。具体来说，对于翻转角为 14°和饱和恢复时间为 80ms，在反映真实心肌组织浓度的 T(1) s 范围内，可以采集到相似的信号。在一个受试者中的初步结果表明了这种新方法的潜力。该方法可以实现电影心脏灌注和更高信噪比效率的采集。
