Department of Neurology, Ahmanson-Lovelace Brain Mapping Center, University of California at Los Angeles, Los Angeles, California 90095-7085, USA.
Magn Reson Med. 2010 Nov;64(5):1289-95. doi: 10.1002/mrm.22630.
Arterial spin labeling (ASL) provides noninvasive measurement of tissue blood flow, but sensitivity to motion has limited its application to imaging of myocardial blood flow. Although different cardiac phases can be synchronized using electrocardiography triggering, breath holding is generally required to minimize effects of respiratory motion during ASL scanning, which may be challenging in clinical populations. Here a free-breathing myocardial ASL technique with the potential for reliable clinical application is presented, by combining ASL with a navigator-gated, electrocardiography-triggered TrueFISP readout sequence. Dynamic myocardial perfusion signals were measured at multiple delay times that allowed simultaneous fitting of myocardial blood flow and arterial transit time. With the assist of a nonrigid motion correction program, the estimated mean myocardial blood flow was 1.00 ± 0.55 mL/g/min with a mean transit time of ∼ 400 msec. The intraclass correlation coefficient of repeated scans was 0.89 with a mean within subject coefficient of variation of 22%. Perfusion response during mild to moderate stress was further measured. The capability for noninvasive, free-breathing assessment of myocardial blood flow using ASL may offer an alternative approach to first-pass perfusion MRI for clinical evaluation of patients with coronary artery disease.
动脉自旋标记（ASL）提供了组织血流的非侵入性测量，但由于对运动的敏感性限制了其在心肌血流成像中的应用。尽管可以使用心电图触发来同步不同的心脏相位，但为了最小化 ASL 扫描期间呼吸运动的影响，通常需要屏气，这在临床人群中可能具有挑战性。这里提出了一种具有可靠临床应用潜力的自由呼吸心肌 ASL 技术，通过将 ASL 与导航门控、心电图触发的 TrueFISP 读取序列相结合。在多个延迟时间下测量动态心肌灌注信号，允许同时拟合心肌血流和动脉传输时间。在非刚性运动校正程序的辅助下，估计的平均心肌血流为 1.00 ± 0.55 mL/g/min，平均传输时间约为 400 毫秒。重复扫描的组内相关系数为 0.89，个体内变异系数的平均值为 22%。还进一步测量了轻度至中度应激期间的灌注反应。使用 ASL 进行非侵入性、自由呼吸评估心肌血流的能力可能为冠状动脉疾病患者的临床评估提供了一种替代首过灌注 MRI 的方法。
