Jann Kay, Hauf Martinus, Kellner Weldon Frauke, El Koussy Marwan, Kiefer Claus, Federspiel Andrea, Schroth Gerhard
Department of Psychiatric Neurophysiology, University Hospital of Psychiatry and University of Bern, Bern, Switzerland.
Diagn Interv Radiol. 2016 Sep-Oct;22(5):481-8. doi: 10.5152/dir.2016.15204.
Arterial spin labeling (ASL) magnetic resonance imaging to assess cerebral blood flow (CBF) is of increasing interest in basic research and in diagnostic applications, since ASL provides similar information to positron emission tomography about perfusion in vascular territories. However, in patients with steno-occlusive arterial disease (SOAD), CBF as measured by ASL might be underestimated due to delayed bolus arrival, and thus increased spin relaxation. We aimed to estimate the extent to which bolus arrival time (BAT) was delayed in patients with SOAD and whether this resulted in underestimation of CBF.
BAT was measured using digital subtraction angiography (DSA) in ten patients with high-grade stenosis of the middle carotid artery (MCA). Regional CBF was assessed with pseudocontinuous ASL.
BATs were nonsignificantly prolonged in the stenotic hemisphere 4.1±2.0 s compared with the healthy hemisphere 3.3±0.9 s; however, there were substantial individual differences on the stenotic side. CBF in the anterior and posterior MCA territories were significantly reduced on the stenotic hemisphere. Severe stenosis was correlated with longer BAT and lower quantified CBF.
ASL-based perfusion measurement involves a race between the decay of the spins and the delivery of labeled blood to the region of interest. Special caution is needed when interpreting CBF values quantified in individuals with altered blood flow and delayed circulation times. However, from a clinician's point of view, an accentuation of hypoperfusion (even if caused by underestimation of CBF due to prolonged BATs) might be desirable since it indexes potentially harmful physiologic deficits.
动脉自旋标记（ASL）磁共振成像用于评估脑血流量（CBF），在基础研究和诊断应用中越来越受到关注，因为ASL提供了与正电子发射断层扫描关于血管区域灌注的类似信息。然而，在患有狭窄闭塞性动脉疾病（SOAD）的患者中，由于团注延迟到达以及自旋弛豫增加，ASL测量的CBF可能被低估。我们旨在估计SOAD患者团注到达时间（BAT）延迟的程度，以及这是否导致CBF被低估。
使用数字减影血管造影（DSA）测量10例颈内动脉中重度狭窄患者的BAT。用伪连续ASL评估局部CBF。
与健康半球的3.3±0.9秒相比，狭窄半球的BAT延长至4.1±2.0秒，但差异无统计学意义；然而，狭窄侧存在显著的个体差异。狭窄半球大脑中动脉前、后区域的CBF显著降低。严重狭窄与更长的BAT和更低的定量CBF相关。
基于ASL的灌注测量涉及自旋衰减与标记血液输送到感兴趣区域之间的竞争。在解释血流改变和循环时间延迟个体的CBF量化值时需要特别谨慎。然而，从临床医生的角度来看，灌注不足的加重（即使是由于BAT延长导致CBF低估所致）可能是可取的，因为它指示了潜在有害的生理缺陷。
