Objective

Improving the readout for arterial spin labeling with multiple post-labeling delays (multi-PLD ASL) through a flip angle (FA) sweep towards increasing contrast-to-noise ratio for long PLD images.

Methods

Images were acquired from 20 healthy subjects and 14 patients with severe, asymptomatic carotid artery stenosis (ACAS) in a 3T MRI scanner. Multi-PLD ASL images with conventional and proposed (FA sweep) readouts were acquired. For patients, magnetic resonance angiography was used to validate the multi-PLD ASL results. Perfusion values were calculated for brain regions irrigated by the main cerebral arteries and compared by analysis of variance.

Results

For healthy subjects, better contrast was obtained for long PLDs when using the proposed multi-PLD method compared to the conventional. For both methods, no hemispheric difference of perfusion was observed. For patients, the proposed method facilitated the observation of delayed tissue perfusion, which was not visible for long PLD using the conventional multi-PLD ASL.

Conclusion

We successfully assessed brain perfusion of patients with asymptomatic CAS using multi-PLD ASL with FA sweep. We were able to show subtle individual differences. Moreover, prolonged arterial transit time in patients was observed, although they were considered asymptomatic, suggesting that it may not be an adequate term to characterize them.

中文翻译：

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动脉自旋标记的对比度优化，具有用于脑血管评估的多个标记后延迟。

客观的

通过翻转角 (FA) 扫描提高具有多个标记后延迟 (multi-PLD ASL) 的动脉自旋标记的读数，以提高长 PLD 图像的对比度噪声比。

方法

图像是在 3T MRI 扫描仪中从 20 名健康受试者和 14 名患有严重无症状颈动脉狭窄 (ACAS) 的患者身上获取的。获得了具有传统和建议（FA 扫描）读数的多 PLD ASL 图像。对于患者，磁共振血管造影用于验证多 PLD ASL 结果。计算由大脑主动脉灌注的大脑区域的灌注值，并通过方差分析进行比较。

结果

对于健康受试者，与传统方法相比，当使用所提出的多 PLD 方法时，长 PLD 获得了更好的对比度。对于这两种方法，没有观察到灌注的半球差异。对于患者，所提出的方法促进了延迟组织灌注的观察，这对于使用传统多 PLD ASL 的长 PLD 是不可见的。

结论

我们使用多 PLD ASL 和 FA 扫描成功评估了无症状 CAS 患者的脑灌注。我们能够表现出细微的个体差异。此外，观察到患者动脉传输时间延长，尽管他们被认为是无症状的，这表明用这个术语来描述他们的特征可能不够充分。