Abstract：
Arterial spin-labeled perfusion and blood oxygenation level-dependent functional MRI are indispensable tools for noninvasive human brain imaging in clinical and cognitive neuroscience, yet concerns persist regarding the reliability and reproducibility of functional MRI findings. The circadian rhythm is known to play a significant role in physiological and psychological responses, leading to variability in brain function at different times of the day. Despite this, test-retest reliability of brain function across different times of the day remains poorly understood. This study examined the test-retest reliability of six repeated cerebral blood flow measurements using arterial spin-labeled perfusion imaging both at resting-state and during the psychomotor vigilance test, as well as task-induced cerebral blood flow changes in a cohort of 38 healthy participants over a full day. The results demonstrated excellent test-retest reliability for absolute cerebral blood flow measurements at rest and during the psychomotor vigilance test throughout the day. However, task-induced cerebral blood flow changes exhibited poor reliability across various brain regions and networks. Furthermore, reliability declined over longer time intervals within the day, particularly during nighttime scans compared to daytime scans. These findings highlight the superior reliability of absolute cerebral blood flow compared to task-induced cerebral blood flow changes and emphasize the importance of controlling time-of-day effects to enhance the reliability and reproducibility of future brain imaging studies.
摘要：
动脉自旋标记灌注和血氧水平依赖性功能磁共振成像是临床和认知神经科学中不可缺少的非侵入性人脑成像工具。然而,对于功能性MRI检查结果的可靠性和可重复性仍然存在担忧.众所周知，昼夜节律在生理和心理反应中起着重要作用，导致大脑功能在一天中的不同时间变化。尽管如此,大脑功能在一天中不同时间的重测可靠性仍然知之甚少。这项研究检查了在静息状态和精神运动警觉测试期间使用动脉自旋标记灌注成像进行六次重复脑血流测量的测试-重测可靠性，以及一组38名健康参与者在一整天内由任务引起的脑血流变化。结果表明，在全天的休息和精神运动警惕性测试中，绝对脑血流量测量具有出色的重测可靠性。然而,任务诱导的脑血流变化在不同的大脑区域和网络中表现出较差的可靠性。此外，可靠性在一天内的较长时间间隔内下降，特别是在夜间扫描与白天扫描相比。这些发现强调了与任务诱导的脑血流量变化相比，绝对脑血流量具有更高的可靠性，并强调了控制一天中的时间效应以增强未来脑成像研究的可靠性和可重复性的重要性。
