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Updated: Jul 17, 2026
Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling
Published on: May 30, 2011
Test-retest reliability and time-of-day variations of perfusion imaging at rest and during a vigilance task
Bowen Guo1, Tianxin Mao1, Ruiwen Tao1
1Center for Magnetic Resonance Imaging Research & Key Laboratory of Brain-Machine Intelligence for Information Behavior (Ministry of Education and Shanghai), School of Business and Management, Shanghai International Studies University, Shanghai 201620, China.
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.
Insights
Reliable brain imaging requires accounting for time of day. Absolute cerebral blood flow measurements show high reliability, unlike task-induced changes, which vary significantly.
Area of Science:
- Neuroimaging
- Cognitive Neuroscience
- Physiology
Background:
- Functional MRI (fMRI) is crucial for brain imaging but faces reliability concerns.
- Circadian rhythms influence brain function, causing time-of-day variability.
- Test-retest reliability of brain function across different times of day is understudied.
Purpose of the Study:
- To assess the test-retest reliability of arterial spin-labeled (ASL) perfusion imaging over a full day.
- To compare the reliability of resting-state and task-induced cerebral blood flow (CBF) changes.
- To investigate the impact of time of day on brain imaging reliability.
Main Methods:
- ASL perfusion imaging was used to measure CBF in 38 healthy participants.
- Six repeated measurements were taken at rest and during the psychomotor vigilance test (PVT).
- Reliability was assessed across different times of day, including nighttime scans.
Main Results:
- Absolute CBF measurements demonstrated excellent test-retest reliability at rest and during the PVT throughout the day.
- Task-induced CBF changes showed poor reliability across brain regions and networks.
- Reliability decreased with longer intervals and was lower during nighttime scans.
Conclusions:
- Absolute CBF measurements are more reliable than task-induced CBF changes in ASL imaging.
- Controlling for time-of-day effects is essential for improving fMRI reliability and reproducibility.
- Future studies should consider circadian influences for more robust findings.
