Short-term apparent brain tissue changes are contributed by cerebral blood flow alterations.

Area of Science:

• Neuroimaging
• Neuroscience
• Radiology

Background:

• Structural MRI (sMRI) studies often report apparent tissue changes (ATC) following neuropsychological training.
• The underlying causes of these ATC, particularly in short-term studies, remain unclear.
• Cerebral perfusion (blood flow) influences T1-weighted MRI signals, potentially contributing to ATC.

Purpose of the Study:

• To investigate the contribution of brain perfusion changes to short-term apparent tissue changes (ATC) observed in structural MRI.
• To determine if manipulating cerebral blood flow (CBF) affects sMRI-detected tissue alterations.

Main Methods:

• Acquired sMRI data before and after interventions designed to alter global and regional brain perfusion.
• Interventions included caffeine intake (to reduce CBF) and a sensorimotor task (to increase CBF).
• Voxel-wise regression was used to compensate for CBF alterations in the sMRI data.

Main Results:

• Caffeine intake led to reduced CBF and apparent tissue density in the temporal cortex, anterior cingulate cortex, and limbic areas.
• A sensorimotor task increased CBF and apparent tissue in overlapping brain regions.
• Correcting for CBF changes substantially suppressed the observed ATC patterns in both experimental conditions.

Conclusions:

• Brain perfusion significantly contributes to short-term apparent tissue changes detected by longitudinal T1-weighted structural MRI.
• Findings suggest that CBF variations must be accounted for in short-term longitudinal sMRI analyses to accurately interpret tissue changes.