Cerebral perfusion and arterial transit time changes during task activation determined with continuous arterial spin...

Area of Science:

• Neuroimaging
• Physiology
• Medical Physics

Background:

• Perfusion imaging using arterial spin labeling (ASL) is sensitive to the time it takes for blood to travel from the labeling region to the tissue of interest.
• This transit time can confound the interpretation of ASL signals, particularly during functional activation studies.

Purpose of the Study:

• To investigate and differentiate the contributions of blood transit time and actual tissue perfusion to the signal changes observed in ASL images during motor and visual stimulation.
• To assess the impact of transit time variations on ASL-based activation imaging.

Main Methods:

• Functional ASL imaging was performed during motor and visual tasks.
• Analysis focused on quantifying changes in fractional transit time and fractional perfusion.
• Comparison of signal changes in ASL sequences with and without delayed acquisition was performed.

Main Results:

• Fractional decreases in transit time were observed to be comparable in magnitude to fractional increases in perfusion.
• Transit time changes were identified as the primary driver of ASL signal alterations in standard ASL sequences (without delayed acquisition).

Conclusions:

• Transit time variations significantly influence ASL signal changes during functional activation.
• Accurate interpretation of ASL activation requires accounting for transit time effects, especially in sequences lacking delayed acquisition.
• Findings have implications for understanding arterial control of cerebral blood flow and optimizing ASL imaging protocols.