Subject-specific timing adaption in time-encoded arterial spin labeling imaging.

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging Techniques

Background:

• Arterial spin labeling (ASL) is challenged by arterial transit time (ATT) variability, leading to arterial transit delay (ATD) artifacts.
• Suboptimal post-labeling delay (PLD) and bolus durations hinder accurate cerebral blood flow (CBF) and ATT quantification, particularly in pathological conditions and with Hadamard-encoded pseudocontinuous ASL (H-pCASL).

Purpose of the Study:

• To develop and evaluate an adaptive algorithm for optimizing pCASL sub-bolus timing.
• To assess the impact of individually adjusted timing on CBF and ATT quantification accuracy and variability.

Main Methods:

• Utilized an adaptive Walsh-ordered pCASL sequence with an automatic feedback algorithm to individually adjust pCASL sub-bolus timing in five healthy volunteers.
• Compared quantification results (CBF, ATT, standard deviations) with recommended and suboptimal timings using 3 T MRI.

Main Results:

• The algorithm successfully adjusted pCASL sub-bolus PLD individually within recommended ranges for healthy subjects.
• Demonstrated mean intra-subject adjustment deviations of 47.15 ms (single-shot) and 44.5 ms (segmented acquisition) across three repetitions.

Conclusions:

• Initial assessment in healthy volunteers shows promise for the adaptive timing algorithm.
• Further studies are required to validate transferability to patient populations and assess clinical benefits.