Cerebral border zones between distal end branches of intracranial arteries: MR imaging.

This study had institutional review board approval; informed consent was obtained from all participants. The study purpose was to prospectively determine whether a longer arterial transit time (ATT), from the proximal vasculature in the neck toward the distal end branches of the intracranial arteries, can be utilized to identify cerebral border zone regions. A magnetic resonance (MR) imaging method based on noninvasive arterial spin-labeling (ASL) perfusion MR imaging with image acquisition at a series of increasing delay times was used to quantify regional ATTs. Fifteen healthy volunteers (age range, 22-34 years; nine men, six women) were included. ASL perfusion MR imaging demonstrated an increase in ATT in the cerebral border zone regions, extending from the frontal and occipital horns of the lateral ventricle to the frontal and parietooccipital cortices, relative to ATT in non-border zone regions. Cerebral blood flow and arterial blood volume in these anterior and posterior border zone regions were significantly lower (P < .001) than in non-border zone regions.