Angiography is critical for visualizing cerebral blood flow in intracranial steno-occlusive diseases. Current 4D magnetic resonance angiography (MRA) techniques primarily focus on macrovascular structures, yet few have quantified hemodynamic timing. This study introduces a novel model to estimate macrovascular arterial transit time (mATT) derived from arterial spin labeling (ASL)-based 4D-MRA. We provide examples of our method that visualize mATT differences in patients with intracranial steno-occlusive disease (moyamoya and atherosclerosis) and changes in mATT resulting from the cerebrovascular reactivity response to an acetazolamide (ACZ) injection. Furthermore, we present a method that projects sparse arterial signals into a 3D native brain-region atlas space and correlate regional mATT with other hemodynamic parameters of interest such as tissue transit time and cerebrovascular reactivity. This approach offers a non-invasive, quantitative assessment of macrovascular dynamics, with potential to enhance understanding of large-vessel and tissue-level hemodynamics and augment monitoring of treatment outcomes in steno-occlusive disease patients. Furthermore, it sets the stage for more in-depth investigations of the macrovascular contribution to brain hemodynamics.

The authors have declared no competing interest.

This study was funded by the W.M. De Hoop Foundation the Janivo Foundation and Friends of UMC Utrecht & Wilhelmina Childrens Hospital and an NWO VIDI grant.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

For patient scans, the Medical Ethics Review Committee of the University Medical Centre Utrecht declared that the Medical Research Involving Human Subjects Act (WMO) did not apply to the present research since all study measures were part of routine clinical practice.

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All data produced in the present study may be made available upon reasonable request to the authors