Quantify blood transit time in cerebral arteries using 4D-MRA with example clinical application in moyamoya disease

Motivation: 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. Goal(s): This study introduces a novel model to estimate macrovascular arterial transit time (mATT) derived from arterial spin labeling (ASL)-based 4D-MRA. Approach: Our method allows to visualize mATT differences throughout the brain in patients with intracranial steno-occlusive disease, as well as changes in mATT resulting from the cerebrovascular reactivity response to an acetazolamide (ACZ) injection. Results: We quantify signal dynamics from 4D-MRA enabling comparison with complementary 3D hemodynamic parameter maps or structural information. Impact: 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.