Dynamic pseudo-continuous arterial spin labeling angiography using a 3D-radial multi-spoke spoiled gradient-recalled sequence.

Purpose: Accurate identification of arterial feeders and draining veins is critical for treatment decision-making in patients with intracranial high-flow vascular lesions. Currently available MRI sequences lack the temporal and spatial resolution needed for this task. A novel time-resolved pseudo-continuous arterial spin labeling (ASL) angiography sequence with high spatial and temporal resolution was developed, and image quality metrics relevant to clinical performance were assessed.

Methods: Ten volunteers and eight patients with intracranial high-flow vascular lesions underwent a brain MRI protocol, augmented with the new sequence with multi-spoke (1-3) readouts and dynamic, sliding-window reconstruction. For each of the acquisitions, image quality was assessed using a 5-point Likert scale, as well as SNR and SNR efficiency. Spatial and temporal resolution and acquisition time were compared with standard-of-care sequences used to assess high-flow vascular lesions.

Results: The time-resolved angiographic sequence achieved high isotropic spatial resolution (0.68 mm³), comparable to time of flight (TOF) MRA, but higher than that of contrast-enhanced (CE)-MRA, and a higher temporal resolution (200 ms) than CE-MRA. Multi-spoke acquisitions demonstrated a significant increase in SNR and SNR efficiency compared to single-spoke acquisitions while maintaining an overall high image quality rating and at a 31% reduced scan time relative to the single-spoke variant.

Conclusion: This study demonstrated the clinical feasibility of a novel time-resolved ASL sequence using a multi-spoke 3D-radial readout with a vessel-signal optimized flip angle sweep. Sufficient SNR, superior spatial and temporal resolution to CE-MRA, and a comparable spatial resolution to TOF MRA were achieved in a clinically reasonable acquisition time.