MOdulation-Guided ENcoding (MOGEN) Scheme for Vessel-Encoded Arterial Spin Labeling

Vessel-encoded arterial spin labeling (VEASL) enables simultaneous, non-contrast imaging of multiple vascular territories that is useful for differential diagnosis and treatment monitoring of cerebrovascular diseases. However, the existing encoding methods are signal-to-noise ratio (SNR) inefficient.

We developed a MOdulation-Guided ENcoding (MOGEN) scheme that directly exploits the inversion spatial modulation profile to obtain SNR-efficient encoding matrix. Simulations, phantom tests, and healthy volunteer scans were performed to demonstrate its feasibility in multiple application scenarios.

Simulation studies demonstrated that MOGEN achieves significantly higher theoretical SNR efficiency than previous methods for both four- and six-artery configurations. In healthy volunteers, MOGEN improved in vivo SNR by approximately 15% and provided more robust vessel decoding, particularly when the spatial modulation deviated from a cosine profile. In patients with Moyamoya disease, MOGEN enabled reliable visualization of collateral pathways even when scan time was reduced to ˜5 min for six arteries. Furthermore, by considering vessel size with multi-voxel vessel representation, MOGEN enhanced single-artery selectivity in vessel-encoded angiography. We also demonstrated that a straightforward approach of off-resonance correction for VEASL at ultra-high field was feasible by using MOGEN.

MOGEN offered several benefits for VEASL, including high SNR efficiency, flexible spatial modulation and PCASL parameters selection, vessel size consideration, and straightforward off-resonance correction, thereby substantially improving robustness and usability of VEASL across various applications.