Cerebral Time-of-flight Magnetic Resonance Angiography at Ultra-low-field: A Preliminary Study at 0.055 Tesla

Recent development of ultra-low-field (ULF) MRI presents opportunities for low-cost and portable brain imaging in point-of-care scenarios or/and low- and mid-income countries. Magnetic resonance angiography (MRA) is an essential part of MR neuroimaging protocols especially for stroke assessment, yet its feasibility at ULF remains unknown. In this study, we explore the time-of-flight MRA at 0.055 Tesla. We demonstrate cerebral MRA using flow-compensated gradient echo sequences, enabling visualization of main cerebral arteries and veins. We envision that usable and quality brain MRA can be potentially achieved at ULF with further sequence/reconstruction optimization and use of intravascular contrast agent.