Ultra‐low‐field magnetic resonance angiography at 0.05 T: A preliminary study

• Published in: NMR in biomedicine Vol. 37; no. 11; pp. e5213 - n/a
• Main Authors: Su, Shi, Hu, Jiahao, Ding, Ye, Zhang, Junhao, Lau, Vick, Zhao, Yujiao, Wu, Ed X.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.11.2024
• Subjects: Adult; Angiography; Arteries; Bifurcations; Blood; Blood flow; Blood vessels; brain; Carotid arteries; Carotid artery; Cerebral Arteries - diagnostic imaging; Contrast agents; Contrast media; Feasibility studies; Female; Humans; Image contrast; Image quality; Jugular vein; Magnetic resonance; magnetic resonance angiography; Magnetic Resonance Angiography - methods; Magnetic shielding; Male; Medical imaging; MRI; Neck; Neuroimaging; noncontrast enhancement; Radio frequency; Reproducibility of Results; Scanners; Signal quality; Three dimensional flow; time‐of‐flight; Two dimensional flow; ultra‐low‐field; Veins; Veins & arteries; Young Adult; time‐of‐flight; noncontrast enhancement; MRI; ultra‐low‐field; brain; neck; magnetic resonance angiography
• ISSN: 0952-3480; 1099-1492; 1099-1492
• DOI: 10.1002/nbm.5213

We aim to explore the feasibility of head and neck time‐of‐flight (TOF) magnetic resonance angiography (MRA) at ultra‐low‐field (ULF). TOF MRA was conducted on a highly simplified 0.05 T MRI scanner with no radiofrequency (RF) and magnetic shielding. A flow‐compensated three‐dimensional (3D) gradient echo (GRE) sequence with a tilt‐optimized nonsaturated excitation RF pulse, and a flow‐compensated multislice two‐dimensional (2D) GRE sequence, were implemented for cerebral artery and vein imaging, respectively. For carotid artery and jugular vein imaging, flow‐compensated 2D GRE sequences were utilized with venous and arterial blood presaturation, respectively. MRA was performed on young healthy subjects. Vessel‐to‐background contrast was experimentally observed with strong blood inflow effect and background tissue suppression. The large primary cerebral arteries and veins, carotid arteries, jugular veins, and artery bifurcations could be identified in both raw GRE images and maximum intensity projections. The primary brain and neck arteries were found to be reproducible among multiple examination sessions. These preliminary experimental results demonstrated the possibility of artery TOF MRA on low‐cost 0.05 T scanners for the first time, despite the extremely low MR signal. We expect to improve the quality of ULF TOF MRA in the near future through sequence development and optimization, ongoing advances in ULF hardware and image formation, and the use of vascular T1 contrast agents. The preliminary feasibility of TOF MRA at 0.05 T was demonstrated for the first time despite the extremely low MR signal. The large primary cerebral arteries and veins, carotid arteries, jugular veins, and artery bifurcations could be identified in both raw GRE images and maximum intensity projections.