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Abstract #1630

Optimization of Flip Angle in Arterial Spin Labeling-based Ultra-Short TE MRI for Brain MR Angiography

Koji Fujimoto1, Kanae Kawai Miyake1, Sachi Okuchi2, Yuichiro Monzen1, Rimika Imai3, Hiroshi Kusahara3, Jumpei Fujimoto2, Yasutaka Fushimi2, and Yuji Nakamoto2
1Advanced Imaging in Medical Magnetic Resonance, Graduate School of Medicine, Kyoto University, Kyoto, Japan, 2Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan, 3MRI Systems Division, Canon Medical Systems Corporation, Otawara, Japan

Synopsis

Keywords: Blood Vessels, Blood vessels, UTE, ultrashort TE, ASL, TOF, MRA

Motivation: Ultra-short TE sequences enable better visualization of flow within the vessels; However, optimal flip angle to achieve visualization of both proximal and distal vessels for ASL-based UTE-MRA remains unclear.

Goal(s): To quantitatively measure signal intensity and vessel voxel count in key vascular structures, and clarify the FA that maximizes these measures.

Approach: UTE MRA were acquired at FAs ranging 1-15. in 1° increments. Signal intensities and voxel counts were measured at the ACA, MCA, vertebral arteries, and carotid arteries.

Results: FA 6-8° provided optimal visualization for distal part of ACA and MCA. Higher FAs provided higher signal intensity in proximal vessels.

Impact: ASL-based MRA with Ultra-short TE sequence was examined with 1° FA increments and its relationship with vessel signals were quantitatively measured. This provides a guide for improving vessel visualization in UTE-MRA.

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Keywords