Fast projective carotid MR angiography using arterial spin-labeled balanced SSFP

Area of Science:

• Magnetic Resonance Imaging
• Vascular Imaging
• Cardiovascular Imaging

Background:

• Carotid artery imaging is crucial for assessing stroke risk.
• Traditional angiography methods often require electrocardiographic (ECG) gating, increasing scan times.
• Developing faster, non-gated techniques is essential for clinical efficiency.

Purpose of the Study:

• To evaluate pulsed arterial spin-labeled (ASL) balanced steady-state free precession (bSSFP) for rapid, non-gated carotid artery imaging.
• To compare different ASL bSSFP sequence configurations for projective depiction of carotid arteries.

Main Methods:

• Six volunteers underwent 1.5 T MRI using a 2D ASL bSSFP sequence.
• Tested configurations included full field-of-view (FOV) with and without ECG gating, parallel acceleration, and half-FOV acquisition.
• Compared vessel-to-background contrast-to-noise ratios (CNRs), vessel lengths, and diameter measurements against 3D time-of-flight (TOF) angiography.

Main Results:

• Pulsed ASL bSSFP visualized carotid arteries effectively over extensive lengths.
• No significant difference in projected vessel length or CNR was observed with or without ECG gating.
• Non-accelerated and half-FOV scans yielded higher CNRs and vessel lengths compared to parallel-accelerated scans.
• Carotid diameter measurements showed strong agreement with 3D TOF angiography (ICC=0.810).

Conclusions:

• Pulsed ASL bSSFP is a rapid and effective technique for projective carotid angiography.
• Electrocardiographic (ECG) gating is not essential for this technique.
• Scan time can be further reduced by employing parallel imaging or reduced FOV strategies.