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

Purpose: To determine whether pulsed arterial spin-labeled (pulsed ASL) balanced steady-state free precession (bSSFP) imaging allows for rapid projective depiction of the carotid arteries without electrocardiographic (ECG) gating. Materials and Methods: The carotid arteries of six volunteers were scanned at 1.5 T using an ASL two-dimensional bSSFP sequence. Three configurations were tested, with and without ECG gating: (a) full field-of-view (FOV) acquisition (scan time = 48 s), (b) full-FOV acquisition with parallel acceleration of 2 (24 s), and sequence C (half-FOV acquisition (24 s). Vessel-to-background contrast-to-noise ratios (CNRs) and vessel lengths were compared between sequence configurations. Vessel caliber measurements were compared with those obtained from three-dimensional time-of-flight (TOM angiography. Results: The carotid arteries were seen over extensive lengths with ASL two-dimensional bSSFP. Projected vessel length and vessel-to-background CNR did not differ with ECG gating (P = NS). Nonaccelerated full-FOV and half-FOV scans provided larger apparent vessel-to-background CNR and slightly longer vessel lengths than the parallel-accelerated scans (P < 0.01). Carotid diameter measurements were in agreement with those obtained from three-dimensional TOF (intraclass correlation coefficient = 0.810; P < 0.001). Conclusion: pulsed ASL bSSFP is a fast technique for projective carotid angiography that may not require ECG gating. Acquisition time may be decreased with reduced FOV or parallel imaging strategies.