TOF-MRA using Multi-Oblique-Stack Acquisition (MOSA)

Purpose: To alleviate the intrinsic limitation of current time-of-flight magnetic resonance angiography (TOF-MRA) techniques, which are insensitive to in-plane blood flow due to the flow saturation effect. Materials and Methods: A multi-oblique-stack acquisition (MOSA) technique was proposed in this study to tackle this TOF problem by acquiring two or more TOF image stacks bearing different orientations. The MOSA approach was evaluated in human brain MR angiograms by integrating it with the widely used multiple overlapping thin-slab acquisition (MOTSA) technique. Two TOF image sets in different orientations were acquired using MOTSA. They were combined pixel-by-pixel by taking the maximum intensity value. Maximum intensity projection (MIP) was then performed, and the resulting MRA quality was assessed. Results: The results demonstrated that MR angiograms obtained by MOSA-MOTSA were clearly improved compared to those acquired by conventional MOTSA in the same scan time. Conclusion: MOSA clearly demonstrates its advantage over conventional TOF acquisition in visualizing in-plane blood flows.