Improving the image quality of 3D FLAIR with a spiral MRI technique. Issue 1 (8th August 2019)

• Record Type: Journal Article
• Authors: Li, Zhiqiang; Pipe, James G.; Ooi, Melvyn B.; Kuwabara, Michael; Karis, John P.
• Is Part Of: Magnetic resonance in medicine. Volume 83:Issue 1(2020)
• Page Start: 170
• Page End: 177
• Publication Date: 2019-08-08
• Subjects: 3D -- FLAIR -- rapid MRI -- spiral; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.27911
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: Fluid‐attenuated inversion recovery (FLAIR) nulls the CSF signal and is widely used in neuro MRI exams. A 3D scan can provide high SNR, contiguous coverage, and reduced sensitivity to through‐plane CSF flow. In this work, a 3D spiral FLAIR technique is proposed to improve the image quality of conventional 3D Cartesian FLAIR. Methods: The 3D spiral FLAIR sequence incorporated a spiral‐in/out readout to preserve higher scan efficiency and eliminate off resonance‐induced artifacts observed with a commonly implemented spiral‐out readout, a compensation approach to minimize phase errors due to the concomitant fields accompanying the spiral gradient, and an adapted variable flip angle scheme to preserve scan efficiency and maintain a long and stable echo train. 3D Cartesian and spiral FLAIR (~6 min each) were acquired on a 3 Tesla scanner from 6 subjects (age range: 31‐64 years; mean: 39.5). Two neuroradiologists rated the images in a blinded fashion on a 5‐point scale. The noise performance was assessed quantitatively. Results: Compared to 3D Cartesian FLAIR, 3D spiral FLAIR exhibits greater reduction of artifacts from CSF, especially anterior to the brain stem (rated better in 4 cases), artifacts attributed to blood/flow in the deep brain (better or much better in all 6 cases), and superior overall image quality (much better in 5 cases) despite residual susceptibility artifacts near the nasal cavity. Quantitative assessment demonstrates ~1.5× higher average SNR than Cartesian data. Conclusion: 3D spiral FLAIR achieves higher SNR, reduced CSF, and blood/flow artifacts, providing an alternative to 3D Cartesian FLAIR for neurological exams.