Balanced spin‐lock preparation for B1‐insensitive and B0‐insensitive quantification of the rotating frame relaxation time T1ρ. Issue 5 (9th November 2020)

• Record Type: Journal Article
• Authors: Gram, Maximilian; Seethaler, Michael; Gensler, Daniel; Oberberger, Johannes; Jakob, Peter M.; Nordbeck, Peter
• Is Part Of: Magnetic resonance in medicine. Volume 85:Issue 5(2021)
• Page Start: 2771
• Page End: 2780
• Publication Date: 2020-11-09
• Subjects: artifacts correction -- quantitative MRI -- relaxation -- spin‐locking -- T1rho -- T1ρ; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.28585
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: Accurate and artifact‐free T1ρ quantification is still a major challenge due to a susceptibility of the spin‐locking module to B0 and/or B1 field inhomogeneities. In this study, we present a novel spin‐lock preparation module (B‐SL) that enables an almost full compensation of both types of inhomogeneities. Methods: The new B‐SL module contains a second 180° refocusing pulse to compensate each pulse in the preparation block by a corresponding pulse with opposite phase. For evaluation and validation of B‐SL, extensive simulations as well as phantom measurements were performed. Furthermore, the new module was compared to three common established compensation methods. Results: Both simulations and measurements demonstrate a much lower susceptibility to artifacts for the B‐SL module, therefore providing an improved accuracy in T1ρ quantification. In the presence of field inhomogeneities, measurements revealed an increased banding compensation by 79% compared with the frequently used composite module. The goodness of the mono‐exponential T1ρ fitting procedure was improved by 58%. Conclusion: The B‐SL preparation enables the generation of accurate relaxation maps with significantly reduced artifacts, even in the case of large field imperfections. Therefore, the B‐SL module is suggested to be highly beneficial for in vivo T1ρ quantification.