Comparison of multi echo T2 relaxation and steady state approaches for myelin imaging in the central nervous system

• Published in: Scientific reports Vol. 11; no. 1; p. 1369
• Main Authors: Dvorak, Adam V., Ljungberg, Emil, Vavasour, Irene M., Lee, Lisa Eunyoung, Abel, Shawna, Li, David K. B., Traboulsee, Anthony, MacKay, Alex L., Kolind, Shannon H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.01.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 631/1647/245/1628; 631/378/2606; 631/378/2606/1666; 692/53; 692/698/1688/1366; Central nervous system; Humanities and Social Sciences; Magnetic resonance imaging; multidisciplinary; Multiple sclerosis; Myelin; Neuroimaging; Science; Science (multidisciplinary); Spinal cord
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-80585-7

The traditional approach for measuring myelin-associated water with quantitative magnetic resonance imaging (MRI) uses multi-echo T 2 relaxation data to calculate the myelin water fraction (MWF). A fundamentally different approach, abbreviated “mcDESPOT”, uses a more efficient steady-state acquisition to generate an equivalent metric (f M ). Although previous studies have demonstrated inherent instability and bias in the complex mcDESPOT analysis procedure, f M has often been used as a surrogate for MWF. We produced and compared multivariate atlases of MWF and f M in healthy human brain and cervical spinal cord (available online) and compared their ability to detect multiple sclerosis pathology. A significant bias was found in all regions (p < 10 –5 ), albeit reversed for spinal cord (f M -MWF =  − 3.4%) compared to brain (+ 6.2%). MWF and f M followed an approximately linear relationship for regions with MWF <  ~ 10%. For MWF >  ~ 10%, the relationship broke down and f M no longer increased in tandem with MWF. For multiple sclerosis patients, MWF and f M Z score maps showed overlapping areas of low Z score and similar trends between patients and brain regions, although those of f M generally had greater spatial extent and magnitude of severity. These results will guide future choice of myelin-sensitive quantitative MRI and improve interpretation of studies using either myelin imaging approach.