Myelin Assessment in Neurodegeneration: Correlation of R1 Relaxation and Diamagnetic Susceptibility in White Matter Using χ-Separation

Motivation: Accurately assessing myelin content in white matter is vital for tracking neurodegenerative disease progression. Standard MRI metrics like R1 are affected by factors like iron, highlighting the need for a specific myelin marker Goal(s): This study explores the correlation between R1 and diamagnetic susceptibility (χ_dia) in white matter, evaluating χ_dia's suitability as a myelin-specific marker. Approach: Twenty-seven patients with Parkinsonian syndromes underwent MP2RAGE and QSM imaging at 3T. χ_dia maps and R1 maps were compared across 48 white matter regions. Results: Low overall correlation between R1 and χ_dia suggests R1 reflects additional influences, while χ_dia may better indicate myelin in specific regions. Impact: A novel methodχ-separation enables myelin assessment in neurodegenerative white matter, reducing iron's confounding effects. This method allows researchers to study myelin independently, potentially enhancing diagnostic precision in neurodegenerative disease Synopsis