Correlation analysis between quantitative-T2 and diffusion-MRI measurements in human white matter: a study across different field strengths.

Motivation: Quantitative MRI is increasingly translated to low (<=0.55T) and high (>=7T) field strengths. Yet, differences in the underlying biophysics across field strengths remain poorly understood. Goal(s): To identify and understand deviations in the correlation of T2 and diffusion metrics at extreme field strengths. Approach: Quantitative T2 and diffusion MRI maps were computed from a comprehensive MRI protocol at 0.55T, 1.5T, 3T, and 7T. Results: We observe decreased correlation between T2 relaxation and diffusivity at high field strengths, while the results at 0.55T align well with clinical field strengths, which shows the ground for optimization of experimental design at low- and ultra-low fields. Impact: T2 and diffusion-MRI commonly complement each other in clinical imaging. Our results show a similar correlation of related metrics, suggesting shared information on tissue properties, which can be used to optimize experimental design at low- and ultra-low fields.