Alexander Ruh1, Philipp Emerich1, Dmitry S. Novikov2, Valerij G. Kiselev1
1Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany; 2Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States
The correlation time of diffusing spins in magnetically heterogeneous tissues is often commensurate with the timing of MRI experiments. This results in a time dependent transverse relaxation rate that for long times approaches the monoexponential limit. Here we show that the power law of this approach represents the statistics of large-scale organization of magnetic microstructure. The origin of this effect is the self-averaging, which is inherent to diffusion narrowing, when spins are exploring microstructure via diffusion. The present results enable an analysis scheme alternative to a previously proposed spectral domain approach, which enlarges options for future quantifications.