Correlation between intra-axonal T2 and histological axon diameter in rat brain

Motivation: Alteration of the axon radii has been previously linked with neurodevelopmental disorders and neurologic pathologies. The possibility of resolving submicrometric axon diameter yields the potential to open new diagnostic avenues. Goal(s): Validation of the previously presented surface-based relaxation model, assessing the feasibility of estimating axon diameter based on intra-axonal transverse relaxation times. Approach: Correlating diffusion-relaxation MRI data acquired in an ex-vivo rat sample and axon diameter measures based on histology data in the Corpus Callosum. Results: The results confirm the previously reported linear relationship between intra-axonal T2 and axon diameter as estimated based on histology. Impact: This first direct validation experiment of the relationship between intra-axonal T2 and axon diameter employing a surface-based relaxation model could pave the way for a novel biomarker in neurological disease.