White matter tract integrity (WMTI) metrics are sensitive to changes in the normal-appearing white matter (NAWM) of multiple sclerosis (MS) patients and might provide a more pathologically specific, clinically meaningful, and practical complement to standard diffusion tensor imaging-derived metrics, according to a recent study. Researchers sought to characterize the nature and extent of pathological changes in the NAWM of MS patients using novel diffusion kurtosis imaging-derived WMTI metrics and to investigate the association between these WMTI metrics and clinical parameters. They examined 32 patients with relapsing-remitting MS and 19 age- and gender-matched healthy controls who underwent MRI and neurological examination. They found:

• Mean diffusivity and radial extra-axonal diffusivity were significantly increased while fractional anisotropy, axonal water fraction, intra-axonal diffusivity and tortuosity were decreased in MS patients compared with controls.

• Axonal water fraction in the corpus callosum was significantly associated with the expanded disability status scale score.

• With the exception of the axial extra axonal diffusivity, all metrics were correlated with the symbol digits modality test score.

Citation: de Kouchkovsky I, Fieremans E, Fleysher L, Herbert J, Grossman RI, Inglese M. Quantification of normal-appearing white matter tract integrity in multiple sclerosis: a diffusion of kurtosis imaging study. [Published online ahead of print April 19, 2016]. J Neurol. doi:10.1007/s00415-016-8118-z.