Is diffusion anisotropy an accurate monitor of myelination? Correlation of multicomponent T2 relaxation and diffusion tensor anisotropy in human brain.

We compare T2-relaxation and diffusion tensor data from normal human brain. The relationships between myelin-water fraction (MWF) and various diffusion tensor measures [e.g.

Linear combination of multiecho data: short T2 component selection.

The myelin sheath, which is wrapped around the axons in the brain, can be affected by many diseases, resulting in cognitive and physical disability. Other work showed water in the myelin sheath has a T2 approximately 15 ms. The current standard technique to estimate the fraction of myelin water in vivo is to collect multiecho data and fit the decay curves using a nonnegative least-squares (NNLS) algorithm.

Evolution of focal and diffuse magnetisation transfer abnormalities in multiple sclerosis.

Magnetisation transfer (MT) imaging provides indirect information on tissue structure abnormalities in areas that otherwise may appear normal on conventional MRI. We determined the evolution of MT changes in normal appearing white matter (NAWM) and lesion on serial examination of 9 multiple sclerosis (MS) patients and age matched controls. The mean NAWM MT ratio (MTR) was found to correlate strongly (R = 0.

Robust myelin water quantification: averaging vs. spatial filtering.

The myelin water fraction is calculated, voxel-by-voxel, by fitting decay curves from a multi-echo data acquisition. Curve-fitting algorithms require a high signal-to-noise ratio to separate T(2) components in the T(2) distribution. This work compared the effect of averaging, during acquisition, to data postprocessed with a noise reduction filter.

Normal-appearing white matter in multiple sclerosis has heterogeneous, diffusely prolonged T(2).

T(2) relaxation in normal-appearing white matter (NAWM) of multiple sclerosis (MS) patients was reexamined using more complete sampling and analysis of decay curves, and to assess focal vs. diffuse abnormalities. Nine MS patients and 10 controls were scanned using a single-slice 32-echo pulse sequence with a 10-ms echo spacing.