Changes in DWI and MRS associated with white matter hyperintensities in elderly subjects

Objective: To assess normal-appearing white matter (NAWM) characteristics by magnetic resonance spectroscopy (MRS) and diffusion-weighted imaging (DWI) in elderly subjects. Methods: The authors studied 60 volunteers (mean age 72.6 years; SD 4.7; range 64 to 84 years) without signs of neurologic illness. They used DWI and spectroscopic imaging to investigate whether there were changes in the NAWM that related to the presence of white matter hyperintensities (WMH). Results: The authors found a correlation (p < 0.001) between the apparent diffusion coefficient in the NAWM and the total volume of WMH. The metabolite ratios N-acetylaspartate/creatine and N-acetylaspartate/choline of the NAWM also correlated significantly with total WMH volume. These correlations were independent of age. Conclusions: Damage associated with WMH is detectable in NAWM.