1 H-MRS Differentiates White Matter Hyperintensities in Subcortical Arteriosclerotic Encephalopathy From Those in Normal Elderly

Abstract

Background and Purpose White matter hyperintensities in MRI of the brain are often seen in normal elderly subjects. Radiologically, these hyperintense regions are similar to those in symptomatic patients with subcortical arteriosclerotic encephalopathy (SAE). Our aim was to discriminate white matter hyperintensities (WMH) on MRI in patients with SAE from similar appearing changes in normal elderly. Methods Three groups of elderly patients were studied: symptomatic patients with WMH of SAE (n=5); asymptomatic subjects with diffuse, confluent WMH (n=4); and elderly control subjects (n=5). Proton density images revealed WMH in the occipital lobes. Proton magnetic resonance spectroscopy ( 1 H-MRS) was used to acquire spectra in these hyperintensities. Metabolite concentrations were calculated from peak areas of N -acetylaspartate (NAA), creatine (Cre), and choline (Cho). Results The NAA/Cre and NAA/Cho ratios were reduced in the SAE group compared with the two asymptomatic groups ( P <.05). NAA was decreased and Cho elevated in SAE compared with control subjects ( P <.05). The average volumes of WMH in the SAE group (65.5 cm 3 ) and in asymptomatic control subjects (59.4 cm 3 ) were similar, and greater than those of the normal control group (4.0 cm 3 ). Conclusions Proton MRS discriminates WMH in SAE patients from those in asymptomatic elderly, suggesting differing causes of the hyperintensities.