Proton Magnetic Resonance Spectroscopy and Gadolinium‐DTPA Perfusion Imaging of Asymptomatic MRI White Matter Lesions

In the elderly, asymptomatic white matter hyperintensities are common on T₂‐weighted magnetic resonance imaging (MRI). In symptomatic patients, such MRI appearances correlate with varied postmortem findings including demyelination or stroke. What structural correlates underlie the T₂ hyperintensities in patients whose lesions are asymptomatic is controversial. Therefore, in order to investigate the underlying metabolism and perfusion in white matter lesions (exhibiting T₂ hyperintensity), 13 patients underwent proton magnetic resonance spectroscopy and dynamic gadolinium‐DTPA perfusion‐weighted MR imaging. N‐acetyl aspartate (NA) levels were reduced in the lesions compared with age‐matched controls (P = 0.031), implying neuronal/axonal loss. Creatine levels were also reduced (P = 0.001). Choline levels were unchanged in the lesions. Lactate was identified in the lesions of 5 of the 13 patients. Although not statistically significant, perfusion studies exhibited a trend toward lower cerebral blood volumes in patients with high grade extracranial carotid stenosis and lactate‐containing lesions. These findings suggest that neuronal/axonal loss underlies the majority of T₂‐weighted asymptomatic lesions in the older population, and in many cases these changes may be due to chronic ischemia.