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Further observations on the pathology of subcortical lesions identified on magnetic resonance imaging
M I Chimowitz1, M L Estes, A J Furlan
1Department of Neurology, University of Michigan Medical Center, Ann Arbor.
Abstract:
We performed postmortem magnetic resonance imaging and pathologic examinations on the brains of seven consecutive patients older than 50 years of age who died of non-neurologic causes. Multiple hyperintense subcortical lesions were identified in each patient, and a total of 29 lesions were examined histologically (eight rims, six caps, six punctate lesions, and nine patches). Rims were characterized by subependymal gliosis and loss of the ependymal lining; caps were associated with myelin pallor, gliosis, and arteriosclerosis; punctate lesions were characterized by dilated perivascular spaces and perivascular gliosis; and patches were associated with myelin pallor and dilated perivascular spaces. The pattern of myelin pallor defined the size and shape of caps and patches. Arteriosclerosis was identified in six of six caps, three of six punctate lesions, and in three of nine patches. These data indicate that (1) each type of hyperintense subcortical lesion has a distinct pathologic correlate; (2) arteriosclerosis is not invariably associated with all types of hyperintense subcortical lesions on magnetic resonance imaging; and (3) myelin pallor appears to contribute to the magnetic resonance imaging signal at 1.5 tesla.
Insights
Postmortem MRI and pathology reveal distinct causes for hyperintense subcortical lesions in older adults. Arteriosclerosis is not always present, but myelin pallor influences MRI signals.
Area of Science:
- Neuroimaging
- Neuropathology
- Geriatric Medicine
Background:
- Hyperintense subcortical lesions are common findings in older adults on magnetic resonance imaging (MRI).
- The precise pathological basis for these MRI signals remains incompletely understood.
Purpose of the Study:
- To correlate distinct types of hyperintense subcortical lesions observed on postmortem MRI with specific pathological findings.
- To investigate the association between arteriosclerosis and different lesion types.
- To determine the role of myelin pallor in generating MRI signals.
Main Methods:
- Postmortem magnetic resonance imaging (MRI) was performed on the brains of seven patients over 50 years old who died of non-neurologic causes.
- Histopathological examination was conducted on 29 identified hyperintense subcortical lesions, including rims, caps, punctate lesions, and patches.
- Lesions were analyzed for gliosis, myelin pallor, arteriosclerosis, and dilated perivascular spaces.
Main Results:
- Each type of hyperintense subcortical lesion demonstrated a unique pathological correlate.
- Rims showed subependymal gliosis and ependymal lining loss; caps exhibited myelin pallor, gliosis, and arteriosclerosis.
- Punctate lesions were characterized by dilated perivascular spaces and gliosis; patches showed myelin pallor and dilated perivascular spaces. Arteriosclerosis was not universally present across all lesion types.
Conclusions:
- Distinct pathological substrates underlie different hyperintense subcortical lesion morphologies seen on MRI.
- Arteriosclerosis is not an invariable feature of all hyperintense subcortical lesions.
- Myelin pallor significantly contributes to the hyperintense signal observed on 1.5 tesla MRI.