MRI findings key pathology markers of 4R-tauopathies

SEATTLE — MRI biomarkers were significantly associated with glial tau pathology and could aid in the diagnosis of certain neurodegenerative diseases, a presenter said at the 2022 American Academy of Neurology annual meeting.

“Progressive supranuclear palsy and corticobasal degeneration are the two most common sporadic forms [of four-repeat tauopathies]. They share overlapping pathological features, such as deposits of tau in both neurons and glia,” Arenn F. Carlos, MD, of the department of neurology at the Mayo Clinic, told attendees. “However, the distribution of the pathology differs between the two.”

Carlos and colleagues sought to determine the relationship between tau lesion burden and MRI volume loss and diffusion tensor imaging (DTI) white matter tract abnormalities in these four-repeat tauopathies.

They evaluated 47 patients using 3T MRI, including volumetric and DTI scans, and made postmortem pathological diagnoses of progressive supranuclear palsy (n = 28) and corticobasal degeneration (n = 19). Researchers graded tau lesion types in disease-specific regions and correlated regional volumes, fractional anisotropy and mean diffusivity with tau lesion scores.

Results showed that a greater amount of total tau burden — particularly glial lesions — correlated with volume loss in the globus pallidus, subthalamic nucleus, substantia nigra, red nucleus and midbrain.

In addition, neuronal lesions were associated with volume of the precentral cortex, and decreased fractional anisotropy and increased mean diffusivity in the superior cerebellar peduncle were associated with glial tau in cerebellar dentate and red nucleus.

Researchers also observed increased subcortical white matter mean diffusivity correlated with total tau in superior frontal and precentral cortices.

“In the future, generating PET tracers able to specifically, or even preferentially, bind to glial tau lesions might help us uncover some mechanisms of disease progression,” Carlos said.