A visual scale to rate amygdalar atrophy on MRI

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Visual rating scales are standard for assessing brain atrophy in neurodegenerative diseases.
• Limbic Predominant Age-Related TDP-43 Encephalopathy (LATE) is characterized by early and severe amygdalar atrophy.
• No specific visual rating scale currently exists for amygdalar atrophy.

Purpose of the Study:

• To develop and validate a visual rating scale for assessing amygdalar atrophy on MRI.
• To establish reliability and validity of the new scale.

Main Methods:

• Developed stringent criteria for grading amygdalar atrophy (none, mild/moderate, severe) using T1-weighted MRI.
• Assessed inter- and intra-rater reliability with 100 scans by three neuroradiologists.
• Evaluated convergent validity against FreeSurfer volumetry (1943 patients) and criterion validity against autopsy-confirmed LATE (96 patients).

Main Results:

• High intra- and inter-rater agreement (weighted Cohen's Kappa 0.71-0.93) for visual amygdalar atrophy ratings.
• Strong association between visual ratings and amygdalar volumes (p≤0.001).
• Association observed between LATE neuropathologic changes and visual amygdalar atrophy ratings (p=0.057).

Conclusions:

• The proposed visual amygdalar atrophy scale is reliable and valid.
• This scale serves as a practical tool for routine radiological reporting.
• It enhances diagnostic accuracy for dementia, particularly for identifying LATE.