Construction and Validation of the Modified Parietal Atrophy Index by Magnetic Resonance Imaging in Patients With Alzheimer's Disease in a Memory Clinic.

Magnetic resonance imaging (MRI) is pivotal to the evaluation of cerebral atrophy in Alzheimer's disease (AD). Although there are several scoring systems to identify atrophy in areas of interest, the possibility of having a simple and practical scale focused on evaluating parietal atrophy by MRI in a single axial slice in T2-Flair sequencing would be highly advantageous. We develop and validate the Mimenza-Aguilar-Herrera (MAH) visual scale to determine the degree of modified parietal atrophy by analyzing the posterior cingulate gyrus in an MRI axial slice in T2 weighted sequencing in individuals with early AD. Patients with AD, mild cognitive impairment, and other dementias were included. Interrater and intrarater concordance was analyzed with Cohen's kappa. ROC analysis was used to determine sensitivity/specificity. The relationship between medial parietal atrophy (MPA) and the MMSE and MoCA scores, age, educational level, and sex was determined by linear regression. Interrater concordance in the MPA-MAH was moderate, 0.83 (p = 0.001). The area under the curve in the mild AD group was 0.74, with a sensitivity of 71.67% and a specificity of 76.19% (p < 0.001). An association was detected between a MPA score > 1 [OR 5.1 (95% CI: 2-12.9, p < 0.001)], MMSE < 24 pts, [OR 4.5 (95% CI: 1.2-17.6, p = 0.026)], and MoCA < 24 pts, after adjusting for age and sex. The MAH scale proved useful in diagnosing early AD, with comparable performance to validated scales such as Koedam's and Scheltens'. This instrument could allow a quick and easy evaluation.