Evaluation of Whole Brain Health in Aging and Alzheimer's Disease: A Standard Procedure for Scoring an MRI-Based Brain Atrophy and Lesion Index

Background: The Brain Atrophy and Lesion Index (BALI), a semi-quantitative rating scale, has been developed to evaluate whole brain structural changes in aging and Alzheimer's disease (AD). Objective: This study describes a standard procedure to score the BALI and train new raters for reliable BALI evaluation following this procedure. Methods: Structural MRI of subjects in the Alzheimer's Disease Neuroimaging Initiative dataset who had 3.0T, T1, and T2 weighted MRI scans at baseline and at 6, 12, and 24 month follow-ups were retrieved (n = 122, including 24 AD, 51 mild cognitive impairment patients, and 47 healthy control subjects). Images were evaluated by four raters following training with a step-by-step BALI process. Seven domains of structural brain changes were evaluated, and a total score was calculated as the sum of the sub-scores. Results: New raters achieved > 90% accuracy after two weeks of training. Reliability was shown in both intra-rater correlation coefficients (ICC >= 0.92, p < 0.001) and inter-rater correlation coefficients (ICC = 0.88, p < 0.001). Mean BALI total scores differed by diagnosis (F >= 2.69, p= 0.049) and increased consistently over two years. Conclusion: The BALI can be introduced using a standard procedure that allows new users to achieve highly reliable evaluation of structural brain changes. This can advance its potential as a robust method for assessing global brain health in aging, AD, and mild cognitive impairment.