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.