Reliability of the MRI‐based Brain Atrophy and Lesion Index in the evaluation of whole‐brain structural health

BACKGROUND: The Brain Atrophy and Lesion Index (BALI), which evaluates several common aging‐related MRI changes in combination, has been validated as a feasible method to assess the status of structural brain health. Previous studies have been based primarily on older participants and high‐field MRI. Here, we tested the generalizability of the BALI by examining its measurement properties in a wide age range at both high and conventional MRI field strengths. METHODS: Subjects (n = 229) who had T2WI at either 1.5T or 3.0T were grouped into younger (age ≤ 60 years) and older (age > 60 years) groups. Image evaluation and scoring were performed independently by two experienced neuroradiologists who have mastered the BALI method. Inter‐ and intrarater agreement rates were examined comparing age groups and field strengths. RESULTS: The intraclass correlation coefficient for the BALI total score was consistently high under each experimental condition (interrater ICC ≥ 0.92, 95% CI: 0.84‐0.96), with no statistical difference between age groups (Fisher Z = 1.43) or field strengths (Z = 0.60). The reliability for BALI category subscores ranged between moderate and perfect (eg, 0.85 vs 0.57 for GA), similar for both age groups and typically greater at 3.0T than at 1.5T. CONCLUSION: The BALI based on T2WI can be reliably applied to the evaluation of the whole‐brain health of both younger and older adults at both field strengths, even though high‐field MRI is preferable.