Developing a Multi-Ethnic Normative Brain Morphometry Reference for Nigeria Using a National Multisite MRI Cohort

Brain morphometry, encompassing measurements of regional grey matter volume, cortical thickness, sulcal depth, and white matter volume, is fundamental to neurological disease diagnosis, progression monitoring, and neurosurgical planning. All current normative neuroimaging databases are derived from non-African populations and are demonstrably non-transferable to Nigerians due to differences in brain size, gyrification patterns, and intracranial volume. This study aims to establish the first multi-ethnic normative brain morphometry reference dataset for Nigeria using a national multisite three-Tesla MRI cohort. A stratified sampling strategy will enrol 600 healthy adult volunteers (100 per geopolitical zone, equally distributed by sex) across six participating academic medical centres. Participants will undergo three-dimensional T1-weighted structural MRI. FreeSurfer automated cortical parcellation will provide regional cortical thickness and volume measurements, while FSL FIRST will segment subcortical structures. Intracranial volume will be estimated using automated tools validated for African brains. Bayesian multilevel models will account for scanner, site, age, sex, and ethnicity in developing normative reference ranges. This normative database will be released as an open-access resource for Nigerian and African neuroscience researchers, constituting an original scientific contribution of national significance and establishing the methodological standard for Nigerian neuroimaging research.

Keywords: brain morphometry, normative database, multi-ethnic, MRI, Nigeria