Investigating cortical thickness in children on ultra-low-field and high-field MRI

Motivation: Ultra-low-field MRI is expanding access to MRI technology worldwide. Cortical thickness is a key brain measure that influences neurodevelopmental outcomes. However, data from paediatric ultra-low-field MRI is lacking. Goal(s): To examine cortical thickness measures using ultra-low-field and high-field MRI. Approach: Paired MRI scans were obtained on 40 children aged 3-4 years in the DolPHIN-2 study on ultra-low-field (64mT) and high-field (3T) scanners in Cape Town, South Africa. Cortical thickness metrics were compared across brain regions. Results: Ultra-low-field MRI cortical thickness measures correlated with high-field (moderate-strong effect), although with consistently lower values. Correspondence was best in larger regions and restricting to high-quality ultra-low-field scans. Impact: Paediatric cortical thickness measurements may be obtained using ultra-low-field MRI that correspond with high-field MRI and improve with scan quality. Further work is needed to advance ultra-low-field acquisition and processing pipelines to optimise cortical thickness and assess other cortical metrics.