Establishing MRI-based thresholds for corpus callosum in children aged 1–6: a comparison of typical development and cerebral palsy-associated morphometry

The corpus callosum (CC) is central to neurodevelopment, and morphometric abnormalities are linked to atypical development. This study aimed to establish age-dependent and age-independent MRI-based cutoffs defining normative CC morphology in children aged 1–6 years, distinguishing typically developing children from those with cerebral palsy (CP). This retrospective analysis included 116 children (58 with CP, 58 age-matched controls) who underwent brain MRI. Seven CC parameters were measured: thickness of the genu, body, splenium, and isthmus, plus overall CC area and fronto-occipital length (FOL). Receiver Operating Characteristic (ROC) analyses identified optimal age-dependent and age-independent cutoffs. The two groups were well matched for age (3.45 ± 1.55 vs. 3.36 ± 1.43 years; P = 0.736) and sex (46.6% vs. 41.4% female; P = 0.575). Age-independent cutoffs above 424 mm² for CC area and 7.5 mm for splenium thickness aligned with normative ranges. Splenium thickness was highly discriminative, ranging from 7.5 mm in younger children to 9 mm in older groups. Genu cutoffs ranged from 7.25 mm in 1-2-year-olds to 9.5 mm in older children, while age-independent genu and isthmus thresholds of 8.5 mm and 3.95 mm further defined normal morphology. The identified age-dependent and age-independent CC cutoffs provide reference points for evaluating CC development in early childhood, enabling clinicians to assess growth patterns objectively and identify atypical trajectories. Further research is needed to clarify the neurophysiology of these variations and their diagnostic or prognostic implications.