Diagnostic value of diffusion tensor imaging derived metrics as biomarkers of cerebral changes in developmental delay

CONTEXT: Children with developmental delay (DD) can be rehabilitated if an early diagnosis and intervention is done. A negative magnetic resonance imaging (MRI) study utilizing routine sequences makes it difficult for the clinician to convince the family toward a long-term rehabilitation schedule. Diffusion tensor imaging (DTI) can demonstrate deranged myelination in developmentally delayed children having normal routine MRI. AIM: To evaluate the role of DTI-derived metrics for assessment of deranged myelination in developmentally delayed children having normal routine MRI. STUDY SETTING AND DESIGN: Prospective case control observational study conducted over a cross-section of referrals at a university-based teaching institute over a period of 2 years. PATIENTS AND METHODS: Fifty cases of DD and 15 age-sex matched controls (age group of 2-12 years) were included from those presenting voluntarily to the pediatric out-patient services. Routine MRI and DTI were performed in both the groups following a standard protocol. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were calculated in certain pre-defined regions. STATISTICAL ANALYSIS: Central tendency was measured for each of the metrics using mean. Inter- and intra-group comparisons were performed using t-test. RESULTS: Twenty-three regions of interest with 46 variables were included in the final analysis. Nineteen (82.60%) regions of interest showed at least one statistically significant variable, while 24 out of 46 (54.34%) variables showed statistical significance for future consideration. The important regions to be evaluated in a case of DD are the corpus callosum, bilateral forceps minor and forceps major, bilateral parietal lobes, bilateral post-central gyrus, and bilateral posterior limb internal capsule (PLIC). The regions which did not show any significance are bilateral pars triangularis and right frontal lobe. Other regions remained indeterminate and need further evaluation. CONCLUSION: DTI demonstrates myelination abnormality in children with DD, having a normal routine MRI.