Normative Measurement of Apparent Diffusion Coefficient on Brain Magnetic Resonance Imaging

Background Normal brain aging is associated with microstructural alterations that influence tissue water diffusivity. Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping provides quantitative assessment of brain tissue characteristics and is widely used in clinical neuroradiology. However, ADC values vary according to age, anatomical location, MRI acquisition parameters, and population characteristics. Establishing normative ADC values is essential for accurate interpretation of diffusion abnormalities and differentiation of physiological variation from pathological changes. This study aimed to evaluate regional ADC values across selected brain regions among individuals with normal brain MRI findings and assess variations according to age, sex, and hemispheric laterality. Methods A quantitative cross-sectional observational study was conducted among 87 individuals aged 12–86 years with clinically normal brain MRI examinations. MRI examinations were performed using a 1.5 Tesla scanner. ADC values were measured in selected bilateral brain regions, including the caudate nucleus, thalamus, centrum semiovale, cerebellum, pons, and vermis. Statistical analysis was performed using one-way analysis of variance (ANOVA), independent samples t-test, paired samples t-test, and Spearman correlation analysis. Results The study included 87 individuals with normal brain MRI findings, comprising 33 males and 54 females. Mean ADC values were relatively higher in the adolescent group and remained comparable across adult age groups. No statistically significant association was observed between age and global ADC values (ρ = −0.145, p = 0.179). No significant differences were identified in ADC values between males and females. Most evaluated brain regions demonstrated comparable bilateral ADC values; however, the centrum semiovale showed significantly higher ADC values in the left hemisphere compared with the right hemisphere (p < 0.001). Conclusions This study provides regional normative ADC reference values among individuals with normal brain MRI findings. The observed age-associated variations and hemispheric differences highlight the importance of considering physiological ADC variability during clinical interpretation of diffusion-weighted imaging. These findings may provide supportive reference data for evaluating abnormal ADC patterns within comparable MRI acquisition protocols.