Deciphering the dynamics of the splenium: A comprehensive analysis of flair hyperintensity variations

The splenium of the corpus callosum plays a pivotal role in interhemispheric communication and undergoes various changes with ageing. The present study aimed to elucidate the age-related variations in splenial fluid-attenuated inversion recovery (FLAIR) hyperintensity, providing insights into the normal ageing process of the brain and enhancing the clinical interpretation of magnetic resonance (MR) imaging. In the present retrospective cohort study, cerebral MR imaging of 1,176 patients was analysed following application of strict inclusion and exclusion criteria to isolate age and sex-related changes and other factors that can affect splenium hyperintensity. The present study focused on measuring the thickness (anteroposterior) of splenial FLAIR hyperintensity, with interobserver agreement assessed to ensure measurement reliability. Statistical analyses, including the Mann-Whitney U test for sex comparisons and the Kruskal-Wallis test for age group comparisons, were employed to investigate the effects of age, sex, radiation therapy and Fazekas score on splenial FLAIR hyperintensity. The present study demonstrated a significant increase in the presence of splenial FLAIR hyperintensity and thickness (P<0.001; P=0.006) with advancing age, particularly in individuals >57 years of age. No significant differences were observed between male and female participants, suggesting that these age-related changes were consistent across sex. Splenium hyperintensity thickness was significantly higher in the group that received radiation therapy and in the patient group with a Fazekas score of 3 (0.048, 0.018). Interobserver agreement was evaluated using the intraclass correlation coefficient (ICC) to assess measurement consistency (ICC=0.977; P<0.001). The present study provides crucial insights into the age-related dynamics of the splenium.