The correlation between DTI parameters and levels of AQP-4 in the early phases of cerebral edema after hypoxic-ischemic/reperfusion injury in piglets

摘要

Background: Brain edema during the early stages of hypoxicischemic/ reperfusion (HI/R) injury can be determined using diffusion tensor imaging (DTI). The change in ADC values has been correlated with the change in expression of AQP-4. Objective: To determine cerebral edema at specific time intervals after HI/R injury using DTI modalities and discuss its relationship to the expression of aquaporin-4 (AQP-4). Materials and methods: Thirty newborn piglets were divided into six groups (2, 6, 12, 24, 48 and 72 h) after HI/R injury. The control group subjected to sham surgery included five piglets. DTI scans and immunohistochemistry of AQP-4 expression were performed on piglet brain. The relationship between DTI parameters (FA and ADC values) and the optical density (OD) of AQP-4 expression was determined. Results: In the striatum, ADC values dropped and reached their lowest level at 24 h (F=27.42, P<0.05). In the subcortical border region, ADC values increased after a transient decrease and peaked at 48 h, demonstrating a significant difference from the control group (F=50.25, P<0.05). FA values in the internal capsules and subcortical white matter in HI/R models decreased continuously after HI/R, although no statistically significant difference from the control group was achieved. ADC and OD values of AQP-4 expression were positively correlated (r=0.875, P<0.05). Conclusions: The change in ADC value after HI/R injury correlates with the expression of AQP-4.