Early diffusion tensor imaging findings in animal models of acute diffuse axonal injury

Abstract

Objective To establish animal models of diffuse axonal injury (DAI) and discuss the early functional MRI findings.Methods Twenty-five adult white rabbits were divided into control group (n =5),mild DAI group and severe DAI group (n =6) according to random number.Mild DAI group was subdivided into mild DAI 3 h (n =6),1 day (n =4) and 1 week (n =4) groups.Routine MRI and diffusion tensor imaging (DTI) were performed.Parameters measured were fractional anisotropy (FA),apparent diffusion coefficient (ADC),axial diffusivity (AD) and radical diffusivity (RD).Results Significantly increased FA (P＜0.01) and decreased ADC (P＜0.05) and RD (P＜0.01) were detected in severe DAI group compared to control group,but there was no significant variation in AD between the two groups (P ＞ 0.05).Each parameter remained almost unchanged in mild DAI 3 h group and mild DAI 1 week group,but FA was increased (P ＜ 0.01) and RD decreased (P ＜ 0.05) in mild DAI 1 day group,with no changes of ADC and AD.Conclusion DTI is a sensitive way to detect the occurrence and development of DAI and can provide referential images for early DAI diagnosis. Key words: Brain injuries; Diffuse axonal injuries; Diffusion tensor imaging; Rabbits