Measurement of cytotoxic and interstitial components of cerebral edema in acute hepatic failure by diffusion tensor imaging

Purpose: To use diffusion tensor imaging (DTI) metrics for measuring cytotoxic and interstitial components of cerebral edema (CE) in acute hepatic failure (AHF) patients. CE is a major complication in patients with AHF. Materials and Methods: DTI was perfonned in 20 patients with AHF and 15 controls. Ten patients underwent repeat imaging after recovery from encephalopathy. Various regions of interest (ROIs) were drawn in the white and deep gray matter of the brain for the quantitation of fractional anisotropy (FA), mean diffusivity (MD), spherical isotropy (CS), linear anisotropy (CL), and planar anisotropy (CP) values. Results: Significantly decreased MD values were observed in most brain ROIs in patients compared to controls. Significantly decreased FA. CL with increased CS values was also observed. In survivors with normal clinical profile after 3 weeks, a significant increase in MD and FA values were associated with decreased CS values in some regions compared to baseline study; however, it was still significantly changed compared to controls. Conclusion: Decreased MD and increased CS associated with decreased FA represent cytotoxic and interstitial components of CE, respectively. Incomplete normalization of these metrics in survivors after 3 weeks clinical recovery may be due to incomplete metabolic recovery.