Magnetic Resonance T2-Relaxometry and 2D L-Correlated Spectroscopy in Patients with Minimal Hepatic Encephalopathy

Purpose: To evaluate T-2-relaxation changes in patients with minimal hepatic encephalopathy (MHE) using T-2 relaxometry and to correlate T-2 values with brain metabolites evaluated using 2D magnetic resonance spectroscopy (MRS). Materials and Methods: Eight MHE patients and 13 healthy subjects were evaluated using T-2 relaxometry, and eight patients and nine healthy subjects underwent 2D MRS in right frontal and left occipital regions. Whole-brain T-2-relaxation maps were compared between MHE and control subjects using analysis-of-covariance, with age and gender included as covariates. T2 values derived from the right frontal and left occipital lobes were correlated with the metabolite ratios. Results: Multiple brain regions including anterior and mid cingulate cortices, right anterior and left posterior insular cortices, right prefrontal, medial frontal, and right superior temporal cortices showed significantly increased T2 values in MHE patients compared to control subjects. MRS showed significantly increased ratios of glutamine/glutamate (Glx) and decreased ratios of myo-inositol, taurine, choline, and myo-inositol/choline (mICh) with respect to creatine (Cr_d) in patients compared to controls. Frontal Glx/Cr_d showed significantly positive correlation with T-2 values. Conclusion: MHE patients showed significantly increased T-2 values in multiple brain regions reflecting increased free water content and T-2 values in frontal lobe correlated with the increased Glx/Cr_d ratio.