The role of functional magnetic resonance imaging of the brain in the evaluation of hepatic encephalopathy in cirrhotic patients

Introduction
Hepatic encephalopathy (HE) is a complication of liver failure, with neurological manifestations ranging from minimal HE (MHE) to deep coma (overt HE).

Aim of the study
To demonstrate the role of functional magnetic resonance imaging (magnetic resonance spectroscopy [MRS] and apparent diffusion coefficient [ADC] value) in the assessment and grading of HE in cirrhotic patients.

Material and methods
A prospective cohort study was conducted on three groups: group I – 20 healthy controls, group II – 25 cirrhotic patients with MHE, and group III – 25 cirrhotic patients with overt HE. Each group was subjected to MRS, diffusion-weighted imaging, and neuropsychological examinations. At 1H-MRS, the glutamate/glutamine complex (Glx), myo-inositol (mI), choline (Cho), N-acetyl aspartate (NAA), and creatine (Cr) were determined in the basal ganglia or thalamus. The metabolic ratios and ADC values of Glx/Cr, MI/Cr, Cho/Cr, and NAA/Cr were determined.

Results
The brain metabolite Glx increased with a significant correlation to HE grade (p = 0.001). Other brain metabolites, such as Cho and mI, decreased significantly (p = 0.001). Two brain metabolites (NAA and Cr) remained unchanged across all HE grades and the control group (p = 0.47 and 0.38, respectively). There was an increase in the Glx/Cr ratio and a decrease in the mI/Cr and Cho/Cr ratios. In addition, ADC values were significantly higher in cirrhotic patients with HE than in the control group.

Conclusions
ADC values and 1H-MRS are imaging modalities that have the potential to detect MHE and grade HE in cirrhotic patients.