Multimodality magnetic resonance imaging in hepatic encephalopathy: An update

Table 1 Imaging techniques applied in the diagnosis and investigation of hepatic encephalopathy

MR technique	MR findings or applications
Structural MRI	Diffuse cortical overt brain edema on T2WI and fluid attenuated inversion recovery in acute HE; Bilateral basal ganglia high signal intensity on T1WI in chronic HE; Regional gray matter volume reduction, increased thalamus volume and white matter abnormality
T2* weighted imaging	Abnormal iron deposition in the frontal-basal ganglia-thalamocortical circuits
Diffusion weighted imaging	High signal intensity in subcortical areas and low apparent diffusion coefficient in acute HE;
	High apparent diffusion coefficient in chronic HE
Diffusion tensor imaging	Increased mean diffusivity and decreased fractional anisotropy in chronic HE
1H MR spectroscopy	Depletion of choline and myoinositol;
	Accumulation of glutamine/glutamate
Dynamic susceptibility contrast-enhanced MR perfusion imaging1	Increased cerebral blood flow in the basal ganglia and thalamus
Arterial spin-labeling MR perfusion imaging1	Increased cerebral blood flow;
	To early diagnose HE or predict overt HE after transjugular intrahepatic porto-systemic shunt
Task-related functional MRI1	Attention, visual judgment and working memory impairment in HE
Resting-state functional MRI1	Functional connection alteration of cortico-striato-thalamic pathway;
	Abnormal small-world properties;
	Resting state network (especially default mode network) abnormalities: reduced functional connectivity in the right middle frontal gyrus, left precuneus, and left posterior cingulate cortex in the patients with HE

¹Techniques mainly for research, currently. MRI: Magnetic resonance imaging; HE: Hepatic encephalopathy.