MR imaging features in patients with cirrhosis with or without overt HE
| T1WI Sequence | 1H-MR spectroscopy | MTR | T2/FLAIR Sequence | DWI | |
|---|---|---|---|---|---|
| MR imaging abnormalities | Bilateral, symmetric high signal intensity of the globus pallidus and substantia nigra | Increase in glutamine/glutamate signal; depletion of myo-inositol signal; decrease in choline signal; normal NAA signal | Mild (10%) and diffuse decrease in normal-appearing white matter | Diffuse white matter high signal intensities involving predominantly the hemispheric corticospinal tract; focal high-signal T2 lesions in subcortical hemispheric white matter | Increase mean diffusivity in hemispheric white matter; normal fractional anisotropy |
| Pathogenesis | Increased brain tissue concentration of manganese | Osmolar adaptation of intra-astrocytic accumulation of glutamine | Mild and diffuse brain edema | Mild and diffuse brain edema | Interstitial brain edema |
| Functional consequences | Parkinsonism (particularly if substantia nigra is involved) | Overt hepatic encephalopathy (particularly with increase in glutamine/glutamate) | Functional abnormalities of the corticospinal tract on TMS | Functional abnormalities of the corticospinal tract on TMS; cognitive impairment | Cognitive impairment |
Note:—T1WI Indicates T1-weighted imaging; NAA, N-acetylaspartate; TMS, transcranial magnetic stimulation; FLAIR, fluid-attenuated inversion recovery; DWI, diffusion-weighted imaging; MTR, magnetization transfer ratio.