Magnetic Resonance Studies of the Brain in Liver Disease
- Pp. 160-182 (23)Mark J.W. McPhail, Howard C. Thomas and D. Taylor-Robinson Simon
The diverse neurological manifestations of liver disease pose a diagnostic challenge for modern hepatologists with magnetic resonance (MR) techniques representing a highly profitable avenue to investigate structural and functional aspects of brain dysfunction. The commonest, but not sole neurological manifestation of liver disease, hepatic encephalopathy (HE), is a sequel of both acute and chronic liver failure, ranging from cognitive impairment, only detectable on psychometric evaluation through to confusion, coma and death from cerebral edema. While there is widespread acceptance of its importance, there is little consensus on how best to diagnose and monitor HE. Clinical descriptions, psychometric testing, electroencephalography (EEG) and lately, imaging techniques, such as magnetic resonance (MR) imaging, MR spectroscopy and positron emission tomography (PET) all have their proponents, but most putatively, diagnostic paradigms remain the preserve of research establishments with an interest in HE. Of note, modern clinical MRI scanners with multinuclear MR spectroscopy capabilities and brain mapping software can objectively demonstrate structural and functional cellular changes (such as brain size and astrocyte swelling) using volumetric MRI, magnetization transfer MRI, diffusion-weighted MRI, functional MRI with oxygenation measurements and in vivo <sup>1</sup>H and <sup>31</sup>P MR spectroscopy, with the option of performing many sequences at a single session to maximize information gathering and cohort characterization. These techniques are also transferable to characterize non-HE cases of neurological dysfunction in liver disease, such as primary biliary cirrhosis, the neuropsychiatric sequela of non-cirrhotic chronic hepatitis C infection and metal deposition disorders, such as Wilson’s disease and hemochromatosis. This chapter describes the relative merits of these MR techniques and provides guidance on the directions for future research and translational into clinical practice.