 As a pilot study, the investigators wish to perform MRI scanning on a subset of 10 patients with paracetamol induced acute liver failure. Paracetamol induced acute liver failure is associated with a particularly rapid course, characterised by hepatic encephalopathy and renal impairment. In view of the potential for renal impairment, intravenous contrast will not be used for these scans, but alternative techniques employed such as artertial spin labelling. 