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A variety of modalities is available to image the liver and biliary tract, many offering complementary information; a combination of techniques is often required to make the diagnosis or determine optimal patient management. Ultrasonography (US) is commonly used as the primary investigation as it is safe, cheap and widely available. Computed tomography (CT) has a central role in emergency imaging, cancer diagnosis and staging, surgical planning and assessment of treatment response. Magnetic resonance imaging (MRI) is excellent for interrogating the liver parenchyma, and is the modality of choice for characterizing a focal liver lesion and non-invasive investigation of the biliary tree. Hepatobiliary contrast agents and diffusion-weighted imaging have further improved the accuracy of MRI. This article describes the role of each of these modalities, highlighting several common benign and malignant hepatobiliary disease processes. Other less commonly used modalities such as positron emission tomography-CT, cholescintigraphy and endoscopic ultrasound/cholangioscopy are summarized. Keywords Bile ductsbiliary tract diseasescholangiographycomputed tomographyliverliver diseasesmagnetic resonance imagingMRCPpositron emission tomographyultrasonography

Lack of substantial advances in pre-clinical testing for hepatotoxicity has meant that drug-induced liver injury (DILI) remains an important issue during both the drug development and post-marketing phases. A number of drug-related, genetic and non-genetic host factors influence the risk of DILI in any individual. Demonstration of human leukocyte antigen genotype as a strong risk factor for the development of DILI from a range of drugs has highlighted the role of the adaptive immune system in its pathogenesis; there is accumulating evidence that drug metabolism genes also contribute to some forms of DILI. Early recognition and prompt withdrawal of the drug is essential in preventing serious hepatic failure and is the critical step in the management of adverse reactions. Diagnosis of DILI relies upon index of suspicion, careful evaluation of a temporal relationship between the exposure to a particular drug and the specific clinical event, and exclusion of potential alternative diagnoses. A high negative predictive value of genetic tests can be used to rule out DILI caused by particular drugs and to correctly identify the agent underlying DILI in a patient exposed to two concomitant medications. Keywords Adverse drug reactiondrug-induced liver injuryhepatotoxicityhuman leukocyte antigenMRCPpharmacogenetics

Histopathological assessments play an important role in the diagnosis and management of patients with liver disease. For some conditions, liver biopsy is still routinely used to establish the cause of liver disease. In other circumstances, evaluation of morphological changes provides additional information that is useful for clinical management, for example when assessing disease severity in chronic viral hepatitis and non-alcoholic fatty liver disease. However, with the increased use of non-invasive methods for assessing the severity of liver injury, particularly fibrosis, the role of liver biopsy in this respect is changing. In cases where a dual pathology is suspected, histological assessment can help to identify the main cause of liver injury. In addition, liver biopsy sometimes reveals abnormalities that have not been detected by previous investigations. Histopathological assessment of liver biopsies involves a systematic evaluation of changes involving individual components of the normal liver. The final interpretation of the abnormalities detected depends on clinico-pathological correlation. Sampling variation is a problem, particularly with small needle biopsies, and should be considered as a possible explanation when there is a disparity between clinical and pathological findings. Keywords Liver biopsyliver histologyliver pathologyMRCP