Use of PET/MRI for identification and characterisation of liver lesions

Magnetic resonance imaging (MRI) has long been considered the gold standard for evaluation of hepatic lesions. There has, however, been much recent interest in functional analysis of malignant lesions, and conventional imaging tests are no longer able to answer all the clinical questions. In the current era, anatomical characterisation, e.g. regarding size and density, is no longer deemed adequate. Combined imaging with PET/CT provides clarity and insight but at times can be challenging, especially in certain parts of the body such as the liver, pelvis and brain, where test sensitivity is compromised. PET/MRI, a hybrid imaging technology, can be used to improve upon the soft-tissue contrast offered by MRI and the biochemical and metabolic information provided by PET, with overall improvement in test sensitivity and hence increased diagnostic accuracy and improved tissue characterisation. Furthermore, various radiolabelled PET tracers can be used to improve the accuracy of staging, determination of the extent of disease, evaluation of treatment response, prognostic assessment and differentiation between post-therapeutic changes and tumour recurrence. In this article, we review the advantages of PET/MRI over conventional imaging in identifying and characterising liver lesions.