Detecting and characterising small liver tumours

The successful treatment of liver tumours is more likely if they are found early. The use of high-resolution CT and MRI with contrast enhancement allows more sub-centimetre liver lesions to be detected, but some small tumours remain occult even at surgery with intra-operative sonography. An indication of the accuracy of imaging in detecting liver metastases may be given by the proportion of lesions found which are under 1–2 cm in size. The characterisation of small lesions remains problematic on CT, with benign and malignant tumours showing overlapping imaging features. However, with appropriate use of chemical shift, heavy T2 weighting, gadolinium enhancement, and liver-specific contrast agents, a carefully tailored MRI examination will usually produce diagnostic appearances.