Liver imaging. Clinical applications and future perspectives.

Primary hepatocellular carcinoma and liver metastases affect several million people each year. The main imaging modalities to detect and assist diagnosis of primary and secondary liver tumours include MR imaging, CT, and US. The value of these techniques is further increased by the use of contrast agents which increase the sensitivity, and sometimes also the specificity, of the investigations. The relative advantages and drawbacks of the different contrast agents and imaging modalities in the detection and characterisation of liver tumours are discussed. Currently there is no consensus amongst investigators as to which is superior, due to the technical complexities and number of combinations possible within each of the different modalities. There continues to be advances in the hardware and software of imaging equipment, as well as a trend to develop new contrast agents with more organ-specificity. These include those targeting the hepatocytes, such as mangafodipir trisodium (MnDPDP, Teslascan), and those with reticuloendothelial cell specificity, such as the superparamagnetic iron oxides. These developments have the potential for making significant contributions to the diagnostic value of imaging procedures and, by reducing the number of investigations necessary to reach a final diagnosis, having a significant and beneficial impact on the pharmaco-economics of patient health care.