[Advancement of the imaging for hepatic malignancies]

The development of CT and MR imaging technology represents a significant advancement. On CT imaging,the advent of multi-detector row CT (MDCT) scanners enables an increase in both scanning speed and spatial resolution. Multiphasic dynamic study is useful for the detection of hepatocellular carcinomas (HCCs) which are demonstrated as hyperattenuated lesions during the hepatic arterial phase. Many investigators assess the optimal timing for detection of HCCs by using the evolving MDCT, and have demonstrated the high detection rate for HCCs. Thanks to the increase in spatial resolution along the z-axis,we are now able to generate high-quality CT angiography and multiplanar reformations without complicated interpolation steps. These CT angiography and MPR images of patients with malignant hepatic tumors (e.g., HCCs, cholangiocellular carcinomas) are very useful for preoperative evaluation. On the other hand, the development of MR fast imaging techniques allows rapid breath-hold, whole-liver imaging. Superparamagnetic iron oxide (SPIO) is a liver-specific particulate magnetic resonance (MR) imaging contrast agent that is taken up by the reticuloendothelial system of the liver. SPIOenhanced MR imaging is useful for the detection of hepatic metastases. The advent of parallel imaging techniques improves the quality of images obtained with diffusion weighted (DW) imaging of the liver. DW imaging demonstrates high accuracy in the detection of hepatic metastases. Recently, in Japan, positron emission tomography (PET)-CT has also been employed for evaluation of hepatic metastases.