Recently, positron-emission tomography (PET) systems have been introduced in many institutions around Japan and their clinical importance should increase in the management of many malignant diseases particularly systems using 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG). Since March 2004, we have been using the first PET/computed tomography (CT) scanner in Japan with 4-slice multidetector CT (MDCT) and now have introduced a second PET/CT scanner with 8-slice MDCT because of its excellent diagnostic capability and higher throughput capacity than that of the ordinal PET scanner. MDCT was a landmark in the history of CT in 1998. Subsequently, 8-, 16-, 32-, and 40-slice MDCT was developed in rapid succession. Finally, 64-slice MDCT became commercially available in 2005. In the future, 256-slice MDCT and flat-panel CT will appear in the clinical setting. Using these MDCT systems, we can now obtain multidimensional CT images very easily. These multidimensional images are less-invasive methods that are gradually phasing out the use of invasive angiography including digital subtraction angiography. In this article we describe the current features of PET/CT and multidimensional CT using MDCT.