Multidetector CT (MDCT, multislice CT, multidetector-row CT, multisection CT) represents a breakthrough in CT technology. It has transformed CT from an transaxial cross-sectional technique into a true 3D imaging modality that allows for arbitrary cut planes as well as excellent 3D displays of the data volume. Multislice CT scanners provide a huge gain in performance that can be used to reduce scan time, to reduce section collimation, or to increase scan length substantially. The following article will provide an overview of the principles of multislice CT scanning. It describes the various detector systems and gives an introduction to the most important acquisition and reconstruction parameters. The article describes how reconstruction of thick multiplanar reformations can be used to take advantage of the 3D capabilities of multislice CT while keep radiation exposure to a minimum.