Multislice CT in imaging the liver

The objective of this paper is to address the dramatic impact of multislice CT (MSCT) in imaging the liver. Standard helical (spiral) CT has finally allowed for scanning the majority of the liver during the critical portal venous phase (PVP). This is often referred to as the ‘optimal temporal window’. In general, it occurs following a 70 s scan delay and is coincidental with the maximal delivery of contrast via the portal vein that provides 80% of the hepatic blood supply. This yields maximal conspicuity between low-attenuation lesions and the dramatically enhanced normal liver parenchyma at routine injection rates of 2–3 ml/s. Most importantly, these scanners, when compared to single-slice scanners, avoid impinging on the ‘equilibrium’ phase where tumors can become isodense/invisible. The introduction of MSCT with four, eight and 16-detector systems has significantly increased imaging speed. Volumetric CT will continue to increase speed in the future. This provides a number of important gains that will be described.