The technique and potential clinical applications of multiplanar reformation (MPR) of imaging data from helical computed tomography (CT) to display images of the blood vessels in the abdomen and the thorax are described. Helical CT was performed following bolus intravenous contrast material enhancement in patients with suspected tumor involvement of vessels in various regions of the body. The axial images were stacked to form a volume of imaging data from which a plane could be selected to display the desired vascular image in a two-dimensional format. Various techniques were used to change the image plane so that different vessels in different regions of the body could be displayed, including the splanchnic vessels around the pancreas, the portal veins and hepatic artery in the porta hepatis, the renal vessels, and the venae cavae and aorta. Rotation from a coronal or sagittal plane was necessary to display most vessels. The technique is practical and reproducible, but it requires that the operator be knowledgeable about vascular anatomy. Helical CT angiography with MPR has the potential to display vascular images that are similar to angiograms.