How has multidetector computed tomography (MDCT) changed the evaluation of the liver, pancreas, and biliary system?
MDCT allows for the rapid acquisition of images using very thin collimation (0.6 mm) and reconstruction intervals (0.5 mm). Using these true isotropic volumetric data sets, exquisite multiplanar reformations (MPR) in the coronal, sagittal, or any other imaging plane can be created.
Imaging can be performed in the noncontrast computed tomography (NCCT) phase, early hepatic arterial phase (HAP), late HAP, and the portal venous phase (PVP) depending on the clinical indication. The early HAP is approximately 20 seconds after injection, the late HAP is 35 to 40 seconds after injection and the PVP is 60 to 70 seconds after injection, with the dominant contrast effect in the liver occurring in the PVP. This ability to image rapidly can take advantage of the dual blood supply of the liver—75% from the portal vein (PV) and 25% from the hepatic artery.
MDCT improves the imaging of the hepatic vasculature. It is very helpful in preoperative or preintraarterial chemotherapy planning and for the detection of hepatic infarctions, aneurysms and pseudoaneurysms, PV thrombosis, or strictures. Liver volumes prior to hepatic resection can also be estimated using volume-rendered images.