Helical CT scanning, with the rapid acquisition of a volumetric data set, has resulted in a dramatic increase in sensitivity and specificity in the evaluation of hepatic abnormalities. The appropriate contrast enhancement, intravenous contrast and oral contrast, is necessary when imaging the abdominal organs, especially the liver. With helical CT, complete scanning of the liver can be accomplished in less than 20 seconds. Multiple scans through the liver can be performed corresponding to various phases of hepatic enhancement including arterial, venous and equilibrium as well as delayed phases. Multiphase CT can result in increased lesion detection and the pattern of enhancement on these different phases can result in lesion characterization. Since the entire liver can be scanned in a single breath hold, misregistration artifacts caused by voluntary or involuntary motion are reduced or eliminated. Additionally, thinner slices can be acquired and reconstructed at finer intervals when compared with conventional CT. Therefore, the effect of partial volume averaging of small lesions is reduced with resultant improvement in lesion detection and characterization.
