Attenuation changes in periportal region during triple-phasic contrast- enhanced CT

Objective: To evaluate attenuation changes in the periportal regions of the liver during triphasic contrast CT. Materials and Methods: The study group consisted of 93 patients, all of whom underwent triphasic contrast- enhanced CT with a helical scanner for survey of liver disease. The three phases included the arterial phase, portal venous phase, and equilibrium phase. Attenuation changes in the periportal area in each phase were evaluated in every patient. Factors surmised to be related with periportal low attenuation, including elevation of venous pressure, presence of ascites, cardiac enlargement, and lymphadenopathy of the porta hepatis and lesser omental region, were also evaluated. Results: Periportal low attenuation was seen in 65 patients (69.8%) in the portal venous phase where the liver parenchyma showed the largest attenuation value. Among them, periportal low attenuation was continuously observed in every phase in 13 patients (13.9%), while it was confirmed only in the portal venous phase in 28 patients (30.1%), and in 24 patients (32.2%) in the portal venous phase plus either the arterial or equilibrium phase. None of the factors that were investigated could be related to the appearance of periportal low attenuation. Conclusion: Periportal low attenuation was a relatively common finding in the portal venous phase of triphasic contrast CT, whereas it was less usual in the arterial or equilibrium phase.