Cirrhotic liver enhancement on dual-phase helical CT: comparison with noncirrhotic livers in 146 patients.

The purpose of this study was to prospectively determine any differences in vascular and liver enhancement between patients with cirrhosis and patients without cirrhosis during both the arterial and portal venous phases on dual-phase helical CT.Fifty-eight patients with histologically proven cirrhosis (group 1) and 88 without cirrhosis (group 2 = normal findings on CT, group 3 = metastases, group 4 = other liver diseases) underwent dual-phase helical CT of the liver. Attenuation values of liver and vessels were measured on unenhanced scans and on scans obtained during the arterial and portal venous phases. The mean enhancement values per time interval (5 sec) were determined. Results were analyzed taking into account various intrinsic patient parameters.We found no statistically significant difference in terms of mean vascular enhancement and mean liver enhancement during the arterial imaging phase for each time interval among all the groups. The mean peak enhancement and mean liver enhancement during the portal venous phase were significantly lower in group 1 than in other groups. Time to peak enhancement was significantly delayed in group 1.In spite of the hepatic arterial buffer response, mean liver enhancement during the arterial phase was not significantly different in patients with cirrhosis compared with patients without cirrhosis. Although portal vein enhancement did not differ significantly, enhancement of cirrhotic liver was significantly lower during the portal venous phase and delayed, presumably because of decreased peripheral portal perfusion. The contrast injection protocol may be tailored to optimize conspicuity of hypovascular tumor.