Contrast-enhanced dynamic ultrasonography of the liver:: optimization of hepatic arterial phase in normal volunteers2

Background: To optimize hepatic arterial phase timing in contrast-enhanced dynamic ultrasonography (US) of the liver. Methods: Dynamic US was performed by using a microbubble-specific mode in 22 healthy volunteers after bolus injection of SH U 508A. Images were analyzed to determine whether hepatic arterial and portal venous phases could be temporally discriminated. Delay times to contrast enhancement at the hepatic artery (A(ini)) and portal vein (P-ini) and the delay time until the signals between both vessels became inseparable (A(end)) were determined. Results: The hepatic arterial and portal venous phases could be temporally discriminated in all subjects. A(ini), P-ini, and A(end) (mean +/- standard deviation) were 11.0 +/- 2.0, A 14.8 +/- 3.6, and 22.6 +/- 5.1 s, respectively. Conclusion: In hepatic contrast-enhanced dynamic US, hepatic arterial phase scanning should be commenced earlier than 11 s and terminated after 23 s post-injection.