Role of multiphase scans by multirow-detector helical CT in detecting small hepatocellular carcinoma.

Aim: To evaluate the role of multiphasic scanning by multirow-detector helical CT (MDCT) in detecting small hypervascular hepatocellular carcinoma (SHCC).

Methods: Multiphasic scanning was carried out in 75 patients with SHCC with Marconi MX8000 CT scanner. The early arterial phase (EAP), late arterial phase (LAP) and the portal venous phase (PVP) scans were started at 21 s, 34 s and 85 s respectively. The mean difference of CT values between tumor and liver parenchyma for each scanning phase was measured, and the sensitivity of detection of SHCC in each of these phases and in the combined phase was calculated and statistically analyzed.

Results: The mean difference of CT values between tumor and liver parenchyma was significant in 71 lesions > or =1 cm in three phases (P<0.05). In 91 tumor foci, the detectability of SHCC was 45.1%, 83.5% and 92.3% in EAP, LAP and double arterial phases (DAP), respectively. The early arterial phase plus the portal venous phase and the double arterial phase plus the portal venous phase were 94.5%, 97.8%, respectively. Whereas the detectability in LAP plus PVP and in DAP plus PVP had no statistical difference.

Conclusion: The utility of faster speed and thinner slice MDCT and multiphase scanning protocol can improve the detectability of hypervascular small hepatocellular carcinoma. Among which LAP is superior to EAP in depicting the lesions.