Abstract 109: The Usefulness of Double Arterial Phase Imaging of Multislice Helical CT for the Detection of Hypervascular Hepatocellular Carcinoma
AUTHORS:
T. Murakami, MD, PhD, T. Kim, MD, S. Takahashi, MD, M. Takamura, MD, Y. Narumi, MD, H. Nakamura, MD, PhD, et al.
ABSTRACT:
PURPOSE: We assess whether double arterial phase imaging of multi-slice helical CT will improve detection of hypervascular hepatocellular carcinoma (HCC).
METHOD AND MATERIALS: 25 patients with 39 hypervascular HCC nodules (3-50 mm in diameter, mean 20 mm) underwent double arterial phase imaging of multi-slice helical CT for the whole liver. Single-level CT scanning with IV injection of 15 ml of 300 mgI/ml of non-ionic contrast medium at a rate of 5 ml/sec was performed to determine delay time to start the early arterial phase scan. At the time of measured delay after IV administration of 2ml/kg of the contrast medium at a rate of 5ml/s, the early and late arterial phase images were obtained serially during a single breath-hold with interscan delay of 6.1 sec. 4i mode, x-ray beam thickness of 10mm, pitch of 1:6, and scan time of 10.5 sec for each phase were employed. 40 prospective reconstruction images of 5mm thickness for each phase were obtained. The early and late arterial phase images were separately interpreted for detection of hypervascular HCC nodules by three observers who were unaware of tumor burden in the liver. A combination of surgical resection, Iodized oil CT obtained 1 week and 1 month after transcatheter arterial chemoembolization with iodized oil and follow up imaging examinations were employed as the gold standard. Sensitivity and positive predictive values for early arterial phase alone, late arterial phase alone, and double arterial phase (early and late arterial phases combined) were calculated and compared by McNemar's test.
RESULTS: The double arterial phase images could detect 12 nodules and 3 nodules that were missed by the early and late arterial phase images respectively. The sensitivity and positive predictive values for hypervascular HCC nodules was 56% and 88% for the early arterial phase, 79% and 84% for the late arterial phase, and 87% and 97% for the double arterial phase. The double arterial phase imaging showed significantly superior sensitivity to the early arterial phase for detecting HCC nodules (p<0.01). The double arterial phase imaging showed least number of false positive lesions, though there was no statistically significant difference in sensitivities between the double-arterial phase and the late phase.
CONCLUSIONS: The double arterial phase imaging is recommended to improve the detection of hypervascular HCC nodules and reduce false positive lesion.
