MDCT of the Liver and Hypervascular Hepatocellular Carcinomas: Optimizing Scan Delays for Bolus-Tracking Techniques of Hepatic Arterial and Portal Venous Phases
- 1 July 2006
- journal article
- research article
- Published by American Roentgen Ray Society in American Journal of Roentgenology
- Vol. 187 (1), W25-W32
- https://doi.org/10.2214/ajr.04.1878
Abstract
OBJECTIVE. The purpose of our study was to determine the optimal scan delays required for hepatic arterial and portal venous phase imaging and for the detection of hypervascular hepatocellular carcinomas (HCCs) in contrast-enhanced MDCT of the liver using a bolus-tracking program. SUBJECTS AND METHODS. CT images (2.5-mm collimation, 5-mm thickness with no intersectional gap) detected an increase in the CT value of 50 H in the lower thoracic aorta. The images were obtained after an IV bolus injection of 2 mL/kg of nonionic iodine contrast material (300 mg I/mL) at 4 mL/s in 171 patients, who were prospectively randomized into three groups with scans commencing at 5, 20, and 45 seconds; 10, 25, and 50 seconds; and 15, 30, and 55 seconds for the first (acquisition time: 4.3 seconds), second (4.3 seconds), and third (9.1 seconds) phases, respectively, after a bolus-tracking program. CT values of the aorta, spleen, proximal portal veins, liver parenchyma, and hepatic veins were measured. Increases in CT values from unenhanced to contrast-enhanced CT were assessed using a contrast enhancement index (CEI). Spleen-to-liver and HCC-to-liver contrasts were also assessed. A qualitative degree of contrast enhancement in each organ was prospectively assessed by two independent radiologists. RESULTS. At 10-15 seconds, the CEI of the aorta reached 300-336 H and that of the spleen reached 97-108 H without significant enhancement of liver parenchyma (15-25 H). The CEI of the proximal portal veins moderately increased (75-104 H) at 10-15 seconds, but no significant enhancement of hepatic veins was observed (24-51 H). The CEI of liver parenchyma peaked (59-63 H) at 45-55 seconds, when the CEIs of the aorta (117-125 H) and spleen (73-82 H) decreased. Spleen-to-liver contrast (81-84 H) was highest at 10-20 seconds and HCC-to-liver contrast (39-44 H) was highest at 10-15 seconds. The qualitative results correlated well with quantitative results. CONCLUSION. The optimal scan delays for hepatic arterial and portal venous phases after the bolus-tracking program detected threshold enhancement by 50 H in the lower thoracic aorta for the detection of hypervascular HCCs were 10-15 and 45-55 seconds, respectively.Keywords
This publication has 26 references indexed in Scilit:
- Peak Contrast Enhancement in CT and MR Angiography: When Does It Occur and Why? Pharmacokinetic Study in a Porcine ModelRadiology, 2003
- Aortic and Hepatic Enhancement and Tumor-to-Liver Contrast: Analysis of the Effect of Different Concentrations of Contrast Material at Multi–Detector Row Helical CTRadiology, 2002
- Abdominal Helical CT: Evaluation of Optimal Doses of Intravenous Contrast Material—A Prospective Randomized StudyRadiology, 2000
- Effect of Injection Rate of Contrast Medium on Pancreatic and Hepatic Helical CTRadiology, 1999
- Aortic and hepatic peak enhancement at CT: effect of contrast medium injection rate--pharmacokinetic analysis and experimental porcine model.Radiology, 1998
- Hepatic lesion characterization in cirrhosis: significance of arterial hypervascularity on dual-phase helical CT.American Journal of Roentgenology, 1997
- Multiple-phase helical CT of the liver for detecting small hepatomas in patients with liver cirrhosis: contrast-injection protocol and optimal timing.American Journal of Roentgenology, 1996
- Hepatocellular carcinoma: evaluation with biphasic, contrast-enhanced, helical CT.Radiology, 1996
- Single-pass CT of hepatic tumors: value of globular enhancement in distinguishing hemangiomas from hypervascular metastases.American Journal of Roentgenology, 1995
- Hepatic helical CT: contrast material injection protocol.Radiology, 1994