Characterization of Focal Liver Lesions by Means of Assessment of Hepatic Transit Time with Contrast-enhanced US

Abstract

To assess whether hepatic transit times (HTTs), as measured with contrast material-enhanced ultrasonography (US), can help predict the nature of focal liver lesions. The study was approved by the local institutional ethics committee, with written informed patient consent. A total of 402 patients were enrolled in the study. HTT, the time between the appearance of the microbubble contrast agent in the hepatic artery and its appearance in the hepatic vein, was measured in the contrast pulse sequencing mode after injection of a sulphur hexafluoride microbubble US contrast agent. Logistic regression was used to identify factors indicative of the malignant or nonmalignant status of focal liver lesions. Receiver operating characteristic (ROC) analysis was performed to determine the predictive value of the HTT. Observed HTTs for malignant focal liver lesions (mean, 6.2 seconds; range, 2-10 seconds) were significantly lower than those for nonmalignant lesions (mean, 9.5 seconds; range, 4-25 seconds; P < .001). ROC analysis revealed cutoff values of 7 seconds for HTT and 0.879 for area under the ROC curve. For HTTs of 7 seconds or shorter, hepatic malignancies were detected with a sensitivity of 79%, a specificity of 80%, a positive predictive value of 53%, and a negative predictive value of 93%. No malignant lesions had an HTT longer than 10 seconds. HTT alone could be a good predictor for nonmalignancy of focal liver lesions.