Liver Mass Evaluation with Ultrasound: The Impact of Microbubble Contrast Agents and Pulse Inversion Imaging

Stephanie R. Wilson; Peter N. Burns

doi:10.1055/s-2001-15342

Seminars in Liver Disease, Table of Contents

Semin Liver Dis 2001; 21(2): 147-160
DOI: 10.1055/s-2001-15342

Liver Mass Evaluation with Ultrasound: The Impact of Microbubble Contrast Agents and Pulse Inversion Imaging

Stephanie R. Wilson¹ , Peter N. Burns²

¹Section of Ultrasound, Toronto General Hospital-University Health Network, and Medical Imaging, University of Toronto, Toronto, Canada
²Department of Medical Biophysics, Sunnybrook and Women's College Health Sciences Centre, and Medical Biophysics, University of Toronto, Toronto, Canada

Abstract

ABSTRACT

Liver mass evaluation includes two essential elements-lesion detection and lesion characterization. Both of these are greatly improved on sonography with the addition of contrast agents and the use of specialized imaging techniques, particularly pulse inversion imaging. Ultrasound contrast agents are comprised of tiny microbubbles of gas that interact with the ultrasound beam producing an enhancement of the Doppler signal from blood. Pulse inversion imaging allows preferential detection of the signal from the microbubble agents with suppresion of the signal from background tissue. Two imaging techniques include a low mechanical index (MI) nondestructive method to show lesional vascularity and a high MI destructive mode that produces disruption of the bubbles in a single frame. The latter allows for quantitative assessment of the relative enhancement of a lesion as compared with the adjacent liver parenchyma, which is a reflection of the relative vascular volumes. Vascular imaging has shown characteristic and reproducible features of common liver masses, including hemangioma, focal nodular hyperplasia, hepatocellular carcinoma, and liver metastases. Delayed postvascular enhancement of the normal liver, a phenomenon that is unique to certain classes of microbubble contrast agents, allows detection of more and smaller malignant lesions than on baseline.

KEYWORD

Contrast agents - liver - neoplasm - pulse inversion imaging - ultrasound

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References

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