Ultraschall Med 2018; 39(01): 69-79
DOI: 10.1055/s-0042-104645
Original Article
© Georg Thieme Verlag KG Stuttgart · New York

Evaluation of Perfusion Quantification Methods with Ultrasound Contrast Agents in a Machine-Perfused Pig Liver

Bewertung der Methoden zur Quantifizierung der Perfusion mittels Ultraschallkontrastmittel bei maschineller Perfusion einer Schweineleber
Michalakis Averkiou
1   Bioengineering, University of Washington, Seattle, United States
,
Christina P. Keravnou
2   Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
,
Maria Louisa Izamis
2   Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
,
Edward Leen
3   Hammersmith Hospital, Imperial College London, United Kingdom of Great Britain and Northern Ireland
› Author Affiliations
Further Information

Publication History

01 September 2015

17 February 2016

Publication Date:
03 May 2016 (online)

Abstract

Purpose To evaluate dynamic contrast-enhanced ultrasound (DCEUS) as a tool for measuring blood flow in the macro- and microcirculation of an ex-vivo machine-perfused pig liver and to confirm the ability of DCEUS to accurately detect induced flow rate changes so that it could then be used clinically for monitoring flow changes in liver tumors.

Materials and Methods Bolus injections of contrast agents in the hepatic artery (HA) and portal vein (PV) were administered to 3 machine-perfused pig livers. Flow changes were induced by the pump of the machine perfusion system. The induced flow rates were of clinical relevance (150 – 400 ml/min for HA and 400 – 1400 ml/min for PV). Quantification parameters from time-intensity curves [rise time (RT), mean transit time (MTT), area under the curve (AUC) and peak intensity (PI)] were extracted in order to evaluate whether the induced flow changes were reflected in these parameters.

Results A linear relationship between the image intensity and the microbubble concentration was confirmed first, while time parameters (RT and MMT) were found to be independent of concentration. The induced flow changes which propagated from the larger vessels to the parenchyma were reflected in the quantification parameters. Specifically, RT, MTT and AUC correlated with flow rate changes.

Conclusion Machine-perfused pig liver is an excellent test bed for DCEUS quantification approaches for the study of the hepatic vascular networks. DCEUS quantification parameters (RT, MTT, and AUC) can measure relative flow changes of about 20 % and above in the liver vasculature. DCEUS quantification is a promising tool for real-time monitoring of the vascular network of tumors.

Zusammenfassung

Ziel Die Bewertung der dynamischen kontrastverstärkten Sonografie (DCEUS) als Methode zur Messung des Blutflusses in der Makro- und Mikrozirkulation einer Ex-Vivo maschinellen Perfusion einer Schweineleber. Bestätigung, dass DCEUS in der Lage ist, die induzierten Veränderungen der Flussrate exakt nachzuweisen und somit in der Klinik zur Überwachung von Flussveränderungen in Lebertumoren eingesetzt werden kann.

Material und Methoden Bolus-Injektionen der Kontrastmittel in die Leberarterie (HA) und die Pfortader (PV) wurden an 3 Schweinelebern mit maschineller Perfusion verabreicht. Die Flussänderungen wurden durch die Pumpe des maschinellen Perfusionssystems verursacht. Die induzierten Flussraten waren klinisch relevant (150 – 400 ml/min für HA und 400 – 1400 ml/min für PV). Die Quantifizierungsparameter aus den Zeit-Intensitätskurven [Anstiegszeit (RT), mittlere Laufzeit (MTT), Fläche unter der Kurve (AUC) und Spitzenintensität (PI)] wurden extrahiert, um zu bewerten, ob die induzierten Flussänderungen von diesen Parametern widergespiegelt wurden.

Ergebnisse Eine lineare Beziehung zwischen der Bildintensität und der Konzentration der Mikrobläschen wurde zuerst bestätigt, während die Zeitparameter (RT und MMT) unabhängig von der Konzentration gezeigt wurden. Die induzierten Flussänderungen, die sich von den größeren Gefäßen zum Parenchym verbreiten, werden durch die Quantifizierungsparameter reflektiert. Insbesondere die Parameter RT, MTT und AUC korrelierten mit Veränderungen der Flussrate.

Schlussfolgerung Die maschinelle Perfusion der Schweineleber ist ein hervorragendes Testsystem für den DCEUS-Quantifizierungsansatz bei der Untersuchung des Lebergefäßsystems. Die DCEUS-Quantifizierungsparameter (RT, MTT und AUC) können die relativen Flussänderungen in etwa 20 % und mehr im Gefäßsystem der Leber messen. Die DCEUS-Quantifizierung ist eine vielversprechende Methode für die Echtzeitüberwachung des Gefäßsystems von Tumoren.

 
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