A New Technique for Assessing Renal Transplant Perfusion Preoperatively Using Contrast-Enhanced Ultrasound (CEUS) and Three-Dimensional Ultrasound (3DUS) – A Porcine Model Pilot Study

Zusammenfassung

Ziel: Diese Pilotstudie hat das Ziel, die Durchführbarkeit des kontrastverstärkten Ultraschalls (CEUS) in Nierentransplantaten zu bewerten, die sich vor Transplantation an hypothermen Perfusionsmaschinen befinden. Wir beurteilen die renale Durchblutung der Maschinen-perfundierten porcinen Nieren mit CEUS (Mastricht-Kategorie II). Material und Methoden: 5 Nieren wurden bis zu 24 h nach Ankunft an die hypotherme Maschinenperfusion angeschlossen. Die Nieren wurden dann mit einer Niedrig-MI-kontrastspezifischen Voreinstellung gescannt und ein Bolus von 0,5 ml Sonovue-Kontrastmittel wurde verabreicht. Die kontrastspezifischen Ultraschallbilder wurden in 2-D und 3-D aufgenommen. Ergebnisse: An der Perfusionsmaschine zeigten die 5 Nieren variable Flussraten (10 – 37 ml/min bei 30 mmHg). Die CEUS-Technik stellte in 4 Nieren gute Perfusion und Strömungsprofile dar, die den in vivo gesehenen entsprachen. Eine Niere hatte bis zur interlobären Region durchgängige Arterien, aber keine Kontrastfüllung in Rinde oder Mark. Kleine Perfusionsdefekte wurden in 2 der perfundierten Nieren gesehen. Schlussfolgerung: CEUS scheint eine brauchbare Methode zur Bestimmung der globalen Perfusion und kleiner Defekte in Nieren vor Transplantation zu sein. Die Flussmuster in vitro scheinen denen in vivo zu entsprechen und es ist noch weitere Arbeit erforderlich, um die Relevanz der gemessenen Durchflussdynamiken zu bewerten.

Abstract

Purpose: This pilot study aims to assess the viability of using contrast-enhanced ultrasound (CEUS) in renal grafts while they are on hypothermic perfusion machines prior to transplantation. We assessed the vascularity and renal perfusion of machine-perfused porcine kidneys (Maastricht category II) using CEUS. Materials and Methods: Five kidneys were placed on hypothermic machine perfusion for up to 24 hours after retrieval. The kidneys were then scanned with a low MI contrast-specific preset and a bolus of 0.5ml of Sonovue contrast agent was administered. Contrast-specific ultrasound images of the kidney were acquired in 2D and 3D. Results: The five kidneys demonstrated variable flow rates on the perfusion machine (10 – 37 ml/min at 30 mmHg). The CEUS technique demonstrated good perfusion and flow patterns, similar to those seen in vivo, in four kidneys. One kidney had patent arteries up to the interlobar region but no contrast filling in the cortex or medulla. Small perfusion defects were seen in two of the perfused kidneys. Conclusion: CEUS appears to be a viable technique for assessing global perfusion and small defects within kidneys prior to transplantation. The flow patterns seen in vitro appear to correspond to those seen in vivo. Further work is required to evaluate the relevance of the flow dynamics measured.

Key words

kidney transplant - contrast-enhanced ultrasound - three-dimensional ultrasound - volume ultrasound

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