Bench-to-bedside review: Contrast enhanced ultrasonography - a promising technique to assess renal perfusion in the ICU

Antoine Schneider,Mark Goodwin,Rinaldo Bellomo,Lynne Johnson,Anthony Schelleman

doi:10.1186/cc10058

Antoine Schneider, Mark Goodwin + Show 3 more

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https://doi.org/10.1186/cc10058

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Journal: Critical Care	Publication Date: Jan 1, 2011
Citations: 97	License type: cc-by

Affiliation: Monash University, Austin Hospital

Abstract

Acute kidney injury (AKI) is common in critically ill patients and associated with important morbidity and mortality. Although alterations in renal perfusion are thought to play a causative role in the pathogenesis of AKI, there is, to date, no reliable technique that allows the assessment of renal perfusion that is applicable in the ICU. Contrast-enhanced ultrasound (CEUS) is an ultrasound imaging technique that makes use of microbubble-based contrast agents. These microbubbles, when injected into the bloodstream, allow visualization of vascular structures and, with contrast-specific imaging modes, detection of blood flow at the capillary level. Some recent CEUS-derived approaches allow quantification of blood flow in several organs, including the kidney. Current generation ultrasound contrast agents have strong stability and safety profiles. Along with post-marketing surveillance, numerous studies report safe administration of these agents, including in critically ill patients. This review presents information on the physical principles underlying CEUS, the methods allowing blood flow quantification and the potential applications of CEUS in critical care nephrology, currently as a research tool but perhaps in the future as a way of monitoring renal perfusion.

Highlights

Acute kidney injury (AKI) is common and severe in critically ill patients, with a reported incidence between 1 and 30% and mortality between 28 and 90%, dependingThe pathophysiology of AKI remains poorly understood
As renal function is intimately linked to organ blood flow, alterations in renal perfusion are considered key to the pathophysiology of AKI
Based on the non-linear properties of microbubbles submitted to acoustic pressure, these imaging modes use a combination of changes in pulse phase and amplitude to selectively minimize tissue echoes and enhance ultrasound contrast agent echoes

Summary

Introduction

Acute kidney injury (AKI) is common and severe in critically ill patients, with a reported incidence between 1 and 30% and mortality between 28 and 90%, depending. Imaging methods such as scintigraphy or magnetic resonance imaging (MRI) are much more accurate and can provide valuable information on kidney perfusion [7,8] Their use in the ICU is limited by equipment availability, costs and their requirement for extensive and prolonged patient manipulation, which is associated with risk and major logistic challenges. Based on the non-linear properties of microbubbles submitted to acoustic pressure, these imaging modes use a combination of changes in pulse phase and amplitude to selectively minimize tissue echoes and enhance ultrasound contrast agent echoes. They all make use of low mechanical index (MI) imaging. Blood flow quantification by CEUS Since microbubbles remain confined to the intravascular space, and have a rheology similar to that of red blood cells, contrast uptake as a function of time can be used to estimate quantitative perfusion parameters, such as regional blood volume or blood flow

Theories and methods

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Conclusion