Quantitative Renal Perfusion Measurements in a Rat Model of Acute Kidney Injury at 3T: Testing Inter- and Intramethodical Significance of ASL and DCE-MRI

Bernhard K Krämer,Sarah Klotz,Frank G Zöllner,Simone Hoeger,Charalambos Tsagogiorgas,Fabian Zimmer,Nick Ashton,Lothar R Schad

doi:10.1371/journal.pone.0053849

Abstract

ObjectivesTo establish arterial spin labelling (ASL) for quantitative renal perfusion measurements in a rat model at 3 Tesla and to test the diagnostic significance of ASL and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in a model of acute kidney injury (AKI).Material and MethodsASL and DCE-MRI were consecutively employed on six Lewis rats, five of which had a unilateral ischaemic AKI. All measurements in this study were performed on a 3 Tesla MR scanner using a FAIR True-FISP approach and a TWIST sequence for ASL and DCE-MRI, respectively. Perfusion maps were calculated for both methods and the cortical perfusion of healthy and diseased kidneys was inter- and intramethodically compared using a region-of-interest based analysis.Results/SignificanceBoth methods produce significantly different values for the healthy and the diseased kidneys (P<0.01). The mean difference was 147±47 ml/100 g/min and 141±46 ml/100 g/min for ASL and DCE-MRI, respectively. ASL measurements yielded a mean cortical perfusion of 416±124 ml/100 g/min for the healthy and 316±102 ml/100 g/min for the diseased kidneys. The DCE-MRI values were systematically higher and the mean cortical renal blood flow (RBF) was found to be 542±85 ml/100 g/min (healthy) and 407±119 ml/100 g/min (AKI).ConclusionBoth methods are equally able to detect abnormal perfusion in diseased (AKI) kidneys. This shows that ASL is a capable alternative to DCE-MRI regarding the detection of abnormal renal blood flow. Regarding absolute perfusion values, nontrivial differences and variations remain when comparing the two methods.

Highlights

Most renal and renovascular diseases like renal artery stenosis or renal insufficiency are initially without any symptoms or pain
The dynamic contrast-enhanced magnetic resonance imaging (DCE-Magnetic resonance imaging (MRI)) values were systematically higher and the mean cortical renal blood flow (RBF) was found to be 542685 ml/100 g/min and 4076119 ml/100 g/min (AKI). Both methods are able to detect abnormal perfusion in diseased (AKI) kidneys. This shows that arterial spin labelling (ASL) is a capable alternative to Dynamic contrast-enhanced (DCE)-MRI regarding the detection of abnormal renal blood flow
The rats were examined without any incidents and ASL and DCE-MRI data sets were obtained from each rat

Summary

Introduction

Most renal and renovascular diseases like renal artery stenosis or renal insufficiency are initially without any symptoms or pain. ASL does not have this disadvantage as it is a completely non-invasive method that uses magnetically labelled water protons in arterial blood as an endogenous tracer [7,8] This way, by combining one of the three main labelling schemes (pulsed labelling (PASL) [8,9,10,11], continuous labelling (CASL) [12] or pseudo-continuous labelling (pCASL) [13]) with an adequate imaging sequence, a perfusion sensitive experiment can be designed. With the advent of fast imaging sequences that are less susceptible to field inhomogeneities, applications in the abdomen became possible Due to their high perfusion, the kidneys have been one of the first sites where ASL was applied outside the brain and several studies have shown the feasibility of quantitative renal perfusion for healthy, diseased and transplanted kidneys [15,16,17,18,19,20]

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