Magnetic resonance imaging evaluation of renal ischaemia–reperfusion injury in a rabbit model

Abstract

What is the central question of this study? Renal ischaemia-reperfusion injury occurs in various clinical settings. The clinical diagnosis of ischaemia-reperfusion injury is routinely based on biochemical and haematological tests, which cannot evaluate the function of a single kidney. New magnetic resonance imaging techniques to identify the pathophysiological changes in the renal outer medulla were evaluated. What is the main finding and its importance? This study demonstrated that susceptibility-weighted imaging is a feasible non-invasive tool for imaging and evaluating physipathological changes in the renal outer medulla after ischaemia-reperfusion injury. The aim was to evaluate the feasibility of susceptibility-weighted imaging (SWI) as a tool to identify the changes in the renal outer medulla (OM) in a rabbit model of renal ischaemia-reperfusion injury (IRI). New Zealand rabbits were used (control group n = 10; IRI group n = 40). The rabbits in the IRI group were subjected to left renal artery clamping for 60 min. T2-weighted (T2WI) and SWI examinations were performed at 1, 12, 24 or 48 h after reperfusion (each n = 10). After the examinations, the kidneys were submitted to histological evaluation. The contrast-to-noise ratio (CNR) for the left renal OM was measured using T2WI and SWI. The T2WI and SWI scores of the integrity of the renal OM were evaluated. There were significant differences between T2WI CNRs and SWI CNRs in the control group and the IRI 1, 12 and 48 h time points (all P < 0.05). No significant difference was found between T2WI and SWI CNRs at IRI 24 h (P > 0.05). The mean SWI scores of renal OM in the IRI 1 and 12 h subgroups were both significantly lower than that in the control group (all P < 0.05). The only significant difference in the mean T2WI scores of renal OM was observed between the control and IRI 1 h groups (P < 0.05). Susceptibility-weighted imaging has a significant advantage in evaluation of healthy renal OM over conventional magnetic resonance imaging, and it is a feasible non-invasive tool for imaging and evaluating changes in the renal OM after IRI.

Evaluation of renal ischemia‐reperfusion injury by magnetic resonance imaging texture analysis: An experimental study

“…A previous study found obvious changes in the renal outer medulla on SWI after renal IRI, and the integrity of the hypointense outer medulla on SWI showed significant differences at various time points after IRI 12 . This study further investigated the correlation between renal IRI on SWI with histopathology.…”

“…24 A previous study found obvious changes in the renal outer medulla on SWI after renal IRI, and the integrity of the hypointense outer medulla on SWI showed significant differences at various time points after IRI. 12 This study further investigated the correlation between renal T A B L E 4 Receiver operating characteristic curve analysis of texture features in the differentiation of the kidney at 1 and 12 hours after reperfusion from that at 24…”

“…Blood oxygen level–dependent MRI quantitatively assesses the oxygenation‐level changes in renal IRI 10,11 . A previous study found that SWI could reflect the degree of renal IRI and that SWI changes may be related to renal blood supply 12 ; however, it did not clarify the correlation between SWI and histopathology in renal IRI. Magnetic resonance imaging texture analysis provides a quantitative approach for the characterization of the properties of tissues by the statistical analysis of the pixel distribution in the image, which is more objective and more repeatable than qualitative and semiquantitative analysis 13,14 .…”

Recent advances in medical image processing for the evaluation of chronic kidney disease

“…Mie et al have investigated the feasibility of SWI on human kidneys (Mie et al, 2010). SWI signal was found to be affected by perfusion alterations and tissue fibrosis in animal models (Pan et al, 2017;J. G. Zhang et al, 2018).…”

“…G. Zhang et al, 2018). Pan et al have demonstrated the sensitivity of SWI after renal reperfusion where the SWI score has decreased and returned to baseline over 48h after reperfusion injury (Pan et al, 2017). Additionally, Zhang et al have shown a decrease of SWI signal ratio and a strong correlation with fibrosis staging (J. G. .…”