Abstract
PurposeThe aim of the study was to investigate microstructural changes occurring in unilateral renal ischemia-reperfusion injury in a murine animal model using synchrotron radiation.Material and MethodsThe effects of renal ischemia-reperfusion were investigated in a murine animal model of unilateral ischemia. Kidney samples were harvested on day 18. Grating-Based Phase-Contrast Imaging (GB-PCI) of the paraffin-embedded kidney samples was performed at a Synchrotron Radiation Facility (beam energy of 19 keV). To obtain phase information, a two-grating Talbot interferometer was used applying the phase stepping technique. The imaging system provided an effective pixel size of 7.5 µm. The resulting attenuation and differential phase projections were tomographically reconstructed using filtered back-projection. Semi-automated segmentation and volumetry and correlation to histopathology were performed.ResultsGB-PCI provided good discrimination of the cortex, outer and inner medulla in non-ischemic control kidneys. Post-ischemic kidneys showed a reduced compartmental differentiation, particularly of the outer stripe of the outer medulla, which could not be differentiated from the inner stripe. Compared to the contralateral kidney, after ischemia a volume loss was detected, while the inner medulla mainly retained its volume (ratio 0.94). Post-ischemic kidneys exhibited severe tissue damage as evidenced by tubular atrophy and dilatation, moderate inflammatory infiltration, loss of brush borders and tubular protein cylinders.ConclusionIn conclusion GB-PCI with synchrotron radiation allows for non-destructive microstructural assessment of parenchymal kidney disease and vessel architecture. If translation to lab-based approaches generates sufficient density resolution, and with a time-optimized image analysis protocol, GB-PCI may ultimately serve as a non-invasive, non-enhanced alternative for imaging of pathological changes of the kidney.
Highlights
Renal ischemia-reperfusion (I/R) accounts for the majority of acute kidney injury cases [1], which often progress to chronic kidney disease [2]
Ill patients present with a decrease of renal function, i.e. glomerular filtration, there are no established laboratory tests for a reliable diagnosis of ischemia-reperfusion damage, so that renal biopsy remains the diagnostic standard of reference with all its risks and potential complications [5]
By performing volumetric and histogram analysis of the functional kidney compartments after ischemia-reperfusion damage, we demonstrate quantitative non-invasive assessment of pathophysiological processes with Grating-Based Phase-Contrast Imaging (GB-phase-contrast imaging (PCI))
Summary
Renal ischemia-reperfusion (I/R) accounts for the majority of acute kidney injury cases [1], which often progress to chronic kidney disease [2]. Ill patients present with a decrease of renal function, i.e. glomerular filtration, there are no established laboratory tests for a reliable diagnosis of ischemia-reperfusion damage, so that renal biopsy remains the diagnostic standard of reference with all its risks and potential complications [5] Morphological imaging modalities such as ultrasonography, computed tomography and magnetic resonance imaging are not ideally suited for detection of renal parenchymal disease, as early changes rather affect the ultrastructure and function than gross morphology [6]. PCI of the kidney without the use of a contrast agent has so far only been performed using crystal-based phase imaging techniques [15,17,18,19] These studies already demonstrate the innovative potential of this technique to depict the smallest anatomical structures and detect parenchymal renal disease such as glomerulosclerosis in hamster kidneys [15]. Several studies on biomedical samples conducted at polychromatic x-ray sources have shown improved imaging of parenchymal lung disease [25], breast lesions [26,27], cartilage [28], and atherosclerotic plaques [29] at good density resolution and reasonable spatial resolution
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
