title: X-ray phase-contrast tomography of renal ischemia-reperfusion damage.
abstract: OBJECTIVE
  The aim of the study was to investigate microstructural changes occurring in unilateral renal ischemia-reperfusion injury in a murine animal model using synchrotron radiation.
  
  
  METHODS
  The 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.
  
  
  RESULTS
  GB-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.
  
  
  CONCLUSIONS
  In 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.
authors.affiliation: Chair of Biomedical Physics, Department of Physics (E17), Munich, Bavaria, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Velroyen
authors.affiliation: Chair of Biomedical Physics, Department of Physics (E17), Munich, Bavaria, Germany; Medical Radiation Physics, Lund University, Lund, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Bech
authors.affiliation: Chair of Biomedical Physics, Department of Physics (E17), Munich, Bavaria, Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Zanette
authors.affiliation: Chair of Biomedical Physics, Department of Physics (E17), Munich, Bavaria, Germany.
authors.forename: Jolanda
authors.initials: J
authors.lastname: Schwarz
authors.affiliation: European Synchrotron Radiation Facility, Grenoble, France.
authors.forename: Alexander
authors.initials: A
authors.lastname: Rack
authors.affiliation: Institute of Pathology, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Tympner
authors.affiliation: Department of General, Trauma, Hand, and Plastic Surgery, Ludwig-Maximilians-University Hospital Munich, Munich, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Herrler
authors.affiliation: Institute for Clinical Radiology, University Hospitals Munich, Munich, Germany; Comprehensive Pneumology Center, University Hospital, Ludwig-Maximilians-University and Helmholtz Zentrum Munich, Munich, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Staab-Weijnitz
authors.affiliation: Institute for Clinical Radiology, University Hospitals Munich, Munich, Germany.
authors.forename: Margarita
authors.initials: M
authors.lastname: Braunagel
authors.affiliation: Institute for Clinical Radiology, University Hospitals Munich, Munich, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Reiser
authors.affiliation: Institute for Clinical Radiology, University Hospitals Munich, Munich, Germany; Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
authors.affiliation: Chair of Biomedical Physics, Department of Physics (E17), Munich, Bavaria, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Pfeiffer
authors.affiliation: Institute for Clinical Radiology, University Hospitals Munich, Munich, Germany; Department of Radiology, University Hospital Tuebingen, Tuebingen, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Notohamiprodjo
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D000818:Animals; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted; D007672:Kidney Cortex / Q000000981:diagnostic imaging* / Q000473:pathology; D007679:Kidney Medulla / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015427:Reperfusion Injury / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D017356:Synchrotrons; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods