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- Title
Early effects of an x-ray contrast medium on renal T<sub>2</sub>*/T<sub>2</sub> MRI as compared to short-term hyperoxia, hypoxia and aortic occlusion in rats.
- Authors
Arakelyan, K.; Cantow, K.; Hentschel, J.; Flemming, B.; Pohlmann, A.; Ladwig, M.; Niendorf, T.; Seeliger, E.
- Abstract
Aim X-ray contrast media ( CM) can cause acute kidney injury ( AKI). Medullary hypoxia is pivotal in CM-induced AKI, as indicated by invasively and pin-point measured tissue oxygenation. MRI provides spatially resolved blood oxygenation level-dependent data using T2* and T2 mapping. We studied CM effects on renal T2*/T2 and benchmarked them against short periods of hyperoxia, hypoxia and aortic occlusion ( AO). Methods Rats were equipped with carotid artery catheters (tip towards aorta) and supra-renal aortic occluders. T2*/T2 mapping was performed using a 9.4-T animal scanner. CM (1.5 mL iodixanol) was injected into the thoracic aorta with the animal in the scanner followed by 2 h of T2*/T2 mapping. For T2*/T2 assessment, regions of interest in the cortex ( C), outer medulla ( OM), inner medulla ( IM) and papilla ( P) were determined according to morphological features. Results Hyperoxia increased T2* in C (by 17%) and all medullary layers (25-35%). Hypoxia decreased T2* in C (40%) and all medullary layers (55-60%). AO decreased T2* in C (18%) and all medullary layers (30-40%). Upon injection of CM, T2* increased transiently, then decreased, reaching values 10-20% below baseline in C and OM and 30-40% below baseline in IM and P. Conclusion T2* mapping corroborates data previously obtained with invasive methods and demonstrates that CM injection affects renal medullary oxygenation. CM-induced T2* decrease in OM was small vs. hypoxia and aortic occlusion. T2* decrease obtained for hypoxia was more pronounced than for AO. This indicates that T2* may not accurately reflect blood oxygenation under certain conditions.
- Subjects
X-rays; MAGNETIC resonance imaging; HYPEROXIA; HYPOXEMIA; CONTRAST media; ARTERIAL occlusions; LABORATORY rats; KIDNEY physiology
- Publication
Acta Physiologica, 2013, Vol 208, Issue 2, p202
- ISSN
1748-1708
- Publication type
Article
- DOI
10.1111/apha.12094