Kidney

Renal oxygenation

The magnetic properties of the haemoglobin in the blood change with oxygenation and this can be imaged non-invasively by blood oxygenation level-dependent MRI (BOLD MRI); deoxyhaemoglobin acting as an endogenous contrast agent.

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Parametric maps of a mouse kidney; on the M0 image, the anatomy of the kidney is clearly visible. When the O2 concentration of the gas mixture the animal was breathing was decreased, the MRI parameter T2* also decreased, indicating poorer oxygenation of the kidney. This technique can be used to investigate the pathofysiology of kidneys of different transgenic mouse models for kidney diseases characterised by hypertension and hypokalaemia (Bailey lab).

Nanoparticle enhanced MRI scanning to detect cellular inflammation

Ultrasmall paramagnetic particles of iron oxide- (USPIO-) enhanced magnetic resonance imaging (MRI) can be used to detect experimental chronic allograft damage in a mouse model of kidney transplantation. The figure on the right shows R2* maps of a mouse before and 48h after USPIO injection. Row (a) shows the allograft transplanted kidney (white arrows) compared to native kidney (yellow arrows) for allograft and row (b) the isograft transplanted kidney (white arrows) compared to native kidney (yellow arrows). The iIncreased R2* signal in kidney allograft (top right panel, green colour) was associated with macrophage and iron staining on histology.

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References:

• Menzies RI, et al. An anatomically unbiased approach for analysis of renal BOLD magnetic resonance images. Am J Physiol Renal Physiol. 2013 Sep 15;305(6):F845-52.
• Evans LC, et al. A urine-concentrating defect in 11β-hydroxysteroid dehydrogenase type 2 null mice. Am J Physiol Renal Physiol. 2012 Aug 15;303(4):F494-502.
• Alam SR, et al. Nanoparticle enhanced MRI scanning to detect cellular inflammation in experimental chronic renal allograft rejection. Int J Mol Imaging. 2015;2015:507909.