Nuclear Magnetic Resonance Tissue Analysis of Acute Renal Artery and Renal Vein Occlusion: The Effect of a Paramagnetic Contrast Agent

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Abstract
To assess the potential sensitivity of NMR for the assessment and detection of renal vascular insufficiency, NMR spectroscopy was performed on rabbit renal cortices following 45 min of unilateral renal artery or vein occlusion with and without the injection of a paramagnetic contrast material (MnCl2). Renal vein occlusions produced a marked increase in T1 and T2 relaxation times when compared to the contralateral control kidney (mean increase of 18% in T1 and 27% in T2). Renal artery occlusions produced no change in T1 and only a slight increase in T2 (mean increase of 5%). After the i.v. injection of 0.03 mM/kg of MnCl2, T1 of the control kidneys was reduced by almost 50%. Relaxation parameters from the kidneys undergoing arterial occlusion did not change after Mn injection when compared to the occluded kidneys without contrast. In the kidneys undergoing venous occlusion, a moderate decrease in T1 resulted from MnCl2. In the absence of a paramagnetic contrast material, NMR discriminates well between normal and (venous occlusion) congested kidneys, but not between normal and acutely ischemic (arterial occlusion) kidneys. In the presence of a renal paramagnetic contrast material, NMR aids in the differentiation of acute unilateral arterial insufficiency, as relaxation times from the normal kidney decline while the ischemic kidney does not change.