Comparison of ionic and non-ionic nitroxide spin labels for urographic enhancement in magnetic resonance imaging.

W Grodd, H Paajanen, U G Eriksson, D Revel, F Terrier, R C Brasch

Index: Acta radiol. 28(5) , 593-600, (1987)

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Abstract

Two nitroxide spin labels (NSL) were compared for in vitro relaxivity and in normal rats for efficiency of urographic enhancement. One of the NSL, PCA, a pyrrolidinyl agent, was ionic and one, NAT, was a non-ionic pyrrolidinyl NSL with multiple hydroxyl substituents for water solubility. Using both NSLs the renal medulla and papilla were noted to show greater contrast enhancement than the cortex, with a maximum enhancing effect between 5 and 15 minutes. Using doses of 1.0 and 2.5 mmol/kg, more than 100 per cent increases in spin echo intensities above the baseline were observed. The lowest tested dose of 0.1 mmol/kg showed an easily detectable enhancing effect for NAT. The good contrast enhancing properties of NAT, considered together with its better acute tolerance, justifies further investigation of this non-ionic compound.