Iron-EHPG as an Hepatobiliary MR Contrast Agent

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Abstract
The paramagnetic metal complex iron(III) ethylenebis-(2-hydroxyphenylglycine) [Fe(EHPG)-] is an effective hepatobiliary contrast agent for liver enhancement in magnetic resonance (MR) imaging. The i.v. administration of 0.2 mmol/kg of Fe(EHPG)- to rats yields a 200% increase in the signal intensity of the liver when using a T1-weighted inversion recovery pulse sequence on a 1.4 T imaging system. Biodistribution studies in rats and a rabbit, along with imaging studies in a dog at 0.6 T, confirm that the complex has significant hepatocellular uptake and appears to be excreted unaltered into the bile. Control experiments with a different Fe complex, Fe(III) diethyl-enetriaminepentaacetic acid, reveal little hepatic affinity and poor enhancement capability due to its extracellular distribution. This initial evaluation of Fe(EHPG)- demonstrates that paramagnetic metal complexes with hepatobiliary specificity are well suited for enhancement of normal liver parenchyma and may increase the sensitivity of MR in the detection of liver disease.
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