Lars-Göran Wistrand

Overhauser-enhanced MR imaging (OMRI)

Purpose: to evaluate a new single-electron contrast agent for Overhauser-enhanced MR imaging. the contrast agents that are currently available give enhancement factors that are too low to make the technique a valid option for routine clinical use Material and Methods: MR images were generated directly following the injection of the substance into rats. the MR scanner was operated at a main magnetic field of 0.01 T and equipped with a separate rf-transmitter tuned to the electron paramagnetic resonance frequency of the contrast agent Results: as expected, the images generated show a high level of enhancement in areas where the contrast agent was present, and a maximum enhancement of 60 times the normal proton signal was obtained in the vascular area. the signal-to-noise ratios in the images were superior to those previously attained Conclusion: the new contrast agent makes it possible to generate MR images with both morphological and functional information at 0.01 T. the signal-to-noise ratios found in the generated images were of the same order as, or better than, those obtained with the standard clinical routine

Use of persistent heterocyclic free-radicals in magnetic resonance imaging

The present invention provides the use of a persistent π-system free radical for the manufacture of a contrast medium for use in magnetic resonance imaging, wherein the electron delocalising π-system of said radical comprises at least one homo or heterocyclic ring, said radical being other than the chloranil semiquinone anion radical or a trityl radical. Also provided are magnetic resonance imaging contrast media containing and methods using such radicals.

Acyloxylation of methylbenzenes by potassium peroxydisulphate

Potassium peroxydisulphate in acetic acid containing 9% trifluoroacetic acid has been shown to oxidize a number of substituted methylbenzenes, yielding nuclear and side-chain acetates. In the presence of copper(II) acetate nuclear substitution is suppressed, and a mixture of side-chain acetate and trifluoroacetates is obtained. This mixture can be hydrolysed to the corresponding benzyl alcohol in total yields varying from 18 to 66%. The mechanism has been investigated and the results obtained support a radical cation pathway.