The invention provides novel persistent free radicals useful in Overhauser MRI being triarylmethyl radicals having as at least one aryl group a group of formula ##STR1## (wherein each X which may be the same or different is an oxygen or sulphur atom or a group CO or S(O).sub.n, (where n is 1 to 3) with the proviso that at least one group X is a sulphur atom or a S(O).sub.n group; R.sup.1 is a hydrogen atom or group of formula --M, --XM, --X--Ar.sup.2, or --Ar.sup.2 where M is a water solubilizing group, and Ar.sup.2 represents a 5-10 membered aromatic ring optionally substituted by a water solubilizing group M; and each of the groups R.sup.7, which may be the same or different, is a hydrogen atom, or a hydrocarbon group or a water solubilizing group M, or two groups R.sup.7 together with the atom to which they are bound represent a carbonyl group or a 5 to 8 membered cycloalkylidene, mono- or di-oxacycloalkylidene, mono- or di-azacycloalkylidene or mono- or di-thiacycloalkylidene group optionally with the ring attachment carbon replaced by a silicon atom, and R.sup.7 where it is other than hydrogen, is optionally substituted by a hydroxyl group, an optionally alkoxylated, optionally hydroxylated acyloxy or alkyl group or a water solubilizing group M)). The novel radicals have good stability, long relaxation times and good relaxivity.
The present invention relates to certain novel triaryl methyl free radicals and their use as image enhancing agents in magnetic resonance imaging (MRI) as well as to contrast media containing such radicals and to the use of such radicals and their non-radical precursors in the manufacture of MRI contrast media.
The present invention relates to certain novel triaryl methyl free radicals and their use as image enhancing agents in magnetic resonance imaging (MRI) as well as to contrast media containing such radicals and to the use of such radicals and their non-radical precursors in the manufacture of MRI contrast media.
Novel triarylmethyl free radicals, their use as image enhancing agents in MRI, in particular to their use in Overhauser enhanced MRI of a sample for determining oxygen concentration of said sample.
An operation instrument for the examination of an object, for example a biopsy needle, a catheter, or a radioactive capsule intended for radiotherapy. The instrument comprises an active component which is adapted to be detected with a nuclear magnetic resonance method, such as magnetic imaging, in such a way that the active component contains a marker which carries NMR-active nuclei and, in interaction with the marker, an enhancer which causes the enhancement of an NMR signal by means of dynamic nuclear polarization as a result of saturating the electron spin system of the enhancer which causes the enhancement of an NMR signal by means of dynamic nuclear polarization as a result of saturating the electron spin system of the enhancer with an external energy, so-called saturation energy. The operation instrument comprises a marker container and a transfer linen for transferring the saturation energy into the enhancer. The marker is housed in a metal foil, and a boundary surface between the transfer line and the marker container is tapered. The transfer line is provided with an inner conductor extending into the marker container over a substantial distance into the interior of the container.
