Abstract: The magnetic resonance catheter antenna includes a first tube having a proximal end and a distal end. A litz wire has a first end and a second end and is looped within the first tube such that the first end and the second end are disposed at the proximal end. A guide wire is disposed within the first tube. A multifilament or solid wire may be used instead of a litz wire. At least the looped portion of the wire is insulated.

Abstract: A magnetic resonance image receiving coil includes a first balloon having a longitudinal axis. An internal surface of the first balloon defines an internal inflatable chamber. A second balloon has a longitudinal axis. The second balloon is disposed about the first balloon. A plurality of longitudinally extending grooves are disposed in one of an external surface of the first balloon and the internal surface of the second balloon. A first wire is disposed in at least one of the grooves. A second wire is disposed in at least a second one of the grooves. Each of the first wire and the second wire is adapted to be electrically connected to an MRI apparatus. In accordance with an alternate embodiment, the first and second wires are disposed in grooves in a sheath which is disposed between the first and second balloons. In accordance with a further alternate embodiment, the first and second wires are disposed in guide tubes that are connected to the external surface of a balloon.

Abstract: Nitroxides useful as MRI enhancing agents are of the formula ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each are alkyl of 1-4 carbon atoms; and R is --alk--COO.sup.- M.sup.+ or --B--N.sup.+ (Alk).sub.3 Hal.sup.- in which alk is alkylene of 1-8 carbon atoms, B is a divalent bond or alkylene of 1-8 carbon atoms, M.sup.+ is an ammonium or metal ion, Alk is alkyl of 1-8 carbon atoms or a corresponding alkyl group substituted by a free or esterified hydroxy group, and Hal.sup.- is Cl.sup.-, Br.sup.- or I.sup.-.

Abstract: Nitroxides useful as NMR contrast enhancing agents for organs are of the formula ##STR1## wherein in the above formulae, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are, g., CH.sub.3 ; R is --B--COO--M.sup.+ or --B--N(alkyl).sub.3 Hal.sup.-, wherein B is a divalent bond or alkylene of 1-8 carbon atoms, M is an ammonium or metal ion and Hal is a halogen atom; are also useful as NMR contrast enhancing agents on joints.

Abstract: Charged, stable, organic nitroxides, e.g., charged by a quaternary ammonium or a Bronsted acid group, are useful as NMR image enhancing agents for cerebrospinal fluid.