Abstract: A camera for use in coincidence imaging includes detector heads (10a, 10b) disposed about an examination region (12). The detector heads (10a, 10b) include septa (36) for absorbing radiation having a relatively large axial angle. The septa, however, cause the sensitivity of the detectors (10a, 10b) to vary as a function of axial position along their face. The relative positions of the detectors (10a, 10b) and the patient are varied so as to reduce septal artifacts. In particular, artifacts arising from second and fourth harmonics may be reduced.

Abstract: A transformable gamma camera includes detectors mounted for circumferential movement with respect to a rotating gantry. The rotating gantry includes radial bores at desired angular positions about the rotating gantry. The stationary gantry includes a docking station such as a bore. A coupling mechanism allows the detectors to be coupled to the bores in the rotating gantry or to the docking station. Each of the detectors is movable radially with respect to the rotating gantry's axis of rotation and tangentially to the imaging region. The gamma camera is readily transformable between 120 degree, orthogonal, and opposed detector configurations; a plurality of aperture sizes can also be defined.

Abstract: An imaging system produces an image of an internal part of an object and a representation of a tool, which representation corresponds to the position of the tool with respect to the actual object. An imaging apparatus defines an examination region. After an image of the object is obtained, the object is moved to a treatment position fixed in relation to the examination region. The object is supported on a moveable table, which is in turn supported on a pair of rails. A reference frame mounted to the imaging apparatus carries radiation detectors for detecting radiation emitted by emitters on a surgical tool. The position of the tool with respect to the reference frame, and hence with respect to the actual object, can therefore be determined.

Abstract: A flexible catheter or other object for insertion into an object is designed for use in connection with magnetic resonance (MR) imaging techniques. The catheter carries a closed loop coil arrangement tuned to the RF excitation frequency used in operation of an MR imager. The coil arrangement includes turns which lie substantially in non-parallel planes when the axis of the catheter is in a straight line. The coil arrangement may include two coils which are constituted by different sections of an electrically conductive track carried on a flexible, insulating substrate. According to another embodiment, the coil arrangement may comprise two separate closed loop tuned coils each constituted by a narrow metallized track carried on a flexible, insulating substrate. In another embodiment, the coil comprises turns of a saddle form.

Abstract: A magnetic resonance imager has a magnetically permeable core and two pole pieces, each pole piece having a face. The pole pieces are arranged on the core such that the pole piece faces are in opposed relationship forming a first gap therebetween. At least one of the pole pieces is comprised of an outer element 23 connected to the core and an inner element 24 connected between the outer element and the first gap. The outer element 23 forms a cup inside which the inner element 24 is disposed. A plurality of screws 11, 12 and 13 are disposed through the outer element 23 and engage the inner element 24 such that a second gap is formed between the inner and outer element. The homogeneity of the magnetic field in the first gap is affected by adjusting the position of the inner element relative to the outer element via screws 11, 12 and 13.

Abstract: A transducer for Overhauser magnetic resonance imaging comprises a cylindrical NMR coil 11 and a two part VHF applicator 12, 13. The applicator and coil are arranged such that the electric field provided by the applicator in use is substantially perpendicular to the coil wires. The VHF applicator is shaped to give a helical field in the region filled by the RF coil, and the RF coil is arranged to be a helix of the opposite handedness. The applicator can comprise a number of similar elements having an electromagnetic resonance mode whose magnetic fled couple to the imaging volume. The elements can be arranged in spirals to form an electric periodic structure.

Abstract: The invention relates to a method for examination of motion of material employing magnetic resonance imaging methods. A magnetic field, which is referred as an auxiliary field is applied over the first area of the object, this auxiliary field is arranged to get smaller as one moves from the first area to the second area, referred as the area to be examined. Partially simultaneously with the auxiliary field a radio frequency pulse, AHP-pulse, is applied on the object, the frequency of the AHP-pulse is the Larmor-frequency corresponding to the strength of the magnetic field in the area to be examined. The length of the AHP-pulse corresponds to the time, which is required for the material to move from the first area to the area to be examined.

Abstract: Two opposite iron core pole pieces of a magnetic resonance medical imager generate a static magnetic field in a patient imaging volume disposed between the pole pieces. Gradient coils are positioned in the face of a pole piece. Thin disc shaped (42, 44) or ring shaped (41) ferromagnetic parts laminated of layers cut favorably from transformer sheet material are attached to the face of the pole piece. Each layer is electrically insulated from adjacent layers and surfaces by enamel or fixing glue. To reduce eddy currents in these layers, narrow, radially oriented slots (43, 45) are cut in these layers before lamination. The slots are oriented in the adjacent layers so as not to coincide resulting in improved conduction of the magnetic flux in the imaging volume during the production of gradient magnetic fields by the gradient coils.

Abstract: An SLP pulse is applied to an object to be imaged preceding one or more excitation pulses (a.sup.o or a) of a known magnetic resonance imaging technique. The SLP pulse tilts the nuclear magnetization away from the direction of B.sub.o, locks the magnetization with the rotating magnetic component and returns the magnetization back to the direction of B.sub.o. The known magnetic resonance imaging technique used with the SLP pulse includes applying at least one excitation pulse to generate transverse magnetization in the object. The excitation pulse causes the angle between the nuclear magnetization and B.sub.o to be less than 90.degree..

Abstract: An electron spin resonator (ESR) is used to compensate for temporally varying instabilities in the main magnetic field B.sub.o of a nuclear magnetic resonance imaging apparatus during the derivation of NMR imaging data from an object being imaged. The ESR monitor is placed at a point outside but close to the object such that the ESR monitor is affected by the temporally varying fields. Variances across the ESR caused by gradient fields are compensated for such that the output of the ESR is independent of the strength of the gradient fields. The ESR output is used to reduce the influence of said instabilities on the imaging data.

Abstract: A probe (3) for use in in vivo imaging of a microscopic internal region (1) of a patient's body using magnetic resonance techniques incorporates a member (7) having a surface having a pattern of projections (9) formed thereon. In use the surface contacts the surface of the region to trap between the projections molecules in the region, thereby to restrict diffusion of the molecules and so improve resolution of the image obtained.

Abstract: A contact sensor apparatus with improved sensitivity is provided. A frame defining a surface upon which contact detection is desired has two electrically conductive sheets held in spaced parallel relationship by a plurality of electrically non-conductive insulating spacers attached to the face thereof. A contact force distributor is sandwiched between the outside electrically conductive sheet and a graphics layer. Contact forces on the graphics layer, that are in alignment with the spacers, are redistributed to areas between adjacent spacers by the contact distributor.

Abstract: A magnetic resonance apparatus including an r.f. coil arrangement (13) for detecting and/or exciting magnetic resonance in a body in use of the apparatus, the coil arrangement comprising a cylindrical coil (25) and two saddle coils (29) which are disposed in register on opposite sides of the cylindrical coil and conform to the surface of the cylindrical coil.In use of the apparatus the coil arrangement is disposed with the axes of the coils lying in a plane orthogonal to the direction of a static field applied to the body.