Bruker Analytische Messtechnik Gmbh

Bruker Medizintechnik Gmbh

Bruker Analytik Gmbh

Bertold Knuttel

Michael Westphal

Wolfgang H Muller

Gunther R Laukien

Dieter Ratzel

Hartmut Schmidt

Alexander Knuttel

Hans Post

Peter Brunner

An RF coil system (1) for an MR tomograph comprising a magnet coil system and a gradient coil system is characterized in that the RF coil system is constructed of two partial systems (2, 2') which are arranged essentially laterally reversed with respect to a plane z=0 containing the centre of the measuring volume and have a distance g/2 from the plane z=0, and that each partial system (2, 2') comprises at its axial end facing the plane z=0, a compensation section (3, 3') for homogenizing the RF field drop in the measuring volume caused by the axial gap between the partial systems (2, 2') as compared with an axially continuous and undivided RF coil system (1). The RF coil system (1) in accordance with the invention allows lateral access to the investigation volume in the radial direction and/or offers the possibility to integrate in the RF coil system an adjustment, fixing or support ring surrounding the investigation volume.

RF coil system for an MR measuring means

Magnet arrangement for a one-sided NMR tomography system having a permanent magnetic ring (4) of an outer radius R.sub.a and an inner radius R.sub.i and being magnetized axially in the direction of the z-axis and extending in the axial direction up to a plane E (z=z.sub.E) for generating a homogeneous magnetic field B in a measuring volume (2) is characterized in that, in a radial region R&lt;R.sub.i, at least one further permanent magnetic field-generating element, which is rotationally symmetric, is arranged with respect to the plane E on the same side as the permanent magnetic ring (4) at an axial distance from plane E, whereby a depression V is formed on the surface of the magnet arrangement (1) facing plane E and that the permanent magnetic field-generating elements generate at least 90%, preferably 99% of the homogeneous magnetic field B in the measuring volume (2). In this manner, NMR examinations of the skin or other regions which are close to the surface can be carried out in a particularly easy manner.

Magnet arrangement for an NMR tomography system, in particular for skin

An NMR tomography magnet system (1) comprises a cryostat having a horizontal room temperature bore (2) with a diameter d between 20 cm and 40 cm having a vessel (3) filled with liquid helium. In intimate thermal contact with the liquid helium is a superconducting solenoid coil (4) with a horizontal axis (100; z=0) for the production of a static homogeneous magnetic field B in a homogeneity volume (5) within the room temperature bore (2). The center of the homogeneity volume is located at a separation l.sub.m from an axial end (z=0) of the room temperature bore (2) and the outer skin (6) of the cryostat exhibits, at the depth l.sub.m from an axial end of the room temperature bore (2) and at least in an angular region about the horizontal cryostat axis (100), minimum separations h.sub.e, h from the inside of the room temperature bore (2) whereby l.sub.m, h.sub.e &lt;35 cm, preferentially&lt;30 cm, and h&lt;50 cm. In this fashion, an investigational apparatus for partial body applications, in particular, for the investigation of human extremities is made available which can be manufactured with compact construction in an economical fashion. The apparatus facilitates high imaging resolution with low stray fields and, in particular, allows for investigations of patients with the patients assuming a comfortable body position.

Partial body tomograph

A magnet system for nuclear spin resonance spectroscopy, in particular for in-vivo spectroscopy and tomography on a limb or a shoulder of a human body (partial-body tomography) comprising a superconductive magnet coil arrangement having coil sets (2a, 3a; 2b, 3b) arranged at an axial spacing one from the other, for generating a static homogeneous magnetic field in an examination volume, and further a coil frame (6) carrying the coil sets and a cryostat intended for cooling the windings, is characterized by the fact that the windings are rigidly interconnected by the coil frame at low temperature and that there is provided a transverse room-temperature access (50) to the examination volume which extends over approximately 180.degree. in circumferential direction, related to the axis (4) of the magnet coil arrangement. This enables examinations to be carried out at ease.

Magnet system

In an NMR apparatus with a system of gradient coils for the production of a magnetic field gradient within a measurement volume (1) within a field coil, the transverse gradient coils are constructed unsymmetrically with respect to the z=0 plane dividing the measurement volume (1), however largely mirror symmetric to a x=0 or y=0 plane containing the z axis, and possess only two partial coils (20', 20''; 40', 40'') whose windings each exhibit the same winding direction. The axial gradient coils are cylindrically symmetric with respect to the z axis and totally unsymmetric with respect to the z=0 plane, and consist of at least two partial coils which are arranged on differing sides of z=0 plane, whereby the partial coils on one side largely exhibit the opposite winding direction than the coils on the other side, and whereby the number of coils with a particular winding direction is not equal to the number of coils with the opposite winding direction. In each case, it is thereby achieved that the measurement volume (1) is displaced to a, relative to the z axis, axial end of the apparatus so that access to the measurement volume (1) is substantially improved.

Gradient coil system

A nuclear magnetic resonance spectrometer, in particular a nuclear spin tomograph serving to investigate biological samples, comprising a magnetic coil for generating a substantially homogeneous magnetic field in a volume under examination, and a set of shim coils for eliminating any remaining inhomogeneities of the magnetic field is characterized in that at least one additional electric conductor, preferably an additional shim coil, is provided which may be arranged in the volume under examination, in the direct vicinity of the sample, that the additional conductor is designed in such a way that it will generate an inhomogeneous magnetic field when loaded with current, and that it can be loaded with currents of a type generating inhomogeneous magnetic fields which will eliminate, at least partially, and in a selected area in the sample, local field inhomogeneities resulting from susceptibility variations within the sample, for example. This enables the accuracy of the spectroscopy results to be improved.

Nuclear magnetic resonance spectrometer

Nuclear spin tomograph

For recording the nuclear magnetic resonance in selected areas of a body for the purpose of representing body cross-sections in the form of images (NMR tomography), wherein the nuclear spins of a selected type present in the area of one plane of the body are subjected to a superimposed gradient field varying in the selected cross-sectional plane, and selectively excited, the excitation of the nuclear spins is effected by application of a pulse sequence which induces the nuclear spins to supply at one stage a number of chronologically successive induction signals. The induction signals corresponding to each other in chronolical sequence are then processed to obtain separate sets of image signals so that by one single measurement a sequence of cross-sectional images is obtained which differ from each other by the intensity of the excited nuclear spins which varies according to the relaxation times T.sub.1 or T.sub.2. The fact that all images have been obtained by one and the same measurement provides the possibility to determine the relaxation times T.sub.1 and/or T.sub.2 related to the individual image points and to use them on the one hand for purposes of selective image representation and, on the other hand, for improving the image quality.

Method for recording the nuclear magnetic resonance for use in VNMR

Apparatus for producing complete three-dimensional images of a spatial

An electromagnet for generating the constant magnetic field required in NMR tomography includes a superconductive coil system consisting of at least one circular cylindrical field coil (1) and at least one correction coil (2, 3) concentric with the field coil. The coil system is enclosed in a ferromagnetic cylindrical shell (13) whose influence on the homogeneity of the magnetic field is compensated by the particular dimensioning of the field and correction coils. The magnetic field is produced by the coil system (1, 2, 3) in the interior space defined by it, which space is accessible and suitable to receive the body presented for examination. The cylindrical shell (13) may be closed at its ends by ring-shaped ferromagnetic plates (14). The cylindrical shell (13), complete with plates (14), may directly form the exterior wall of the Dewar.

Electromagnet for NMR tomography

An electromagnet for producing the constant magnetic field required in NMR tomography comprises a coil system (1, 2, 3, 4) of the Helmholtz double coil type. The coil system is enclosed in, and supported by, a stable cylindrical shell (5). The influence exerted by the cylindrical shell (5) on the homogeneity of the magnetic field, which is generated by the coil system in an accessible interior space defined by it and suitable to receive the body to be examined, is compensated by the particular dimensioning of the field and error coils (1, 2, 3, 4). The cylindrical shell (5) is best made of a ferromagnetic material having low electric conductivity and is constructed of a plurality of axially serially disposed annular discs (6) which are preferably divided into sectors.

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Rheinstetten, Germany

Bertold Knuttel