Abstract: A portable device is used to measure exposure to magnetic fields and/or exposure to changes of magnetic field. The device (10) includes a first sensor (14) for measuring instantaneous magnetic field strength, and a second sensor (15) which is located adjacent to, and orientated in the same direction as, the first sensor for providing an output indicative of the time rate of change of the magnetic field. An integrator (22) integrates the rate of change output from the second sensor (15) over time to derive relative changes in the magnetic field. A processor (20) is connected to the outputs of at least the first sensor and the integrator. The processor selectively provides an indication of field strength from the output of the first sensor if the output is within the normal operating range of the first sensor, or otherwise from the integrator. A memory (24) is connected to the output of the second sensor (15) to store cumulative exposure to changes in the magnetic field.

Abstract: Biological data, such as human heart rate data, is acquired and processed in a non-linear manner to facilitate an assessment of the physiological state of the subject, and/or to assist in predicting incipient disorders or instability. Determinism, laminarity and recurrence measures are derived for a rolling sample of a time series of said data. The recurrence measure can be the Euclidean threshold (?thresh) at a given recurrence rate. A representation, such a colour coded matrix or multi-dimensional vector, is formed from a combination of the derived determinism, laminarity and recurrence measures. The representation can then be analysed to detect indicators of physiological instability, such as arrhythmia, or to discriminate between arrhythmias. The analysis may be performed visually, or in an automated manner in real time, such as in an ambulatory or implanted device, or post hoc by a bedside monitor.

Abstract: Magnetic resonance systems are provided which employ a shielded, asymmetric magnet to produce an offset dsv. The magnets include at least a first coil C1, which carries current in a first direction, and two coils C2 and C3, which are located at least in part within the internal envelope EC1 defined by the first coil and which carry current in an opposite direction to the first coil. The magnets are shielded by a shielding coil C4, which carries current in a direction opposite to that of the first coil, and/or a ferromagnetic structure (FS). The magnets can include additional coils, such as a fifth coil C5 at the magnet's distal end. The magnets can be used in, for example, orthopedic imaging.

Abstract: Asymmetric radio frequency (RF) coils for magnetic resonance applications are provided. Also provided are time harmonic methods for designing such coils as well as symmetric coils. In addition, methods for converting complex current density functions into discrete capacitive and inductive elements are provided.

Abstract: Bi-planar coil assemblies are disclosed which have DSV's whose centers are offset by distances D from the origins of x,y,z-coordinate systems, where said origins of x,y,z-coordinate systems are coincident with the geometric centers of the coils. The distances D can be of the order of 10-20 centimeters or more. The bi-planar coil assemblies can be used in MRI applications to reduce the feeling of claustrophobia experienced by some subjects. The assemblies also can facilitate the imaging of various joints, including the wrist, elbow, ankle, or knee.

Abstract: Magnetic resonance systems are provided which employ a shielded, asymmetric magnet to produce an offset dsv. The magnets include at least a first coil C1, which carries current in a first direction, and two coils C2 and C3, which are located at least in part within the internal envelope EC1 defined by the first coil and which carry current in an opposite direction to the first coil. The magnets are shielded by a shielding coil C4, which carries current in a direction opposite to that of the first coil, and/or a ferromagnetic structure (FS). The magnets can include additional coils, such as a fifth coil C5 at the magnet's distal end. The magnets can be used in, for example, orthopedic imaging.

Abstract: A radio frequency (RF) coil array is used in resonance imaging and/or analysis of a subject located within a cylindrical space in which a magnetic field is operatively applied in an axial direction (z). The coil array comprises a plurality of coil elements (10, 11, 12, 13) angled relative to each other about the axis of the cylindrical space, each coil element having a pair of main conductors extending generally parallel to the direction of the magnetic field and located on diametrically opposite sides of the cylindrical space, and a pair of connection conductors connected between respective ends of the main conductors. Each coil element has its maximum sensitivity near the centre of the cylindrical space, so that the subject under study is located in a region of maximum sensitivity.

Abstract: Bi-planar coil assemblies are disclosed which have DSV's whose centers are offset by distances D from the origins of x,y,z-coordinate systems, where said origins of x,y,z-coordinate systems are coincident with the geometric centers of the coils. The distances D can be of the order of 10-20 centimeters or more. The bi-planar coil assemblies can be used in MRI applications to reduce the feeling of claustrophobia experienced by some subjects. The assemblies also can facilitate the imaging of various joints, including the wrist, elbow, ankle, or knee.

Abstract: Asymmetric radio frequency (RF) coils for magnetic resonance applications are provided. Also provided are time harmonic methods for designing such coils as well as symmetric coils. In addition, methods for converting complex current density functions into discrete capacitive and inductive elements are provided.

Abstract: Asymmetric radio frequency (RF) coils for magnetic resonance applications are provided. Also provided are time harmonic methods for designing such coils as well as symmetric coils. In addition, methods for converting complex current density functions into discrete capacitive and inductive elements are provided.

Abstract: Asymmetric, compact non-superconducting magnets for magnetic resonance imaging are provided. The magnets have a homogeneous region (the “dsv”) which can be located close to one end of the magnet so as to reduce the sensation of claustrophobia experienced by patients undergoing MRI procedures. The magnets can be designed using a hybrid process in which current density analysis is performed to obtain an initial coil configuration which is then refined using non-linear optimization techniques to obtain a final coil configuration. The hybrid method can incorporate various constraints, including, the location and size of the dsv, the uniformity and strength of the B0 field, stray field strengths outside of the non-superconducting magnet, and field strengths within the magnet's coils. The hybrid technique can also be used to design compact symmetric non-superconducting magnets.

Abstract: Asymmetric tesseral coils and sets for magnetic resonance applications are provided. Also provided are methods for designing such coils, as well as coils generating arbitrary field profiles. In certain embodiments, the coils are rigorously constrained to have finite dimensions.

Abstract: Asymmetric tesseral coils and sets for magnetic resonance applications are provided. Also provided are methods for designing such coils, as well as coils generating arbitrary field profiles. In certain embodiments, the coils are rigorously constrained to have finite dimensions.

Abstract: Asymmetric, compact non-superconducting magnets for magnetic resonance imaging are provided. The magnets have a homogeneous region (the “dsv”) which can be located close to one end of the magnet so as to reduce the sensation of claustrophobia experienced by patients undergoing MRI procedures. The magnets can be designed using a hybrid process in which current density analysis is performed to obtain an initial coil configuration which is then refined using non-linear optimization techniques to obtain a final coil configuration. The hybrid method can incorporate various constraints, including, the location and size of the dsv, the uniformity and strength of the B0 field, stray field strengths outside of the non-superconducting magnet, and field strengths within the magnet's coils. The hybrid technique can also be used to design compact symmetric non-superconducting magnets.

Abstract: Asymmetric radio frequency (RF) coils for magnetic resonance applications are provided. Also provided are time harmonic methods for designing such coils as well as symmetric coils. In addition, methods for converting complex current density functions into discrete capacitive and inductive elements are provided.

Abstract: Asymmetric zonal shim coils and shim sets for magnetic resonance applications are provided. Also provided are Fourier-series based methods for designing such coils as well as symmetric coils.

Abstract: Asymmetric, compact superconducting magnets for magnetic resonance imaging are provided. The magnets have a homogeneous region (the "dsv") which can be located close to one end of the magnet so as to reduce the sensation of claustrophobia experienced by patients undergoing MRI procedures. The magnets can be designed using a hybrid process in which current density analysis is performed to obtain an initial coil configuration which is then refined using non-linear optimization techniques to obtain a final coil configuration. The hybrid method can incorporate various constraints, including, the location and size of the dsv, the uniformity and strength of the B.sub.0 field, stray field strengths outside of the superconducting magnet, and field strengths within the magnet's coils. The hybrid technique can also be used to design compact symmetric superconducting magnets.

Abstract: An NMR probehead is proposed having a generally cylindrical casing extending along a probehead axis. The NMR probehead can be inserted into the room temperature bore of an NMR spectrometer magnet providing, in a measurement region, a homogeneous static magnetic field along the probehead axis. The NMR probehead comprises a cylindrical radio frequency (RF) resonator oriented along a resonator axis and generating essentially homogeneous RF magnetic fields transverse to the resonator axis. In accordance with the invention, the angle between the probehead axis and the resonator axis is different from 0.degree.. In this manner, the inclination of the resonator does not affect the useful RF magnetic field and the signal to noise ratio of the received NMR signal is independent of the inclination angle.

Abstract: A compact magnet is disclosed for high field, superconducting magnets for use in magnetic resonance spectroscopy. The magnet has at least a first and a second group of coils with the or each coil in the first group having wound to provide a negative current density with respect to the other coils. The first group acts to enable the overall length of the magnet to be reduced while maintaining a homogenous field over a central region of the magnet.

Abstract: Asymmetric, compact superconducting magnets for magnetic resonance imaging are provided. The magnets have a homogeneous region (the “dsv”) which can be located close to one end of the magnet so as to reduce the sensation of claustrophobia experienced by patients undergoing MRI procedures. The magnets can be designed using a hybrid process in which current density analysis is performed to obtain an initial coil configuration which is then refined using non-linear optimization techniques to obtain a final coil configuration. The hybrid method can incorporate various constraints, including, the location and size of the dsv, the uniformity and strength of the B0 field, stray field strengths outside of the superconducting magnet, and field strengths within the magnet's coils. The hybrid technique can also be used to design compact symmetric superconducting magnets.