Abstract: A therapy system comprises a therapy module to perform successive deposits of energy in a target zone, the therapy system being provided with a control module is configured to prior the deposits of energy produce an a priori estimate of the induced heating. For example a thermometry module is provided to measure temperature in a measurement field. The induced heating may be derived on the basis of a tissue model from the settings of the therapy module. In particular the therapy module is a high-intensity focuses ultrasound transmitter. A magnetic resonance examination system configured for thermometry is employed as the thermometry module.

Abstract: Fiducials (50) are disposed in an imaging region (14) along with a subject. The fiducials are mounted either to the subject itself, a surgical tool (52), an imaging probe or receive coil (80), or the like. The fiducials are filled with a liquid or gel of a fluorine 19 (Fl19) compound which has a resonance frequency that is only 6% off from the resonance frequency of protons. This enables a common transmitter (22), transmit and receive coils, and receiver (34) to be utilized for both proton and fluorine 19 imaging. The proton and fluorine resonance signals are separately reconstructed into corresponding image memories (42, 64). From the positions of the fiducials, a position calculator (66) determines the position of a fiducial carrying surgical tool or probe relative to the proton image. A depiction of the tool or probe from a look-up table (70) is appropriately positioned and rotated (68) and superimposed on the proton image by a video processor (44).

Abstract: A wireless remote control unit (60) that operates in the radio frequency bandwidth is used for interfacing with a sequence control system (B) and an image processing system (C) from within a magnetic resonance suite (A) in the presence of a magnetic field produced by a main magnet assembly (10). The sequence control system and the image processing system are connected with a first wireless transceiver (30) whose antenna (28) is located within a magnetic resonance suite. The first transceiver (30) communicates with the remote control unit (60) and a second transceiver (32) connected with a transmitter (40) and gradient coil amplifiers (34). Resonance signals received by a radio frequency coil (46) are communicated to the first transceiver (30) by the second transceiver (32) or by a transceiver (46?) mounted on the receiving coil. The receiver coil transceiver also engages in a handshake protocol to identify itself.

Abstract: Fiducials (50) are disposed in an imaging region (14) along with a subject. The fiducials are mounted either to the subject itself, a surgical tool (52), an imaging probe or receive coil (80), or the like. The fiducials are filled with a liquid or gel of a fluorine 19 (Fl19) compound which has a resonance frequency that is only 6% off from the resonance frequency of protons. This enables a common transmitter (22), transmit and receive coils, and receiver (34) to be utilized for both proton and fluorine 19 imaging. The proton and fluorine resonance signals are separately reconstructed into corresponding image memories (42, 64). From the positions of the fiducials, a position calculator (66) determines the position of a fiducial carrying surgical tool or probe relative to the proton image. A depiction of the tool or probe from a look-up table (70) is appropriately positioned and rotated (68) and superimposed on the proton image by a video processor (44).

Abstract: The Overhauser effect is a technique for increasing the signal-to-noise ratio of nuclear magnetic resonance signals. Electron spin resonance is set up for example in a contrast agent 14 injected into a patient by means of a transmitter 3 at the end of a probe 1 to excite an area 15. The excited electrons couple to MR active nuclei and increase the population in the higher energy level. Then, when an NMR signal is transmitted and received via coil 5, more MR active nuclei return to the ground state and create a bigger, enhanced, signal detected by the coil 5, hence promoting increased signal-to-noise ratio on an image formed on the monitor 9. In the invention, the Overhauser effect may be applied to an intra-operative situation by means of probe 1 which is inserted, for example, into a patient in a region of interest.

Abstract: In magnetic resonance imaging apparatus having a resistive electromagnet with a bore 6, r.f. excitation pulse substantially simultaneously excites a number of slices A to D which are phase encoded and frequency encoded in the usual way, the direction of the main field being along the bore of the electromagnet in the direction z. The receive coil consists of an array of coils 5a to 5d which view different spatial regions of the imaging volume and the outputs of which are combined in different ways in order to reduce the number of slice encoding steps in the z-direction needed to distinguish between the slices A to D. Each coil of the array 5a etc. can form part of a two dimensional array in order to reduce the number of phase encoding steps in the phase encode direction.

Abstract: The Overhauser effect is a technique for increasing the signal-to-noise ratio of nuclear magnetic resonance signals. Electron spin resonance is set up for example in a contrast agent 14 injected into a patient by means of a transmitter 3 at the end of a probe 1 to excite an area 15. The excited electrons couple to MR active nuclei and increase the population in the higher energy level. Then, when an NMR signal is transmitted and received via coil 5, more MR active nuclei return to the ground state and create a bigger, enhanced, signal detected by the coil 5, hence promoting increased signal-to-noise ratio on an image formed on the monitor 9. In the invention, the Overhauser effect may be applied to an intra-operative situation by means of probe 1 which is inserted, for example, into a patient in a region of interest.

Abstract: A magnetic probe (1) for use with a magnetic resonance imaging apparatus comprises an electron spin resonance (ESR) magnetometer. The position of the probe (1) tracked by measuring the resonant frequency of an ESR sample (32) in the probe. The resonant frequency is measured in the presence of a gradient sequence which employs three orthogonal, linear gradients. By determining the resonant frequency of the ESR sample in the presence of each of the gradients, the position of the probe can be determined. The probe may be placed on or in an object, and the position of the probe may be displayed on a desired magnetic resonance image of the object.

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: Current supply for MRI magnet having an output impedance which has been tailored to have the desired shape by using voltage and current feedback. The impedance is small at frequencies which are large with respect to the magnet L/R and the impedance is large at very low frequencies.

Abstract: An applicator for coupling an electromagnetic field to a sample to be imaged by magnetic resonance imaging, comprising an electrical periodic structure constructed so as to oscillate with substantially the same phase over its whole length.

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: There is provided a method of electron spin resonance enhanced magnetic resonance imaging of a human or non-human animal body, characterised in that said method comprises administering to said body a physiologically tolerable ionic or ionizable paramagnetic substance capable of associating with a cell membrane lipid.

Abstract: The invention provides method of electron spin resonance enhanced magnetic resonance imaging of a subject, for example a human, animal or inanimate body, in which said subject is exposed to radiation of a frequency selected to stimulate an esr transition in a paramagnetic species in said subject whereby to effect dynamic nuclear polarization, wherein said exposure to radiation is arranged such that within the region of said subject so exposed the capacity of said radiation to stimulate a said transition is relatively enhanced in at least one volume (a region of interest (ROI)), i.e. a method in which one or more regions-of-interest within the subject under study are selected by making it possible for an enhancement agent to act more effectively in that region than outside. The method for example also allows flow processes within a body to be monitored to provide the operator with images or data sets indicative of the spatial and/or temporal characteristics of flow from the ROI.

Abstract: The invention relates to a novel magnetic resonance imaging apparatus. The nuclei, protons or the paramagnetic electrons of an imaged object are cyclically polarized during a period of about one second with a permanent magnet which is then quickly shifted away from the imaged object in a permanent magnet carrier tube, so that the field of the permanent magnet would not have an interfering effect on the immediately following signal-collection for MRI-imaging. The permanent magnet can be manipulated or shifted back and forth in the tube either magnetically, pneumatically, hydraulically or mechanically. The apparatus also includes another permanent magnet or a resistive magnet coil couple, which is located in the tube near the opposite end of the tube, and which generates a homogeneous magnetic field within the imaged area.

Abstract: A method of electron spin resonance enhanced magnetic resonance imaging of a paramagnetic substance-containing sample wherein an image of at least part of the sample is generated from a data set produced by manipulation of enhanced free induction decay signals detected under at least two different sets of operational parameters. The operating parameters which are varied to produce the different sets include the timing of the exposure of the sample to magnetic field gradients and spin resonance stimulating radiations and, optionally, also the amplitude and frequency distribution of the electron spin resonance stimulating radiations. The manipulation of the detected signals produces, for individual image elements, a normalized signal representative of the difference between signals for that element under the different sets of operational parameters.

Abstract: A method of nuclear magnetic resonance investigation of a repeated electromagnetic event in a sample comprises modulation of the nuclear spin polarization achieved during the recovery period between the final magnetic resonance signal detection period of one cycle and the initial signal generation RF pulse of the next cycle. This modulation is performed by giving the sample a different exposure to RF radiation in the different periods, for example by exposure to a different number of 180.degree. pulses in each period or by exposure to a frequency modulated continuous wave RF signal.

Abstract: A magnetic resonance imaging apparatus comprising device for applying a magnetic field to a sample to be imaged, device for applying pulses of MR transition-exciting electromagnetic radiation to the sample, an NMR signal coil for detecting the resulting radiation from the sample, and device for appling pulses of electromagnetic radiation to the sample for stimulating coupled ESR transitions, in which a pulse generating device is coupled to the NMR signal coil and antennas are coupled to the coil and disposed at plural positions along the coil, whereby pulses for stimulating coupled ESR transitions may be transmitted from the pulse generating device through the coil to the antennas and thence into the sample, the antennas being arranged to give a predominantly magnetic coupling to the sample.

Abstract: There is provided an electron spin resonance enhanced magnetic resonance imaging (ESREMRI) apparatus having means arranged to generate a primary magnetic field of a first value during periods of nuclear spin transition excitation and magnetic resonance signal detection for the generation of ESREMRI images of a subject and means arranged to generate a primary magnetic field of a second and higher value during periods of nuclear spin transition excitation and magnetic resonance signal detection for the generation of native MR images of a subject, and preferably also means for combining, e.g. superimposing, ESREMRI and native MR images so generated.

Abstract: The invention provides a magnetic resonance imaging apparatus having a primary field generating means for generating a substantially uniform magnetic field, wherein that said primary field generating means is arranged in use to generate a magnetic field the field direction of which varies with time, e.g. a rotating field. The varying field operates to average out from the magnetic field experienced by the sample being imaged at least some of the external perturbing magnetic fields so reducing the sensitivity of the apparatus to such external fields.