Abstract: Techniques for determining motion states of at least two bodies by an MR-device are provided, wherein the bodies each have a respective target region which is in an anatomic motion comprising a repetitive motion pattern with a motion repetition rate, and in particular, for cardiac and/or respiratory motion. A sequence of individual MR-measurements are performed on the bodies at a MR-repetition rate higher than the motion-repetition rate, wherein nuclear spins of the at least two bodies are excited during the sequence of individual MR-measurements either simultaneously or alternately at navigator times. With the individual MR-measurements, navigator signals are determined, each respective navigator signal indicative of the motion state of at least one of the motion patterns at the navigator time of the navigator signal. These techniques allow simultaneously determining motion states for imaging more than one body with a repetitive motion pattern with reduced preparation time.

Abstract: Techniques for determining motion states of at least two bodies by an MR-device are provided, wherein the bodies each have a respective target region which is in an anatomic motion comprising a repetitive motion pattern with a motion repetition rate, and in particular, for cardiac and/or respiratory motion. A sequence of individual MR-measurements are performed on the bodies at a MR-repetition rate higher than the motion-repetition rate, wherein nuclear spins of the at least two bodies are excited during the sequence of individual MR-measurements either simultaneously or alternately at navigator times. With the individual MR-measurements, navigator signals are determined, each respective navigator signal indicative of the motion state of at least one of the motion patterns at the navigator time of the navigator signal. These techniques allow simultaneously determining motion states for imaging more than one body with a repetitive motion pattern with reduced preparation time.

Abstract: A method for generating positron-emission tomography images of at least one body having a target region which is in an anatomic motion that includes a repetitive motion pattern with a motion repetition rate. PET data is acquired by performing a PET measurement; motion states are determined during the PET acquisition period; the determined motion states are assigned to acquisition times; and PET images are reconstructed from selected PET data. During the PET-acquisition period, a sequence of individual MR-measurements on the body is performed at a MR-repetition rate higher than the motion-repetition rate, wherein nuclear spins of the body are excited during the sequence of individual MR-measurements at navigator times. Navigator signals are determined, each navigator signal being indicative of a motion state of the motion pattern at the navigator time. The motion states are determined by analyzing the navigator signals.

Abstract: A method for determining the position of at least one ferromagnetic particle in an object or a liquid matrix with an MRI system (50). An MRI measurement sequence is applied to a measurement volume (52), in which the particle is situated. At least two projections are recorded per spatial direction, wherein a read gradient is switched in each case for recording a one-dimensional projection in each case. A preselected parameter is modified for each of the two projections and the spatial position of the ferromagnetic particle is ascertained with the aid of the two projections. This facilitates a more reliable and precise determination of the position of a ferromagnetic particle or a bunch of ferromagnetic particles in a liquid matrix, wherein this position is determined in a very short time and requires the application of only a very low pulse in the process.

Abstract: A method for determining the position of at least one ferromagnetic particle (30) in a liquid matrix (31) with an MRI system (50). An MRI measurement sequence (MS1, MS2) is applied (20) to a measurement volume (52) in which the particle is situated. The measurement sequence includes a plurality of individual measurements (E1, E2), during each of which there is a spatially encoding gradient switching operation, including an excitation pulse (1) and signal recording (2), via the MRI system. The measurement sequence has a multiplicity of measurement blocks (MB1, MB2), which each include one or more individual measurements and, in a pause of the spatial encoding, an intermediate gradient (ZW) switched by the MRI system. The intermediate gradients are dimensioned such that, averaged over time, the particle is kept substantially in the same position (M1, M2) over each measurement block.

Abstract: A method for determining the position of at least one ferromagnetic particle (30) in a liquid matrix (31) with an MRI system (50). An MRI measurement sequence (MS1, MS2) is applied (20) to a measurement volume (52) in which the particle is situated. The measurement sequence includes a plurality of individual measurements (E1, E2), during each of which there is a spatially encoding gradient switching operation, including an excitation pulse (1) and signal recording (2), via the MRI system. The measurement sequence has a multiplicity of measurement blocks (MB1, MB2), which each include one or more individual measurements and, in a pause of the spatial encoding, an intermediate gradient (ZW) switched by the MRI system. The intermediate gradients are dimensioned such that, averaged over time, the particle is kept substantially in the same position (M1, M2) over each measurement block.

Abstract: A method for generating magnetic resonance (MR) images or MR spectra of at least one partial area of a moving object with at least one motion sequence that is repeated during consecutive motion states is proposed. In a learning measurement, a monitor signal of the repeating motion sequence is recorded, and MR test data of the partial area of the object are recorded under known measurement conditions, wherein the MR test data is associated with the motion states of the motion sequence. In an evaluation step, the MR test data of the motion states of the motion sequence are compared to each other with respect to at least one parameter, and the variation of the at least one parameter over the motion sequence is determined.

Abstract: A method for generating magnetic resonance (MR) images or MR spectra of at least one partial area (2a) of a moving object (2) with at least one motion sequence that is repeated during consecutive motion states (BZ) is proposed. In a learning measurement, a monitor signal of the repeating motion sequence is recorded, and MR test data of the partial area (2a) of the object (2) are recorded under known measurement conditions, wherein the MR test data is associated with the motion states (BZ) of the motion sequence. In an evaluation step, the MR test data of the motion states (BZ) of the motion sequence are compared to each other with respect to at least one parameter, and the variation of the at least one parameter over the motion sequence is determined.

Abstract: A method for generating MR (magnetic resonance) images of a moving partial area of an object with a repeating motion sequence over comparable motion states, wherein an MR data set, which is encoded for generating an individual MR image of the object, is provided for each motion state from a plurality of successive individual MR measurements with shorter time intervals than a repetition rate of the motion sequence, and wherein at least one navigator data point is generated for each individual MR measurement as an indicator for the comparability of several motion states, is characterized in that a position of the partial area is determined for each individual MR image, from which a function f(t) of the time shift of the position is determined, and the measuring data of the individual MR measurement is phase-corrected in correspondence with its respective motion state using the function f(t) to keep the position of the partial area in a spatially stationary state.

Abstract: A method for generating MR (magnetic resonance) images of a moving object with a repeating motion pattern at comparable motion states, wherein for at least one motion state, a set of MR data which is completely encoded for producing an MR image is provided from a plurality of successive individual MR measurements. The method is characterized in that at least one contiguous region of successive data points is used as indicator within the individual MR measurement, wherein this contiguous region is identically repeated for all individual MR measurements within the respective MR measuring sequence relative to irradiated RF (radio frequency) pulses and switched gradients. This provides reliable allocation of the recorded MR data with the associated motion states, wherein completely encoded sets of MR data can be determined within an optimum time.

Abstract: A method for generating MR (magnetic resonance) images of a moving partial area of an object with a repeating motion sequence over comparable motion states, wherein an MR data set, which is encoded for generating an individual MR image of the object, is provided for each motion state from a plurality of successive individual MR measurements with shorter time intervals than a repetition rate of the motion sequence, and wherein at least one navigator data point is generated for each individual MR measurement as an indicator for the comparability of several motion states, is characterized in that a position of the partial area is determined for each individual MR image, from which a function f(t) of the time shift of the position is determined, and the measuring data of the individual MR measurement is phase-corrected in correspondence with its respective motion state using the function f(t) to keep the position of the partial area in a spatially stationary state.

Abstract: A method for generating MR (magnetic resonance) images of a moving object with a repeating motion pattern at comparable motion states, wherein for at least one motion state, a set of MR data which is completely encoded for producing an MR image is provided from a plurality of successive individual MR measurements with a shorter time separation than a repetition rate of the motion pattern, and wherein at least one data point from each individual MR measurement is used as an indicator for the comparability of several motion states, is characterized in that at least one contiguous region of successive data points is used as indicator within the individual MR measurement, wherein this contiguous region is identically repeated for all individual MR measurements within the respective MR measuring sequence relative to irradiated RF (radio frequency) pulses and switched gradients.

Abstract: A method of correcting disturbing influences on MR (=magnetic resonance) signals of a substance disposed in the measuring volume of an MR apparatus excited by one or more RF (=radio frequency) excitation pulses, wherein an RF excitation pulse is irradiated onto the substance and a time-dependent MR signal generated thereby is detected and digitized in a phase-sensitive fashion, wherein a time dependence (1)&Dgr;&phgr;i(ti) of the phase of an MR signal, relative to a predetermined reference phase &phgr;refi(ti) of a reference signal Srefi(ti), is determined and digitized from a time dependence (1) si(ti) of the detected and digitized MR signal and one or more correction or controlled variables are determined therefrom. Nearly all measuring points are used for determination of the magnetic field deviation and thus for control to guarantee considerably improved control accuracy.

Abstract: The invention concerns a method for correcting linear field inhomogeneities in a magnetic resonance apparatus. After an excitation pulse and application of a phase gradient in a predetermined direction, a data point is taken after a fixed, predetermined time td. This is repeated for systematically changed strengths of the phase gradient and constant td. The phase gradient with maximum measuring signal corresponds to a field correction gradient in the corresponding direction.

Abstract: The invention concerns a method of correcting field inhomogeneities of higher order in a magnetic resonance apparatus After an excitation pulse and action of a phase gradient in a predetermined direction p, a data point is recorded after two predetermined times td1 and td2. This is repeated for systematically modified strengths of the phase gradient and constant td1 and td2, and two sets of signal dependences in the p direction are obtained. The two phase dependences of the two Fourier transformed data sets in the p direction are subtracted. The profile of the difference phase in the p direction corresponds to a field error profile. The method is repeated for several p directions, and coefficients of higher order of a series expansion of the field inhomogeneities in spherical harmonic functions are obtained.

Abstract: A method of correcting disturbing influences on MR (=magnetic resonance) signals of a substance disposed in the measuring volume of an MR apparatus excited by one or more RF (=radio frequency) excitation pulses, wherein an RF excitation pulse is irradiated onto the substance and a time-dependent MR signal generated thereby is detected and digitized in a phase-sensitive fashion, wherein a time dependence (1) &Dgr;&phgr;i (ti) of the phase of an MR signal, relative to a predetermined reference phase &phgr;refi (ti) of a reference signal srefi (ti), is determined and digitized from a time dependence (1) si (ti) of the detected and digitized MR signal and one or more correction or controlled variables are determined therefrom. Nearly all measuring points are used for determination of the magnetic field deviation and thus for control to guarantee considerably improved control accuracy.

Abstract: A method for the production of a two or three-dimensional image with the assistance of magnetic resonance. The measuring data are taken according to the projection method by means of a sequential rotation of projection gradients. The image, however, is generated with 2dFT or 3dFT methods. The projection gradient is advantageously not only rotated between high frequency excitation pulses, but its strength is also changed in such fashion that the measuring points in k-space lie on squares or parallelepipeds.

Abstract: In an SPI method for the n-dimensional NMR imaging of materials with short T.sub.2 -relaxation times, for example cartilage or bones, only one single measurement point in k-space is recorded from the phase encoded FID signal following each RF excitation pulse. A pseudo spin echo (4) is derived from the extracted k-space points which has essentially the same information content as a conventional spin echo signal.

Abstract: A magnetic resonance method is utilized for taking an image of an object. An initial projection is taken by applying a gradient magnetic field having a predetermined direction .phi. and strength G, irradiating a high frequency excitation pulse and sequentially measuring a nuclear resonance signal from the object. The signal dephases under the influence of the gradient magnetic field and the signal measuring points are assigned to points in k-space lying along a vector whose direction is determined by the direction .phi. of the gradient magnetic field, and whose magnitude by the product of the strength of the gradient magnetic field and the time interval between the excitation pulse and the taking of the corresponding measuring point. A further number of n-1 (n>>1) projections are obtained by changing the direction and/or strength of the gradient magnetic field. Additional excitations and measurements are carried out for an additional n'.ltoreq.n projections having measuring points.

Abstract: For recording a nuclear magnetic resonance tomogram according to a Fourier-transform method, a Carr-Purcell-Gill-Meiboom pulse sequence is used for the excitation of a body to produce a sequence of spin-echo signals. A time-limited phase-encoding magnetic gradient field G.sub.X is imposed between each pair of 180.degree. pulses of the sequence. The phase-encoding magnetic gradient field is modified after every 180.degree. pulse so that every spin-echo signal corresponds to a different projection of the body. The magnetic gradient fields used in the recording are regulated in intensity and duration in such a way that a spin-phase condition at each 180.degree. pulse of the pulse sequence remains effectively constant. Thereby, it is possible to construct a complete tomographic recording with a single pulse-sequence excitation, so that the time required for such recordings can be reduced to a fraction of the time needed for recording nuclear-magnetic-resonance tomograms conventionally.