Abstract: A magnetic resonance imaging apparatus according to an embodiment includes sequence controlling circuitry and processing circuitry. The sequence controlling circuitry acquires a first piece of data by executing a first pulse sequence having a first Echo Time (TE) value, to acquire a second piece of data by executing a second pulse sequence having a second TE value different from the first TE value, and to acquire a third piece of data by executing a third pulse sequence having a third TE value different from the first and the second TE values. The processing circuitry extracts a signal related to water, a signal related to a first fat, and a signal related to a second fat, on the basis of the first piece of data, the second piece of data, and the third piece of data.

Abstract: Various approaches of amplifying an NMR signal in response to a transmitted NMR pulse include estimating the characteristic time associated with the NMR signal; transmitting the NMR pulse to the sample and receiving the NMR signal therefrom; and applying a time-dependent amplifier gain to the received NMR signal based at least in part on the estimated characteristic time.

Abstract: In a method and magnetic resonance (MR) apparatus for acquiring MR data from a volume of an object in which first and second excitable spin types are present that differ in their Larmor frequencies by a chemical shift, an MR sequence with at least one radio-frequency pulse sequence selectively excites the first spin type or selectively suppresses MR signals of the second spin type. A B0 map describing the basic field distribution in a region of interest of the volume is established. First and second items of distribution information, which respectively describe the spectral distribution of Larmor frequencies of the first and second spin types, are derived from the B0 map. A pulse sequence parameter that describes the excitation spectrum of the radio-frequency pulse sequence is optimized based on the items of distribution information, with regard to a quality criterion that optimizes selective excitation and/or suppression.

Abstract: A magnetic resonance coil having at least one tuning device for tuning the magnetic resonance coil, a magnetic resonance device, and a method for tuning a magnetic resonance coil are provided. The at least one tuning device includes a plurality of capacitors that are mechanically interlinked.

Abstract: A low-field magnetic resonance imaging (MRI) system. The system includes a plurality of magnetics components comprising at least one first magnetics component configured to produce a low-field main magnetic field B0 and at least one second magnetics component configured to acquire magnetic resonance data when operated, and at least one controller configured to operate one or more of the plurality of magnetics components in accordance with at least one low-field zero echo time (LF-ZTE) pulse sequence.

Abstract: In order to provide a static magnetic field homogeneity adjustment method capable of reducing an arrangement amount of magnetic pieces and achieving desired magnetic field homogeneity with high accuracy in magnetic field homogeneity adjustment, there is provided a static magnetic field homogeneity adjustment method in an imaging space of computing positions of a plurality of magnetic pieces separated from the imaging space through shimming computation with respect to a static magnetic field in the imaging space generated by a magnetic field generation device, and disposing the plurality of magnetic pieces at the positions obtained through the shimming computation, the method including an adjustment step of imposing restriction that a polarity of a magnetic field distribution generated in the imaging space by the magnetic pieces disposed at the positions is either positive or negative during the shimming computation, and adjusting the static magnetic field homogeneity.

Abstract: Apparatus and method that are more efficient and flexible, and obtain and connect high-power RF transmit signals (TX) to RF-coil devices in an MR machine or other devices and simultaneously receive signals (RX) and separate net receive signals NRX) of interest by subtracting or filtering to remove the subtractable portion of the transmit signal (STX) from the RX and preamplifying the NRX and signal processing the preamplified NRX. In some embodiments, signal processing further removes artifacts of the transmitted signal, e.g., by digitizing the NRX signal, storing the digitized NRX signal in a memory, and performing digital signal processing. In some embodiments, the present invention also includes pre-distorting the TX signals in order to be better able to identify and/or remove the remaining artifacts of the transmitted signal from the NRX signal. This solution also applies to other high-power RF-transmit-antennae signals.

Abstract: An imaging unit producing images, and a control unit controlling the imaging unit. The imaging device further comprises: a reference clock unit generating a reference clock; and a signal input/output unit provided between the imaging unit and the control unit and inputting and outputting signals in synchronization with the reference clock generated by the reference clock unit. The control unit comprises: generating unit generating a plurality of control signals; transmitting unit transmitting the plural control signals; receiving unit receiving measurement signals; and extraction unit extracting the measurement signal when the reception times of the measurement signals received by the receiving unit agrees with the extraction timing generated by the generating unit.

Abstract: Various embodiments include apparatus and methods to calibrate a nuclear magnetic resonance tool. Example calibration techniques may include using intended ninety degree pulses as a control mechanism to evaluate echo pulses from generating pulse sequences. Example calibration techniques may include comparing a sequence of measurement signals with a reference sequence. Additional apparatus, systems, and methods are disclosed.

Abstract: A method for creating a first MRI image and a second MRI image is provided. A first echo is read out. A second echo is read out. The first echo readout is used to generate a first image set, with each image pixel being a first linear combination of the first species and the second species. The second echo readout is used to generate a second image set, with each image pixel being a second linear combination of the first species and the second species. The first image set and second image set are combined to obtain a first combined image containing only the first species and a second combined image containing only the second species, comprising combining the first image set and the second image set to generate two pairs of solutions and using a mathematical optimization to choose a correct pair of solutions.

Abstract: A magnetic field measuring method in a magnetic resonance imaging (MRI) apparatus includes applying a radio frequency (RF) pulse to an object, acquiring first and second echo signals from a first readout gradient according to test gradients having different intensities, acquiring third and fourth echo signals from a second readout gradient according to the test gradients having different intensities, and determining a characteristic value of an eddy field based on an echo time (TE) of at least one of the first through the fourth echo signals.

Abstract: A spectrometer includes: (1) a housing defining a volume into which an analyte gas is introduced, the analyte gas including a chiral component; (2) a microwave generator coupled to the housing and configured to apply a microwave pulse to the analyte gas, the microwave pulse being polarized along a first direction; (3) an electric field generator coupled to the housing and configured to apply a switched electric field to the analyte gas, the electric field being oriented along a second direction different from the first direction; (4) a phase-sensitive microwave detector coupled to the housing and configured to detect an induced microwave emitted by the analyte gas, the induced microwave being polarized along a third direction different from the first direction and the second direction; and (5) an analyzer coupled to the phase-sensitive microwave detector and configured to detect an enantiomer of the chiral component based on a phase of the induced microwave.

Abstract: A system for providing a magnetic resonance treatment may include components that provide the system with an ability to treat pain and relieve symptoms of the subject. In another embodiment, a method of providing a magnetic resonance treatment includes components that provide the system with an ability to treat pain, relieve symptoms, provide relaxation, and improve the overall comfort and well-being of the subject.

Abstract: A method is proposed for the simultaneous optimization of an arbitrary number of electromagnetic pulses, which act in a cooperative way, or mutually compensate each other's errors. The method generally relates to pulses which can have improved properties when cooperating with each other compared to single pulses. In experiments with several scans, undesired signal contributions can be suppressed by COOP pulses, which complements and generalizes the concept of phase cycling. COOP pulses can also be used in individual scans. COOP pulses can be optimized efficiently with the aid of an extended version of the optimal-control-theory-based gradient ascent pulse engineering (GRAPE) algorithm. The advantage of the COOP pulse method is demonstrated theoretically and experimentally for broadband and band-selective excitation and saturation pulses.

Abstract: There is provided a superconducting magnet in which magnetization caused by a shielding current of a superconducting winding is eliminated whereby the current to be supplied to the superconducting winding is uniformized, and thus uniformity of the central magnetic field is secured. The superconducting magnet has a superconducting winding composed of a superconductor, and an outer AC winding composed of a superconductor or non-superconductor wound coaxially with the superconducting winding, at an outer side the superconducting winding; and an AC current is supplied to the outer AC winding thereby applying an AC magnetic field in a direction perpendicular to a direction of magnetization caused in the superconducting winding by the shielding current, and thus the magnetization is eliminated. Also, the superconducting magnet has an inner AC winding composed of a superconductor or non-superconductor wound coaxially with the superconducting winding, at an inner side of the superconducting winding layer.

Abstract: A method for shimming a magnetic field is disclosed. The method uses a single shim current to contribute to suppression of more than one geometrical component of an inhomogeneity in the magnetic field without changing the geometry of the shim path. Apparatuses to implement the method are also disclosed. In embodiments the apparatuses comprise substantially commonly oriented shim paths.

Abstract: A magnetic resonance imaging apparatus includes a magnetic assembly including a main magnet and a gradient coil unit and forming a static magnetic field and a gradient magnetic field in the bore thereof, and a gradient controller applying a test gradient waveform to the magnetic assembly, and compensating for a distortion of the magnetic field gradients, caused by eddy currents, by reflecting the actual shape of the applied test gradient waveform.

Abstract: A magnetic resonance (MR) generating a static (BO) magnetic field of 5 Tesla or higher controller is configured to control an MR scanner to perform an MR sequence (14) including: performing an excitation/localization sub-sequence (30) on a subject disposed in the static (BO) magnetic field generated by the MR scanner to excite 1H polarization in a selected spatial region of the subject; performing 5 a polarization transfer sub-sequence (32) to transfer localized 1H polarization generated by the excitation/localization sub-sequence to a selected species of non-proton nuclei; and performing a magnetic resonance spectroscopy (MRS) readout sub-sequence (40) to acquire MRS data for the selected species of non-proton nuclei in the selected spatial region of the subject. The polarization transfer sub-sequence includes a pair of phase 10 distortion canceling trapezoidal 180° refocusing pulses (36, 37) operating on the selected species of non-proton nuclei.

Abstract: Three-dimensional (3D) tomographic image of a target object such as soft-tissue in humans is obtained in the method and apparatus of the present invention. The target object is first magnetized by a polarizing magnetic field pulse. The magnetization of the object is specified by a 3D spatial Magnetic Density image (MDI). The magnetic field due to the magnetized Object is measured in a 3D volume space that extends in all directions Including substantially along the radial direction, not just on a surface as in prior art. This measured data includes additional information overlooked in prior art and this data is processed to obtain a more accurate 3 D image reconstruction in lesser time than in prior art. The methods and apparatuses of the present invention are combined with frequency and phase encoding techniques of Magnetic Resonance imaging (MRI) technique in prior art to achieve different trade-offs.

Abstract: In a magnetic particle imaging apparatus that forms an image of a distribution of magnetic particles based on changes in a magnetic flux generated by magnetization of the magnetic particles, modulation coils that magnetize magnetic particles present in a field free area by applying a modulation magnetic field to the field free area, and detection coils are disposed such as to suppress an influence caused by a magnetic flux of the modulation magnetic field applied by the modulation coils and included in a detected magnetic flux.

Abstract: It is proposed herein to improve the specifications of a low-noise amplifier (LNA) by integrating it in a chip. In order to cover a range of operating frequencies using a single chip, the integrated-circuit amplifier proposed herein comprises an input port configured to receive a magnetic resonance (MR) signal from a radio-frequency (RF) coil, one or more LNAs configured to amplify the received MR signal, and an output port configured to output the amplified MR signal from the one or more LNAs. The operating frequency of the RF coil depends on the field strength. The matching circuit, if present, needs to be tuned to operate at the operating frequency of the RF coil, and depends on the component values in the loop, thus on loop size. In contrast, the proposed integrated-circuit amplifier is capable of directly connecting to RF coils with different loop sizes, without the need for a matching circuit.

Abstract: A method for detecting coupled RF current magnetic resonance (MR) objects in a body and determining MR risk is provided. The body is scanned with reverse circularly polarized RF. MR signals generated by coupling of the reverse circularly polarized RF with the RF current MR objects are detected. The detected MR signals are used to determine a risk value.

Abstract: Provided is a total electrical nuclear-spin polarization device that is applicable to many narrow-gap semiconductor two-dimensional quantum structures such as InSb with a large g-factor and with a mobility having a normal value. A nuclear-spin polarization device 1 creates a state where the Landau-level separation and the Zeeman-level separation in a sample are equal to each other in a magnetic field, thereby crossing different spin states, and detects nuclear-spin polarization from a resistance change at the crossing point caused by the nuclear-spin polarization.

Abstract: A method for correcting image artifacts during the acquisition of magnetic resonance imaging data includes the following steps. At least one part of the linear, location-dependent and spatially constant interference fields arising at the measurement location is determined in a time interval between an excitation point in time and a MR data acquisition point in time.

Abstract: An RF coil system for magnetic resonance applications includes a multi-channel RF coil transceiver and a multi-channel RF coil. The RF coil system is structured for reconfiguration between a plurality of operational modes.

Abstract: The invention relates to a method for optimization of the performance of a multi-channel coil (1) comprising at least three coil elements, wherein the method comprises the following steps: a) Exciting the coil elements of the multi-channel coil (1) by electrical power signals comprising a specific power, wherein the power of the power signals is partially reflected by the coil elements of the multi-channel coil (1), b) Measuring the power which is reflected by the individual coil elements of the multi-channel coil (1) or by the entire multi-channel coil (1) during excitation of the coil elements, c) Tuning the multi-channel coil (1) depending on the measured reflected power so that the performance of the multi-channel coil (1) is improved, wherein d) all coil elements of the multi-channel coil (1) are simultaneously excited, and e) the reflected power is measured during the simultaneous excitation of all coil elements of the multi-channel coil (1).

Abstract: An RF coil for MR Imaging that can change a resonance frequency easily and instantaneously in response to a nuclide to be imaged without exchange and adjustment and that also causes only small lowering of sensitivity. The RF coil has a sub coil for changing a resonance frequency of the transmitting/receiving RF coil for transmitting and receiving an MR signal between itself and a nuclide that is an object to be imaged. The sub coil is equipped with a switch, and at the time of switching-on, shifts the resonance frequency of the RF coil by changing an inductance value of the RF coil in a noncontact manner using inductance coupling.

Abstract: When imaging for sensitivity distribution measurement is performed, a whole-body coil for both transmission and reception and a specified coil used for the present imaging are used as a reception coil, while being switched. The switching of the reception coil is performed by switching between the whole-body coil and the specified coil for each echo in the same encode step. An image created from the echo obtained by the specified coil is divided by an image created from the echo obtained by the whole-body coil to calculate the sensitivity distribution of the specified coil. The sets of data used for the calculation are almost simultaneously obtained, thus providing accurate sensitivity distribution with no influence derived from the movement of a subject. The sensitivity distribution is used to correct the image obtained by the present imaging. Alternatively, the sensitivity distribution is used for the folding operation of parallel imaging.

Abstract: Extended-coverage magnetic resonance imaging coils with optimized homogeneity in longitudinal sensitivity are described. One exemplary coil includes four elements, where two of the elements are opposed-solenoid imaging elements and two of the elements are single loop imaging elements.

Abstract: Methods and systems for obtaining intravascular magnetic resonance images of blood flow are disclosed. In preferred forms, a train of radio frequency (RF) pulses is produced by an intravascularly introduced RF transmitter positioned in proximate location to the blood flow so as to create a continuous stream of coherently excited protons of the blood flow. The coherently excited protons of the blood flow are sampled as the protons freely precess while flowing through a region of three dimensional space unaffected by the ongoing intravascular RF excitation. An image of the sampled coherently excited protons may then be constructed.

Abstract: Featured is a device for NMR or MRI signals from excited nuclei as well as related apparatus, systems and methods. The device includes a strip array antenna including one or more conductor and N reactive tuning components, where N is an integer?1 at least one of the N reactive components is electrically coupled to each of the one or more conductors as well as to ground/virtual ground. The apparent electrical length of the conductors is tuned with the reactive tuning components so it is equal to be about n?/4, where n is an integer?1 and ? is the wavelength of the signal to be detected. The length of the strip also is such as to be substantially in the approximate range of 1.3 times the depth of interest. The strip conductors are also combined with loop coils to form quadrature detectors.

Abstract: Techniques for designing RF pulses may be configured to produce improved magnitude profiles of the resulting magnetization by relaxing the phase constraint and optimizing the phase profiles. In one embodiment, a spinor-based, optimal control, optimal phase technique may be used to design arbitrary-tip-angle (e.g., large and small tip angle) RF pulses (both parallel transmission and single channel). In another embodiment, small tip angle RF pulses (both parallel transmission and single channel) may be designed using a small-tip-angle (STA) pulse design without phase constraint that is formulated as a parameter optimization problem.

Abstract: In a non-cartesian sampling method, in order to reduce an artifact on an image caused by an error of a gradient magnetic field, data for correcting the error caused by the gradient magnetic field are obtained when data used for image reconstruction are obtained, and the data used for the image reconstruction are corrected by using the obtained data for the correction. In order to obtain the data for correcting the error, a block having plural parallel echo signals is measured.

Abstract: In a magnetic resonance tomography apparatus and method for determination of T2-weighted images of tissue with short T2 time, in the framework of a steady-state free precession sequence with non-slice-selective RF excitation pulses and projection-reconstruction methods, in each sequence repetition a first steady-state is read out in the form of a half echo and a second steady-state signal is read out in the form of a further half echo with very short echo times TE1 and TE2=2TR?TE1, and are combined by weighted addition such that an MRT image of tissue with very short T2 time is obtained with the sequence.

Abstract: The present invention is directed to an MRI enhancing device deployable in a body. In one embodiment, the MRI enhancing device is formed of a wire loop and a capacitor that is at least partially formed by the wire used in forming the wire loop.

Abstract: This invention provides a receiving coil that allows a high-quality image of high depth sensitivity to be obtained during vertical magnetic field MRI without limiting selection of a cross section to be imaged and of a phase-encoding axis. A subject's field of view is broadened without deterioration of the coil characteristics. Two orthogonal solenoid coils (3-1 and 4-1) and sub-coils (5-1, 6-1, and 7-1) whose sensitivity distributions each become an odd function in an x-direction, a y-direction, and a z-direction, respectively, with respect to the origin of the sensitivity distribution of each of the solenoid coils are used as multiple sub-coils to construct the receiving coil. This receiving coil is suitable for a high-speed imaging method in which an image is acquired using reduced phase encoding and the image is reconstructed using image folding. In addition, the subject's field of view can be broadened by arranging conductors of the coil appropriately.

Abstract: A magnetic resonance system has a basic magnet system that generates a temporally static, spatially homogeneous basic magnetic field in an examination volume of the magnetic resonance system. At least one radio-frequency system is operated to excite nuclear spins in an examination subject in the examination volume to magnetic resonance, and to detect magnetic resonance signals from the examination subject. An overlay system generates overlay fields in the examination volume. The overlay system has at least one system of the first order and one system of the second order. The system of the first order generates fields that, to a first approximation, exhibit a spatial dependency of the first order. The system of the second order generates fields that, to a first approximation, exhibit a spatial dependency of the second order. A desired gradient and a correction volume are provided to a control device of the magnetic resonance system.

Abstract: Remote adjustment of a selected one of a plurality of adjustable NMR probe circuit components is achieved with a plurality of selectable linear actuators, the selected one of which urges a platen against a respective driven gear, azimuthally locked to its shaft, to displace it axially along that shaft. When the driven gear engages a driving gear a single driving motor is energized and controlled to effect the desired adjustment.

Abstract: Techniques and systems for magnetic resonance imaging. In one aspect, preparatory pulse sequences precede alternating repetition time steady state free precession (ATR SSFP) pulse sequences to enable image acquisition before reaching a steady-state equilibrium. The design of the preparatory sequences is based on a two step process: First an oscillatory residue is expressed in terms of a window (e.g., a Kaiser-Bessel window) and scale parameters. Second the oscillatory residue is minimized to determine the scale parameters according to a desired application (e.g. ATR SSFP, optimized for fat, water, etc.) The preparation scheme described in this specification can be applied to arbitrary repetition times and RF phase cycling combinations.

Abstract: The invention relates to a device (1) for magnetic resonance imaging of a body (7), comprising a main magnet (2) for generation of a stationary and substantially homogeneous main magnetic field within the examination zone, a plurality of wireless receiving units (10a, 10b) placed in or near the examination zone, and sampling means (21a, 21b) operating at a variable sampling frequency for sampling the received MR signals and for converting them into digital signal samples.

Abstract: In a method for adjustment of the field strength of radio-frequency pulses as well as a magnetic resonance measurement system, radio-frequency pulses are emitted by a radio-frequency antenna of a magnetic resonance measurement system in a magnetic resonance measurement. A test volume slice is initially excited by emission of radio-frequency pulses with a defined pulse amplitude by the appertaining radio-frequency antenna and one-dimensional, spatially-resolved characteristic values are determined along an extent direction of the test volume slice. The one-dimensional, spatially-resolved characteristic values respectively represent a local field strength of the B1 field in strips of the test volume slice running perpendicular to the extent direction. An average value of the determined characteristic values is then formed over at least over one determined segment along the extent direction of the test volume slice.

Abstract: A method of recovering and recycling solvents, comprising, during printing or coating of solvent-recoverable and recyclable printing ink composition comprising solvents, a step of recovering the solvents vaporized in a solvent recovery apparatus, a step of separating the solvents obtained into one or more single solvents and/or one or more azeotropic compositions of two or more solvents by multi-stage distillation, and a step of recycling them as a printing ink raw material and/or dilution solvent raw material.

Abstract: A method of adjusting an excitation and detection circuit for nuclear magnetic resonance, the circuit comprising a probe (S) of the type comprising a single coil (L) for transmitting pulses to excite the nuclear spins of a sample immersed in a magnetic field and for detecting a resonance signal from said nuclear spins, said method being characterized by a step of tuning the resonant frequency in reception of said circuit to the Larmor frequency (f0) of the nuclear spins of the atoms that are to be detected. An excitation and detection circuit for nuclear magnetic resonance, said circuit being characterized in that it is adapted to implement an adjustment method as described above.

Abstract: A method for magnetic resonance imaging includes performing a preparatory stage of a MR pulse sequence with an MRI system in which a non-selective RF preparatory pulse is used having a bandwidth such that any spin species having corresponding Larmor frequencies within that bandwidth are affected and the bandwidth is centered at a selected frequency which is offset from a nominal Larmor frequency of the desired spin species being imaged. A time period (TI) elapses during which longitudinal spin magnetization recovers; and then an imaging stage is performed in which an RF excitation pulse is generated to produce transverse spin magnetization of the desired spin species, and in which a set of NMR signals are acquired. An image is reconstructed using the acquired set of NMR signals, and the reconstructed image has reduced artifacts due to B0 field inhomogeneities caused by magnetic susceptibility effects.

Abstract: In a magnetic resonance imaging (MRI) method, in the form of an MRI pulse sequence, and an apparatus for acquiring MRI data from an object, a contrast preparation module is applied to the object for preparing a contrast in the magnetization of nuclear spins of the object, and an imaging module is applied to the object after the contrast preparation module for acquisition of magnetic resonance image data reflecting the prepared contrast. The contrast preparation module includes a train of radio-frequency pulses with the same flip angle magnitude ?, the respective signs of the flip angles alternating from radio-frequency pulse to radio-frequency pulse.

Abstract: A method of magnetic resonance imaging based on rapid acquisition by sequential excitation and refocusing is provided. The method comprises turning on a first time-encoding gradient and applying an excitation pulse in the presence of the first time-encoding gradient. The excitation pulse excites magnetization sequentially along one spatial axis. Thereafter, a first refocusing pulse is applied. A second time-encoding gradient is turned on followed by a second refocusing pulse. A third time-encoding gradient is turned on and a signal is acquired in the presence of the third time-encoding gradient. The third time-encoding gradient sums to zero with the first time-encoding gradient and the second time-encoding gradient for sequential points in space.

Abstract: A method of dynamic magnetic resonance imaging comprising acquiring undersampled magnetic resonance signals for successive temporal time slots. In a space spanned by geometrical space and temporal frequency and on the basic of a priori information the aliased difference magnetic resonance data which are gained by subtracting for respective k-space sampling positions data of a baseline magnetic resonance image from the undersampled magnetic resonance signals are decomposed into difference data which essentially pertain to individual spatial positions at individual time slots.

Abstract: A nuclear magnetic resonance (NMR) method is used to determine a velocity distribution or velocity image of a flowing fluid in a downhole environment. The method comprises applying a radio frequency pulse sequence; applying a magnetic field gradient magnetic field and a gradient pulse duration; measuring a NMR signal; determining a phase characteristic of the NMR signal; and determining the velocity distribution or image of the fluid using the determined phase characteristic, the magnetic field gradient pulse parameters, and a time delay between gradient pulses.

Abstract: A system and method for improving available signal-to-noise ratio (SNR) and speed of MR imaging of hyperpolarized substances is disclosed. The system and method include decoupling spin effects of hydrogen nuclei from non-hydrogen nuclei of interest during sampling of MR signals therefrom. Though the hydrogen nuclei of the hyperpolarized substance may not be directly bonded to the non-hydrogen nuclei of interest, resonance splitting may still impact SNR. Long range decoupling improves T2* time, and thus preserves signal strength and available SNR.

Abstract: A magnetic resonance imaging (MRI) system includes an examination volume (9), a main magnet system (17) for generating a main magnetic field (B0) in the examination volume, a gradient magnet system (25) for generating gradients of the main magnetic field, and a control system (37) for compensating disturbances of the magnetic field caused by mechanical vibrations of the MRI system. The control system is a feed-forward control system which determines a necessary compensation for said disturbances in dependence on an electric current in the gradient magnet system according to a predetermined response relation. Since in most MRI systems the mechanical vibrations are predominantly caused by the altering electric currents in the gradient magnet system and by eddy currents induced thereby, an accurate and reliable compensation for said disturbances is provided, so that artifacts and other distortions of the reconstructed image caused by said disturbances are considerably reduced.