Abstract: A magnetic resonance imaging (MRI) pulse employed in MRI devices and methods that increase the signal-to-noise ratio, allowing thinner slice thicknesses, and allowing more contiguous slices. In an MRI device, a patient is subjected to a constant magnetic field, and then RF pulses are used to excite the atoms in the body of the patient. The atoms release a corresponding RF signal when the atoms relax, which can be measured and mapped into a visual display. The RF pulses used to excite the atoms in the body of the patient use a modified Bessel function. The Bessel function having an approximately rectangular waveform in the frequency domain increases the signal-to-noise ratio, allows thinner slice thicknesses, and allowed more contiguous slices, resulting in a better MR image and a more efficient MRI apparatus.

Abstract: An imaging coil (12) includes multiple end rings (52). A center ring (53) extends parallel to and is coupled between the end rings (52). Multiple legs (86) are coupled between the end rings (52) and the center ring (53). The end rings (52) may have a first radius (R1) that is greater than a second radius (R2) of the center ring (53). The imaging coil (12) may include more than 16 legs. The imaging coil (12) may include multiple capacitor groupings (98) coupled along the end rings (52), each capacitor grouping (98) has multiple capacitors (102) with a coverage area width (W) greater than 5.0 cm. The center ring (53) may be coupled to a ground reference (110) and has low impedance such that the center ring (53) is effectively shorted to the ground reference (110).

Abstract: A magnetic resonance imaging apparatus includes an imaging unit which performs imaging more than once with respect to an imaging target while changing a central frequency of a fat suppression pulse, a generation unit which generates a plurality of images based on magnetic resonance signals obtained by imaging performed more than once, and a calculation unit which calculates factor information of spatial inhomogeneity of a fat suppression effect based on the plurality of images.

Abstract: A method for measuring nuclear magnetic properties (NMR) properties of a formation, the method including applying a magnetic field to nuclei of the formation during a polarizing interval, the magnetic field having a polarizing intensity; changing the magnetic field to a measurement intensity, the measurement intensity applied to the nuclei of the formation during a measurement interval; applying to the formation at least one radio frequency (RF) pulse train during the measurement interval; and measuring an NMR signal from the formation.

Abstract: A system automatically dynamically compensates for inhomogeneity in an MR imaging device magnetic field. An MR imaging compensation system applies swept frequency magnetic field variation in determining an estimate of proton spin frequency at multiple individual locations associated with individual image elements in an anatomical volume of interest and substantially independently of tissue associated relaxation time. For the multiple individual locations, the system determines an offset frequency comprising a difference between a determined estimate of proton spin frequency associated with an individual image element location and a nominal proton spin frequency. The system derives data representing an electrical signal to be applied to magnetic field generation coils to substantially compensate for determined offset frequencies at the multiple individual locations.

Abstract: In an MR imaging method and apparatus which MR images with improved signal intensity, improved signal-noise ratio, improved contrast and improved image homogeneity can be acquired, the polarization state of the magnetic field of the RF pulses radiated into the measurement subject and of the resonance signals emitted by the measurement subject are distorted by the interaction with electrically-active materials of the measurement subject. In the transmission branch of the RF system the RF pulses emitted by a transmission coil are pre-distorted with regard to their polarization state. The sensitivity of the reception branch is optimized such that it is capable of detecting resonance signals independent of their polarization state.

Abstract: A medical imaging system (2) excites multiple nuclei through a single RF amplifier (24). The medical imaging system (2) includes a magnet (10) that generates a main magnetic field (Bo) in an examination region. A gradient coil (14) superimposes magnetic field gradients (G) on the main magnetic field Bo. At least one transmitter (28) generates multi-nuclei excitation pulses associated with at least two different isotopes and two different frequency spectra. The single amplifier (24) sends the multi-nuclei excitation pulses to a RF coil (18, 20) for application to the examination region.

Abstract: An MRI apparatus includes a magnetic resonance imaging (MRI) system having a magnet to impress a polarizing magnetic field, a plurality of gradient coils positioned about the bore of the magnet to impose a magnetic field gradient, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF pulses to an RF coil assembly and to acquire MR images, and a computer programmed to apply a plurality of RF pulses configured to control RF excitation by a transmit coil array such that a waveform shape of each of the plurality of RF pulses is based on optimizing a spatial spectrum.

Abstract: There is disclosed an NMR measurement method of observing plural magnetization transfer patterns in one experiment and observing their respective time-modulated, evolved chemical shifts. In an earlier portion of a pulse sequence, a transition is made from in-phase magnetizations to antiphase magnetizations using RF pulses. In an intermediate portion of the sequence, the antiphase magnetizations are interchanged using 90° RF pulses. In a later portion of the sequence, a transition is made from the antiphase magnetizations to the in-phase magnetizations using other RF pulses. Simultaneously with the interchange of the magnetizations, evolution of chemical shifts is performed by a constant-time evolution technique. In the earlier and later portions of the pulse sequence, evolutions of the chemical shifts can be performed simultaneously because the magnetizations of two nuclei are in lateral magnetization state.

Abstract: A system and method is provided for simultaneously designing a radiofrequency (“RF”) pulse waveform and a magnetic field gradient waveform in a magnetic resonance imaging (“MRI”) system. The method includes determining a desired pattern of RF excitation and determining, from the desired pattern of RF excitation, a plurality of k-space locations indicative of the magnetic field gradient waveform and a plurality of complex weighting factors indicative of RF energy deposited at each k-space location. The method also includes calculating, from the determined k-space locations, the magnetic field gradient waveform and calculating, from the complex weighting factors, the RF pulse waveform that will produce the desired pattern of RF excitation when produced with the calculated magnetic field gradient.

Abstract: A multi-frequency imaging radio frequency (RF) coil operational at three or more different frequencies, with a shifting frequency loop structure proximate the coil and switchably coupled to provide different frequencies when the loop structure is coupled to the coil. In one embodiment one of the frequencies is a proton frequency, one is a sodium frequency, and one of the frequencies is a carbon frequency. One example involves imaging examinations using hyperpolarized compounds.

Abstract: In a method and magnetic resonance apparatus for compensation of contrast inhomogeneities in magnetic resonance images caused by spatial distributions of the radio frequency field associated with the radio frequency pulses that are emitted in order to acquire magnetic resonance (MR) data, multiple individual MR images of a particular region of a subject are recorded with different radio frequency pulse sequences leading to different flip angles. A common contrast-homogenized image for the affected region then is generated based on the different individual images, so that within the contrast-homogenized image, intensity variations due to a distribution of the flip angle are smaller than in the individual images, at least in some areas.

Abstract: According to some embodiments, a synthetic nuclear magnetic resonance (NMR) reference signal is injected into the receive path of an NMR spectrometer, after the NMR probe and before the receive amplifier. The synthetic signal is generated using a transmit path for the same channel or for a different channel than the reference signal detection channel. The reference signal is coupled from a transmit-path reference signal coupler situated before a transmit amplifier to a receive-path reference signal coupler situated between the probe and the receive amplifier. The reference signal couplers may include passive directional couplers and/or active switches. The synthetic signal samples the receive path of the system but is not substantially affected by intra-probe interactions. Using a well-defined existing NMR channel to generate the reference signal allows superior control of reference signal characteristics, and does not require a dedicated spare channel for the reference signal.

Abstract: The present invention aims to receive a signal of tissue long in T2 at a relatively high level and suppress artifacts. When a magnetic resonance frequency of a component intended for measurement is assumed to be ? and the frequency corresponding to a repetition time TR is assumed to be ?o, an RF pulse obtained by modulating a chemical shift SAT pulse for reducing a signal of a frequency ? with cos (?o·t) is applied as a leading pulse Po and thereafter a pulse sequence of Balanced SSFP is applied. Since a signal leading to the occurrence of artifacts is reduced owing to the effect of the leading pulse, the artifacts can be suppressed. Since a transient state is long in the same manner as conventional, such a signal of tissue long in T2 can be received at the relatively high level and contrast can be kept high by executing data acquisition in the transient state.

Abstract: Disclosed are methods and apparatuses for generating susceptibility-related contrast images, as induced, e.g., by marker material interventional devices used for passive MR-guided interventions, or by particles or cells loaded with marker materials used for molecular imaging, cell-tracking or cell-labeling. Near a local magnetic field perturber a positive contrast signal emanates from local gradient compensation to form, e.g., a balanced SSFP type of echo, whereas everywhere else echoes are shifted outside of the data acquisition window.

Abstract: The NMR device with a magnet utilizes a composition exhibiting a desired value of magnetic susceptibility, wherein the composition comprises a metal ion selected from the group consisting of Gd+3, Fe+3 and Mn+2 and an amorphous material using a ligand or chelating agent to solubilize the metal ion throughout the amorphous material, wherein the magnetic susceptibility of the composition exhibits a desired value at cryogenic temperatures such as nearly zero susceptibility at temperatures at or below 77 K.

Abstract: Through advancing the phase of radio frequency (RF) excitation with each phase-encoding level, a method and apparatus increases the effectiveness of a Magnetic Resonance Imaging (MRI) device by correcting for main magnetic field inhomogeneities without noticeably decreasing the signal-to-noise (SNR) ratio. Increased effectiveness of fast imaging with steady precession (FISP) scans and using FISP scans to image multiple slices. In an MRI device, a patient is subjected to a constant magnetic field, and RF pulses are used to excite the nuclei in the patient's body, which release a corresponding RF signal as the nuclei relax, which is measured and mapped into a visual display. The RF pulses used to excite the nuclei cooperate with a slice select gradient and a phase-encoding gradient. When the RF pulse is phase shifted with each phase-encoding gradient level, improved SNR ratios are observed.

Abstract: An MRI apparatus suitable for realizing selective excitation utilizing multiple RF transmitting coils (parallel transmission) is provided. This MRI apparatus is provided with, as an RF receiving coil or RF transmitting coil, an RF transmitting coil 104 comprising a loop coil 210, primary differential coil 220 and secondary differential coil 230 having a common central axis 201. Upon imaging, the coils 210, 220 and 230 constituting the RF transmitting coil 104 are simultaneously driven by RF signals with the same phase, and only the differential coils 220 and 230 are driven in the second half of irradiation time with phases different by 180° from the phases for the first half.

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: An MRI apparatus which obtains a tomogram of an object by utilizing magnetic resonance includes a calibrating device which figures out a relationship between a center frequency and an optimal gain of RF transmission with respect to a predetermined range of central frequencies, a saving device which saves information expressing said relationship, and a setting device which sets the RF transmission gain according to the center frequency during subsequent scanning by utilizing the saved information.

Abstract: A magnetic resonance imaging apparatus that applies a gradient magnetic field and a radio-frequency magnetic field to a subject in a static magnetic field to image the subject based on magnetic resonance signals emitted from the subject, includes a unit which generates K transmission radio-frequency pulse signals required to produce the radio-frequency magnetic field, an allocation unit which allocates the K transmission radio-frequency pulse signals to K in M transmission signal paths, a connection unit to which at most M radio-frequency coils are attachable and which selectively connects the M transmission signal paths and M reception signal paths to the radio-frequency coils, a selection unit which selects N in magnetic resonance signals which are respectively received by the at most M radio-frequency coils and transmitted through the at most M reception signal paths, and a unit which performs reception processing for each of the selected N magnetic resonance signals.

Abstract: A magnetic resonance system has a basic magnet that generates a static basic magnetic field in an examination volume, and a whole-body antenna that emits a homogeneous radio-frequency field in the examination volume, the homogeneous radio-frequency field exhibiting an excitation frequency so that nuclei in an examination subject in the examination volume are excited to emit magnetic resonance signals, and a radio-frequency shield. The radio-frequency shield is arranged between the whole-body antenna and the basic magnet. The whole-body antenna is arranged between the radio-frequency shield and the examination volume. The radio-frequency shield is fashioned to exhibit a high shielding effect in a shielding frequency range that encompasses the excitation frequency. The shielding effect drops to a significantly lower shielding effect on both sides at side bands adjoining the shielding frequency range.

Abstract: Diagnostic and Therapy apparatus and methods use non-ionizing radiations which are based on integration of nuclear magnetic resonance and radiation manipulation. Quantitative diagnostics integrate the following devices: manual control digital filter/selector (18), frequency matrix monitor (25), frequency image monitor (26), and control panel (28). Therapy integrates the following devices: resonating antenna for radio frequency (4), low radio frequency signal processor/modulator (10), radio frequency pulse amplifier (13) and central pulse control (16). Internal parameters of the emission, such as frequency, power and polarity are selectively manipulated to personalize the therapy and to significantly improve the levels of selectivity and/or differentiation of all the processes.

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: The present invention relates to a magnetic resonance imaging system, to a magnetic resonance imaging method for operating a magnetic resonance imaging system and to a computer program for operating a magnetic resonance imaging system.

Abstract: The effects of prior pulses are to be enhanced. A pulse string which monotonically decreases the flip angle is inserted between the prior pulse in one round and the imaging pulse in the previous round, and a pulse string which monotonically increases the flip angle is inserted between the prior pulse and the imaging pulse in one round. A return from the steady state to the equilibrium state can be achieved not only for on-resonance magnetization but also for off-resonance magnetization before the prior pulse is applied. Therefore, the effects of the prior pulse P can be fully attained. Further, not only on-resonance magnetization but also off-resonance magnetization can be brought close to the steady state before the imaging pulse is applied.

Abstract: A Class-E amplifier has been adapted for use in the radio frequency section that drives a transmit coil of a magnetic resonance imaging (MRI) system. The Class-E amplifier responds to a radio frequency carrier signal and a control signal by producing a radio frequency excitation signal for driving the transmit coil. The Class-E amplifier includes a pickup coil that senses a signal emitted from the transmit coil and produces a feedback signal that is used to alter the control signal and thereby control production of the radio frequency excitation signal.

Abstract: A Class-E amplifier has been adapted for use in the radio frequency section of a magnetic resonance imaging (MRI) system. A drive signal is produced by modulating the envelope of a radio frequency carrier signal and then is applied to a switch in the Class-E amplifier. The switch is connected in series with a choke between a supply voltage terminal and circuit ground with an output node formed between the choke and the switch. The output node is coupled to circuit ground by a shunt capacitor. In a preferred embodiment, a pair of such amplifiers, that are ? radians out of phase, are connected to each rung of a transverse electromagnetic transmit array type radio frequency coil of the MRI system.

Abstract: A method and system are described for compensating for non-uniformity of excitation field B1+ in magnetic resonance imaging (MRI) of an object. The variation in the RF excitation field B1+ is measured over a region of interest (ROI) in the object, the B1+ field causing nuclear spins in the object to flip at a flip angle when B1+ is applied to the object. The flip angle profile is designed to be proportional to a reciprocal of the measured variation in the excitation field B1+. One or more control parameters of the estimated flip angle profile is adjusted, in accordance with the measured variation in B1+, so as to cancel out variation in actual flip angle until a profile of the actual flip angle is achieved that is substantially uniform throughout the ROI.

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.

Abstract: In a method, device and magnetic resonance tomography system for monitoring a radio-frequency apparatus in which radio-frequency pulses are emitted at temporal intervals and in which measurement values representing the power of the radio-frequency pulses are measured at temporal intervals, the measurement values are used to determine exposure values that represent a physiological effect that the radio-frequency pulses have on a subject exposed to the radio-frequency pulses. Based on a number of exposure values, exposure-monitoring values are respectively formed and the radio-frequency apparatus is limited in function if an exposure-monitoring value reaches or exceeds an exposure limit value.

Abstract: A method for producing images of a subject containing M spin species using a magnetic resonance imaging (MRI) system includes obtaining N k-space data matrices from N k-space data sets acquired with the MRI system using a pulse sequence with an individual associated echo time. The k-space data matrices each include corresponding data at the same plurality of k-space locations and time stamps are tracked for each k-space location. For each k-space location, a set of linear equations in k-space is solved. The set of linear equations relates corresponding data from the N k-space data matrices, echo times and time stamps to desired calculated k-space data. Calculated data in k-space which is corrected for chemical shift is produced corresponding to each k-space location and aggregated to obtain a k-space calculated data set. The k-space calculated data set is transformed to image space to obtain a corresponding image.

Abstract: An apparatus includes acquiring means for acquiring echo data of a plurality of views in which a phase difference between water and fat is 2?/m with spins within a subject brought to the SSFP state and repeating the acquisition for k=0 through M?1 with a step difference in a phase of an RF pulse of 2?·k/M; transforming means for conducting Fourier transformation on the echo data based on the phase step difference; separating means for separating water data and fat data respectively in F(0) term and F(1) term of the Fourier-transformed data using the phase difference between water and fat; adding means for obtaining a sum of absolute values of at least the water data or fat data in the F(0) term and F(1) term; and image producing means for producing an image based on the sum data.

Abstract: The present invention concerns a method and an apparatus for phase-calibrating an MRI pulse sequence which is used to calculate a linear phase and a constant phase to perform phase calibration on the scanned data, wherein a corresponding pre-scan without a phase encoding gradient is performed before a diagnostic scan. A reference echo is selected from the echoes obtained in the pre-scan. On the basis of the reference echo the constant phase is calculated to be used in performing the phase calibration in the scan. The constant phase that is obtained is correct and not affected by phase jumping. A further image reconstruction performed on the phase-calibrated data produces clear and artifact-free images.

Abstract: An embodiment of the invention relates to a device for performing NMR or ESR analysis. The device comprises a detection unit, a magnet, and a disk having a magnetic pattern. The detection unit comprises a sample holding space for holding a sample and a microcoil for detecting NMR or ESR signals generated within the sample. The magnet generates a static magnetic field within the sample. The disk and magnetic pattern, when rotating, generate an excitation magnetic field, which, together with the static magnetic field, creates an NMR or ESR within the sample. Other embodiments of the invention encompass methods for performing NMR or ESR analysis using the device and methods of making such devices.

Abstract: In a method for magnetic resonance imaging, whereby magnetic resonance signals in a region of interest of an examination subject are generated in an examination by applying radio-frequency pulses of a first transmission field strength and the magnetic resonance signals are acquired in a spatially coded manner and allocated to volume elements of the region of interest in order to obtain one or more magnetic resonance images of the region of interest, the sensitivity of each volume element of the region of interest with respect to a modification of the first transmission field strength is determined, deviations of the first transmission field strength from a reference field strength are measured during the examination, and the magnetic resonance signals acquired in the examination are corrected on the basis of the sensitivity determined for each volume element and on the basis of the measured deviations of the first transmission field strength from the reference field strength.

Abstract: A sensitivity encoding method (SENSE) is used to acquire an MR image having a reduced field of view. The number of aliased replicates caused by surrounding object boundaries is calculated for each image pixel location to obtain optimal aliasing artifact suppression without reducing image SNR.

Abstract: In a method for controlling a radio-frequency device, and a magnetic resonance tomography system and a radio-frequency control device wherein the method is implemented, the RF device of a magnetic resonance tomography system is emitted during a magnetic resonance measurement of an examination subject that is moving relative to the transmission field of the RF device. The RF device emits RF pulses at chronological intervals, and measurement values are measured at chronological intervals. At chronological intervals, position values are determined that represent a current position of the examination subject relative to the transmission field. On the basis of the measurement values and the position values, exposure values are determined that represent a physiological degree of effectiveness that the RF pulses have on the subject exposed to the RF pulses. Based on a multiplicity of exposure values, exposure control values are respectively formed.

Abstract: In a method of spatial encoding in magnetic resonance experiments, encoding kernels are imposed into the magnetization signal during the excitation or re-focussing process using a transmit array coil. Separate transmit array coil elements are provided so that in a particular phase encode direction, z in this case, they can be driven to produce partially orthogonal B1 fields, Tt(r), that exhibit a Fourier phase distribution given by Tt(r)=T0ei(ktTz)=T0ei(t?kzz).

Abstract: In a MRI system having a FID detector unit and a computer unit for processing FID signals, phase errors introduced into the FID signal at the detector unit are corrected at the computer unit by transmitting a pilot signal from the computer unit to the detector unit, processing the pilot unit along with a detected FID signal at the detector unit, transmitting the processed signals to the computer unit, obtaining the pilot signal and FID signal at the computer unit, and combining the pilot signal and the FID signal whereby phase errors cancel.

Abstract: An MRI pulse sequence control system includes a pulse sequence controller, a controller, and a performance monitor module. The pulse sequence controller generates pulse sequence control data. The controller controls scanner devices according to the control data. The performance monitor module monitors performance of the controller during an MRI scanning procedure and provides controller performance information to the pulse sequence controller. The pulse sequence controller modifies the control data in response to the controller performance information. The controller responds to the control data during the MRI scanning procedure. A process for detecting errors in an MRI scan process includes monitoring performance of the controller during the MRI scanning procedure. Controller performance information is provided to the scanning pulse sequence controller. Control data generated by the scanning pulse sequence controller is modified in response to the controller performance information.

Abstract: In a magnetic resonance tomography method and apparatus for avoiding peripheral interference signals in magnetic resonance tomography when using spin-echo sequences, the average frequency and the bandwidth of the radio-frequency excitation pulse differ from the average frequency and the bandwidth of the radio-frequency refocusing pulse(s), and the amplitude of the slice selection gradients activated during the radio-frequency excitation pulse differing from the amplitude of the slice selection gradient(s) activated during the radio-frequency refocusing pulse, such that the excitation slice of the RF excitation pulse and the refocusing slice of the RF refocusing pulse(s) in the homogeneous volume (FOV) of the basic magnetic field are superimposed, while the excitation slice of the RF refocusing pulse(s) in the non-homogeneous volume of the basic magnetic field are separated locally, and an echo signal is thereby prevented in the non-homogeneous volume.

Abstract: Magnetic resonance methods are provided for determining the mass of samples in vials (1) in a production line, each sample having a net magnetisation capability, including the steps of applying a first magnetic field in a first direction in an interrogation zone (25) for creating a net magnetisation within a sample located within the interrogation zone (25), applying an alternating magnetic field in a second direction in the interrogation zone (25) for temporarily changing the net magnetisation of the sample located within the interrogation zone (25), monitoring energy emitted by the sample as the net magnetisation of the sample returns to its original state and generating an output signal whose current amplitude is proportional to the energy emitted, comparing the current amplitude with like data obtained from at least one similar sample of known mass, and determining the mass of the sample.

Abstract: A magnetic resonance data acquisition method includes designating a plurality of parameters that are representative of conditions for acquiring data from a magnetic resonance apparatus, at least one of the parameters being variable; designating at least one objective function measuring the quality of the acquired magnetic resonance data; optimizing the at least one objective function using an optimization algorithm to find at least one set of optimum values for the parameters characterizing data acquisition; configuring the magnetic resonance apparatus with the parameters determined above, configuring by one set of the optimum values of the parameters, and instructing a magnetic resonance imaging apparatus to apply the field to the target of the data acquisition to acquire the data.

Abstract: The present invention provides a system and method of MR scan prescription to achieve in a fast, simple, and effective manner the optimal peak excitation field strength for a given pulse shape and flip angle such that the minimum TR for the MR scan can be optimized and based on SAR constraints. The present invention provides a technique to obtain optimal B1 parameters for an arbitrary shape and flip angle of an excitation pulse in real-time while satisfying SAR and/or RF hardware limits to determine the minimum achievable repetition time for a pulse sequence. The present invention is particularly applicable with breath-hold and cardiac imaging techniques that are carried out at relatively high field strengths.

Abstract: A system for the detection of narrowband signals in wideband noise that combines information across two frequency channels that straddle the frequency of the target signal. Two band pass filters having center frequencies that straddle the frequency of the target signal and that have phase transfer functions that differ by 180 degrees relative to each other at the frequency of the target signal. The presence of the target signal is detected by performing a running cross-correlation of the outputs of saturating, non-linearities that follow from the filters, and determining when the output of the running cross-correlator drops below a predetermined threshold due to the phase shift between the two filter responses caused by the presence of the target signal.

Abstract: In a method and magnetic resonance tomography apparatus for spatially resolved measurement of the magnetic high frequency field distribution in the apparatus, a double echo high frequency pulse sequence with a first excitation pulse following by at least two refocusing pulses are emitted for generation of a first echo and a following second echo. At least the excitation pulse is slice selective. In an excitation layer defined by the slice selective excitation pulse a first echo image and second echo image are spatially resolved by using suitable gradient pulses for phase or frequency encoding Using the relationships of the amplitudes of the first and second echo image in the various locations the flip angles representing the field strength at the relevant locations in the relevant slice are determined.

Abstract: There is disclosed a method of finding a reliable optimum value of a measurement condition in an NMR measurement. This method starts with gaining NMR measurement data while varying the value of the measurement condition to be optimized. Then, a certain property is extracted as a numerical value from the measurement data. A plot is made of the measurement data versus the value of the measurement condition to create a curve. A model equation coincident with the measurement condition, its range, and the certain property extracted as a numerical value is established. Curve fitting is done in which constants of the model equation are varied such that the equation agrees the created curve. The constant values of the model equation and their standard deviation are obtained by curve fitting. An optimum value of the measurement condition is obtained from the results.

Abstract: One aspect of the invention is a method for reconstructing a moving table MR image. The method comprises receiving an input array that includes a plurality of uncorrected k-space data points. The method further comprises clearing a summation array. For uncorrected k-space data points in the input array the following steps are performed. A kernel associated with the k-space data point is obtained. Corrected data is created in response to the k-space data point, the input array and the kernel. Creating the corrected data includes correcting the uncorrected k-space data point for gradient non-linearities, where the correction is performed in k-space, and correcting the uncorrected k-space data point for table movement. The corrected data is added into the summation array. The image is reconstructed in response to the data in the summation array.

Abstract: A method of inducing spin excitation by employing RF transmission fields of time-varying spatial characteristics in order to better control the overall distribution of spin excitation. The MRI transmit inductor system generates an RF transmission of particular spatial characteristics, followed by one or more additional RF transmissions with different spatial characteristics, where the additional RF transmissions alter the spin excitation produced by the first RF transmission. The spin excitation can be provided by a sequence of two or more discrete RF transmissions with different spatial characteristics, by a single RF transmission that has continuously varying spatial characteristics, by using successive RF transmissions of the primary and higher order modes of a volume coil, and/or by an RF transmission from a volume or surface coil followed by a second RF transmission from one or more local surface coils.