Abstract: Quantitative determination and evaluation of the flavor stability of fermented alcoholic beverages are performed by measuring the changes of the amount of spin adduct from the formation behavior of active oxygen with passage of time using an ESR apparatus and either determining the value on the time axis of the inflection point of changes of the amounts of spin adduct (defined as the active oxygen formation lag time) or determining the amount of spin adduct after a predetermined time has elapsed after the start of measurement (defined as the active oxygen formation activity). The longer the active oxygen formation lag time or the lower the active oxygen formation activity, the greater the oxygen resistance of the fermented alcoholic beverage, thus making it possible to evaluate that fermented alcoholic beverage as having good flavor stability.

Abstract: An apparatus using nuclear magnetic or quadrupole resonance to detect selected nuclei in a specimen (e.g., specimens containing a class of explosives or narcotics). The apparatus includes a pulsing unit to generate an RF pulse or a train of pseudo-random RF pulses used in stochastic NQR. Each of the pulses has an RF signal reaching a full amplitude within a quarter-cycle (substantially no pulse rise delay) and having a recovery delay of less than Q/.pi. cycles (substantially no recovery delay). The apparatus also includes a transmitter (e.g., a coil) to irradiate the specimen with a train of pseudo-random RF pulses and to detect after each pulse a resonance signal generated by the specimen in response to each corresponding pulse of the train of pseudo-random RF pulses. The pulsing unit has a capacitor connected to a DC power source by a first switch and connected to the coil by a second switch. When the first switch is closed, the DC power source charges the capacitor.

Abstract: In a method in the form of a single pulse sequence for operating a nuclear magnetic resonance tomography apparatus, suitable for use with a chronologically constant inhomogeneity of the basic magnetic field N radio-frequency excitation pulses (N<2), spaced with a time spacing T, are emitted onto an examination subject, under the effect of a magnetic field gradient in a first direction, the radio-frequency excitation pulses respectively having different frequency bands adjoining one another. Subsequently, radio-frequency refocusing pulses spaced with a time spacing of T/2 are emitted, with the nth radio-frequency excitation pulse and the nth radio-frequency refocusing pulse having respective frequency bands that substantially agree.

Abstract: In an inspecting method based on nuclear magnetic resonance, a burst wave having a plurality of sub-pulses frequency-modulated with a high frequency is generated, the burst wave is amplitude-modulated with at least a function which repeats polarity inversion, the amplitude-modulated burst wave is irradiated, as an exciting high frequency pulse, to an object to be inspected, and gradient magnetic fields are generated in predetermined pulse sequence to measure a nuclear magnetic resonance signal.

Abstract: The invention describes an improved NMR imaging technique having particular application in imaging of solid objects using gradient echo techniques. By applying a so called 90.degree. rf pulse substantially at zero gradient crossing it is possible to obtain frequency encoded information about an object being imaged, using a so called gradient echo technique. However, profile degradation occurs as a result of the very large magnetic fields which are used which spoil the rf pulse. By shortening the length of pulses below 90.degree. it has been possible to improve gradient echo imaging. However, this has resulted in the reduction in the signal-to-noise ratio of the echo following each pulse. The present invention overcomes this problem by providing a rapidly oscillating magnetic field gradient and applying a radio frequency pulse away from a zero gradient crossing and by substantially phase rotating the resultant profile.

Abstract: The invention relates to a method of determining prefocused pulses with sufficiently low power and short duration to allow multi-slice in-vivo spectroscopic imaging of humans. The method has two main stages, analytic and numerical. In the analytic stage a magnetization response is selected with certain desired characteristics such as prefocused time. During the numerical stage, the response is then transformed into an RF pulse for use in magnetic resonance imaging. The theoretical response to the RF pulse is evaluated and characteristics such as duration and amplitude may be altered to meet further requirements. The theoretical response is then transformed into an RF pulse for use in magnetic resonance imaging or for further application of the numerical stage.

Abstract: Spatial NMR information is obtained from a sample by applying a magnetic field having a static component and two orthogonal periodically-varying gradient components. A recurring cycle of rf excitation pulses is applied. One of the gradient components is reduced in amplitude from its maximum to zero over a period and the other gradient component is subsequently increased from zero to its maximum over a period. The said periods are both longer than the cycle time.

Abstract: A technique has previously been described for generating optimal RF pulse sequences using finite impulse response filter techniques to calculate the Fourier series which would yield the desired z and xy magnetizations in a magnetic resonance imaging device. Such a technique is now extended to allow for control of the input pulse shape as well as the frequency response. Since the peak power is limited by the amplifier power and the total energy of the pulse is limited by the specific absorption rate (SAR) of the tissue or sample, it is desired to limit the peak power and total energy of the input pulse without degrading the resulting excitation. This is accomplished by recognizing that the total energy of the pulse is encoded in the lowest order Fourier series coefficients of the frequency response and then specifying the total energy of the pulse as a design parameter to the RF pulse synthesis algorithm. Peak power of the pulse may also be limited by selecting roots for .beta.(.omega.), where M.sub.z (.omega.

Abstract: A microwave spectrometer includes a sensing chamber into which is introduced a gas or constituent to be analyzed. Microwave radiation is introduced into the chamber and any of the chamber resonant frequency, the microwave frequency, and the center frequency of the absorption peak are varied independently. The resultant variation in intensity of the microwave radiation in the chamber is monitored to determine the concentration of the gas within said chamber. The spectrometer may include a frequency measuring and reference system for measuring the resonant frequency of the chamber.

Abstract: An improved rapid acquisition relaxation enhanced (RARE) imaging method for measuring nuclear magnetic resonance in selected regions of a body is disclosed. The improved RARE imaging method includes introducing an evolution phase of time duration t.sub.2 between the excitation pulse and the first refocusing pulse of the multi-echo train. The evolution phase is introduced to influence the magnetization of the observed nuclei in such a fashion that the intensity and/or phase of the subsequent signals are influenced as a function of this evolution phase. This allows the effects of flow, motion, diffusion and local magnetic field inhomogenities to be measured.

Abstract: A nuclear magnetic resonance cross polarization probe uses a dual-coil arrangement in which a single-turn inner coil is surrounded by a solenoid coil. The inner coil is tuned to the frequency of a relatively high Larmor frequency nuclei type, such as proton. The solenoid coil is tuned to a lower Larmor frequency nuclei type. An inner sample region surrounded by the inner coil has a first magnetic field component induced by an electrical signal at the relatively high frequency in the inner coil. An electrical signal at the lower frequency is input to the solenoid coil and results in the generation of a magnetic field alternating at the lower frequency. This field induces a current in the inner coil at the lower frequency that, in turn, induces a magnetic field component in the inner region at the lower frequency.

Abstract: Magnets (12) create a temporally constant magnetic field through an examination region (14). Radio frequency coils (26, 34) and a transmitter (24) transmit radio frequency saturation pulses (52) and the resonance excitation and manipulation pulses of a magnetic resonance imaging sequence (72) into the examination region. Gradient amplifiers (20) and gradient coils (22, 32) create magnetic field gradients across the examination region for spatially focusing the saturation, for spoiling (62, 66, 70) residual transverse magnetization and for frequency and phase encoding in the magnetic resonance imaging sequence. A sequence controller (40) includes a saturation pulse controller (44) for generating the saturation pulse (52) and slice select gradients (58) and a steady state sequence controller (48) for generating the imaging sequence (72). The saturation is spectrally focused by limiting the frequency of the saturation pulse to selected frequencies.

Abstract: In applications where a tuned coil is used as a receiving antenna, the coil's resistance can produce excessive noise. If a low-loss coil is used, such as with cooled or supercoductive wire, the resulting Q results in inadequate bandwidth. To provide the desired bandwidth without additional losses the coil and its tuning capacitor are periodically de-energized using one or two switches. This sets the signal to substantially zero where it starts again to build up, effectively widening the bandwidth. The resulting signal is synchronously detected to provide the in-phase and quadrature signals. In an NMR system this enables the performance to be limited by sample or object noise. In MRI systems using an oscillating readout bias, the shorting is timed with the transition of the bias waveform.

Abstract: An MRI automatic power control system comprises a first unit for exciting each of a plurality of regions of a subject under examination with an excitation radio-frequency pulse of a different power, a second unit for acquiring magnetic resonance signals from the plurality of regions excited by the first unit, a third unit for identifying a maximum magnetic resonance signal contained in the magnetic resonance signals acquired by the second unit from the plurality of regions of the subject, and a fourth unit for storing the power of an excitation radio-frequency pulse that has provided the maximum magnetic resonance signal identified by the third unit as the optimum power of the excitation radio-frequency pulses.

Abstract: When image information obtained on the basis of an NMR signal, e.g. MRI, is acquired, a radio frequency pulse is set so that a strong signal can be obtained particularly from a portion of interest among the sample. To accomplish this object, the occurrence of signals from portions of the sample other than the selected portion of interest is inhibited in advance of obtaining information (an image) of the sample. Various radio frequency pulses are then irradiated to the sample and a suitable radio frequency pulse is determined on the basis of the resulting signal.

Abstract: An NMR system includes a transceiver which receives NMR signals of varying amplitude during a scan. The gain of the receiver is dynamically changed during the scan to provide an optimal SNR figure without overranging the transceiver's A/D converter. The acquired NMR signals are normalized prior to image reconstruction using correction factors for gain and phase stored in a normalization table.

Abstract: A method for exciting transverse magnetization by irradiating a nuclear spin system subjected to a constant magnetic field with a frequency-modulated rf-pulse ("chirp"-pulse) and with a further frequency-modulated rf-pulse (further chirp-pulse) for refocusing the magnetization, is characterized in that the rf-pulse-(P1) and the further rf-pulse (P2) overlap each other in time at least partially. Thus, the duration of the pulses can be reduced.

Abstract: A local frequency generator employing a single crystal oscillator, latches and direct digital synthesizer circuits digitally produces all signals needed in the transmitter channel of a MRI system to generate MRI transmitter RF pulses. The local frequency generator is operable in both the single side band and double side band modes and has the capability of switching between the modes. The generator is constructed with a phase resetting capability for providing the plural output frequencies needed for making plural MRI slices.

Abstract: An NMR parallel imaging method and apparatus in a single sequence has a plurality of RF pulses applied substantially simultaneously, each having a different frequency, in the same contiguous time period in a subinterval of time during which the select slice magnetic gradient is applied, to activate a plurality of different physical slices. The refocusing RF pulses also comprise a plurality of RF pulses each having a different frequency, applied non-simultaneously but within the same slice select magnetic gradient in the same subinterval of time. A plurality of echo signals from the plurality of different excited slices are then read out during the same single read out magnetic pulse in the same subinterval. The method and apparatus of the present invention can be applied in MRI spin echo, pre-saturation or inversion.

Abstract: A method of producing slicing planes in a nuclear magnetic resonance imaging system capable of obtaining a thin slice thickness easily. RF pulses for sequentially exciting a plurality of excitation planes for determining slicing planes are generated, wherein frequencies of the RF pulses are sequentially controlled such that each two adjacent ones of excitation planes have a mutually overlapping region and two separate non-overlapping regions. Then the generated RF pulses are applied to an object to be examined which has been placed in appropriate static and gradient magnetic fields for obtaining nuclear magnetic resonance signals from the slicing planes defined by the excitation planes in accordance with the mutually overlapping region and the separate non-overlapping regions of each two adjacent ones of the excitation planes.

Abstract: A prescan for an MRI system (FIG. 1) automatically sets the rf power level to produce an excitation field that nutates spins in the image plane the amount prescribed by the scan. Nutation angle is measured with a pulse sequence comprised of three slice selective excitation pulses that produce a set of frequency encoded NMR echo signals (E.sub.1, S.sub.1, E.sub.2, E.sub.23, E.sub.13). Nutation angle is calculated at locations in the image slice from the Fourier transformation of these signals and the maximum nutation angle is employed to calculate the final rf power level setting for the scan.

Abstract: An MRI apparatus comprises a magnet system producing a homogeneous magnetic field along the z axis. A plurality of wire conductors arranged in a "bird cage" configuration are supplied with a circularly rotating RF field centered near the Larmor frequency .omega..sub.o. The wire conductors receive a voltage source V.sub.p having a frequency .omega..sub.p, which is less than the Larmor frequency. The voltage source V.sub.p rotates about the wire conductors at a frequency of .omega..sub.s, which is much less than the frequency .omega..sub.p, to successively apply the voltage V.sub.p to each pair of diametrically opposed wire conductors in a manner which is ordered as a spatial cylindrical harmonic rotating at a frequency .omega..sub.s. The voltage source V.sub.p produces electric fields in the object which generate linear magnetic field gradients in the object. The voltage source V.sub.

Abstract: In a magnetic resonance imaging system having an automatic power control function for adjusting the transmission power of an RF pulse so as to set a desired flip angle of a spin, in an automatic power control mode, a plane including only a portion of an object to be examined in an imaging region having a uniform field intensity, e.g., a transaxial plane or a plane slightly inclined from the transaxial plane is excited by a gradient magnetic field Gz in the direction of the body axis of the object as a slice gradient magnetic field regardless of a plane to be imaged. The peak values of MR echo signals are detected while the transmission power of the RF pulse is changed. An RF pulse transmission power at which the maximum peak value appears is detected from these detection values. The transmission power of the RF pulse in imaging, i.e.

Abstract: In a magnetic resonance imaging apparatus adapted for a spin-echo method using a 90.degree. pulse as a selective excitation pulse and a 180.degree. pulse as a refocus pulse, MR signal is acquired with their phase difference changed in increments of a fixed angle with each frequency encoding step. This permits the phase difference between an echo signal used for imaging and an FID signal unnecessary for imaging to be changed in increments of the fixed angle with each encoding step. Thus, a zipper artifact based on the FID signal will be produced in a position corresponding to the fixed angle in an MR image reconstructed through Fourier transform of the acquired signal. The proper setting of the fixed angle of the phase difference permits the zipper artifact to be shifted to any position in the MR image.

Abstract: An NMR scanner performs a prescan before each NMR scan sequence in which the optimal RF excitation frequency is automatically determined and applied to the scanner's transceiver. The prescan sequence includes a pair of NMR measurements which provide data that allows the precise RF excitation frequency to be determined.

Abstract: A magnetic resonance experiment is described in which a sample under test is subjected to a sequence of gradient magnetic fields and RF pulses and resultant pulse echoes are monitored. At least one of the RF pulses comprises a prefocused, phase-modulated, time-asymmetric RF pulse.

Abstract: Temporal B.sub.o shifts in NMR spectroscopy and/or imaging systems arising from pulsed field gradient induced eddy currents result in the distortion of free induction decay signals. A method of compensation of this distortion through modulation of the sender and/or receiver signal in opposite concert with the induced B.sub.o shifts is introduced. The method has the advantage of having a fast response and of not altering the magnetic gradient field. (FIG.

Abstract: A method for generating a spectrum of NMR signals with rectangular characteristic in the frequency space by radiating a sequence of RF pulses onto a sample in the homogeneous magnetic field is presented. The RF pulses of the sequence are amplitude modulated and the enveloping function of the sequence consists of a superposition of bell-curve-shaped RF pulses with optimized positions of the maxima, pulse widths and peak amplitudes. The response signals, in dependence on the standardized frequency, shift, approximate virtually ideally, a rectangular function. The method is applicable with success especially in image generation for NMR tomography, in multidimensional NMR spectroscopy, as well as in volume selective NMR spectroscopy.

Abstract: MRI Apparatus for obtaining a spin-echo signal applies a self-refocusing RF pulse with variable delay in the spin-echo signals following application of the RF pulse. The RF pulse is designed using the Shinnar-LeRoux algorithm B.sub.1 (t)=SLR.sup.-1 {A.sub.n (z), B.sub.n (z) } with A.sub.n '(z) substituted for A.sub.n (z).A.sub.n '(z) is slightly non-minimum phase and equals P(z) A.sub.n (z) where P(z) is a unit amplitude phase function chosen to compensate the phase of B.sub.n (z). The RF pulse can be designed for a specific delay, a specific power constraint, and small tip angle.

Abstract: In addition to the usual winding of an MRI RF receive coil, a second, opposite sense, winding is connected to the same pair of RF output terminals and linked to at least part of the same space as the first winding. One or more serially connected RF switches in the second winding selectively connect it in circuit only during transmission of NMR RF nutation pulses. Under these conditions, any transmitted RF fields linked to the first winding are also linked to the second winding. Accordingly, any induced RF currents flowing in the receive coil windings produce self-cancelling effects in the tissue being imaged (thereby reducing possible distortion of the desired transmit fields being used for NMR nutation purposes).

Abstract: In a multiple coil type magnetic resonance imaging system, MR signals can be obtained at high S/N ratio and over a large image region. The magnetic resonance imaging system includes: a plurality of receiving coils for receiving a plurality of MR signals generated from plural portions of an object under medical examination; a plurality of filters coupled to the plural receiving coils, for filtering the plurality of MR signals to obtain a plurality of filtered MR signals; a processor and a filter passband setting circuit for setting passbands of the plurality of filters in such a manner that the plurality of filtered MR signals have preselected frequency bands different from each other; and, an adder for adding the filtered MR signals with each other which are derived from the filters coupled to at least two receiving coils selected from the plurality of receiving coils.

Abstract: In magnetic resonance spectroscopy and imaging, it is usually necessary to obtain spectra only from desired, localized regions of an examination subject. This is accomplished by subjecting the examination subject to a selective radio-frequency (RF) pulse. A method for optimizing the pulse shape of such a radio-frequency pulse includes the steps of exciting a spin system with a frequency-selective radio-frequency pulse, reading out the resulting echo signal, cutting off high-frequency signal components of the echo signal using a filter, and employing the filtered echo signal as the optimized radio-frequency pulse shape.

Abstract: A double-tuned NMR sample excitation coil has a first end connected through a first balancing inductor to ground and a second end connected through a second balancing inductor to a low-frequency (LF) capacitor tuning and matching network. Two two balancing inductors have inductance less than 50% but greater than 10% that of the excitation coil. Each balancing coil is tuned by a capacitor network to an independent resonant frequency when disconnected from the sample coil that is less than 95% but greater than 60% of the final high frequency (HF) resonance. Moreover, both such independent resonant frequencies are equal within 10%. Broadband operation is possible under a variety of temperatures and the circuit works with high-speed sample spinners.

Abstract: A dielectric resonator is used in a magnetic resonance examination apparatus comprising a magnet system (31, 32) for generating a steady magnetic field in an examination space (2), a transmitter device (12, 13, 18, 28) for generating an RF field to be superposed on the steady magnetic field in an object (30) to be examined, a device for producing a resonance step-up of the RF field active in the object (30) to be examined, and a device for detecting magnetic resonance signals generated in the object (30) to be examined. Stronger B.sub.1 fields are created by at least one dielectric resonator (1, 5, 10, 16, 17, 20, 21) which neighbors the object (24) to be examined and which comprises a dielectric having a relative dielectric constant .epsilon..sub.

Abstract: In a magnetic resonance imaging system, an RF power amplifier is employed to boost an RF pulse to sufficient strength to excite the nuclear spins in a subject. The non-ideal behavior of the amplifier distorts the shape of an excitation pulse, and this distortion in turn degrades a slice profile. The distortion of the RF signal is manifested by nonlinearity in amplification and in incidental phase modulation. By determining the amount of nonlinearity and the phase modulation resulting from the power amplification, the baseband RF signal can be predistorted or prewarped to offset the distortion resulting from amplification. Improved slice selectivity results therefrom.

Abstract: In NMR pulse experiments transverse magnetization is excited by irradiating the nuclear spin system with a two pulse sequence of a first RF chirp pulse and a second RF chirp pulse, generated after a defocusing time interval .tau.. The pulse duration of the second chirp pulse is half the duration of the first pulse, and the amplitude of the second chirp pulse is approximately three times the amplitude of the first chirp pulse. The first pulse being a 90.degree.-pulse, the second pulse being a 180.degree.-pulse, a refocusing of the magnetization vectors occurs at a time .tau.'=.tau.+.tau.180.degree. after elapse of the second chirp pulse, and acquisition of the resulting echo signal is started at peak of the echo.

Abstract: An NMR imaging system includes a prescan procedure in which the RF transmit power level is calibrated to produce an optimal, uniform RF field. Pulse sequences are conducted at a series of RF power levels and from the resulting acquired NMR data the power level which produces the most uniform signal across the extent of the subject being imaged is determined.

Abstract: An rf generator for magnetic resonance imaging apparatus including a modulator in which a carrier is modulated with an envelope signal, and a transmitter stage which is connected subsequent to the modulator generator in which the implementation of the modulating signal enables the expenditure for the transmitter stage be substantially reduced in that the modulator comprises a first modulator section in which the envelope signal is converted into a series of equally long digital pulses whose density corresponds to the amplitude of the envelope signal, in that k different kinds of pulses are provided, in that during each pulse of a given kind the carrier is always switched on with a given phase position which deviates from the phase positions of the carrier which are associated with the pulses of the other kinds by 360.degree./k or an integer multiple thereof, and in that the resultant pulse-wise switched, preferably square-wave carrier acts as a switching signal for the transmitter stage.

Abstract: An NMR signal measuring method for simultaneously measuring RF field components inducing in RF coils and spinning in opposite directions. The components spinning in opposite directions are measured separately and the measuring results are compared for the elimination of faults.

Abstract: A method of simultaneous multinuclear magnetic resonance imaging and spatially localized NMR spectroscopy is disclosed. Clinical implementation of the disclosed method allows routine in vivo NMR spectroscopy studies without significantly increasing the time of conventional MR imaging studies. A unique sequence of rf excitation and magnetic gradient pulses is used which allows chemical shift imaging data to be acquired simultaneously with conventional imaging data. A deconvolution method extracts the chemical shift information for analysis and display.

Abstract: A magnetic resonance imaging system includes magnetic resonance signal detecting means (1, 2, 3, 4, 7, 8, 10) for detecting a magnetic resonance signal from an object to be examined, receiving means (9) for phase-sensitive detecting and amplifying the magnetic resonance signal, data acquiring means (11) for sampling and digitizing the magnetic resonance signal obtained by the receiving unit (9), and image reconstructing means (12) for performing image reconstruction on the basis of the magnetic resonance signal and the sampling data obtained by the data acquiring means (11).

Abstract: A method for simultaneously obtaining a three-dimensional nuclear magnetic resonance (NMR) angiographic image of moving spins associated with fluid flow in a region of a living organism sample, and a three-dimensional NMR image of stationary tissue in the same sample region, by immersing the sample in a main static magnetic field; nutating, in an excitation subsequence of each of a plurality of NMR sequences, the nuclear spins and the generating a flow-encoding magnetic field gradient selected to cause a resulting NMR response echo signal from the spin of a moving nucleus to be different from the NMR response echo signal from the spin of a substantially stationary nucleus.

Abstract: The invention relates to a magnetic resonance imaging device comprising a transmitter/receiver which, with the exception of a few components is all digital. The transmitter comprises a digital frequency synthesizer, a single sideband modulator and a selective power amplifier, the single sideband modulator being controlled by a phase locked loop oscillator. The receiver comprises a selective pre-amplifier, a frequency mixing stage which is connected either to an output of the phase locked loop oscillator or to an output of the single sideband modulator, and an analog-to-digital converter which samples the output signal of the frequency mixing stage. The demodulation frequency for the receiver is chosen so that, after demodulation, a frequency band is obtained which is situated to one side of 0 Hz.

Abstract: In NMR images, which are constructed from resonance signals, for example with Fourier zeugmatography, due to coherent interferences, for example, as a result of "leak-through" of NMR signals from one sequence to a next sequence of resonance signals, artefacts can occur in the images, which, depending upon the kind of interference, become manifest in the image as interference lines, ghost images or conspicuous dots. A method is disclosed of reducing the influence of these interferences by smearing the artefacts out over the image as noise. For this purpose, the phase of the reference signals is randomly modulated between measuring cycles of the resonance signals. The reference signal is used to form excitation pulses for producing resonance signals in a body and further in synchronous detection of the resonance signals.

Abstract: In a magnetic resonance imaging or spectroscopy apparatus, radio frequency pulses of a selected size are applied to cause a corresponding tip angle. However, the actual tip angle which results varies with, for example, coil loading and patient geometry. For accuracy of the resultant image or data, the RF pulse size is adjusted or calibrated to produce a selected tip angle precisely - most commonly 90.degree. and 180.degree. tip angles. To calibrate the 90.degree. tip angle, a sequence of three like pulses (.alpha.-.alpha.-.alpha.) is applied. In each repetition, the pulses are varied in magnitude to produce tip angles around 90.degree. and the actual resulting tip angles are determined. The RF pulse size that produces or is projected by a least-squares fit to produce the exact 90.degree. tip angle is determined. To calibrate the 180.degree. tip angle, the pulse sequence includes the RF pulse (.alpha.) determined to produce the 90.degree. tip followed by two additional RF pulses (.beta.). The sequence (.alpha.

Abstract: Method and apparatus for more rapidly capturing MRI data by receiving and recording NMR RF responses in plural substantially independent RF signal receiving and processing channels during the occurrence of an NMR RF response. The resulting plural data sets respectively provided by the plural RF channels are then used to produce multiply phase-encoded MRI data from the single NMR RF response. Practical examples are disclosed for reducing required MRI data capturing time by factors of at least about one-half.

Abstract: Frequency tuning and coupling capacitances in MRI RF receive coils are typically realized, at least in part, as reverse biased varactor diodes. During RF tuning of the transmit coil (i.e., so as to achieve resonance and matched impedance conditions), at least some if not all of the varactors associated with the receive coil are forward biased so as to simultaneously maximize detuning of the receive coil to resonant frequencies removed as far as possible from that of the transmitter coil being tuned while also then substantially reducing the Q of the receive coil.

Abstract: Radio frequency pulses (40, 50, 60) having tip angles in the range of 5.degree. to 15.degree. are applied concurrently with slice select gradient pulses (42, 52, 62) to tip a component of the magnetization into a transverse plane. Phase encode gradients (44, 54, 64) phase encode magnetic resonance echoes (48, 58, 68) which are collected in the presence of read gradients (46, 56, 66). The magnitude of components of the slice select , read, and phase encode gradients along three system axes (grad1, grad2, grad3) are different in conjunction with each echo such that each echo represents a view of data along a different slice through a region of interest. The tip angle (.alpha.) and duration (t) between RF pulses are selected such that the magnetization of dipoles within the most recently selected slice regrows along the magnetic field axis until it is indistinguishable over integrated noise from the magnetization corresponding to other dipoles in the image region.

Abstract: The present invention pertains to an extremity coil for magnetic resonance imaging. The extremity coil includes means for varying the aperture of the coil, and means for supporting the coil. Additionally, the extremity coil can include means for varying the resonant frequency of the coil.

Abstract: The "spoiled FLASH" nuclear magnetic resonance (NMR) method avoids image artifacts which may be caused by transverse magnetization remaining at the end of a TR period of a partial experiment by applying an additional "spoiler" slice gradient pulse ("SP") after the detection of a gradient echo ("Signal") and before the application of the radio frequency pulse (RF) of the following partial experiment. The amplitude-time integral, i.e. the duration and/or the amplitude of the additional spoiler slice gradient pulses is incremented and/or decremented from partial experiment to partial experiment of a given total experiment. Each spoiler amplitude may be repeated after a time of the order of T.sub.2.