Abstract: A method serves for recording spin resonance spectra of test samples having at least three groups of spins. A first group is coupled to a second group, while a third group is uncoupled relative to the second group but has a spectral position, e.g. chemical shift, which is substantially identical only to that of the first group. For obtaining an isolated image of the signal of the first group, one suppresses the signal of the third group. A pulse sequence of three r.f. pulses (10, 13, 17) are irradiated upon the sample in a manner known as such. The second r.f. pulse (13 ) is applied in such a way that the magnetization of the spins of the first group and of the second group is transferred to a state of double-quantum coherence by coherence transfer. Then, a first magnetic gradient field pulse (15) of a predetermined pulse surface (.epsilon..sub.2), with dephasing effect for the double-quantum coherence, is exerted upon the sample. The third r.f.

Abstract: An actuating drive for controllable adjustment of a plurality of actuators in a nuclear resonance spectrometer is characterized in that the actuating drive has a drive train with a drive shaft (9) that can be driven by an electric drive motor (3) and with a plurality of drive train outputs, for coupling to the actuators, each of which can be individually coupled to the drive shaft by means of a changeover device. This enables the actuators to be adjusted automatically.

Abstract: A new geometry for a radio frequency coil design in which longitudinal conductors of the coil lie on two parallel planes. The currents in the conductors of one plane run in the opposite direction to those of the other plane. For the case of discrete conductors, field maps illustrate that the homogeneity and sensitivity of the biplanar design are superior to that of a saddle coil, and when the design is optimized, the homogeneity is almost as good as that for comparable discrete cosine or birdcage coil designs. The measured B1 map of an optimized, single-tuned biplanar coil in accordance with the invention thus compares favorably to that of an equivalent discrete cosine coil and demonstrates excellent homogeneity in the central region of the coil.

Abstract: A non-destructive spoilage detection method of detecting spoilage of a nutritional product having a water activity of at least 0.9 has the steps of: subjecting a nutritional product in a non-metallic sealed container to nuclear magnetic resonance spectroscopy followed by recording the peak free induction decay value associated with an initial nuclear magnetic resonance spectroscopy of the nutritional product. Subsequently the nutritional product is subjected to nuclear magnetic resonance spectroscopy and at least one other peak free induction decay value associated with the nuclear magnetic resonance spectroscopy of the nutritional product is recorded. Over time, at least two of the peak free induction decay values are compared from which a determination is made whether spoilage of the nutritional product is indicated. Preferably subjection of the nutritional product to nuclear magnetic resonance spectroscopy occurs on a regular basis and at approximately the same temperature of the nutritional.

Abstract: A method for noninvasively detecting osteoporosis in human subjects by means of NMR imaging is described. In the preferred embodiment, a series of images are acquired whereby the echo time TE is incremented until a predefined number of images, each differing in echo time, has been acquired. The images are then displayed, a region of interest (ROI) is selected and mean signal amplitudes are computed (block 46). The mean signal amplitude values are then used as inputs for the curve fitting procedure that computes T2* (block 48). The final step of the process compares the computed value of T2* with a normal baseline (block 50), which permits the subject to be classified as either normal or osteoporotic (block 52).

Abstract: This invention presents a method and an apparatus for examining and determining the viscosity of a liquid sealed in a container by applying a centrifugal force to the container, detecting a change in the surface form of said liquid by the means of a sensor, and measuring either a lapse of time from the application of centrifugal force to the time when the output voltage of the sensor reaches a predetermined level or a voltage output of the sensor upon a predetermined lapse of time from the application of a centrifugal force, thereby examining and determining the viscosity of the liquid to find out whether there is any quality change in the liquid without destroying the container.

Abstract: A signal function S(t.sub.1, t.sub.2) is obtained from a plurality of coherence transfer pathways in a single acquisition by preparing a molecular system in a coherent non-equilibrium state, and alternately and sequentially detecting signals at individual sampling points, in t.sub.2, from the plurality of coherence transfer pathways by using gradient refocusing of a new pathway after signal detection at a sampling point in another pathway. A frequency domain spectrum S(.omega..sub.1,.omega..sub.2) is constructed by first Fourier transforming the time domain signals S(t.sub.1, t.sub.2) in the t.sub.2 dimension and producing real and imaginary components which modulate as sine and cosine signals in t.sub.1. The real (.omega..sub.2) cosine (t.sub.1) components are combined with the imaginary (.omega..sub.2) sine (t.sub.1) components to form a complex data set S(t.sub.1, .omega..sub.2) that is amplitude modulated in t.sub.1. The complex data set is then Fourier transformed in the t.sub.

Abstract: The quadrature channels of an RF generator in an NMR spectrometer are aligned relative to one another by applying pulse sets to pairs of channels that are 180.degree. out of phase. The effect of the pulses in one channel is the opposite of the pulses in the other channel. As a result, the magnetization of the sample returns to the direction in which it started when the amplitudes of the pulses applied to each channel are equal. The magnetization returns to the initial direction even in the presence of RF inhomogeneities. The characteristic magnetization pattern can be easily observed and used to adjust the relative pulse amplitudes equal and the absolute pulse amplitudes to .pi./2.

Abstract: There is disclosed a gradient magnetic field coil for use in a magnetic resonance imaging system for imaging an imaginary or virtual cross-section of a desired portion of a subject to be inspected, utilizing a magnetic resonance phenomenon. The gradient magnetic field coil includes a coil bobbin and coil windings fixedly mounted on the coil bobbin. The coil bobbin includes a tubular body portion of a honeycomb construction having a number of vacancies formed in a wall of the tubular body portion, a sheet-like outer peripheral portion of a constrained damping structure fixedly secured to an outer peripheral surface of the body portion to reinforce the body portion, and a sheet-like inner peripheral portion fixedly having at least one layer and secured to an inner peripheral surface of the body portion to reinforce the body portion. The generation and continuation of vibrations in the coil bobbin are controlled or suppressed directly by the coil bobbin itself, thereby minimizing the generation of noise.

Abstract: Disclosed is a method of detecting NMR signals indicative of a short T.sub.2 species in the presence of a long T.sub.2 species by utilizing magnetization transfer between species without requiring an auxiliary RF amplifier and with reduced power deposition (SAR). One or more zero degree RF pulses are applied to a body containing the short T.sub.2 species and the long T.sub.2 species with the pulses being at the resonant frequency. The RF pulses provides selective magnetization saturation of the short T.sub.2 species, and the RF pulses are spaced in time to allow magnetization transfer from the short T.sub.2 species to the long T.sub.2 species. Gradients can then be applied to the body for signal localization with signals detected from the long T.sub.2 species due to magnetization transfer from the short T.sub.2 species being indicative of the presence of the short T.sub.2 species. The signals are indicative also of the magnetization transfer between species.

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

Abstract: A gated amplifier drives a gradient coil when the gate signal is applied and the gate signal also controls an FET switch to disconnect a shim power supply from shim coils and connects the shim power supply instead to a dummy load. When the gate signal is removed, the shim coil is restored to operation from the shim power supply.

Abstract: A method for suppressing fat in a magnetic resonance image of a target organ, wherein fat is present in the vicinity of the target organ involves subjecting the target organ to electromagnetic energy so as to cause an organ signal response and a fat signal response related to the magnetization of the organ and the fat, respectively. The subjecting to electromagnetic energy involves subjecting the target organ to a saturation preamble and thereafter subjecting the target organ to an offsetting spin-echo sequence. The organ and fat responses are detected and image information based on the responses is generated. The saturation preamble, selectively excites and then dephases a particular substance, such as fat, in the vicinity of the target organ. Preferably exciting and then dephasing involves subjecting the target organ to a Hore 1-3-3-1 signal.

Abstract: Two-dimensional nuclear magnetic resonance spectroscopy with a frequently repeated sequence comprises four high-frequency pulses and acting together with a homogeneous stationary magnetic field upon an examination area, which sequence contains two 180.degree. pulses, halfway between which a third pulse is located. The pulse of the sequence are preceded by a first pulse, whose distance from the second pulse, which is equal to or larger than the relative distance of the other pulses, is varied during the repetition of the sequence. This method is particularly suitable for in vivo examinations of the human body in that during three of the four pulses magnetic gradient fields are operative, whose gradients extend mutually perpendicular to each other, and before and after the third high-frequency pulse a magnetic gradient field is operative having such a duration and such a gradient that the time integral across this field has the same value before the third pulse as after the third pulse.

Abstract: A method of nuclear magnetic resonance angiographic imaging capable of reducing an imaging operation time.

Abstract: The acquisition of radial lines in 2-D Fourier space (k-space) allows the realization of the extremely short echo times useful in the imaging of short-T.sub.2 species and flow using Magnetic Resonance (MR). The disadvantage of this imaging method, which is also known as projection reconstruction, is that in order to prevent aliasing at a given resolution, .pi. times as many excitations are required as the conventional 2-D Fourier transform or spin-warp acquisition. Disclosed is an acquisition and reconstruction method that reduces the required number of radial lines and excitations by using the properties that projections are real or have slowly varying phase and the at radial acquisition methods are oversampled at the center of k-space. This method preserves resolution while reducing imaging time at the expense of signal-to-noise ratio (SNR). This has been verified with both phantom and human subjects.

Abstract: A method and apparatus for directly measuring the time-averaged streamwise momentum in a turbulent stream use a probe which has total head response which varies as the cosine-squared of the angle of incidence. The probe has a nose with a slight indentation on its front face for providing the desired response. The method of making the probe incorporates unique design features. Another probe may be positioned in a side-by-side relationship to the first probe to provide a direct measurement of the total pressure. The difference between the two pressures yields the sum of the squares of the cross-stream components of the turbulence level.

Abstract: A nuclear magnetic resonance imaging system has a power supply with a regulator for a gradient coil, the gradient coil generating a gradient magnetic field. Circuitry is provided for measuring changes in the flux density of the gradient magnetic field, and forming an actual value of the flux density from those measurements. The actual value is compared to a predetermined value, and the gradient field is regulated so that the flux density corresponds to the predetermined value.

Abstract: An electron spin resonance spectrometer which is dedicated to a specific narrow range of tasks is reduced in size such that, as contrasted with the usual laboratory ESR spectrometers, it is easily and readily portable and can be carried to various locations to conduct tests. It uses a much smaller magnet structure than usual, a self contained single board computer, and a microwave source which is adjustable by the computer. The microwave source operates in the 2 GHz range and is connected through a circulator with a matching circuit which inductively couples the microwave signal to a sample chamber/resonator positioned in the magnetic field of the magnet structure. An oscillator provides a audio frequency signal which is combined with a slow ramp signal from the computer to modulate the output of the magnet structure.

Abstract: The sensitive detection of explosives and narcotics by nuclear quadrupole resonance (NQR) is performed at low rf power by assuring that the rf field strength is larger than the local magnetic field. Additionally, it has been recognized that signal-to-noise ratio of a signal induced by a specimen of fixed size decreases by only the square root of the coil size. Thus, rather than scaling power linearly with coil size, as conventionally done to maintain the same rf field intensity, the power need only be increased by the square root of the increased coil size to assure maintenance of the same signal to noise ratio. This technique permits the use of larger coils than previously used. The invention is useful for both volume coils and surface coils.