Abstract: A gradient magnetic field irradiation method comprising irradiating RF pulses and a slice plane selection gradient magnetic field to excite an atomic nucleus of a slice plane, irradiating then first, second and third frequency encoding gradient magnetic fields under the following condition and receiving NMR signals during the irradiation of the third frequency encoding gradient magnetic field:(A) (1/k)-(4/n)+1=0where a ratio of intensity of the first, second and third frequency encoding gradient magnetic field is k:n:1;(B) the irradiation time of the first and second frequency encoding gradient magnetic fields is T/k and 2T/n, respectively, when the irradiation time of the third frequency gradient magnetic field is 2T; and(C) a time interval between the start timing of the irradiation of the first frequency encoding gradient magnetic field and the start timing of the irradiation of the second frequency encoding gradient magnetic field is equal to a time interval between the start timing of the irradiation of

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: An NMR radio-frequency (RF) coil is made up, in the preferred embodiment, of upper and lower coil assemblies. Each coil assembly includes a tuned circuit. In operation, only one of the tuned circuits is energized, while the other is mutually inductively coupled such that they resonate together as one circuit at substantially the same frequency. A first set of latches is provided to fasten the lower coil assembly to a patient cradle. A second set of latches is utilized to fasten the upper coil assembly to the lower while permitting relative longitudinal motion between the two assemblies.In another embodiment, which does not utilize mutual inductance, the tuned circuits on each assembly are electrically connected to form a complete coil by means of, for example, an electrical plug-and-jack arrangement.

Abstract: In a magnetic resonance imaging apparatus comprising an array consisting of several rf coil elements, a bandpass filter is coupled to corresponding individual coils of the array, the outputs of the bandpass filters being connected to form a signal summing device. As a result, a substantial part of the imaging is sequentially performed, so that the construction of the image processing device may be simpler and the risk of image artefacts is reduced. The array forms a linear series of surface coils, a common axis of which coincides with the measurement gradient field direction.

Abstract: A magnetic resonance and apparatus in which an examination zone is exposed, preferably repeatedly, with a sequence in which the same RF pulse is both selective to fat, for acting in a fat suppression scheme within the sequence and is configured for inducing substantial magnetization transfer contrast. Design parameters are given for a 1-2-1 binomial RF pulse and a 1-2-1-1-2-1double binomial RF pulse having a 0.degree. net flip angle at the Larmor frequency of water protons and a nominal 180.degree. net flip angle at the Larmor frequency of fat bound protons. The partial derivatives of the latter nominal flip angle with respect to chemical shift and with respect to RF amplitude are each zero. Each of these RF pulse designs is implemented by a pulse which is substantially rectangular in amplitude, but which has alternations of phase between 0.degree. and 180.degree. during its duration to form the sub-pulses.

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: A method of selectively exciting nuclear spins in a limited three-dimensional volume comprising the steps of applying a plurality of subpulses in the presence of three orthogonal magnetic gradients (G.sub.x, G.sub.y, G.sub.z) over a period of time to define a k-space trajectory including a plurality of stacked two-dimensional k-space spirals arranged in pairs with each pair having an outward spiral and an inward spiral, the steps of one spiral to the next spiral corresponding to gradient pulses (G.sub.z) alternately at the edge and at the origin of each k-space spiral plane. The selective three-dimensional excitation pulse can be used with a non-selective 90.degree. pulse to the volume prior to applying the plurality of RF subpulses and allowing nuclear spins in the volume to precess, then applying the plurality of RF subpulses to selectively refocus nuclear spins in the volume, and detecting and echo signal.

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 single sequence for the formation of a plurality of images of the same selected nuclei but with each image having a different contrast characteristic is disclosed. MRI signals are acquired during the first time interval which comprises a plurality of first intervals with each of the first intervals being substantially the same. During the first time interval, the selected nuclei are phase encoded by a different magnetic phase encoding gradient. The sequence continues to acquire a second plurality of MRI signals from the same plurality of selected nuclei. The second time interval comprises a plurality of second intervals different from the first intervals. During the second interval, the selected nuclei are phase encoded by a different magnetic phase encoding gradient but with the magnetic phase encoding gradient being the same as or a subset of those during the first time interval.

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: In magnetic resonance imaging various error sources lead to deterioration of the image quality. One class of errors is formed by errors which vary only slowly over the time required to sample a data line but vary substantially over the time required to acquire data for the complete magnetic resonance image. These error sources are, for example external magnetic fields, motion due to respiration, drift in amplifiers or drift phenomena in permanent magnets due to temperature influences. It is proposed to utilize mutually intersecting data lines in the Fourier domain so as to estimate these error sources and to use these estimates to correct the data sets obtained before execution of image reconstruction.

Abstract: An NMR probe having RF shield means to confine the RF magnetic field to an axial region having a length less than the length of the coil form.

Abstract: A spinning apparatus for conducting magnetic resonance spectroscopy on a sample, having: an inner holder for the sample; mechanism for spinning the inner holder, while positioned in a magnetic field, about its axis; and a substantially nonmagnetic mechanical first bearing for supporting the first end-portion of the inner holder. Also, a spinning apparatus having: an inner holder for the sample; mechanism for spinning the inner holder, while positioned in a magnetic field, about its axis; a first and second bearing for supporting, respectively, a first and second end-portion of the inner holder; an outer housing for retaining the inner holder; mechanism for spinning the outer housing about its axis; and a substantially nonmagnetic mechanical third bearing for supporting the right end-portion of the outer housing. Also included is a device for measuring the magnetic resonance spectrum of a sample.

Abstract: In an NMR solid-state imaging experiment, a pulsed gradient is interleaved between subcycles of a line-narrowing RF pulse sequence in such a manner that the RF and gradient fields do not overlap in time, the subcycles of RF modulation which occur between gradient pulses are either cyclic or anti-cyclic and symmetric.The line-narrowing pulse sequence can be broken into subcycles, each of which is dipolar decoupling to at least a zero-order approximation. The gradient pulses are intercalated between a selected set of the subcycles which are symmetric. In this manner the prior art zero-order decoupling of the line narrowing interaction and the gradient interaction is extended to include the zero order and all odd order terms in the Magnus expansion of the average dipolar Hamiltonian. If the selected subcycle is dipolar decoupling to second order, then the gradient will also be decoupled to second order.

Abstract: In an NMR solid-state imaging experiment, second averaging is carried out during the experiment to reduce the effects of unwanted interactions that obscure the results of an interaction of interest. The second averaging is arranged so that the second averaging interaction and the interaction of interest are along the same axis, but are separated in time. The second averaging interaction is further designed to introduce a multiple of .pi./2 phase offset between applications of the interaction of interest. In this way, even when the sum of the actual resonance frequency and the second averaging frequency are zero, the spin dynamics are still modulated and a second averaging takes place.An additional advantage is provided in that the resonance frequency can be sampled in such a fashion that the second averaging frequency does not appear in the observed resonance frequency.

Abstract: A circuit for detuning a resonator in a nuclear magnetic resonance imaging apparatus has an output connected to a terminal of the resonator via a high-frequency line composed of two conductors. The resonator is shortened at this terminal with a shorting capacitor that can be short-circuited for detuning the resonator. The length of the high-frequency line is shorter than one-fourth of the wavelength of a high-frequency signal having the operating frequency of the nuclear magnetic resonance imaging apparatus on the high-frequency line. For detuning the resonator the high-frequency line can be terminated at the output with a further capacitor, so that the high-frequency line acts as a short-circuit at the terminal.

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: The invention concerns head for flowthrough NMR spectroscopy in which there is provided, in the interior of a vessel, a replaceable quartz cuvette which can be separated from the vessel, and eluent inflow and outflow tube, and a measurement coil, and which has end sections which seal with respect to the vessel.The parts constituting the vessel, namely a cylindrical glass casing, a cover, and a base, as well as the replaceable quartz cuvette, can be clamped together with a simple clamping device in such a way that the sample head according to the invention can also be used for high pressure, such as those which occur with SFC (supercritical fluid chromatography) NMR measurements.