Abstract: For simultaneously determining the analytical NMR spectra of a number of samples placed suitably arranged in the measuring site of an NMR measuring apparatus, spatially and timely varying magnetic fields are used. The resulting signals are spatially resolved by a suited processing, for example Fourier transform. Surprisingly, from these signals, analytical NMRs of high resolution can be obtained for each sample. The method can be applied to two-dimensional arrangements of samples, for example a bundle of capillaries imitating a conventional NMR sample tube or a well plate, or three-dimensional arrangements, for example stacks of well plates. The method allows the determination of NMR spectra for analysis or for comparison with anterior spectra for long time behavior studies and quality assessment with only a fraction of time needed for measuring the samples individually.

Abstract: Tissue-mimicking material suitable for phantoms for use with at least ultrasound and MRI have sections of material in contact with each other which mimic ultrasound and magnetic resonance imaging properties of human tissues, and preferably also computed tomography properties, so that the phantom can be used for the testing of imaging by various types of medical imagers. A suitable tissue-mimicking material for use in phantoms of this type includes an aqueous mixture of large organic water soluble molecules, a copper salt, a chelating agent for binding the copper ions in the salt, and a gel-forming material. Small glass beads may be intermixed therewith to provide a selected ultrasound attenuation coefficient without substantially affecting the MRI properties of the material. Larger glass beads may be used in a section to control primarily the ultrasound backscatter coefficient without significant effect on the ultrasound attenuation coefficient.

Abstract: The invention is directed to a method, an instrument and a system for performing verification measurements and corrections of magnetic fields in magnets for Nuclear Magnetic Resonance imaging machines. According to the invention, test elements are used whereof Nuclear Magnetic Resonance images are detected. Then, these actually detected images are compared with the theoretical images which would be obtained in ideal conditions. The number, magnitude and position of correcting magnetic charges are determined from the differences between the actual image and the theoretical image. The invention is also directed to a specific test element and to a Nuclear Magnetic Resonance imaging machine.

Abstract: Methods and apparatuses for performing high throughput magnetic resonance imaging spectroscopy, e.g., to screen libraries of chemical or biological compositions for a compound of interest, are provided. Methods of identifying metabolic disorder genes, modulatory compounds and catalysts, and methods of optimizing reaction conditions, using high throughout MRI screening, are also provided.

Abstract: This invention relates to a method for MR imaging using a moveable RF receiving coil assembly that is swept over the region of interest to be imaged during the imaging protocol.

Abstract: Obtaining fast dipole size estimation with less influence of noise by using a regional dipole model. An artificial neural network section 30 executes regional dipole size estimation using a neural network having coupling coefficients representing coupling states among as plurality of units and thresholds thereof.

Abstract: The present invention relates to a method of manufacturing a human tissue phantom for evaluation of electromagnetic wave environment. The present invention suggests the human tissue phantom having reproductibility, being different from liquid type, after elapse of a certain period and preventing the air-gap occurring after insertion of probe, by using a composite material which is composed of a shape memory polymer as a base material and a dielectric material and a conductive material as the fillers, and also suggests the method of manufacturing the whole human body phantom.

Abstract: An MRI apparatus and method useful for both industrial applications and medical applications is provided. The apparatus and procedures are capable of estimating the value of a continuous property, such as concentration, viscosity or the like by interpolating or extrapolating from a model derived from training sets of data representing measurements of samples with known properties. A number of techniques are provided for objectifying the analysis. Cluster analysis techniques can be used to supplement, assist or replace subjective judgments by trained operators. Calculations or judgments regarding similarity can be made with respect to stored libraries of signatures, particularly where the library of stored signatures is obtained objectively, e.g., using cluster analysis, standardization and calibration. The signatures can be expanded signatures which include non-MR as well as MR data.

Abstract: An MRI system includes an MR cylinder, a radio frequency (RF) coil (or antenna), preliminary processing circuitry, and a computer processing system. The RF receiver produces an electrical signal to the preliminary processing circuitry representative of the sensed magnetic field. The preliminary processing circuitry provides a measurement data signal S (which is in the frequency domain) to the computer processing system, which includes a computer processor and a memory. The computer processor stores measurement data signal S as a data matrix M.sub.2 in a larger data matrix M.sub.3 that contains zero values in memory locations surrounding data matrix M.sub.2. This is referred to as zero-padding. The computer processor performs (zero-padded) Fourier transformation on data matrix M.sub.3 to produce an interpolated image data matrix I.sub.D. Interpolated image data matrix I.sub.D is processed through enhancement filtering to provide an enhanced image data matrix I.sub.E that has improved visibility of vessels.

Abstract: Pulsed NMR system for industrial measurements comprising sample throughput system (P, LI, V1, V2) and user system controls (104) to establish digitized free induction decay (FID) curves (C), from which fast Gaussian, slower modified Gaussian or preferably slower Gaussian, and exponential components are determined using a Marquardt-Levenberg iteration technique, and using regression techniques to correlate the FID curve components to the physical quantities of the target nuclei.

Abstract: A programmable tag for being readable remotely and in a manner which does not require that the tag be held in a particular orientation, includes a first layer of material with electron spin resonance absorption, a second layer of hard magnetic material, and a third layer of soft permeable magnetic material. The second layer and third layer are in close proximity to the first layer. The second layer and the third layer impose a magnetic bias field on the first layer.

Abstract: A calibration procedure for correcting geometric errors in MRI images due to gradient field non-linearities and magnetic field inhomogeneities includes performing a 3D scan on a calibration phantom. The calibration phantom contains an array of tapered rods that produce an array of spots in reconstructed slice images. Spot sizes and positions enable position errors to be measured throughout the bore of the imaging system. Corrective coefficients are produced from these 3D error measurements that enable subsequent patient images to be corrected for warping errors in object position.

Abstract: An improved method of assaying local metabolite concentrations the chemical entity (CE) of interest, of a living subject by non-invasive means using magnetic resonance (MR) spectroscopy employs acquiring an MR response signal for a naturally occurring, abundant marker material of known concentration, such as water (H.sub.2 O) from the subject. An MR response signal is also acquired from the CE being assayed, e.g., adenosine triphosphate (ATP) with phosphorus (.sup.31 P) nuclei producing the MR response signal. The subject is replaced with a test phantom having a known concentration of the marker material and a reference concentration standard (e.g., phosphate) having the same resonant nuclei as the CE. Both sets of MR response signals are again acquired. The volume of tissue contributing to the CE MR response signal in the subject is deduced from the ratios of marker material MR response signals from the subject and phantom and the known concentration of the test phantom.

Abstract: The invention provides a specific measure of iron stores in vivo using magnetic resonance imaging. T.sub.2 relaxation times in both lower-to-mid field strength magnetic resonance imaging instruments and a higher field strength instrument is evaluated. T.sub.2 obtained at the higher field strength instrument is subtracted from T.sub.2 obtained at the lower field strength instrument. This difference, T, is then correlated with a quantitative measure of the iron stores in vivo in the scanned tissue. A two-dimensional or multidimensional map of the scanned tissue is then constructed on the basis of T to visually identify different tissue types as being normal or abnormal, either through a visual determination based on gray scales or a numeric comparison based on quantitative measure. The introduction of artificial or nonbiological substances as opposed to natural ferritin, is permitted for further diagnostic use by application of this methodology.

Abstract: The invention relates to a modification of electron spin resonance enhanced magnetic resonance imaging (ESREMRI) in which two magnetically responsive materials (contrast agents) are introduced into the sample being investigated, one contrast agent serving as an ESREMRI free induction decay signal enhancing agent and the other as enhancement suppressing agent. In this way, image contrast may be enhanced further for regions in which the suppressing agent distributes poorly or not at all or which the suppressing agent reaches at a later time than the enhancing agent.

Abstract: Tissue mimicking phantoms for NMR imagers are produced having a base tissue mimicking material enclosed within a sealed container. The base tissue mimicking material is a gel solidified from a mixture of agar, animal hide gelatin, water, glycerol, and anti-bacterial agents such as n-propanol, p-methylbenzoic acid, and formaldehyde. The formaldehyde also serves to cross link the animal hide gel and thereby raise the melting point of the tissue mimicking material to a temperature above normal ambient temperatures. This base tissue mimicking material is stable both in dimensions and NMR properties over long periods of time. Contrast resolution inclusions are formed within the base tissue mimicking material which have T.sub.1, T.sub.2, or both which differ from the corresponding values for the base tissue mimicking material, thereby allowing these inclusions to be imaged and distinguished from the surrounding material.

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: A subject (22), such as a human patient, is positioned with a region of interest (24), such as the liver, close proximity to a phantom (12). A Volume image through the liver, the phantom, and adjacent portions of the subject are collected (40) with a magnetic resonance scanner. The phase component of the magnetic resonance data is reconstructed (50) into a three-dimensional phase map. An actually measured field map H.sub.m (r) is determined (42) from the phase map. A geometric model of the volumes occupied by the liver, the phantom, and adjacent portions of the subject are defined mathematically (44). A calculation routine (46) calculates a calculated or estimated field map H.sub.c (r) of the distortions to the magnetic field in the phantom which would be caused by the model.

Abstract: A grid system for interfacing MRI with other imaging modalities. The system includes a grid of contrast material which is compatible with MRI and other imaging modalities and a means to reproducibly position the subject in relation to the grid. The grid system is also used to plan radiotherapy and surgical biopsy procedures.

Abstract: Both an antipilferage marker and a system therefor is provided that uses magnetic spin resonance phenomena to generate unique and identifiable signals. The marker generally comprises a substrate which supports a material that generates and identifiable signal as a result of either nuclear magnetic resonance, nuclear quadrupole, electron spin resonance, electron paramagnetic resonance, ferromagnetic resonance, ferrimagnetic resonance, antiferrimagnetic resonance, domain wall resonance or spin wave resonance or spin-echoes. A magnetic material is further provided on the substrate for applying a magnetic field to the resonant material. In the system of the invention, a microwave or radio frequency source emits electromagnetic radiation which is absorbed by the resonant material which in turn reemits electromagnetic radiation having a specific and readily detectable frequency signature.

Abstract: There is disclosed herein a nuclear magnetic resonance apparatus for testing body fluids for a constituent, for example, blood for glucose. The apparatus includes a principal magnet, a magnetizable coil, and a circuit for energizing the coil for energizing and realigning molecules and detecting changes resulting from relaxation of said field and analyzing said changes. The apparatus is compact and adapted to receive and test an extremity or vessel carrying a body fluid. The coil is constructed to be positioned adjacent the extremity or vessel to be tested. Circuit means are provided for energizing the coil to energize and realign molecules adjacent said coil, so as to permit molecules adjacent said coil to assume an aligned position and for sensing changes in position when the coil is deenergized, which is indicated by spectra having peaks corresponding to various molecular bonds.

Abstract: A cylindrical tube with closed ends contains an imaging fluid and a variety of imaging structures enclosed. Included is a slice thickness structure with a hole pattern in a chevron shape where the number of imaged holes determines the slice thickness. Slice planarity is determined by a number of contiguous disks with grooved patterns set at rotated angles with respect to each other. Geometric distortion and resolution are also measured by structures contained within the enclosure. Finally, the position of the first and last slices in a multiscan series is measured for accuracy by ramp wedges placed on the end caps of the enclosure. And lastly, air is entrapped in closed cell foam so there are no unconstrained bubbles migrating in the enclosure.

Abstract: A phantom for diagnosis by nuclear magnetic resonance imaging comprises a container made of a synthetic resin and a hydrogel sealingly contained in the container. The container has at least one opening into which a sample material is inserted. The hydrogel is prepared by charging an aqueous solution of a polyvinyl alcohol into the container, cooling the aqueous solution to minus 10.degree.C. or lower to obtain a cooled frozen mass and thawing the cooled frozen mass. Also disclosed is a method for determining resolution power or discrimination capacity of an NMR imaging apparatus.

Abstract: There is disclosed a method of accurately calculating the magnetic field strength at an arbitrary position in an ESR (electron spin resonance) spectrum using Mn.sup.2+ marker. The spectrum contains an ESR signal arising from an unknown sample and an ESR signal arising from a reference sample containing Mn.sup.2+ marker. The resonating magnetic field strengths H.sub.ci and H.sub.cj of two absorption lines of the six absorption lines arising from Mn.sup.2+ are calculated from the applied microwave frequency, the nuclear spin quantum numbers m.sub.Ii and m.sub.Ij producing the two absorption lines, a predetermined g value g.sub.o intrinsic to Mn.sup.2+, and a predetermined isotropic hyperfine coupling constant A. The magnetic field strength H.sub.cx at a position of interest in the ESR spectrum is determined from the distance between the absorption lines, the distance between the position and one of the two absorption lines, and the magnetic field strengths H.sub.ci, H.sub.cj.

Abstract: In order to optimize the determination of radio-frequency energization in an NMR experiment, the Schrodinger equation is written relative to the amplitude of probability of the wave function of spins resonating at a given resonance frequency wherein the Hamiltonian depends on the frequency and on the radio-frequency energization to which they are subjected. Analytical polynominal expressions are deduced for the probability amplitudes at the end of the energization as a function of the resonance frequency. The coefficients are optimized by means of calculation algorithms, from which the characteristics of the energization are deduced.

Abstract: There is disclosed herein a nuclear magnetic resonance apparatus for testing body fluids for a constituent, for example, blood for glucose. The apparatus includes a principal magnet, a magnetizable coil, and a circuit for energizing the coil for energizing and realigning molecules and detecting changes resulting from relaxation of said field and analyzing said changes. The apparatus is compact and adapted to receive and test an extremity or vessel carrying a body fluid. The coil is constructed to be positioned adjacent the extremity or vessel to be tested. Circuit means are provided for energizing the coil to energize and realign molecules adjacent said coil, so as to permit molecules adjacent said coil to assume an aligned position and for sensing changes in position when the coil is deenergized, which is indicated by spectra having peaks corresponding to various molecular bonds.

Abstract: A computed tomography system which includes both a high-energy imaging apparatus (such as an X-ray computed tomography device) and also one or more phantoms whose solid characteristics generally correspond to the density and shape (preferably including external and internal contours) of the existing object to be imaged. The phantom is used for differential error-correction techniques, which permit very accurate imagining of the contours of bones in vivo. The accurate images thus derived permit fabrication of orthopedic prostheses which have an extremely accurate fit to existing bone structure.

Abstract: The amplitude of specific spectroscopic components are measured by first finding their frequency in the presence of inhomogeneity. A large stable component, usually the water line, is used as a frequency standard to determine the amount of frequency shift in each voxel. The frequency standard is used to determine the relative frequencies of each of the desired spectroscopic components. In one approach the entire hydrogen spectrum is envelope detected with the beats between the water line and the spectroscopic components used to provide a stable spectrum, immune to inhomogeneity.

Abstract: A method of finding error distribution in the static magnetic field and distribution of deviations from straight lines in the gradient magnetic fields of an NMR imaging apparatus which employs the applied spin-warp method. A phantom whose shape has been known is measured in the read-out gradient magnetic fields having different polarities to obtain two spin density distribution images. The two images are then compared with the shape of said phantom to measure the distortion distributions of the images. Error in the static magnetic field and deviations of the gradient magnetic fields from the straight lines are analyzed from the distortion distributions. From the thus obtained error distribution, furthermore, distortion induced in imaging the object is estimated, and the distortion contained in the image that is reconstructed from the spin density of the object by the spin-warp method is corrected using the thus estimated value.

Abstract: A magnetic resonance (MR) system and method for determing absolute image intensities (MR numbers) comparable to "CT" numbers by removing the dependence of the intensity measurement on system dependent parameters. The dependence of the intensity measurement on system parameters is removed by determining the absolute gain of the receiver portion of the MR system. The absolute gain is a function of the loaded gain and the unloaded gain of the receiver system, the loaded gain is divided by the unloaded gain to provide a normalization factor which is multiplied by output data to provide the absolute values of intensity of absolute MR numbers.

Abstract: The invention relates to a method and an apparatus for determining the cut (percentage) of one component of a multiphase fluid flowing in a pipeline, for example, oil or other hydrocarbon in a fluid flow that comprises oil, water, gas, and soil components, by use of NMR analysis. The fluid is flowed through an apparatus specifically designed to perform the analysis on the flowing fluid. Carefully sequenced 90.degree. pulse series are used to take advantage of the different spin relaxation times of the selected atomic species when they are constituent parts of molecules having inherently different levels of random molecular motion. The timing between pulses in a series and between series of pulses is chosen so that NMR emissions from unwanted matter do not occur, and FID peaks from the desired matter are registered.

Abstract: A material for diagnosis by nuclear magnetic resonance imaging is provided. The material comprises a hydrogel having a high water content. The hydrogel is prepared by the steps of casting an aqueous polyvinyl alcohol solution into a mold, cooling the case aqueous solution to obtain a cooled frozen mass and thawing the cooled frozen mass. The cooling and thawing steps may be repeated up to eight cycles. The hydrogel is also prepared by subjecting the cooled frozen mass to a partial dehydration step in vacuum.

Abstract: An automatic shimming system for correcting inhomogeneties in magnetic resonance magnetic fields. The static magnetic field is mapped using three dimensional phantoms that comprise a plurality of samples including at least an element having non-zero nuclear magnetic moments spatially distributed to enable uniquely locating each sample with only two locating gradients.

Abstract: A method for providing spin density distribution images of an object, discriminated with respect to plural chemical shifts. This method is performed by repeating a measurement sequence in a spin warp imaging method, of the spin data plural times, with a time difference .DELTA..tau. between a time interval .tau..sub.1 from spin excitation to a 180.degree. RF pulse and a time interval .tau..sub.2 from the 180.degree. RF pulse to a peak of a spin echo, altering .DELTA..tau. in the ways corresponding the number of chemical shifts to be discriminated from one another, subjecting the respective spin data to two-dimensional Fourier transform to provide plural sets of spin data for respective coordinates in a spatial domain, and solving simultaneous equations of the sets of spin data to provide spin densities corresponding to the respective chemical shifts.

Abstract: An agent for contrast enhancement in nuclear magnetic resonance imaging is disclosed. Micellular particles such as phospholipid vesicles are associated with or enclose a paramagnetic material. The particles may be formulated with an agent, such as cholestrol, to promote vesicle stability and water exchange across the vesicle bilayer. The vesicles may or may not have antibodies or other cell recognition targeting agents attached to the surface to provide specific targeting. The vesicles provide enhanced target specificity, reduced burden of toxic contrast material and amplified contrast enhancement.

Abstract: A coil for conducting examination of a patient in a nuclear magnetic resonance apparatus has a flat surface coil for spectroscopic in vivo examination of the patient and a calibration substance disposed within the coil. The coil is placed in the patient during examination, and the calibration subject supplies a nuclear magnetic resonance signal measurable by the coil as a reference.

Abstract: A reference object (24) is disposed in an image region (20) with a subject (22) to be examined. The reference object has known parameters such as relaxation time, spin density, dimensions, and position. Magnetic resonance signals in which the spatial position of resonating nuclei is encoded in the relative phase and frequency thereof are sampled and temporarily stored in a view memory (56). A Fourier transform (60) is performed to convert the stored signals view into a representation of at least the positions and spin density of the resonating magnetic dipoles of the subject and reference object. The parameters of the reference object measured from the image representation are compared or inverse transformed back to data space for comparison with actual parameters of the reference object or thresholds. Based on the comparison, the resonance signals or the image representation are adjusted.

Abstract: A method of suppressing at least one undesired resonance response signal while facilitating reception of at least one other desired NMR response signal from a coupled spin resonance in NMR spectroscopy, utilizes a pair of alternating sequences of RF signal pulses, with each sequence having an initial .pi./2 RF pulse, followed by a .pi. RF signal pulse having a temporal midpoint at a time interval T after the temporal midpoint of the initial pulse (where T=n/4J, with n being an odd integer and J being the spin coupling constant of the hydrogen nuclei) and a final .pi. RF signal pulse with a temporal midpoint at twice the time interval T after the temporal midpoint of the first .pi. RF signal pulse in that sequence. Only one of the pair of sequences is provided with a polarization transfer narrowband .pi. RF signal pulse symmetrically disposed about a temporal midpoint located at substantially a time interval T after the first .pi.

Abstract: In the preferred and illustrated embodiments hereof, a method and apparatus for conducting NMR moisture measurements is set forth. In various forms, hydrogen transient NMR signal peak amplitude values indicative of total hydrogen concentration of the tested material space. The hydrogen concentration is converted by a constant into water concentration. In one embodiment, a comparison is made between the NMR peak voltage of the unknown material and the NMR peak voltage from a standard sample having a specified water content to obtain a calibration for determining moisture content as a weight percentage in the tested specimen. If the densities of the two samples vary, the weights of each are necessary for accurate measurements. An alternative procedure involves determining moisture and material from the hydrogen in the water and in the material itself. In this procedure, the spin-spin relaxation T.sub.2 for the moisture is preferably more than three times longer than the T.sub.

Abstract: An NMR imaging method for measuring a magnetization distribution of an article under test, particularly the magnetization distribution including a longitudinal relaxation effect, by a Fourier imaging method with identification of polarity of the magnetization distribution.A homogeneous phantom is measured by the Fourier imaging method and image-reconstructed so that a reference image data which reflects a phase rotation inherent to an NMR imaging apparatus is obtained. Then, a magnetization distribution of an article under test is obtained in a similar measurement and image reconstruction sequence, and products of the reference image data and the image data of the article under test are stored as the signs to represent the polarity of magnetization of the article under test.

Abstract: An object which can provide a reference for measuring the intensity of a primary magnetic field, is positioned in the vicinity of a subject being examined. A variation in the primary magnetic field intensity is detected, based on a frequency shift of data observed of the object, and is used to control the primary magnetic field intensity, or reference frequency for phase detection, or to correct image data. In this manner image quality is prevented from being degraded due to the variation of the primary magnetic field intensity.

Abstract: In a method of operating a nuclear magnetic resonance (NMR) spectrometer in relation to a sample comprising two types of nuclei, a sequence of radiofrequency pulses and delay periods is applied using two different radiofrequency coils, one for each type of nucleus, each coil providing an inhomogeneous radiofrequency field, so that the two coils generate separate but overlapping sensitive volumes for each of the two types of nuclear species, whereby signal intensity is substantially limited to the overlap volume.

Abstract: In a magnetic resonance imaging system, a reference sample made of material including predetermined atomic nuclei to be tomographed is disposed on the side of an object under inspection in a tomographing field (an area to be tomographed) of an MR image. In collecting projection data by detecting the MR signal, the magnitude of the projection data on the reference sample is detected. A substantial gain of an MR signal amplifying section is adjusted according to the detected magnitude.

Abstract: An in vivo assay for quantifying the mineral content of bone comprises placing living bone into or adjacent to the coil of a nuclear magnetic resonance (NMR) spectrometer, recording a .sup.31 P NMR spectrum while the bone is stationary, and comparing the spectrum obtained with the NMR spectrum of a reference standard containing a known concentration of a reference compound. The assay can be used to diagnose and determine the efficacy of treatment of osteodystrophy if used in conjunction with radiographic densitometry to estimate the calcium content of the bone.

Abstract: A quality control phantom for a computed tomographic imaging instrument, such as a nuclear magnetic resonance scanner, is provided for the on-site calibration and standardization of image slice offset and angulation so as to maintain and insure proper operation. The phantom includes a cylindrical slab-like cast acrylic casing or body having a frustoconical groove formed therein. The groove is filled with a known material to effect a signal from the instrument. A scan taken by the NMR instrument across the frustoconical groove at an angle perpendicular to the central axis of the groove yields a circular image. The method for determining the image slice offset includes the step of relating the diameter of two such circular images so as to verify the distance one such image is from the other along the central axis of the groove. A scan taken by the NMR instrument across the frustoconical groove at an angle other than perpendicular to the central axis of the groove yields an elliptical image.

Abstract: A phantom for use in assessing the performance of an NMR imaging apparatus which enables quantitative assessments of image slice width and spatial resolution under different conditions of contrast to be made, and which enables an assessment of overall performance of the apparatus to be made to facilitate comparison of the performance of the apparatus when operating in different modes. The structure and methods of use of the phantom are described.

Abstract: A method for providing a high-spatial-resolution NMR image, having resolved artifact-free NMR images of chemically-shifted nuclei, includes: forming independent NMR images having imaging components due to each of the chemically-shifted nuclei; registering and combining the images to eliminate one of the components and produce a composite image containing the other component and a negative of the other component offset by the chemical shift; and forming a resolved image of the component by processing the composite image to eliminate the negative. The resolved image may then be combined with one or more of the NMR images to produce a resolved image of the first component. The method requires only 2N projections to form the two independent N-by-N NMR images.

Abstract: It is desired to promote magnetic homogeneity of materials, including structural elements, present in the sensitive volume of a gyromagnetic analysis apparatus. Where the sample is rotated along an axis transverse to the field the requirement reduces to establishing axial homogeneity. Plugs which match the solvent magnetic susceptibility are employed to constrain a sample within the central region of an RF probe coil thereby appearing relatively invisible in the magnetic sense to the instrument. The susceptibility of materials can be tailored to achieve a desired value to suppress magnetic perturbation without introducing extraneous signals.

Abstract: (CH.sub.3).sub.3 SiNSO is produced by the reaction of ((CH.sub.3).sub.3 Si).sub.2 NH with SO.sub.2. Also produced in the reaction are ((CH.sub.3).sub.3 Si).sub.2 O and a new solid compound [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ]. Both (CH.sub.3).sub.3 SiNSO and [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ] have fluorescent properties. The reaction of the subject invention is used in a method of measuring the concentration of SO.sub.2 pollutants in gases. By the method, a sample of gas is bubbled through a solution of ((CH.sub.3).sub.3 Si).sub.2 NH, whereby any SO.sub.2 present in the gas will react to produce the two fluorescent products. The measured fluorescence of these products can then be used to calculate the concentration of SO.sub.2 in the original gas sample. The solid product [NH.sub.4 ][(CH.sub.3).sub.3 SiOSO.sub.2 ] may be used as a standard in solid state NMR spectroscopy, wherein the resonance peaks of either .sup.1 H, .sup.13 C, .sup.15 N, or .sup.29 Si may be used as a reference.