Abstract: Magnetic resonance imaging data lines or views are generated and stored in a magnetic resonance data memory (56). The number of views or phase encode gradient steps N along each of one or more phase encode gradient directions is selected (70) to match the dimensions of the region of interest. A discrete Fourier transform algorithm (94) operates on the data in the magnetic resonance data memory to generate an image representation for storage in an image memory (96). Unlike a fast Fourier transform algorithm which requires a.sup.N views or data lines, where a and N are integers, the discrete Fourier transform has a flexible number of data lines and data values which can be accommodated. More specifically to the preferred embodiment, the discrete Fourier transform operation is performed by a CHIRP-Z transform or a Goertzel's second order Z-transform which can accommodate any number of data lines or values.

Abstract: In a phase encoded chemical shift imaging (CSI) system, phase shifting in k space is used to shift voxels so as to translate them in one or more dimensions so that one or more voxels maximally encloses an object of interest. The position of a structure of interest is located via a 1H "scout" image, and the Shift Theorem for finite Fourier transforms is applied to shift voxel boundaries in one, two or three dimensions so as to maximally enclose the structure in a minimal number of voxels. Voxel shifts thus may be accomplished computationally by minimal manipulation of the raw data--after the patient has left the imaging facility. The resulting spectral data corresponding to the structure of interest is not as subject to dilution by spectrum of the surrounding tissue.

Abstract: A pattern generator and controller arrangement operates for controlling the component parts of an MRI system. The arrangement comprises a plurality of channels including a main control channel and output channels. The arrangement receives instructions from the system CPU which then leaves the control and outputting to the arrangement, thereby avoiding the necessity of a large expensive CPU to operate the system with versatility and speed.

Abstract: An MRI method and device for fast determination of the transverse relaxation time constant T2 utilizes the fact that this time constant introduces asymmetry into all magnetic resonance echo signals (::exp(-t/T2) enabling determination of the time constant T2 from the asymmetry of the echo signals. During the determination of a spin density distribution the value of the time constant T2 can be determined for each pixel. After Fourier transformation of the resonance signal, integration of the imaginary terms is performed (in the coordinate direction of the measuring gradient). The quotient of the current integral and the real term of the associated pixel is an accurate measure of the time constant T2 in the relevant pixel.

Abstract: This invention relates to the use of a series of Discrete Fourier Transform (DFT) operations to provide multi-dimensional analysis of a molecular specimen.

Abstract: A three-dimensional NMR imaging method using phase encoding field gradients along two direction is disclosed. The measurement of an NMR signal is repeated in such a manner that among all combinations of a plurality of magnitudes of gradient prepared for the phase encoding field gradient along one of the two directions and a plurality of magnitudes of gradient prepared for the phase encoding field gradient along the other direction, combinations in which the magnitude of the phase encoding field gradient along the one direction is not larger than a predetermined value, are selected preceding the remaining combinations. A first image reconstruction processing is performed for data trains acquired on the basis of the precedently selected combinations, thereby obtaining a crude image. The crude image is displayed to confirm whether the location of measurement is proper or not.

Abstract: In order to suppress a doublet structure in a carbon spectrum due to J-coupling between carbon and hydrogen spins in compounds containing at least one CH group, a first magnetic rf field having a frequency equal to the Larmor frequency of carbon is generated, after which a second magnetic rf field having the Larmor frequency of the hydrogen in the relevant CH group is applied to the examination zone, and the spin resonance signal generated is detected. Decoupling is achieved with a reduced rf load in that a magnetic rf pulse having the duration T and the amplitude B.sub.p is generated a predetermined period of time dt after the end of excitation of the carbon, after which the amplitude of the rf field is immediately reduced to a value B.sub.c and the spin resonance signal is detected, the parameters dt, Bc and Bp being chosen so that the modulation of the spin resonance signal caused by the J-coupling is exactly eliminated.

Abstract: In a spectroscopic imaging apparatus utilizing the magnetic resonance phenomenon, a spectroscopic image of phosphorus-31 within a slice portion of a biological body under examination is displayed in a materix form. Furthermore, a proton image of the slice portion is displayed in the same matrix form. In addition, a spectroscopic graph for a selected matrix element of the proton image is displayed.

Abstract: MRI images are selectively resized or "zoomed" by zero padding the time domain data. Fourier Transformation of the time domain data after zero padding provides spatial domain data which when displayed provide an image that is resized relative to images provided from the time domain data without zero padding. A "zoom" or magnification factor can be selected and the quantity of padded zeros varied in response to the zoom factor to provide different zoom ratios. Restricting zoom factors to certain values permits the fast Fourier Transform to be used in Fourier Transformation.

Abstract: An acquisition method for multi-dimensional Fourier transform NMR data allows efficient accumulation of the data and provides artifact suppression in the acquired data under many circumstances. The method comprises performing an excitation pulse sequence having at least one evolution period wherein excited nuclei will at least partially relax. A transient generated from the pulse sequence is collected and stored, and the sequence is repeated with the evolution period varied in a predetermined manner. Transient information is collected for all values of the evolution period, and then the phase of at least on RF pulse may be varied and the procedure repeated. Subsequently transient information having common evolution periods may be signal averaged to obtain the NMR data. The method avoids residual magnetization effects under many circumstances, and significantly reduces acquisition time for data collection in spectroscopy or imaging environments.

Abstract: MR imaging method and apparatus are disclosed in which one image is displayed such that a high-resolution image of a partial region obtained by measurement according to a low-speed sequence is inserted into a low-resolution whole image obtained by measurement according to a high-speed sequence.

Abstract: Truncation artifacts in NMR images are reduced by splicing to the truncated data extrapolated high frequency data derived from the truncated image. The truncated data is Fourier transformed into image space and processed with an edge enhancing filter. The retransformed, filtered data yields edge derived high frequency information that may augment the truncated data. The spliced truncated data and edge enhanced data are then reconstructed into an artifact reduced image. In one embodiment, the edge enhancement is performed by iterative passes of a modified Sigma filter. The spliced data is blended with the truncated data near the regions of the splice by means of a weighted average.

Abstract: A method for correcting distortion of a reconstructed image caused by non-uniformity of a static magnetic field in an NMR imaging apparatus, wherein the non-uniformity of a three-dimensional static magnetic field is measured, and the measurement data is stored in the form of a matrix having a size smaller than the size of a matrix used in image reconstruction; then, data on a two-dimensional plane, corresponding to a slice plane of the reconstruction image, is taken out from the matrix, and based on that data, a distortion correcting table is produced and is enlarged to agree with the size of the matrix used in image reconstruction, so that distortion of the reconstructed image is corrected using the enlarged distortion correcting table.

Abstract: A method to recover MRI signals resulting from the application of time varying gradients. The raw MRI signal is demodulated, low pass filtered, and digitized using an A/D converter sampling linearly at the Nyquist rate. The samples from the A/D converter are compiled into a vector, which is multiplied by a least squares estimator matrix (H*H).sup.- H*, where H is a matrix whose mkth element, in the case of a sinusoidal gradient, is given by ##EQU1## This multiplication is repeated for each vector of samples from the A/D converter, and the vectors resulting from the multiplication are accumulated to form the columns of a matrix, the rows of which are Fourier transformed to obtain the MRI image.

Abstract: A method and apparatus for the compensation of an eddy current magnetic field in the magnetic field of a pulsed gradient coil in an MR scanning apparatus, wherein: an MR-active sample is positioned along a given coordinate axis within a magnetic field of the gradient coil and away from its isocenter; a plurality of time-sequential gradient coil pulses are applied to the gradient coil for generating a corresponding plurality of gradient magnetic field pulses; the sample is irradiated with an RF excitation pulse a given time delay which is increased following application of each of the gradient coil pulses, so as to generate a plurality of time-sequential MR signals; each of the MR signals are measured, Fourier transformed and stored as data, the data representative of the eddy current magnetic field; correction coefficients are calculated for compensating the magnetic field of the gradient coil with respect to the eddy current magnetic field using peak frequency shift data determined from the stored data; and

Abstract: A magnetic resonance image synthesizing system comprising a magnetic field generating section for generating a static magnetic field, a gradient magnetic field and a radio-frequency magnetic field and for irradiating those magnetic fields to an object to be examined, a receiver for detecting a magnetic resonance signal supplied from the object to be examined, a processing unit for calculating and constructing an MR image and distribution of blood velocity or relaxation time on the basis of the detected nuclear magnetic resonance signal, a sequence control section for controlling the gradient magnetic field and the radio-frequency magnetic field as well as the receiver, a display unit for displaying an MR image, and a manipulation section for specifying a necessary position on the screen of the display unit, the processing unit further making the display unit display an MR image calculated and synthesized on the basis of scanning parameters and a blood velocity or relaxation time defined in accordance with a p

Abstract: The transceiver of an NRM instrument includes a digital synthesizer that produces an analog carrier signal which can be controlled in both frequency and phase and which can be frequency and phase modulated. The analog carrier signal is mixed with reference signals to boost its frequency to the Larmor frequency of the instrument.

Abstract: The Gibb's artifact in magnetic resonance images is reduced by asymmetrically sampling acquired F.I.D. signals to obtain data, time domain filtering the obtained data with a filter that reduces overshoot, degrades resolution but increases SNR. Then obtaining symmetrical data by complex conjugating the time domain filtered data which improves the resolution, compresses the overshoot, but decreases SNR. Processing the symmetrical data to obtain images with insignificant Gibb's artifacts.

Abstract: A magnetic resonance spectrometer in which an analog-to-digital converter in the receiving branch converts the spin resonance signals, or a spin resonance signal transposed to a lower frequency range, into a digital signal, and in which a Fourier transformation circuit is located in a signal path subsequent to the analog-to-digital converter. The signal path between the analog-to-digital converter and the Fourier transformation circuit includes at least one combination of a digital filter and a sampling frequency reducing circuit. The output signal of the reducing circuit has sampling frequency which has been reduced by an integer factor with respect to its input signal and, the reduced sampling frequency is a non-integer factor lower than the frequency of the signal on the output of the digital filter.

Abstract: A method of high-speed magnetic resonance imaging in which the object to be imaged is placed in a high static magnetic field. Nuclear spins are excited in an image area by applying a pulse of radio frequency magnetic field. Optionally, a first gradient field, termed a slice selection gradient, may be applied in conjunction with the RF excitation pulse such that spins are excited only in a selected plane of the object. Following an encoding pulse sequence and rephasing of the nuclear spins by the application of a 180.degree. radio frequency pulse, mutually orthogonal phase-encoding and readout gradients are alternatively applied in the image plane to effect a traversal through spatial frequency domain (k-space). In a preferred embodiment of the invention, the readout gradient is applied as a continuous sinusoidal wave, resulting in a slight overlap between the phase-encoding and readout gradients. If phase errors vary slowly in time, only a partial k-space trajectory is required.

Abstract: A magnetic resonance system is arranged to invert the polarity of a slicing gradient magnetic field pulse each time the selective excitation is repeated, and additively combine two types of imaging data corresponding to the opposite polarities of the slicing gradient field pulse to form a magnetic resonance image.

Abstract: There is disclosed a magnetic resonance imaging method which permits a scan to be made in a short time by collecting only the data that is used to reconstruct an image. The method is initiated by defining a circular region whose center lies at the point in a two-dimensional Fourier plane at which the spatial frequency is zero. The Fourier plane corresponds to a region containing an image to be reconstructed. The spin echo signals emanating from a region inside the circular region are observed by an ordinary Fourier method, said region having a length greater than a predetermined length as measured in the direction in which data obtained by the observation is read out. The spin echo signals emanating from the remaining region inside the circular region are observed while shortening the time for which a reading gradient magnetic field is applied whenever an excitation is effected and, at the same time, effecting an additional phase shift encoding.

Abstract: An incomplete set of magnetic resonance image data is collected and stored in a view memory (40). The incomplete set of image data includes a central or first set of data values (42, 42') and half of the remaining data values (44, 44'). A symmetric data set which fills the other remaining half (46, 46') of the data values is generated (90) by determining the complex conjugate of each value of the incomplete data set. The incomplete and symmetric data sets are Fourier transformed (64, 94) to create first and second images f.sub.1 (x,y) and f.sub.2 (x,y). The first and second images are multiplied (100, 104) by conjugately symmetric phase correction values e.sup.i.phi.(x,y) and e.sup.-i.phi.(x,y) from a phase correction memory (70) to produce phase corrected images. The first and second phase corrected image representations are summed (110) and displayed (114). The phase correction values .phi.

Abstract: In order to have the number of times of signal measurements in a phase encode direction or a readout direction and raise the speed of imaging, the following steps are performed by way of example:(i) For a measurement region E required by a conventional method, any desired partial region E.sup.+ is set (here, the combination between the region E.sup.+ and a region obtained by moving the region E.sup.+ in point symmetry with respect to the origin of a measurement space includes the region E).(ii) A signal h.sup.+ is measured on the region E.sup.+.(iii) An image is reconstructed from the signals h.sup.+ on a region neighboring the origin, thereby to obtain a phase image .theta..(iv) A reconstructed image is obtained by a predetermined computation employing .theta..

Abstract: Separation of spectral components is achieved by acquiring radio frequency (RF) signals using a two dimensional scan sequence wherein the bandwidth of at least one of the RF pulses is less than or equal to the Larmor frequency difference of the spectral components. The slice select gradient pulse applied during the application of the RF pulse of limited frequency is smaller than the slice select gradient pulses applied during application of the other Rf pulses.

Abstract: A magnetic resonance imaging method and a device for realizing the same for obtaining a magnetic resonance image having corrected phases, wherein the device comprises a construction for generating a static magnetic field, gradient magnetic fields and a radio-frequency magnetic field, irradiating an object to be tested with these magnetic fields and detecting nuclear magnetic resonance signals coming from the object to be tested; a sequence-controlling portion controlling the irradiation of the object to be tested with the gradient magnetic fields and the radio-frequency magnetic field and the detection of the nuclear magnetic resonance signals; and a processing device for reconstructing complex image data on the basis of the nuclear magnetic resonance signals thus detected.

Abstract: Images of, e.g., a vascular tree, are obtained in a shorter-than-usual time by deliberately undersampling the object, which results in aliasing, and then processing the undersampled data to eliminate the effects of the aliasing.

Abstract: A pulse sequence of an NMR system is disclosed which produces two spin echo signals which may be acquired. In addition, one or more gradient echos are produced and acquired. The gradient echo data is combined with the spin echo data to improve signal to noise ratio, provide T.sub.2 ' mapping, reduce motion induced artifacts, measure and correct for RF pulse imperfections, and to provide improved T.sub.2 measurement.

Abstract: A method and associated system are disclosed for suppressing the undesirable effect of noise found in signals, such as from a magnetic resonance miager's (MRI) receiving antenna. The method convolves a sampled real and secondary signal taken from a signal detector with a transfer function, which is expressed in terms of the power spectrum of the measured signal with noise and measured power spectrum of the noise.

Abstract: Synchronous apparatus capable of a variety of operational states responds to a sequence of digital control words, each specifying a desired state and persistence time of the state. The control words are furnished to the apparatus from a self-clocked FIFO in accord with the persistence code. A selected sub-sequence of digital control words in ROM is placed in an auxiliary FIFO upon detection of a corresponding token in the main sequence and control is passed to the auxiliary FIFO to furnish the sub-sequence to the apparatus. At the conclusion of the sub-sequence control is returned to the main FIFO and the main sequence is resumed.

Abstract: A data communications network for magnetic resonance imaging (MRI) systems provides characteristics ideal for low noise operation and low cost at speeds as high as 1 Mbytes/sec and provides a serial data bus for performing medium speed control and data acquisition functions. System architecture is extremely versatile and also low in cost. Each node of the communications system may be provided with an interface implemented with electronically programmable array logic (EPLD) applications specific integrated circuits (ASIC) with 1800 equivalent gates per CMOS integrated circuit. The resulting chip set is self clocking (no local oscillator is required) and nominally provides 20 bits of latched output and input with parity checking in a four-chip set configuration. A minimal two-chip set configuration can be used for nodes that need only 4 bits of latched input and output data (while still supporting parity checking). Different types of peripherals can easily be accommodated, and the bus is self configuring.

Abstract: A hierarchial library of spectra representing the point-by-point characteristics of known samples is created. Vectors representing each spectrum are classified according to their similarlity and dissimilarity. Vectors representing unknown samples are compared to known groups of vectors according to similarity until a near match is found.

Abstract: A magnetic resonance excitation pulse (50, 150, 250) is applied to excite resonance in selected dipoles in an examination region. A second radio frequency pulse (60, 160, 260) induces a primary echo which is phase encoded by a phase encode gradient (56, 156, 256) with a first phase encode angle. Optionally, an additional phase encode gradient (356) may be applied after the primary echo to remove the first phase encoding. A third radio frequency pulse (70, 170, 270) rotates the magnetization, typically 90.degree., to cause a stimulated echo (72, 172, 272) which is phase encoded in accordance with a second phase encode gradient (78, 178, 278). Optionally, another phase encode gradient pulse (378) may be applied after the stimulated echo to remove the second phase encoding.

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: In an nuclear magnetic resonance imaging system for acquiring a tomographic image of an object of interest at a high speed by use of time-varying gradient magnetic fields, a weighting factor is used in reconstructing an image through the calculation of a correlation of data of a detected nuclear magnetic resonance signal with data of a reference signal, thereby controlling the point spread function and/or the signal-to-noise ratio in each point on the reconstruction image. Also, the effect of relaxation, chemical shift and/or static magnetic field inhomegeneity, which would otherwise degradate the image quality, can be corrected. Further, a velocity of the object of interest at each point on the reconstruction image can be measured.

Abstract: To display the information, as an image, regarding the moving portion of the object without the aid of the doctor, the image is reconstructed on the basis of the observed NMR signal and the image phase information is calculated from the image intensity information derived from the reconstructed image, and the phase information calculated is displayed as the image.

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 for encoding n parameters in multi-dimensional Fourier NMR spectroscopy. In NMR tomography, recording a third parameter is rendered possible without any additional input, in addition to the determination of the two-dimensional data required for generating an image, by generating phase-encoded double signals. During Fourier transformation the double signals lead to a striated pattern which is characteristic of the amount of the parameter It is possible in this manner to represent in NMR images in particular the velocity of a flowing material or, for example, variations of the static magnetic field, the susceptibility and the chemical displacement.

Abstract: The magnetic resonance (MR) imaging system, in which magnetic resonance is caused on the spin of a specific nucleus using a gradient field and a excitation pulse, and, through observation of an MR signal, an image representing the density distribution of that nucleus in a target region of a body is attained, provides at least one of a density distribution image of protons in water of the body and that of protons in the body's fat. First image data comprising complex image data representing the distribution of the spin in a water phantom and second image data comprising complex image data representing the spin distribution in the body are obtained. The first and second image data are acquired in the excitation sequence in which the phase of the MR signal for the water protons is opposite to that of the fat protons. By comparing the first and second image data, it is discriminated which one of the densities of water and fat protons in the second image data is dominant.

Abstract: An NMR imaging method for obtaining a tomographic image of an object through two-dimensional Fourier transformation imaging. After a whole image of a predetermined slice is displayed, a given field of view having a given size and located at a given position in the image is designated. On the basis of data derived from this designation, setting values for magnetic field generators and a signal detector are arithmetically determined for limiting the region in which the NMR signal is generated and the region to be imaged, whereby local imaging of the aforementioned field of view is conducted with high resolution. Further, division of an image resulting from the imaging operation is automatically corrected by exchanging positionally the divided image blocks with each other.

Abstract: An incomplete set of three dimensional magnetic resonance data is collected and stored in acquired data memory (40). The incomplete data set is complete with respect to first and second directions and incomplete with respect to a third direction. However, the acquired data set has data along the third direction between .+-.n central values and half the remaining values. One dimensional inverse Fourier transforms (64, 66) are performed with respect to the first and second directions to create an intermediate data set (68). A phase correction array or plurality of phase correction vectors p(r) are generated from the intermediate data and stored in a phase correction memory (82). A symmetric data set (100) is created as the complex conjugate of the intermediate data set. The intermediate and symmetric data sets are one dimensionally inverse Fourier transformed (96, 104) with respect to the third direction one vector at a time to produce vectors of first and second complex image arrays (f.sub.A, f.sub.

Abstract: Where short TR MRI imaging sequences are required (e.g., for contrast media imaging), NMR signal strength losses are reduced by including an extra peparatory nutation pulse at an interval TR prior to the usual nutation sequence used to elicit an NMR RF response. The "dead time" during such a TR interval for one slice is utilized for eliciting and receiving NMR RF responses from at least one other slice and sending the extra preparatory nutation pulse into yet another slice thus effecting a multi-slice procedure with an effective TR less than the actual time between repetitions of a complete multi-slice projection sequence while yet retaining high signal strength.

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: A magnetic resonance imaging system includes a field generation section, an excitation section, an excitation control section, a resonance data acquisition section, and an image generation section. The field generation section generates a static magnetic field, a gradient magnetic field, and a selective excitation pulse. The excitation section controls the field generation section to apply the static field, the gradient field, and the pulse to an object, at a predetermined timing, to selectively excite a magnetic resonance phenomenon in a specific slice of the object. The excitation control section controls the excitation section to excite a plurality of slices. The excitation control section causes the excitation section to excite a certain slice of the object, and causes the excitation section to excite another slice, separated from the previous slice at least by a thickness of the slice determined by the selective excitation pulse, within an excitation-repeating time.

Abstract: A pattern generator and controller arrangement operats for controlling the component parts of an MRI system. The arrangement comprises a plurality of channels including a main control channel and output channels. The arrangement receiver instructions from the system CPU which then leaves the control and outputting to the arrangement, thereby avoiding the necessity of a large expensive CPU to operate the system with versatility and speed.

Abstract: Reduced T2 decay is achieved through use of at least one asymmetrically truncated RF nutation pulse and an asymmetrically sampled NMR RF response with missing asymmetric data being supplied by complex conjugate synthesis.

Abstract: A method and related apparatus are provided for correcting for a phase error in MRI observed values which represent a scan line which passes through the origin of Fourier space. The phase error is estimated by calculating the phase of the sum of the observed values. The observed values are then modified as a function of the estimated phase error. To minimize the effect of T.sub.2 decay, the phase error may be estimated by calculating the phase of the sum of the product of each pair of observed values on the scan line which have been relocated symmetrically, one on each side of the Fourier space origin.

Abstract: Near real time imaging of materials within a body is accomplished by subjecting a body area to a predetermined plurality of applications of short repetition time NMR pulse sequences and constructing an image from data corresponding thereto. The image is continuously updated by collecting data from repetitive applications of one or more short repetition time NMR pulse sequences subsequent to the plurality of applications wherein each of the applications of one or more pulse sequences consists of fewer applications than the plurality of applications of pulse sequences. The imaging data from each of the applications of one or more pulse sequences is repetitively substituted for corresponding imaging data previously used to construct the image in order to provide for continuous partial updating of the image.

Abstract: A method for simultaneously receiving a different NMR response signal from each of a plurality of closely-spaced surface coils, first provides an array of a plurality of the surface coils, each positioned so as to have substantially no interaction with all adjacent surface coils. A different NMR response signal is received from an associated portion of the sample enclosed within an imaging volume defined by the array. Each different NMR response signal is used to construct a different one of a like plurality of NMR images of the sample, with the plurality of different images then being combined, on a point-by-point basis, to produce a single composite NMR image of a total sample portion from which NMR response signal contribution was received by any of the array of surface coils. Interactions between non-adjacent surface coils are minimized by coupling each onto an associated preamplifier.

Abstract: Phase error contributions in pixels of a complex image of a nuclear magnetization distribution in a body region due to inhomogeneities of the steady, uniform magnetic field which are caused by the magnetic susceptibility of, for example a patient to be examined and by eddy currents are eliminated by processing the resonance signals obtained in multiple cycles of different magnetic field characteristics according to the assumption that the phase error varies smoothly as a function of the location in the complex image. A corrected phase and the corresponding phase error of a given pixel are determined and then the corrected errors of the next adjacent pixels are sequentially determined and a corrected phase 0 or .+-..pi. assigned to the respective next adjacent pixel, if the phase difference between its phase and the known phase error of the preceding pixel is modulo 2.pi. in intervals (-.DELTA.,.DELTA.), (.+-..pi.-.DELTA.,.+-..pi.+.DELTA.