Abstract: A magnetic resonance angiogram (MRA) is acquired using a pulse sequence that samples k-space at a projection angle. The acquired NMR signal is sensitized to spin motion with a bipolar motion encoding gradient and the pulse sequence is repeated to sample k-space at a set of different projection angles. A phase image is reconstructed from the acquired NMR signals using a filtered backprojection technique. Additional sets of projections with different motion encoding directions are acquired at interleaved projection angles, and the reconstructed phase images are combined to provide a velocity image.

Abstract: A method of magnetic resonance imaging a flowing liquid flowing through a rectangular cross-section column of space, wherein imaging readings are obtained from points throughout the column by utilizing a frequency encoding gradient to define the position of a reading point in the direction of the long axis of the column; defining the position of a reading point in a plane normal to the long axis of the column using one of phase encoding gradients and echo-planar blips; using one of phase encoding gradients and echo-planar blips with odd echoes and even echoes to acquire readings in two distinct regions of k-space; and obtaining readings in each plane normal to the long axis of the column from a 32×32 matrix of reading points using 16 phase encoding steps and 8 echo planar interleaves. Alternatively, the step of obtaining may be accomplished by varying the velocity phase sensitivity of the frequency encoding gradient to achieve a continuously varying phase sensitivity across k-space.

Abstract: A 3DFT MRA dynamic study is performed using a contrast agent to enhance image contrast. A monitor pulse sequence is performed at a high temporal rate to monitor the magnitude of the NMR signal produced in a monitor region after the contrast agent is injected into the patient. When the monitor signal reaches a threshold value, the patient is signaled and the 3DFT image data set is acquired.

Abstract: A system and method for correcting systematic errors that occur in MR images due to magnetic gradient non-uniformity is disclosed for use with parametric analysis. A GradWarp geometric correction operation is applied in reconstructing quantitative parametric analysis images in regions of gradient non-uniformity. The method includes generating an error map of magnetic gradient strength as a function of distance for an MR image scan and acquiring MR data that contain such systematic errors. The method next includes either calculating a measured diffusion image, a phase difference image, or similar image, based on the acquired MR data, and then calculating a corrected parametric image using the error map and the measured diffusion image, the phase difference image, or other similar parametric image. The method is incorporated into a system having a computer programmed to perform the aforementioned steps and functions.

Abstract: An NMR logging tool has a conducting permanent magnet with its axis parallel to the borehole axis to produce a static field in a portion of the formation surrounding a borehole that is parallel to the borehole axis. A dipole RF antenna with the dipole axis orthogonal to the borehole axis is used to produce an RF magnetic field orthogonal to the static field. The same antenna is used to receive the echo signals from excited nuclei in the formation. A number of gapped ferrite strips on the permanent magnet shield the permanent magnet from the RF field and enhance the RF field. Another form of the tool may be used for making Measurement-While-Drilling measurements with the permanent magnet set in a recess on a drilling collar.

Abstract: With an apparatus according to the invention it is possible to detect an object's velocity transverse to the direction of propagation of an interacting field. Such transverse movement is detected by applying a field that oscillates spatially in the transverse direction. The method used in the apparatus is applicable where wave energy is used to sense or detect an object by its scattering properties when using either sound waves or electro-magnetic waves. The movement can be detected according to the field properties. The field represented by the sampling pulse must feature a spatial oscillation in the directions, where the velocity components are of interest. Such a transversely oscillating field is e.g. generated by using apodization on individual transducer elements and a special focusing scheme. The apparatus uses waves of either sound or electro-magnetic radiation.

Abstract: In order to provide a magnetic resonance imaging method and apparatus which avoids artifacts due to the motion of a subject when the imaging is conducted with the interval between time phases reduced, a two-dimensional Fourier space is divided into a plurality of regions A,A'-D,D' symmetrically with respect to the frequency axis kx, and data acquisitions for the peripheral regions B and B', C and C', and D and D' are sequentially conducted with the data acquisition for the central regions A and A' interposed each time. At this time, the data acquisition is conducted alternately for each TR in a pair of symmetric regions, thereby minimizing the time difference between symmetric data.

Abstract: In order to perform an ECG-gating imaging MR scan with an exact ECG-gating time predetermined, in an MRI system and MR imaging method, an ECG signal of a patient is acquired. A preparing MR scan with a region containing an object to be imaged of the patient starts at each of a plurality of time instants when a plurality of different delay times elapse respectively from a plurality of reference waves included and repeated in series in the signal, thus a plurality of preparing images being produced. An appropriate or optimum ECG-gating time instant is determined using the plurality of preparing images. The imaging MR scan with the region of the patient is then performed in synchronization with the appropriate or optimum ECG-gating time instant. For example, both of the preparing MR scan and the imaging MR scan are based on the same type of pulse sequences. The pulse sequences include a fast SE sequence, a sequence rooted in the fast SE sequence, or a segmented fast FE sequence.

Abstract: A method for depicting the anatomy and quantitative tissue strain of a biological tissue. A spatially resolved, double quantum filtered, nuclear magnetic resonance frequency spectrum is acquired from either .sup.1 H or .sup.2 H nuclei in the tissue. Values in the time domain or frequency domain representations of the free induction decay signal are mapped in 2 spatial dimensions so as to selectively depict histological layers of the tissue anatomy. The residual quadrupolar or dipolar splitting is calculated from the free induction decay signal, and then correlated with a tissue strain value by utilizing a known formula describing the correlation between residual quadrupolar or dipolar splitting and tissue strain. The tissue strain value is then mapped in two spatial dimensions.

Abstract: A method is disclosed to reconstruct multiphase MR images that accurately depict the entire cardiac cycle. A segmented, echo-planar imaging (EPI) pulse sequence is used to acquire data continuously during each cardiac cycle. Images are retrospectively reconstructed by selecting views from each heartbeat based on cardiac phase.

Abstract: An MRI system produces a series of image frames of a blood vessel using a cardiac gated, M-mode Fourier-velocity-encoding pulse sequence. The pulse-wave velocity of a velocity wave traversing the field of view of the image frames is determined by cross correlating a selected reference image frame with the other image frames to locate the relative position of the velocity wave in each of those other image frames, and calculating the propagation velocity of the velocity wave from its relative positions in those other image frames.

Abstract: In order to prevent image quality degradation which occurs when a flow compensating pulse is applied in a pulse sequence according to the fast spin echo technique, a bipolar pulse constituted of gzfcf and gzmfcf (FIG. 5) is incorporated in the slice gradient before an inversion pulse applied immediately before the flow compensating pulse constituted of fcrdep and fcrrep incorporated in the read gradient in the pulse sequence, thereby imparting a phase shift equal to a non-linear phase shift due to the flow compensating pulse constituted of fcrdep and fcrrep.

Abstract: A method is provided for determining errors in MR imaging which result from translational motion of an object. In accordance with the method, an MR point source is rigidly joined to the object in selected spatial relationship, and for movement in unison therewith. An MR system is operated to acquire an overall k-space signal which represents an image of the object and of the point source collectively, the overall k-space signal being contaminated by phase errors which result from the motion. A k-space data set which represents an image of the point source alone, and which remains contaminated by the phase errors, is filtered or separated out from the overall k-space signal. The MR system is operated in selected association with the point source to acquire a reference k-space data set, which represents an image of the point source alone but which is unaffected by the phase errors resulting from the motion.

Abstract: An MR oximetry measurement of % O.sub.2 employs a pulse sequence comprised of a T.sub.2 preparatory segment and an image data acquisition segment. The pulse sequence is used in methods for measuring coronary flow reserve and for measuring myocardial oxygen consumption.

Abstract: NMR data for imaging perfusion of blood is acquired from a series of slice locations using a cardiac gated NMR pulse sequence. Data for the slice locations are acquired by a corresponding series of data acquisition segments performed during the R--R interval of each cardiac cycle. Selective rf saturation pulses are interleaved with the data acquisition segments to uniformly condition spin magnetization in each slice location.

Abstract: In a method for providing an MR image of a section taken through an object, wherein the section is acquired in the presence of in-plane translational motion of the object, an MR system is operated to acquire a set of imaging data points from the section, the set of imaging data points being contaminated by phase errors resulting from the motion. The MR system is further operated to acquire a plurality of correction data point sets, each correction data point in one of said sets being acquired along an alignment line or other trajectory and at a location coinciding with the location of one of the imaging data points. The imaging data points respectively coinciding with the correction data points comprise, collectively, a subset of the imaging data points. The phase difference between each correction data point set and its corresponding subset of imaging data points is determined, and then used to remove the phase errors from the set of imaging data points.

Abstract: Various flowmeters (10, 70, 80) each have at least one NMR sensor (12, 72, 82) for measuring the various flow parameters of a flowing fluid. The NMR sensor may be used to provide a gradient magnetic field, which provides separate velocities when the fluid is multiphase (FIG. 10). The flowmeters may also be used to measure flow rate directly. The flowmeters may also be used to determine the separate flow fractions of a multiphase fluid.

Abstract: An MRI system acquires NMR signals and digitizes them at a fixed sample rate. A lower, prescribed sample rate is obtained by transforming the acquired NMR signal using a weighting function calculated from scan parameters. The transformation includes multiplying by the weighting function and convolving the NMR signal with the complex conjugate of the weighting function.

Abstract: There are provided body movement measuring means for measuring the movement of an object of inspection and control means for controlling at least means for applying a gradient magnetic field and means for applying a high frequency magnetic field. The control means performs a sequence for measuring an echo by applying a phase-encoding gradient magnetic field quantity a plurality of times with the same phase-encoding gradient magnetic field quantity and repeatedly executes the sequence while varying the phase-encoding gradient magnetic field quantity.

Abstract: A dynamic MRA study of a subject is performed using a 3D echo-planar imaging pulse sequence. Four phase encoding views are acquired for each pulse repetition period (TR) and this enables higher resolution images to be acquired without a reduction of temporal frame rate or a loss of image CNR.

Abstract: Resonance is excited in a first slab (12) and manipulated to generate a plurality of data lines (16, 18) which span a fraction of k-space, e.g. a quarter of the phase encoding steps along a y-direction. Resonance is then excited in a second slab (22) displaced from the first slab and another series of data lines are generated. A resonance is excited and data lines generated in a plurality of additional slabs (32, 42). A resonance is excited in a slab (52) which partially overlaps the slab (12), e.g., has three of four slices in common. A series of data lines in the slab (52) are phase encoded with a different fraction of k-space. Two sets of differently phase encoded data sets have been generated in the example of FIGS. 2a and 2b.

Abstract: An MRI scan is conducted in which velocity encoded NMR data is acquired for a slice through the heart. Velocity images and magnitude images are reconstructed at multiple cardiac phases and masks are formed using the magnitude images. The masks are applied to the velocity images to isolate the left ventricle, and rigid body motion is calculated and subtracted from the masked velocity images to indicate deformation of the left ventricle.

Abstract: A magnetic resonance imaging sequence synergistically combines Half Fourier Transform complex conjugation with shared echo imaging. The Half Fourier Transform complex conjugation reduces data acquisition time and permits the data acquisition per scan to be accomplished with a single RF transmission loop. The shared echo imaging provides multiple images of an image plane from a single scan, yet with different contrast and a larger number of slices. In an alternative embodiment, phase correction is provided between the non-shared echo responses.

Abstract: Fast spin echo pulse sequences are adjusted to reduce, or eliminate image artifacts caused by Maxwell terms arising from the linear imaging gradients. The waveforms of the slice selection, phase encoding and readout gradients are adjusted in shape, size or position to eliminate or reduce the phase error caused by the spatially quadratic Maxwell terms.

Abstract: A nuclear magnetic resonance imaging scheme suitable for an imaging of a physiological function information on a living body. The scheme uses a pulse sequence for realizing a first imaging scheme for obtaining the blood vessel image and a second imaging scheme for obtaining the physiological function image such as a brain function image by a single execution of the pulse sequence, where the first imaging scheme is executed before the second imaging scheme by controlling resolutions and imaging regions for the respective imaging schemes appropriately. The pulse sequence can also realize a third imaging scheme for obtaining the physical shape image, which is to be executed between the first imaging scheme and the second imaging scheme. The physiological function image can be obtained by selecting valid data from the image data acquired with/without stimulation or load by using the t-test, and determining active portions from the selected valid data by using the paired t-test.

Abstract: A gradient coil (1) to generate switched magnetic field gradients in an nuclear spin resonance (NMR) device consisting of one or several current paths (a, b) following windings and being arranged on the surface of a geometric body is characterized in that at least two electrical current paths (a, b) are provided for, running geometrically essentially parallel to each other and being electrically connected in parallel, which current paths cross n times per winding, wherein n is an integer with n.ltoreq.8, preferably n=1 or n=2. In this way, eddy current generation by current re-distributions on the gradient coil conductor strips and thereby a time-dependent distortion of the generated magnetic field gradient inside the volume of interest of the NMR apparatus is considerably reduced.

Abstract: A method is disclosed to reconstruct multiphase MR images that accurately depict the entire cardiac cycle. A segmented, gradient-recalled-echo sequence is modified to acquire data continuously. Images are retrospectively reconstructed by selecting views from each heartbeat based on cardiac phase rather than the time elapsed from the QRS complex. Cardiac phase is calculated using a model that compensates for beat-to-beat heart rate changes.

Abstract: A magnetic resonance (MR) imaging method uses chemical shift and/or slice selective inversion pulse to create angiograms of coronary arteries. In one embodiment blood is doped with a contrast enhancement agent and a sequence of slice selective and chemical shift selective inversion pulses are applied. Detection RF pulses then generate an image signal. In another embodiment two sequential chemical shift inversion pulses are applied followed by detection RF pulses for imaging.

Abstract: The invention relates to an MR method with reduced motion artefacts in which the displacement of a pulsating object, or of a part thereof, which is present in an examination zone is continuously measured relative to a reference position, and in which the reconstruction of an MR image utilizes exclusively MR signals acquired from the examination zone while the displacement from the reference position reaches or falls below a threshold value. This gating is enhanced in accordance with the invention in that prior to the acquisition of the MR signals there are generated phase encoding gradients k.sub.y) which act on the examination zone with different time integrals and that the threshold value (v.sub.s) can be varied in dependence on the respective phase encoding gradient (k.sub.y).

Abstract: Flyback imaging is combined with echo planar imaging (EPI) for improved readout flow properties. For increases in imaging time of 50% or less, significant improvements in imaging are realized. The partial flyback improves partial-Fourier EPI and inside-out EPI and can be applied to any EPI trajectory.

Abstract: A method of heating a target region by ultrasound radiation includes determination of a position of the target region by a magnetic resonance method. The device for carrying out this method includes an ultrasound device and an MR device. By determining movement of the target region utilizing the MR device (100) and an appropriate magnetic resonance method, and by coupling the movement information to the ultrasound device (118) by an electric signal (122, 124), it is achieved that the ultrasound device can be controlled by the movement information. Various possibilities exist for controlling the ultrasound device. According to a first possibility, the focal region is adjusted to be situated within the target region in order to generate ultrasound.

Abstract: An MR method for the reduction of motion artefacts is applicable to procedures where a plurality of MR data sets concerning an object to be examined are acquired successively in time. Because the object to be examined is liable to move during the period of time required to acquire an MR data set for the reconstruction of a high-resolution MR image, the high-resolution MR image often contains disturbing motion artefacts. In order to avoid such motion artefacts in the high-resolution MR images, first a plurality of MR data sets are acquired for low-resolution MR images; this operation can be performed within a shorter measuring period. Image transformation parameters are determined from the comparison of the low-resolution images so as to be taken into account for the reconstruction of the high-resolution MR image from the MR data sets acquired.

Abstract: The present invention intends to easily perform arithmetic operations for determining flow velocities without making phase correction and to reduce the aliasing error. To this end, a plurality of data pieces having phase sensitivity are measured using phase contrast pulse sequences in a magnetic resonance diagnostic apparatus. When four data pieces having phase sensitivity of tetrahedral type are acquired, four measured images are obtained. Individual measured images have vector values at corresponding points. Predetermined pair images are subjected to an arithmetic operation for determining an angle between two vectors at individual points on the images, the thus obtained phase images are added and a sum image is multiplied by a suitable coefficient to produce an x-direction flow velocity image. Flow velocity images in y and z directions are similarly obtained and images determining the magnitudes of flow velocities can also be produced.

Abstract: MRA data is acquired from a large region of interest by translating the patient to successive stations at which successive portions of the MRA data set are acquired. Patient movement is chosen to track a bolus of contrast agent as it passes through the region of interest to achieve maximum image contrast. In one embodiment a stationary local coil is supported adjacent the patient to acquire the MRA data and in another embodiment a multi-segment local coil moves with the patient and its segments are sequentially switched into operation.

Abstract: A bipolar, phase-encoding, pre-phaser pulse is employed in each shot of a multi-shot EPI pulse sequence to smooth the phase-encoding gradient first moment throughout the scan. The first moment of the pre-phaser pulse is calculated for each shot in the scan and is played out at the beginning of each shot after the RF excitation.

Abstract: The present invention is a technique of, and system for, imaging vascular anatomy over distance considerably greater than the maximum practical field of view of a magnetic resonance imaging system while using substantially one contrast agent injection. The technique and system of the present invention acquires image data of a plurality of image volumes which are representative of different portions of the patient's body. The image data of each image volume includes image data which is representative of the center of k-space. The acquisition of image data which is representative of the center of k-space is correlated with a concentration of contrast agent in the artery(ies) residing in the image volume being substantially greater than the concentration of contrast agent in veins and background tissue adjacent to the artery(ies).

Abstract: A magnetic resonance imaging method comprises exciting spins in an investigation volume via a radio frequency pulse and the signal produced thereby is subsequently read-out after appropriate spatial encoding following a short echo time te. Repetition of the sequence required for spatial encoding occurs in a time interval tr under appropriate variation of the spatially encoding gradient. The radio frequency pulse utilized for excitation has a short time duration and therefore a large excitation band width so that a projection image through a thick projection slice is produced under application of no slice selection gradient or with only a weak slice selection gradient. The time interval tr is sufficiently minimized that the image recording time required for recording of an image lies in the range of one EKG cycle or below. This process of recording a projection image is continuously repeated and a contrast medium bolus administered during the course of this sequential recording.

Abstract: Signal fall-off in axial EPI images as well as its variations is corrected by compensating the EPI pulse sequence with gradient pulses that serve to balance the phase dispersion caused by Maxwell terms. Four embodiments are described which employ the slice-selection gradient to compensate the EPI pulse sequence and a fifth embodiment employs the readout gradient.

Abstract: Contrast preparation based on Modified Driven Equilibrium Fourier Transfer generates T1 weighted images for assessment of the myocardial perfusion with contrast agent first-pass kinetics. The preparation scheme produces T1 contrast with insensitivity to arrhythmias in prospectively triggered sequential imaging thereby eliminating one of the major sources of problems in potential patient studies with previously employed contrast preparations schemes.

Abstract: A method is provided for use in constructing an MR image associated with the flow of blood or other fluid through an imaging volume, wherein material flowing through a selected voxel of the imaging volume is distinguished from static material. The method includes the step of applying a first MR pulse sequence to the imaging volume to produce a first MR data signal, having a magnitude which encodes first and second flow parameters for respective voxels comprising the volume, and having a phase which encodes a third flow parameter. The method further includes the step of applying a second MR pulse sequence to the volume, to produce a second MR data signal which indicates the content of respective voxels without flow encoding. The first and second MR data signals are compared to one another, such as by computing the difference therebetween, to determine the presence or absence of flowing material in respective voxels of the imaging volume.

Abstract: A method for performing motion-compensated spectral-spatial selective magnetic resonance imaging. The method includes applying a radio frequency (RF) spectral-spatial excitation pulse sequence to a region of a body. The excitation sequence includes a binomial pulse train including at least two sub-pulses. The binomial pulse train also provides spectrally selective excitation of a selected resonance frequency at the predetermined field strength. The method also includes applying to the same body region an oscillating slice selection gradient so that each sub-pulse of the binomial pulse train is applied during portions of the oscillating gradient having the same polarity. The oscillating gradient further includes at least one extra gradient switch added to the end of the oscillating gradient for providing a balanced gradient for inherently motion-compensated slice selection.

Abstract: A method to null a phase relevant to a high-order moment and minimize an echo time TE when a GMN or flow-encoding gradient pulse is employed. The first to n-th trapezoidal-wave pulses of which polarities are alternately mutually opposite are applied as a gradient pulse. The amplitude g and pulse duration t of the first trapezoidal-wave pulse, and the slope k of pulses of the first trapezoidal-wave pulse are given as initial values. Parameters including a plurality of known pulse duration coefficients b.sub.1, b.sub.2, etc. determining pulse durations b.sub.1.t, b.sub.2.t, etc. of the first to n-th trapezoidal-wave pulses, and unknown magnetic field gradient strength coefficients a.sub.1, a.sub.2, etc. determining amplitudes a.sub.1.g, a.sub.2.g, etc. of the second and subsequent trapezoidal-wave pulses are given.

Abstract: To compensate for magnetization transfer effects that result from use of a labeling pulse to label inflowing blood, at least two control pulses are used. The control pulses have a total compensating flip angle that equals the flip angle of the labeling pulse, and are applied to the same volume to which the labeling pulse is applied. Advantageously, the labeling and control pulses are adiabatic.

Abstract: A magnetic resonance angiography method for acquiring angiographic images using any or all of three different types of selective presaturation pulses to the particular parts of the body for enhancing vascular imaging. The three types are:1) an inversion pulse applied prior to the application of a burst of RF pulses used for tipping the spins designed to eliminate signals from unwanted blood entering the field of view being imaged,2) inversion pulses applied between the first inversion pulse and the first of the Rf pulses used to suppress blood not properly suppressed by the first type of suppression pulses, such as fast flowing blood, and3) saturation pulses applied within the burst of RF pulses to suppress signals from slow flowing blood when in the 2D acquisition mode. Special heart and breath gating methods are also described that enable good compromises between image quality and scan time.

Abstract: Within a selected slice or slab, diffusion sensitizing gradients (54, 56) and read gradients (66, 68) are induced along each of a pair of orthogonal axes (G.sub.x, G.sub.y). The motion sensitizing gradient pulses sensitize excited magnetic resonance to diffusion in a preselected diffusion direction (D) which is orthogonal to a selected read gradient direction. The diffusion sensitizing gradients are rotated by sin(.theta.+.pi./2) and cos(.theta.+.pi./2) and the read gradients are rotated by sin.theta. and cos.theta. to generate a plurality of angularly displaced data lines. The diffusion sensitivity direction remains perpendicular to the read direction in each of the angularly displaced data lines. The phase of each data line is determined (90) and shifted (94) to compensate for linear translations. The data values within each data line are shifted (86) to center the peak amplitude of the data line at a preselected position to compensate for higher order motion.

Abstract: In a method and apparatus for phase contrast MR angiography, for topically resolved flow acquisition, bipolar flow coding gradients are activated before readout of nuclear magnetic resonance signals. By using flow coding gradients of different amplitudes in successive measurements within a pulse sequence, nuclear magnetic resonance signals are obtained that are differently sensitive to flow. A larger range of flow velocities can thereby be covered.

Abstract: A dynamic MR angiography technique, MR digital subtraction angiography (MR DSA), based on fast acquisition, contrast enhancement and complex subtraction is described. When a bolus of contrast is injected into a patient, data acquisition begins, dynamically acquiring a thick slab using a fast gradient echo sequence for 1060 sec. Similar to x-ray DSA, a mask is selected from the images without contrast enhancement, and later images are subtracted from the mask to generate angiograms. Complex subtraction is used to overcome the partial volume effects related to the phase difference between the flowing and stationary magnetization in a voxel.

Abstract: An off-resonance magnetization transfer contrast (MTC) RF-pulse (54, 64) is used in magnetic resonance angiography (MRA) to suppress the signal of various stationary tissues, such as brain tissue while avoiding significant suppression of signal from blood flowing in a general direction of blood flow into a slice being imaged. Application of a magnetic gradient (55, 65, 85) during the MTC RF-pulse (54, 64) directed in the general direction of blood flow increases the magnetization frequency offset (86) relative to the center frequency of the MTC RF-pulse for points within and feeding blood to the slice. The MTC RF-pulse thus causes only a small signal reduction of the blood flowing into the slice in the general direction of blood flow while producing a saturation of any blood flowing into the slice in the opposite direction. Consequently, both time and RF-power needed for a separate presaturation pulse can now be used for the MTC RF-pulse.

Abstract: A sequence controller (40) controls the pulses applied by the radio transmitter (24) and the gradient amplifiers (20) and gradient coils (22) such that each repetition includes a prepreparation sequence segment, such as a presaturation sequence segment and a magnetization transfer contrast correction (MTC) segment, and a plurality of image sequence segments. More specifically, each of the image sequence segments induce resonance, phase and frequency-encode the resonance, and generate one or more views of data, all within a corresponding one of a plurality of slabs or sub-regions (74.sub.1, 74.sub.2, . . .) of an image volume (72). More precisely to the preferred embodiment, the imaging sequence segments interleave the slabs such that resonance is not excited concurrently in adjacent slabs, without exciting resonance and collecting a view in a non-adjacent slab. The views are sorted (80) by slab and stored in corresponding slab data memories (82).

Abstract: A phase unwrapping method is provided comprising a post-processing MR operation for an array of phase-related MR data elements. The method includes the steps of defining a Region of Interest, of comparing each data element with the first and second data elements which are adjacent thereto in the array, in order to generate respectively corresponding first and second gradient values. A subset of the data elements is constructed, wherein a data element is assigned to the subset only if its corresponding first and second gradient values are less than a selected threshold value VENC/2. The data element subset is employed to generate a fitted phase function having a value at the position of each data element in the array, and the value of the fitted function thereof, for a given data element, is subtracted from the measured value thereof.