Abstract: For increasing the sensitivity of an MR apparatus when measuring comparatively high frequencies, the radio frequency excitation measurement coil (10, 30) is divided into two individual symmetrically drivable and readable coil halves (32, 34), respectively. The mutual connection of central connections of the coil halves can be realized by means of a balun (54) but for this purpose any other symmetrical form of coupling, for example using a strip-line transformer (70) or suitably dimensioned coaxial cables (60, 62) may alternatively be used.

Abstract: An NMR scanner apparatus uses a permanent magnet comprised of an assembly of magnetic material formed of a substantial number of low energy permanent magnetic elements producing magnetic flux and arranged in at least one row of columns. A frame of magnetically soft material provides a return path for the magnetic flux and provides a surface from which the columns of magnetic elements extend. A flux concentrator plate is disposed adjacent to a surface of the assembly and recessed a sufficient distance from the edge of the assembly to inhibit the loss of magnetic flux. The flux concentrator plate and the frame sandwich the magnetic assembly therebetween. A pole piece consisting of a soft magnetic material is disposed adjacent to a surface of the flux concentrator plate. The pole piece defines a scanning area substantially smaller than the area of the adjacent surface of the flux concentrator plate such that the pole piece exhibits parallel lines of magnetic flux for inducing polarization in living tissue.

Abstract: A system for controlling the spin rate of a sample in an NMR spectrometer using an ON/OFF valve controlled by a digital system to regulate flow of a gas between a source and a sample spinner. A spin rate detector supplies rate information to the digital control. The digital control varies the ON/OFF valve duty cycle to control the spin rate.

Abstract: An electronic module for generating gradient energization signals in magnetic resonance imaging to correct for eddy current effects. An energization profile is modified by an amount related to the magnitude of eddy current fields generated in the vicinity of a gradient coil. This modification produces an energization profile resulting in a gradient magnetic field corresponding to the magnetic field the unmodified energization profile would have produced but for the presence of induced eddy currents.

Abstract: For the representation of images of regions selected from the interior of an examination subject, coils are provided for the application of a primary magnetic field and of magnetic gradient fields to the examination subject. An electrical conductor configuration detects the deflection of the atomic nuclei of the examination subject from their position of equilibrium as a result of high frequency magnetic excitation pulses. The configuration is formed by two interspersed individual conductor configurations adapted for respective different measurement frequencies. Each configuration comprises parallel conductors connected at their ends and arranged in spaced relation to an electrically grounded surface to form a transmission line configuration resonant at a respective one of the measurement frequencies.

Abstract: A rheology test system includes a self-propelled vehicle, a computer contained in the vehicle and a rheology flow loop skid mounted in an outboard storage compartment of the vehicle. The rheology flow loop skid includes an obliquely mounted helical conduit through which laminar flow is maintained. The helical loop is mounted on a base near an inboard side thereof, and instrumentation is mounted on an outboard side of the base so that the apparatus can be readily used while mounted on the vehicle. Improved connecting pipes provide a more compact construction and a more easily assemblable and disassemblable construction.

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 blood flowmeter applies a continuous transverse excitation signal and a constant, homogeneous polarizing magnetic field to blood flowing through an active region. The polarizing magnetic field is contoured at opposite boundaries of this active region, and by switching these contours and collecting the resulting NMR signals, data is obtained from which the various components of blood flow may be calculated.

Abstract: A drilling fluid density measurement system uses a continuously operating bubble measurement system for an oil or gas well. A microprocessor correlates the signal output from a differential pressure transmitter connected to a pair of self-cleaning pressure probes which are positioned in a circulating drilling fluid. By manipulating solenoid valves, the microprocessor controls the intermittent zeroing of the output signal from the differential pressure transmitter and controls a periodic level check to determine if the pressure probes are submerged in the drilling fluid.

Abstract: An NMR radio-frequency coil is made up of a plurality of conductive segments evenly spaced about the peripheries and interconnecting a pair of conductive loop elements. Each conductive segment includes at least one reactive element which may include a variable capacitive or inductive element.

Abstract: In an NMR tomography method, the nuclear spins are caused by a pulse sequence to supply in one pass a number of successive induction signals, whereupon the induction signals corresponding to each other as regards their succession in time are processed by calculation to form a plurality of image signal sets corresponding to a sequence of section images which differ from each other by the intensity of the induction signals varying according to the relaxation time T.sub.1 or T.sub.2.

Abstract: An NMR radio-frequency coil is made up of a plurality of conductive segments evenly spaced about the peripheries and interconnecting a pair of conductive end-cap elements. Each conductive segment includes at least one reactive element which may include a variable capacitive or inductive element.

Abstract: An improved NMR imaging system that minimizes truncated time function generated artifacts on a real time basis by selecting sampling points on the FID generated signals either as a function of a varying magnetic field gradient or at varying sampling intervals.

Abstract: An NMR imaging method which provides a three-dimensional image representative of the two-dimensional distribution of nuclear spin species resolved by chemical shift or the local spectra resolved by two-dimensional location. After the excitation of nuclear spins and the phase-encoding by application of a field gradient G.sub.y, a periodically inverting field gradient G.sub.x is generated to yield a continuous echo train. The echo train is sampled and separated into data of odd-numbered echoes and data of even-numbered echoes which data are in turn reconstructed into two-dimensional data arrays, respectively. The data thus reconstructed are three-dimensional Fourier-transformed.

Abstract: In a method of assessing drilling conditions during a drilling operation measurements of torque applied (TOR), weight on bit (WOB), rate of penetration (ROP), and rotation speed (ROT) are gathered. Computed therefrom is a history (60, 61) of points (x, y) where x=(TOR/WOB) and y=(ROP/ROT).sup..gamma. : .gamma. being a derived constant indicative of down hole geometry. Trends in this history are monitored to assess drilling conditions. For example in soft plastic rock migration 62 towards the origin and in hard plastic rock migration 63 towards the abscissa is indicative of drill bit wear.

Abstract: An NMR imaging apparatus and method for detecting a nuclear spin resonance signal from an object, which is placed in a magnetic field, to produce images of the object. At an instant when the spins come into phase after the signal detection by a first spin excitation, RF magnetic field pulses are applied for rotating the direction of the spin to that opposite to the initial state. After that, the spin excitation and the signal direction of second time are conducted to measure the data which are different in the effect of the relaxation time from the first measurements. By repeating these sequences, it is possible to produce a plurality of images such as an intensity image or a relaxation time enhanced image.

Abstract: The disclosure relates to nuclear spin tomography equipment in which means (22, 24) are provided for the control of the acquisition of the Fourier rows of the measurement matrix as a function of a respiration signal. The equipment includes a Fourier row counter (25) which influences a circuit (26) that controls the measurement signal acquisition. In a first embodiment of the invention the measurement signal acquisition is always released for all rows outside a predetermined region, but is a function of the respiration phase signal inside this region. The predetermined row region may comprise approximately 10% of all rows to be measured and should lie symmetrically about the center of the matrix. A further reduction of the measuring time is realized, according to another embodiment of the invention, by dispensing altogether with measurement in the row edge region of the matrix.

Abstract: The invention relates to a coil arrangement intended for an NMR testing apparatus for collecting NMR information about a target to be examined, said arrangement comprising first coil means (2) for exciting the nuclei of a target area and for receiving a signal emitted by the nuclei of a target area. The arrangement further includes second coil means (6) for gaining the amplitude of a signal emitted by a limited section of a target and connected to said first coil means, said gain being in proportion to the amplitude of a signal connecting from another section of a target. This is a way of improving the ratio of a signal connecting to said first coil means (2) from said limited section of a target to the electric noise created in the signal collection unit and in a target. The invention can be preferably applied to NMR imaging units which, in addition to mapping the entire body, can be used for the examination of smaller subdomains, such as the eye, ear, limbs etc.

Abstract: Hybrid fast scan magnetic resonance imaging is performed by using, for example, both a two dimensional Fourier transform (2DFT) method using phase encoding prior to data collection and an echo planar technique which phase encodes by using an oscillating gradient during data collection. In this hybrid imaging, the amplitude of the oscillating gradient determines the time savings achieved in imaging. The hybrid scan has particular application for medical diagnostic imaging since it is advantageous that such imaging be conducted as rapidly as possible.

Abstract: The invention relates to a well test method for determining the physical characteristics of a system made up of a well and a subsurface formation containing a fluid such as a hydrocarbon. A change in the flow rate of said fluid is produced for a short period (duration t.sub.P of the order of a few minutes) so as to obtain a flow pulse resembling a Dirac pulse; the variations .DELTA.P of the down-hole fluid pressure is measured during said short period and then during the subsequent period of return to the initial state of the well-formation system, and the experimental pressure curve thus obtained is compared with the curves of a double network of type curves representing, as a function of a common parameter, the pressure P.sub.D and its derivative P'.sub.D with respect to time, by matching the branch of the experimental curve corresponding to the short period with a curve P.sub.D and the branch of this curve corresponding to the subsequent period with the curve P'.sub.D of the same parameter.