Abstract: In the case of a method for the generation of nuclear magnetic resonance (NMR) signals from a measuring volume with test substance which is exposed to a highly homogeneous stationary magnetic field B.sub.0, by irradiation of a sequence of at least two radio frequency (RF)-pulses into the measuring volume, wherein the at least two RF-pulses excite nuclear spins of the test substance within the measuring volume in a resonant manner within a frequency band which is narrow with respect to their frequency, the phases of the at least two RF-pulses are selected in dependence upon their frequency in such a manner that the phases of the NMR signals generated by each individual of the at least two RF-pulses are randomised in such a manner that the vectorial sum over the signal intensities of the individual signals is zero, whereas the combination of the at least two RF-pulses leads to the development of observable coherent magnetization of the test substance.

Abstract: Data is produced from asymmetrical echo data, and an MR image is reconstructed from the data thus produced. Namely, inverse Fourier transformation is performed on center echo data, thereby producing phase data. The phase data is inverted in polarity, thereby producing polarity-inverted phase data. Fourier transformation is performed on the polarity-inverted phase data in a readout direction, producing phase-correction data. Inverse Fourier transformation is performed on the asymmetrical echo data in an encode direction. The phase-correction data and the echo data are convoluted in the readout direction, thereby producing echo-data free of phase distortion. Unmeasured echo data is inferred from the convoluted data by utilizing complex conjugate property of the echo data. Inverse Fourier transformation is performed on the convoluted data and the inferred data in the readout direction, thereby producing an image free of phase distortion.

Abstract: A method for obtaining a time sequence of nuclear magnetic resonance (NMR) tomograms of a certain sectional plane in a measuring volume for observation of variations with time of signal intensities from the sectional plane. The method where k data sets f.sup.'k =f.sub.1.sup.'k . . . f.sub.n.sup.'k are recorded for NMR-tomograms with a low spatial resolution characterized by a parameter n in a time sequence with a waiting time t.sub.w between the acquisition of each data set f.sup.'k. The method where, in terms of time before k data sets f.sup.'k, a data set f=f.sub.1 . . . f.sub.m is recorded for an NMR-tomogram of the same sectional plane with a high spatial resolution characterized by a parameter m (i.e. m>>n). Subsequently, by means of said primarily recorded data set, new data sets f.sup.'k are reconstructed from the successively recorded k data sets f.sup.'k for NMR-tomograms of the sectional plane with a high resolution in space and time.

Abstract: An NMR scanner performs a series of pulse sequences from which NMR data is acquired and used to reconstruct an image. Image contrast is enhanced by magnetization transfer from short-T.sub.2 spin species that are saturated by an off-resonance, substantially rectangular shaped RF saturation pulse applied during each pulse sequence.

Abstract: A magnetic field generating assembly used in NMR apparatus includes a primary magnetic field generator for generating a primary magnetic field which is substantially homogeneous in the working region. The primary magnetic field generator is constructed such that an object to be examined can be introduced from outside the assembly into the working region in a direction transverse to the direction of magnetic flux through the working region. Gradient magnetic field coils are provided for imposing one or more magnetic field gradients through the working region. The gradient magnetic field coils are movable relative to the primary magnetic field generator for positioning locally to the position of an object to be examined in the working region.

Abstract: A magnetic resonant image of an object is produced by subjecting the object to an initial slice selection to provide an active region and by subjecting the active region to a plurality of 180.degree. RF pulses and appropriate amplitude modulated x and y gradients.

Abstract: An RF device (A) under test is connected with ports or jacks (14, 16) of an S-parameter test set (B). An RF input jack (18) is connected with an RF tracking signal output (20) of a spectrum analyzer (C) to receive an RF tracking signal. An output jack (22) is connected with a receiver input (24) of the spectrum analyzer. A mode control (30) internal to the test set is controlled by a programmable control sequence generator (34) of the spectrum analyzer. The mode control controls a switch array (32), preferably PIN diodes, which interconnect the RF input jack (18), the RF output jack (22), the two jacks (14, 16) that are connected to the device under test, and a 50 Ohm termination (54) in four modes to make reflection measurements and two transmission measurements. DC bias jacks (26, 28) are connected with a DC power for injecting a DC component into the RF signals applied to the device under test.

Abstract: A process and an apparatus for leak testing a package. The method includes placing a sheet-like and airtight wrapper around a part of the package liable to leakage, e.g. a closing element. Applying a higher pressure to the outside than to the inside of the wrapper for causing the wrapper to fit closely around the part of the package and for hermetically sealing the wrapper from a part of the package outside the part to be tested. Sealing the measuring space between the enveloped part of the package and the wrapper pressed against it from the surrounding space by applying a measuring pressure in the closed measuring space which is different from the pressure then prevailing in the package, and for measuring the change of pressure in the closed measuring space for a determined measuring time.

Abstract: In an MR (magnetic resonance) imaging method, not only eddy current field is compensated, but also a gradient field vibrated by a mechanical vibration caused by the eddy current is compensated. The method for imaging a biological body under medical examination by utilizing a magnetic resonance phenomenon under influence of a static magnetic field and a gradient magnetic field to acquire an MR image of a preselected slice portion within the biological body, comprising the steps of: producing a first drive current on which an eddy current field compensating current has been superimposed: producing a vibrating-field compensating current for compensating a gradient field vibrated by the eddy current; and superimposing the vibrating-field compensating current on the first drive current to obtain a second drive current. The second drive current is supplied to a gradient coil assembly for generating a gradient field whose vibrating field component has been compensated.

Abstract: The invention concerns a nuclear resonance well logging tool for insertion into a borehole with a permanent magnet which is magnetized perpendicularly to its axis and with means to transmit and to detect high frequency signals whereby the transmission and detection coils are orthogonal. The arrangement is configured for CW operation. The permanent magnet or the transmission and detection coil arrangement may rotate around the axis in order to modulate the nuclear resonance signals.

Abstract: Disclosed is a gradient magnetic field generator for an MRI system including a bobbin, formed of a non-magnetic body, being shaped into an appoximate hollow cylinder, and gradient coils embedded in the bobbin for generating gradient magnetic fields with supplied currents. The bobbin is formed such that thickness of the axial central portion of the bobbin is thicker than that of the axial end portions for enhancing the rigidity on the axial central portion.

Abstract: A permanent magnet for nuclear magnetic resonance imaging that provides an intense and highly homogeneous magnetic magnetic field is disclosed. The magnet is made up of a set of rings having two sub-sets of rings of permanently magnetized polygonal blocks, wherein the rings of a sub-set of rings are substantially concentric. In addition, the rings of the two sub-sets are complementary in terms of magnetization. Each ring of a sub-set is separated from its complementary ring by a space that is substantially the same for all pairs of complementary rings. The rings have a regular polygonal structure and are made up of blocks that also have regular polygonal shapes.

Abstract: A magnetic resonance blood flow imaging method employs a field-echo technique and a gapless multi-slice acquisition technique in which a selective excitation pulse with a flip angle of less than 90 degrees is utilized and a pulse repetition time is set shorter than usual. Imaging data are acquired from multiple slices of a subject under examination while the multiple slices are shifted in sequence in position. A cross-sectional image is reconstructed for each of the multiple slices. Images obtained by performing subtractions on plural images for the same slice are gathered to thereby produce an image of blood vessels of the subject under examination which contain at least two blood vessels which run substantially in parallel and are opposite to each other in the direction of blood flow therein.

Abstract: A gradient magnetic field-generating coil assembly of MR imaging apparatus has a cylindrical core member for carrying coil windings that is divided into at least two cores at a central portion of a magnet bore, a gap is set up between the two cores at the central portion of the magnet bore and each core is provided at its opposite ends with parts for fixing it to the magnet, whereby the natural vibration frequency of the core can be deviated from an exciting force frequency and sound prevailing in the outside of the core and sound in the inside can be brought into interference with each other to thereby suppress vibration of the cores at the central portion of the magnet bore and reduce noise.

Abstract: A magnetic resonance imaging system that:applies gradient pulses in a sequence that elicits large amounts of data early in a scan to provide an evolving image; and reduces the Gibbs artifacts to increase the utility of the evolving images.

Abstract: A magnetic resonance apparatus including an r.f. coil arrangement (13) for detecting and/or exciting magnetic resonance in a body in use of the apparatus, the coil arrangement comprising a cylindrical coil (25) and two saddle coils (29) which are disposed in register on opposite sides of the cylindrical coil and conform to the surface of the cylindrical coil.In use of the apparatus the coil arrangement is disposed with the axes of the coils lying in a plane orthogonal to the direction of a static field applied to the body.

Abstract: A surface coil holder for magnetic resonance imaging wherein the holder is provided with straps or tape for securing the holder to an MRI table and a body part of a patient. By preventing movement of the holder and the patient's body part during examination, image quality is maximized to thereby improve diagnostic accuracy. The holder is dimensioned for receiving a conventional 5" surface coil, and an insert is provided so that the holder can accommodate a conventional 3" surface coil.

Abstract: In a presaturation period, a radio-frequency (RF) pulse for selectively tilting only spins outside an imaging region is applied while a slice selective gradient field Gs is applied, and a spoiler gradient field Gsp for saturating transverse magnetization outside the imaging region is subsequently applied to selectively presaturate the spins outside the imaging region. In a high-speed imaging period after the presaturation period, a sequence TR constituted by an operation of applying a very short rectangular non-selective excitation pulse RF for tilting spins in a slice by a predetermined angle, an operation of applying phase encoding and readout gradient fields Gp and Gr (without applying the slice selective gradient field Gs), and an operation of acquiring an MR signal is performed many times while the amplitude of the phase encoding gradient field Gp is changed, thereby acquiring a one-slice MR signal.

Abstract: A local coil for magnetic resonance imaging employs a cylindrical form supporting a coil array of one or more coil groups arranged circumferentially around the cylindrical form. Multiple coil groups are overlapped to provide electrical isolation between the coil groups preserving the signal to noise ratio inherent in a local coil while providing a greater field-of-view than may be obtained from such coil group.

Abstract: The invention relates to an organic material (5) usable in an electron paramagnetic resonance (EPR) magnetometer, as well as to a probe (3) using said material.The object of the invention is to provide a material simultaneously having a limited line width (EPR), good temperature characteristics and which does not react in the presence of water.This object is achieved with the aid of a radical cation salt of formula(Ar).sub.2..sup.+ X.sup.-in which Ar represents an aromatic hydrocarbon, which is either unsubstituted or substituted by at least one element chosen from within the group constituted by halogen atoms or alkyl and alkoxy radicals and X.sup.- is an anion chosen from among TeOF.sub.5.sup.- or SeOF.sub.5.sup.-.