Abstract: In a method for the simultaneous measurement of spin resonance signals, in particular NMR signals, from layers located at different depths in a test volume, simultaneous excitation of the different layers is effected by a multiple-component rf excitation pulse P.sub.n, consisting of n individual components P.sub.m with the frequencies .omega..sub.m, which act selectively on defined layers m of the test volume, in the presence of a layer-selective gradient, the individual components P.sub.m having a phase displacement .phi..sub.m which is varied from one sequence to the next by successive addition of a constant phase increment .DELTA..phi..sub.m modulo 360 fixed individually for each individual component P.sub.m.

Abstract: The invention relates to opaque synthetic resins containing 1 to 30% by weight of cross-linked beads consisting of a polymer comprised of:(i) 9.9 to 59.9% by weight of at least one radically polymerizable monomer A containing an aromatic residue or nonaromatic monomers A' which contain a halogen;(ii) 90 to 40% by weight of vinyl monomers B which are copolymerizable with these monomers but different from them;(iii) 0.1 to 20% by weight of at least one cross-linking monomer V and(iv) 0 to 10% by weight of a strongly polar monomer Hand where (a) the refractive index of the polymer is higher than that of the polymer matrix and that (b) the average bead size of the beads is in the range of 20 to 50 microns.

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: For recording a nuclear magnetic resonance tomogram according to a Fourier-transform method, a Carr-Purcell-Gill-Meiboom pulse sequence is used for the excitation of a body to produce a sequence of spin-echo signals. A time-limited phase-encoding magnetic gradient field G.sub.X is imposed between each pair of 180.degree. pulses of the sequence. The phase-encoding magnetic gradient field is modified after every 180.degree. pulse so that every spin-echo signal corresponds to a different projection of the body. The magnetic gradient fields used in the recording are regulated in intensity and duration in such a way that a spin-phase condition at each 180.degree. pulse of the pulse sequence remains effectively constant. Thereby, it is possible to construct a complete tomographic recording with a single pulse-sequence excitation, so that the time required for such recordings can be reduced to a fraction of the time needed for recording nuclear-magnetic-resonance tomograms conventionally.

Abstract: NMR tomography permits identification of flowing matter within a closed body, as there is a reduction in signal intensity as a consequence of a saturation of the magnetization in the area of a slice that has been excited for imaging, while freshly inflowing matter has not experienced this saturation and consequently provides a stronger signal. Special excitation sequences permit either virtually complete saturation of stationary tissue, and thus particularly strong emphasis of flowing matter, or excitation of stationary and flowing matter in different zones and with differing intensities, thereby enabling very precise quantitative and even directional flow measurements to be performed.