Method for the simultaneous measurement of nmr signals, in particular for determining flow rates in nuclear spin tomography by means of the multiple slice fourier flow (muff) method

Claim 1

Method for the simultaneous measurement of spin resonance signals, in particular NMR signals, from layers located at different depths in a test volume comprising the steps of: subjecting the test volume to a homogeneous magnetic field in a Z direction and to successive sequences of pulse-shaped gradient fields; subjecting the test volume to multiple-component rf excitation pulses P n , said excitation pulses being synchronized in time with the gradient fields and having n components P m for exciting, due to a respective frequency W m thereof, a spin resonance of the Larmor frequency W m in a defined layer m of the test volume, a variation in space of the Larmor frequency W m being effected in the Z direction by application of a layer-selective gradient, the individual components P m of the multiple-component rf excitation pulse P n being dephased relative to each other by a phase displacement φ m which is varied from one sequence to a next by successive addition of a constant phase increment Δφ m modulo 360° fixed individually for each individual component P m ; applying a read gradient to the test volume in a direction perpendicular to the Z direction at least for a time of appearance of spin echo signal; measuring the spin echo signal during a complete measuring cycle consisting of n or an integral multiple of n sequences; and subjecting the measured spin echo signal to Fourier transformation.