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Abstract

A method of MRT according to the principle of signal generation in the driven equilibrium (DE) or also steady state free precession (SFP) wherein a periodic sequence of RF pulses with a flip angle .alpha. is applied with a time delay TR wherein the phase of these pulses is alternated in subsequent steps, is characterized in that the periodic sequence of RF pulses is preceded by a sequence of (n+1) pulses for which the following conditions are valid: a first excitation pulse with preferred flip angle .alpha..sub.0 =90.degree. precedes the subsequently equidistant sequence of RF pulses at a preferred separation TR/2, the flip angle .alpha..sub.1 of the subsequent pulse is larger than .alpha. and identical or approximately identical to 180.degree., the flip angle .alpha..sub.1 of the i-th pulse in the region i=2 . . . n is selected such that .alpha..sub.i.ltoreq..alpha..sub.i-1 and .alpha..sub.i.gtoreq..alpha. and the phases of these pulses alternate. This permits transfer from the steady state to the DE after few excitation periods such that fluctuating signals of off-resonance spins are largely eliminated and moreover, in the transfer to DE, signals of a higher amplitude compared to normal DE are generated which optimise image quality and contrast.

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First Claim