Method and magnetic resonance apparatus for non-selective excitation of nuclear spin signals in an examination subject

摘要

In a method for non-selective excitation of nuclear spin signals in an examination subject with a magnetic resonance system, RF excitation pulses are radiated to excite nuclear spin signals in the examination subject with simultaneous switching of gradients for spatial coding of the excited nuclear spin signals, wherein the RF excitation pulses are designed such that the base frequency of a radiated RF excitation pulse is adapted to the simultaneously switched gradient. By the dynamic adaptation of the radiated RF excitation pulses to the respective simultaneously switched gradients, artifacts due to insufficiently excited nuclear spins in an examination region to be examined (in particular even in examination regions that are arranged off-center) are avoided.

主权项

1. A method for non-selective excitation of nuclear spin signals in an examination subject in a magnetic resonance (MR) apparatus, comprising:
placing an examination subject in an MR data acquisition unit and exposing the examination subject to a basic magnetic field in the MR data acquisition unit; from a computerized control unit, controlling a scan of the examination subject to acquire MR data therefrom by generating and providing a pulse sequence to the MR data acquisition unit that operates the MR data acquisition unit, with the examination subject therein, to radiate a plurality of non-selective radio-frequency (RF) excitation pulses into the examination subject that each has a base frequency that non-selectively excites nuclear spins in the examination subject and thereby produces MR signals resulting from the excited nuclear spins, while simultaneously activating a phase coding magnetic field gradient that spatially encodes the MR signals, and thereby producing a combined magnetic field in said MR data acquisition unit that is a superimposition of said basic magnetic field and said phase coding magnetic field gradient, said combined magnetic field changing during said scan due to the switching of the phase coding magnetic field gradient; and in said computerized control unit, automatically setting the base frequency of each non-selective RF excitation pulse in said pulse sequence dependent on the combined magnetic field that exists at a time in said pulse sequence at which that respective non-selective RF pulse is radiated, due to the phase coding magnetic field gradient that is simultaneously switched at said time.