| 摘要 |
<p>A method for magnetic resonance spectroscopy (=MRS) or magnetic resonance imaging (=MRI) in which an NMR time-domain signal is created by an RF excitation pulse applied to an object in the presence of an applied magnetic field that may depend on spatial position and/or time, said time-domain signal being generated by an excited transverse nuclear magnetisation precessing about the applied magnetic field, whereby the RF excitation pulse is adapted to cover a whole range of NMR frequencies of interest present in the object, and time-domain signal acquisition takes place during, or during and after the application of the RF excitation pulse, is characterized in that spectral or image data are reconstructed by a matrix product of a reconstruction matrix and a vector of time-domain signal points, the reconstruction matrix being an inversion of an encoding matrix A h ± whose elements are calculated using the formula: A n± = ˆ‘ m = 0 n - 1 P m �¢ e ¹ �¢ ¦ n m ±
wherein n is the running number of a time-domain signal point, ± is the running number of a discrete image or spectral element, P m is the m -th discrete element of the RF excitation pulse in the time-domain, and ¦( n,m, ±) is the phase accrued by the transverse nuclear magnetisation related to the discrete image or spectral element ± in the time between the discrete RF excitation pulse element P m and the time-domain signal point n under the influence of the applied magnetic field. The invention provides an improved method for reconstructing spectral or image data from time-domain signal acquired as describe above, which can be used more versatilely than conventional Fourier transform.</p> |
