Acquistion and Accuracy in Rapid NMR Imaging Methods

摘要: The echo-planar imaging method (EPI) and its variants can acquire data sufficient to form an image in a much shorter time than the Fourier or projection-reconstruction methods. Fundamental requirements on gradient waveforms signal sampling are discussed for EPI SEPI (a variant using sinusoidal waveforms), based k-trajectory formulation of acquisition NMR imaging. Using new simulation method, defects demonstrated which result from failure meet these requirements. Faithful rendition theoretically ideal places severe demands system response rapid It is shown, however, that nonideal need not degrade images if appropriate reconstruction computations used. Transfer functions noise power spectra derived SEPI, ratio two used derive observer signal-to-noise ratios simple visual interpretive tasks. shown performance differ significantly between some tasks, same system.