REDUCTION OF PHASE ERROR GHOSTING ARTIFACTS IN THIN SLICE FAST SPIN-ECHO IMAGING

Fast spin-echo (FSE) imaging techniques are very sensitive to the rela tive phase between the 90 degrees (excitation) RF pulse and the 180 de grees (refocusing) RF pulses, In this paper, it is demonstrated that a phase shift can be created between the excitation and refocusing puls es in such a manner that the received signal is divided into two compo nents of distinctly different phase shifts. The nature of these two co mponents is reviewed. It is demonstrated that ghosting artifacts will occur when images are reconstructed from this received signal, The gho sting is shown to be object dependent, A correction technique is prese nted which calculates the phase errors among different echoes based on measurements from a single echo train acquired without phase encoding gradients. The results in both phantom and human studies show that th is method is capable of reducing the ghosting artifact in thin slice F SE images.