ESTIMATING SPATIAL-RESOLUTION OF IN-VIVO MR-IMAGES USING SPATIAL MODULATION OF MAGNETIZATION

Spatial Modulation of Magnetization is shown to provide a means of est imating perceived spatial resolution directly in vivo, On the first ma gnetic resonance system tested, resolution in conventional spin echo i mages was found to be stability limited in the phase encoding directio n and voxel limited (via the Nyquist sampling theorem) in the frequenc y encoding direction both in vitro and in vivo. As the voxel size appr oaches half the stripe separation, fringes of resolved and unresolved stripes are formed across the image, This phenomenon is explained and described mathematically. On a second magnetic resonance scanner, reso lution in the phase encoding direction of fast spin echo images with c entrically ordered phase encoding is shown to be voxel Limited in subs tances with long T-2, with poorer resolution in substances with short T-2, Resolution in fast spin echo images with linearly ordered phase e ncoding was shown to be voxel limited in the phase encoding direction. (C) 1998 Elsevier Science Inc.