Signal-to-noise, resolution, and bias function analysis of asymmetric sampling with zero-padded magnitude FT reconstruction.
This report describes NMR image effects due to sampling asymmetry when using zero-padded magnitude FT reconstruction. With this method, the MTF is not flat over the spatial frequency passband, so resolution cannot be accurately described by a single variable such as voxel size. At small to moderate asymmetry, shortened (reduced window duration) asymmetry provides increased S/N and decreased resolution, whereas shifted (constant window duration) asymmetry yields essentially constant S/N with simultaneously increased and decreased resolution. A bias function expression describes image distortion due to sampling in terms separable from the imaged object. The analyses are consistent with previous descriptions of perceived image differences related to data asymmetry.
Hurst
G C
GC
Department of Radiology, MetroHealth Medical Center, Cleveland, Ohio.
Hua
J
J
Simonetti
O P
OP
Duerk
J L
JL
D000465:Algorithms; D016477:Artifacts; D015982:Bias; D001921:Brain / Q000033:anatomy & histology; D003198:Computer Simulation; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural; D008962:Models, Theoretical; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors