Influence of pre- and postprocessing filters on the image quality of Tc-99m, Ga-67, and TI-201 SPECT

The authors evaluated preprocessing filters to determine their effect on the resolution, contrast, and lesion detectibility of single photon emission. Liver and heart phantom data were acquired with Tc-99m or T1-201. Twelve patient studies with Tc-99m, Ga-67, and T1-201 were evaluated. Data were preprocessed with a nine-point weighted, nonweighted, Butterworth, or no smoothing filter. Preprocessing reduced contrast up to 30% in cold and 10% in hot lesions. In patients, preprocessing did not affect hot lesions, but cold lesions could be obscured. Postprocessing reduced motion artifacts. In conclusion, preprocessing is unnecessary; a proper reconstruction filter is adequate for noise suppression