Semiquantitative analysis of SPECT images using 99Tc(m) -HMPAO in the treatment of brain perfusion after the attenuation correction by the Chang method and the application of the Butterworth filter.
The aim of this work was to optimize the parameters for semiquantitative analysis with regard to the average number of counts per pixel in tomographic projections. The analysed studies were divided into three groups, proportionally, to average the counts per pixel. The analysis of results proved the dependence (P<0.05) between the average geometric contrast of images with the maximum counts per pixel higher than 500, reconstructed with the cut-off frequency fc=0.50fn, and the standard image. Also, the same dependence was found between the group with an average of 200 counts per pixel and the standard image at the cut-off frequency fc=0.40fn. The analysis of the attenuation coefficient, c, showed significant differences. The attenuation coefficient c=0.12 cm-1 as accepted for further studies. Optimization of the matrix order of interpolation filter proved increasing of contrast with decreasing size of the matrix. In conclusion, according to the average number of counts per pixel in a projection the parameters of image reconstruction, particularly the cut-off frequency fc of the Butterworth filter, should be changed. Additionally, an attenuation correction with coefficient c=0.12 cm-1 and interpolation with matrix size equal 7x7 should be applied.
Stelter
P
P
Department of Endocrinology and Metabolic Diseases, K. Marcinkowski Medical University, Poznań, Poland.
Junik
R
R
Krzyminiewski
R
R
Gembicki
M
M
Sowiński
J
J
D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D019690:Technetium Tc 99m Exametazime / Q000493:pharmacokinetics; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods*
D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime