PT - JOURNAL ARTICLE AU - Kemin, Huang TI - <strong>Impact of </strong><strong>different reconstruction algorithms and OSEM reconstruction</strong><strong> </strong><strong>parameters</strong><strong> on </strong><strong>quantitative results </strong><strong>in SPECT/CT</strong> DP - 2018 May 01 TA - Journal of Nuclear Medicine PG - 1800--1800 VI - 59 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/59/supplement_1/1800.short 4100 - http://jnm.snmjournals.org/content/59/supplement_1/1800.full SO - J Nucl Med2018 May 01; 59 AB - 1800Purpose: Impact of different reconstruction algorithms and OSEM reconstruction parameters on quantitative results in SPECT/CT [Abstract Objectives]:To evaluate the effects of 3-dimensional ordered subset expectation maximization(3D-OSEM), 2-dimensional ordered subset expectation maximization(2D-OSEM), filtered-back projection (FBP),and the number of OSEM iterations and subsets on quantitative results in SPECT/CT. Methods: A Jaszczak cylindrical phantom and IEC body phantom were performed with routine SPECT/CT imaging using CT attenuation correction, scatter correction and 3D-OSEM reconstruct image. The system volume sensitivity(cpm/kBq) were acquired from the reconstructed image of Jaszczak phantom study, we calculated the absolute activity concentration (kBq /ml)of the hot sphere from IEC phantom study, then checking computations the quantitative accuracy of all. Change the reconstruction algorithm (2D-OSEM, FBP) and OSEM reconstruction parameters (number of iterations and subsets) to reconstruct the IEC phantom, Compared the difference of quantitative results from different reconstruction algorithms and OSEM iterations and subsets. Results: When reconstructing images with 3D-OSEM, 2D-OSEM and FBP, the average quantitative error of each sphere increases with the decrease of the spherical volume(r= 0.831,0.831,0.826, p all&lt;0.05). The average difference between the quantitative values and the true values of the different volume spheres among the three reconstruction algorithms was statistically significant (F = 8.850, p &lt;0.05), among them that 3D -OSEM was less than 2D-OSEM (352 ± 198 and 423 ± 164 kBq / ml, p &lt;0.05), 2D-OSEM was less than FBP (423 ± 164 and 695 ± 36 kBq / ml, p &lt;0.05).The quantitative error of the seven different volume spheres (26.25 ~0.52ml) decreased with the increase of the number of iterations (r = 0.721, 0.681, 0.691, 0.711,0.845,0.893, p all&lt;0.05), and decreased with the increase of the number of subsets (r = 0.670, 0.694, 0.717, 0.852, 0.956, 0.998, p all&lt;0.05), But there was a significant difference in the variation between different volumetric spheres, the variation of the quantitative error tends to be stable when the number of iterations is greater than 8 and the number of subsets is greater than 6 in the larger sphere (26.25 ~ 5.57ml), and it was stable when the number of iterations is greater than 16,but it was continue to decreasd as the number of subsets increases in the smaller sphere (2.57 ~0.52ml). Conclusions: The quantitative accuracy of 3D- OSEM reconstruction based on CT attenuation correction and scattering correction is significantly better than 2D-OSEM and FBP. Choosing the appropriate OSEM reconstruction parameters is helpful to improve the quantification accuracy in SPECT/CT.