Absolute quantitative phantom of SPECT/CT imaging based on specified reconstruction algorithms and correction methods / 中华核医学与分子影像杂志

ABSTRACT

Objective To investigate the methodology for absolute quantification with SPECT/CT using specified reconstruction algorithms and correction methods,and to determine the influence factors for quantitative accuracy.Methods The routine SPECT/CT imaging were performed with Jaszczak cylindrical phantom and International Electrotechnical Conmission (IEC) body phantom using a given acquisition and reconstruction parameter.The system volume sensitivities(SvoI)were acquired from the reconstructed images of Jaszczak phantom study.The absolute radioactivity of the hot spheres from IEC phantom study was calculated,and then the quantitative accuracies were checked.Differences of absolute quantitative value on quantitative accuracy were compared between 3 dimensional (3D)-ordered-subsets expectation maximization (OSEM) and 2 dimensional (2D)-OSEM,CT attenuation correction (AC) and no attenuation correction (NOAC),scatter correction (SC) and no scatter correction (NOSC),partial volume effect (PVE) correction and no PVE correction.Two-sample t test,one-way analysis of variance and Pearson correlation analysis were used.Results When 3D-OSEM,CTAC,SC and PVE correction were used,the average difference between absolute quantitative value and true value (374 kBq/ml) was-2.49％ in 6 hot spheres,and there was no obvious correlation between the quantitative error and the spheres volume (r=-0.795,P＞0.05).In the absence of PVE correction,the quantitative error of each sphere increased with the decrease of sphere volume (r=-0.852,P＜0.05).Differences of the quantitative value and the true value for 6 hot spheres among different reconstruction/correction methods were statistically significant (F =826.631,P＜0.05).The difference was smaller in 3D-OSEM+CTAC+NOSC than that in 2D-OSEM+CTAC+NOSC(52.83±13.79) vs (61.33 ± 15.00) k Bq/ml (P＜0.05).The similar results were found when comparing differences between 3DOSEM+CTAC+SC and 3D-OSEM+CTAC+NOSC,also between 3D-OSEM+CTAC+NOSC and 3D-OSEM+ NOAC+NOSC(9.33±5.47) vs (52.83±13.79) kBq/ml,(52.83±13.79) vs (307.66±9.24) kBq/ml (both P＜0.05).Conclusions An accurate absolute quantitative value could be obtained with 3D-OSEM reconstruction algorithm,CTAC,SC and PVE correction in SPECT/CT imaging.