Basic Science Investigation
Phantom study of the influence of time of flight and point spread function on PET/CT image quality and standardized uptake value
Huang Kemin, Feng Yanlin, Liang Weitang, Li Lin, Deng Dalang, He Weiping, Feng Yexia
Published 2021-07-25
Cite as Chin J Nucl Med Mol Imaging, 2021, 41(7): 420-424. DOI: 10.3760/cma.j.cn321828-20200220-00060
Abstract
ObjectiveTo explore the influence of time of flight (TOF) and point spread function (PSF) on PET/CT image quality and standardized uptake value (SUV) based on a phantom study.
MethodsPET/CT imaging were performed using Jaszczak phantom and International Electrotechnical Commission (IEC) body phantom respectively, and conventional clinical imaging protocol (3 min/bed) was used for three consecutive imaging. The ordered subsets expectation maximization (OSEM), OSEM+ TOF, OSEM+ PSF and OSEM+ TOF+ PSF were used to reconstruct the raw data respectively. The differences of image resolution, image uniformity, contrast, signal to noise ratio (SNR) and SUV among different reconstruction algorithms were compared by using one-way analysis of variance and the least significant difference (LSD) t test. The correlations between SNR, mean SUV (SUVmean), maximum SUV (SUVmax) and the sphere diameter were analyzed by Pearson correlation analysis.
ResultsThe minimum image resolution for the hot column was 6.4 mm by OSEM and OSEM+ PSF reconstruction, while it was 4.8 mm by OSEM+ TOF and OSEM+ TOF+ PSF reconstruction. The contrast was significantly better by OSEM+ TOF ((78.56±1.21)%) and OSEM+ TOF+ PSF ((78.85±1.17)%) reconstruction than that by OSEM reconstruction ((73.44±1.47)%; F=61.068, t values: 9.503, 10.018, both P<0.001). The maximum and minimum nonuniformity percentages were significantly better for images reconstructed with OSEM+ PSF than those reconstructed with OSEM (F values: 10.286, 27.630, t values: -2.599, 7.698, both P<0.05). In IEC phantom imaging, the SNR and SUVmax of hot sphere were higher by OSEM+ PSF and OSEM+ TOF+ PSF reconstruction than those by OSEM reconstruction (SNR: (98.99±34.76)%, (98.29±28.66)%, (73.64±26.05)%; F=5.712, t values: 3.209, 3.412, both P<0.05; SUVmax: 8.96±2.72, 9.28±2.17, 8.01±2.21; F=3.931, t values: 2.154, 2.863, both P<0.05), but there was no significant difference between OSEM+ TOF and OSEM reconstruction (t values: 0.297, 0.272, both P>0.05). Among the four reconstruction methods, the SNR and SUVmean increased with the increase of the sphere diameter (r values: 0.913-0.963, all P<0.05), but SUVmax in images reconstructed with OSEM+ PSF and OSEM+ TOF+ PSF had no significant correlations with the sphere diameter (r values: 0.496, 0.614, both P>0.05).
ConclusionsUnder specific acquisition and reconstruction conditions, TOF mainly improves image resolution and contrast, while PSF mainly improves image uniformity and SNR. The combination of the two method can obtain better image quality and significantly improve the SUV of hot lesions.
Key words:
Models, structural; Image processing, computer-assisted; Positron-emission tomography; Tomography, X-ray computed; Deoxyglucose
Contributor Information
Huang Kemin
Department of Nuclear Medicine, the First People′s Hospital of Foshan, Foshan 528000, China
Feng Yanlin
Department of Nuclear Medicine, the First People′s Hospital of Foshan, Foshan 528000, China
Liang Weitang
Department of Nuclear Medicine, the First People′s Hospital of Foshan, Foshan 528000, China
Li Lin
Department of Nuclear Medicine, the First People′s Hospital of Foshan, Foshan 528000, China
Deng Dalang
Department of Nuclear Medicine, the First People′s Hospital of Foshan, Foshan 528000, China
He Weiping
Department of Nuclear Medicine, the First People′s Hospital of Foshan, Foshan 528000, China
Feng Yexia
Department of Nuclear Medicine, the First People′s Hospital of Foshan, Foshan 528000, China
