Impact of image reconstruction methods on quantitative accuracy and variability of FDG-PET volumetric and textural measures in solid tumors
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This study aims to assess the impact of different image reconstruction methods on PET/CT quantitative volumetric and textural parameters and the inter-reconstruction variability of these measurements.
A total of 25 oncology patients with 65 lesions (between 2017 and 2018) and a phantom with signal-to-background ratios (SBR) of 2 and 4 were included. All images were retrospectively reconstructed using OSEM, PSF only, TOF only, and TOFPSF with 3-, 5-, and 6.4-mm Gaussian filters. The metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were measured. The relative percent error (ΔMTV and ΔTLG) with respect to true values, volume recovery coefficients, and Dice similarity coefficient, as well as inter-reconstruction variabilities were quantified and assessed. In clinical scans, textural features (coefficient of variation, skewness, and kurtosis) were determined.
Among reconstruction methods, mean ΔMTV differed by -163.5 ± 14.1% to 6.3 ± 6.2% at SBR2 and -42.7 ± 36.7% to 8.6 ± 3.1 at SBR4. Dice similarity coefficient significantly increased by increasing SBR from 2 to 4, ranging from 25.7 to 83.4% between reconstruction methods. Mean ΔTLG was -12.0 ± 1.7 for diameters > 17 mm and -17.8 ± 7.8 for diameters ≤ 17 mm at SBR4. It was -31.7 ± 4.3 for diameters > 17 mm and -14.2 ± 5.8 for diameters ≤ 17 mm at SBR2. Textural features were prone to variations by reconstruction methods (p < 0.05).
Inter-reconstruction variability was significantly affected by the target size, SBR, and cut-off threshold value. In small tumors, inter-reconstruction variability was noteworthy, and quantitative parameters were strongly affected. TOFPSF reconstruction with small filter size produced greater improvements in performance and accuracy in quantitative PET/CT imaging.
• Quantitative volumetric PET evaluation is critical for the analysis of tumors.
• However, volumetric and textural evaluation is prone to important variations according to different image reconstruction settings.
• TOFPSF reconstruction with small filter size improves quantitative analysis.
KeywordsPET-CT Image reconstruction Tumor burden Radiation oncology
Coefficient of variation
Full width at half maximum
3D-OSEM algorithm referred to as HD
Metabolic tumor volume
National electrical manufacturers association
Ordered subset expectation maximization
Positron emission tomography
Point spread function
Standard deviation of inter-reconstruction variation for each VOI
Standard deviation of voxel intensity distribution for each VOI
Standard uptake value
Maximum standard uptake value
Mean standard uptake value
Total lesion glycolysis
Time of flight
Time of flight and point spread function
Volume of interest
Volume recovery coefficients
This study has received funding by the Tehran University of Medical Sciences, Tehran, Iran, under grant number 28212; and Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Compliance with ethical standards
The scientific guarantor of this publication is Mohammad Reza Ay, PhD, Professor of Medical Physics.
Conflict of interest
The authors declare that they have no conflict of interest.
Statistics and biometry
One of the authors has significant statistical expertise.
Written informed consent was waived by the Institutional Review Board.
Institutional Review Board approval was obtained.
• Diagnostic or prognostic study/experimental
• Performed at one institution
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