Nuklearmedizin 2020; 59(02): 147
DOI: 10.1055/s-0040-1708302
Wissenschaftliche Poster
Medizinische Physik II
© Georg Thieme Verlag KG Stuttgart · New York

Reducing [ 18 F]FDG activity levels for whole-body PET/CT examinations of children

H Kertesz
1   QIMP Team, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna
,
T Beyer
1   QIMP Team, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna
,
T Traub-Weidinger
2   Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna
,
J Cal-Gonzalez
1   QIMP Team, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna
,
M Hacker
2   Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna
,
T Kitsos
3   Department of Nuclear Medicine, The Children’s Hospital at Westmead, Sydney
,
K London
3   Department of Nuclear Medicine, The Children’s Hospital at Westmead, Sydney
,
PL Kench
4   Discipline of Medical Imaging Sciences and Brain and Mind Centre, Faculty of Health Sciences, The University of Sydney, Sydney
› Author Affiliations
Further Information

Publication History

Publication Date:
08 April 2020 (online)

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    Ziel/Aim To assess the effect of time-of-flight (TOF) on image quality at reduced count levels for whole-body [18F]FDG-PET/CT studies of pediatric oncology patients.

    Methodik/Methods This study included 29 pediatric oncology patients: 12F/17M, (12±5)-y/o, 13£BMI£28, mean FDG concentration of (3.8±08)MBq/kg. All patients underwent whole-body PET/CT examinations on a Siemens Biograph mCT system with TOF capability (500ps).

    The collected [18F]FDG data was preprocessed to simulate reduced count levels (75 %, 50 %, 35 %, 20 % and 10 % of original counts) by random event removal from the original list-mode (LM) data.

    PET images were reconstructed using the vendor e7-tools with standard OSEM algorithm, OSEM with resolution recovery (PSF), with and without TOF information. A 5mm FWHM Gaussian post-filter was applied to all reconstructions.

    The reconstructed images were evaluated for liver noise, signal-to-noise ratio (SNR), and lesion contrast-to-noise ratio (CNR). Further, the SNR and CNR gains with TOF were calculated.

    Ergebnisse/Results Using OSEM, the mean noise level was 11 % (6 %-18 %), adding the TOF information the noise was reduced to 9 % (6 %-15 %). For PSF reconstructions, TOF helped to further reduce the noise level to 8 %. At 50 % counts, the PSF+TOF mean noise level of 10 % was close to 11 % for the 100 % counts OSEM images.

    When including TOF information the SNR and CNR increased by a factor of 1.2-1.3.

    Schlussfolgerungen/Conclusions A 50 % dose reduction potential in pediatric PET/CT is possible when using a 10 % acceptable threshold on noise levels and iterative reconstruction with PSF+TOF. This quantitative analysis of reference regions will be complemented by qualitative grading of image quality by clinical experts.


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