Elsevier

Translational Oncology

Volume 7, Issue 1, February 2014, Pages 48-54
Translational Oncology

Biases in Multicenter Longitudinal PET Standardized Uptake Value Measurements1

https://doi.org/10.1593/tlo.13850Get rights and content
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Abstract

This study investigates measurement biases in longitudinal positron-emission tomography/computed tomography (PET/CT) studies that are due to instrumentation variability including human error. Improved estimation of variability between patient scans is of particular importance for assessing response to therapy and multicenter trials. We used National Institute of Standards and Technology-traceable calibration methodology for solid germanium-68/gallium-68 (68Ge/68Ga) sources used as surrogates for fluorine-18 (18F) in radionuclide activity calibrators. One cross-calibration kit was constructed for both dose calibrators and PET scanners using the same 9-month half-life batch of 68Ge/68Ga in epoxy. Repeat measurements occurred in a local network of PET imaging sites to assess standardized uptake value (SUV) errors over time for six dose calibrators from two major manufacturers and for six PET/CT scanners from three major manufacturers. Bias in activity measures by dose calibrators ranged from −50%to 9%and was relatively stable over time except at one site that modified settings between measurements. Bias in activity concentration measures by PET scanners ranged from −27% to 13% with a median of 174 days between the six repeat scans (range, 29 to 226 days). Corresponding errors in SUV measurements ranged from −20% to 47%. SUV biases were not stable over time with longitudinal differences for individual scanners ranging from −11% to 59%. Bias in SUV measurements varied over time and between scanner sites. These results suggest that attention should be paid to PET scanner calibration for longitudinal studies and use of dose calibrator and scanner cross-calibration kits could be helpful for quality assurance and control.

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1

This work was supported by a National Cancer Institute Cancer Imaging Program Science Applications International Corporation (SAIC) contract 24XS036-004 and U01 grant CA148131 from the National Institutes of Health.