Standardization of PET/CT Performance Requirements for Whole-Body Quantitative Imaging: An International Proposal

Currently, PET scanner validation phantoms, methods, and acceptance criteria for clinical trials are not standardized. This situation generates substantial inefficiencies with many scanners being tested multiple times for different trials. Herein we propose a standardized PET scanner validation paradigm for clinical trials. Methods: At present, active PET scanner validation programs administered by the European Association of Nuclear Medicine Research Ltd. (EARL), the Society of Nuclear Medicine and Molecular Imaging Clinical Trials Network (CTN), and Australia New Zealand Society of Nuclear Medicine Australasian Radiopharmaceutical Trials Network are reviewed in detail to identify similarities, differences, strengths, and weaknesses. PET criteria that help define the quantitative performance characteristics most critical for clinical trials are identified. Historical quantitative scanner performance capabilities are reviewed, including increasing availability of primary and secondary standard activity measurements for calibration purposes. Methodologies for these phantom-based measurements are reviewed, and standardized approaches are recommended. Results: Phantom requirements, acquisitions, reconstruction, analysis, and acceptance criteria have all been developed to be reasonably aligned with current standard scanner validation approaches, while at the same time recommending improvements and clarifications where programmatic differences were identified. A scanner validation program based on the measurement of radionuclide specific scanner calibration and harmonized recovery coefficient performance is proposed. Quarterly calibration verification of ¹⁸F and annual calibration of other radionuclides are recommended. Accuracy of ±5% for ¹⁸F calibration and ±10% for other radionuclides are proposed acceptance criteria. Annual verification of EARL 2-concordant recovery coefficient performance using a National Electrical Manufacturers Association NU2 image quality phantom or CTN5 phantom imaged at an 8:1 target-to-background contrast is recommended, although contrast recovery coefficients, rather than recovery coefficients, are advised. Conclusion: An internationally standardized PET scanner validation paradigm is proposed. International adoption of such a system combined with a data-sharing system would create a more efficient, robust, uniform, and trustworthy scanner validation environment for clinical trials while improving clinical trial qualification efficiency, decreasing costs and mitigating duplication of testing.