Abstract
PurposeThe objective of this study was to explore the feasibility of harmonising performance for PET/CT systems equipped with time-of-flight (ToF) and resolution modelling/point spread function (PSF) technologies. A second aim was producing a working prototype of new harmonising criteria with higher contrast recoveries than current EARL standards using various SUV metrics.MethodsFour PET/CT systems with both ToF and PSF capabilities from three major vendors were used to acquire and reconstruct images of the NEMA NU2–2007 body phantom filled conforming EANM EARL guidelines. A total of 15 reconstruction parameter sets of varying pixel size, post filtering and reconstruction type, with three different acquisition durations were used to compare the quantitative performance of the systems. A target range for recovery curves was established such that it would accommodate the highest matching recoveries from all investigated systems. These updated criteria were validated on 18 additional scanners from 16 sites in order to demonstrate the scanners’ ability to meet the new target range.ResultsEach of the four systems was found to be capable of producing harmonising reconstructions with similar recovery curves. The five reconstruction parameter sets producing harmonising results significantly increased SUVmean (25%) and SUVmax (26%) contrast recoveries compared with current EARL specifications. Additional prospective validation performed on 18 scanners from 16 EARL accredited sites demonstrated the feasibility of updated harmonising specifications. SUVpeak was found to significantly reduce the variability in quantitative results while producing lower recoveries in smaller (≤17 mm diameter) sphere sizes.ConclusionsHarmonising PET/CT systems with ToF and PSF technologies from different vendors was found to be feasible. The harmonisation of such systems would require an update to the current multicentre accreditation program EARL in order to accommodate higher recoveries. SUVpeak should be further investigated as a noise resistant alternative quantitative metric to SUVmax.
Highlights
The aim of this paper is to explore the feasibility of harmonising performance of positron emission tomography (PET)/computed tomography (CT) systems equipped with the latest PET technologies such as TOF and point spread function (PSF), which were recently commercially released
The primary objective of this study was to find reconstruction modes providing high, yet uniform contrast recoveries within the spheres of the NEMA NU2–2007 body phantom, which could be matched across all generations of PET/CT systems currently used in clinical practice – which would result in quantitative harmonisation of PET/CT systems
Despite possible limitations, we have studied the feasibility of the harmonising state of the art PET/CT system performances, and the results suggest that an update of the EANM Research Limited (EARL) current specification is feasible and achievable in practice
Summary
18F–fluorodeoxyglucose (18F–FDG) positron emission tomography (PET) and computed tomography (CT) hybrid imaging (PET/CT) is an important functional imaging tool being widely used for diagnosis, staging and therapy response evaluation in, e.g., oncology [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. Variability, reproducibility and accuracy of quantitative PET/CT imaging [28,29,30,31,32,33,34] have to be considered Scientific societies such as the European Association of Nuclear Medicine (EANM), American College of Radiology (ACR), American Association of Physicists in Medicine (AAPM), Radiological Society of North America (RSNA) and Society of Nuclear Medicine and Molecular Imaging (SNMMI) are closely collaborating to promote standardisation of practices in order to reduce variability of quantification in multicentre clinical trials.
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