Need for Standardization of ¹⁸F-FDG PET/CT for Treatment Response Assessments

Abstract

Many factors affect standardized uptake values (SUVs) in 18 F-FDG PET/CT. The use of the SUV from a single PET scan in multicenter studies requires the standardization of 18 F-FDG PET/CT procedures. In the context of treatment response assessments (repeated PET scans), many factors may seem to have minor effects on percentage changes in SUVs, provided that imaging procedures are executed in a consistent manner for each subject. However, the use of 18 F-FDG PET/CT in a nonstandardized manner will result in unknown biases and reproducibilities of SUVs and SUV-based response measures. This article provides an overview of the need for standardization in relation to the specific use of SUVs and SUV changes in studies of treatment response assessments. Vi sual inspection of 18 F-FDG PET whole-body studies is important for diagnosis and staging (1). However, quantitative PET is increasingly being recognized as an important tool for prognosis and response monitoring (2-5). For the quantification of 18 F-FDG PET studies, various methods, which differ with regard to the complexity of data collection and (mathematic) analysis, have been described; these include tumor-to-background ratios, standardized uptake values (SUVs), and full kinetic analysis (6,7).Semiquantitative analysis by means of SUVs is clinically feasible because an SUV is available in every clinically obtained whole-body scan. It is a simple index for glucose metabolism and can be obtained with good reliability, provided that 18 F-FDG PET/CT studies (including proper calibration procedures) are acquired in a standardized manner. A recent review of existing guidelines and factors affecting SUV results (8) demonstrated how to obtain accurate and reproducible SUV results in single-center and multicenter settings.

Association Between 18F-FDG Avidity and the BRAF Mutation in Papillary Thyroid Carcinoma

“…This scanner difference might be mitigated by voxel resampling and SUV harmonization for proper quantification, although the spatial resolution and image quality were not optimal for the detection of 18 F-FDG avid lesion on each scanner and were more affected by the partial volume effect. Therefore, we generated two sets of images for each PET/CT examination, i.e., one to provide optimal lesion detection and the other to meet the quantitative harmonizing standards [34], after which both visual analysis of the 18 F-FDG avidity and semiquantitative analysis of the SUV max were performed. The visual analysis was advantageous for small lesion detection, and the kappa statistics showed that inter-observer agreement for analysis of the 18 F-FDG avidity was very good.…”

Role of Positron Emission Tomography for the Monitoring of Response to Therapy in Breast Cancer

“…Both studies found a lower predictive value of DSUV. Nevertheless, the strength of DSUV is to be less affected by technical factors than absolute SUV and to be more reproducible among centers in multicentric trials [17], and its predictive value can be improved by the exclusion of low metabolic tumors at baseline [39].…”

Optimisation and harmonisation: two sides of the same coin?

“…The task at hand is to derive quantitative measures, such as SUV, from the PET/CT studies in a harmonised manner. The figure of merit to be optimised relates to the accuracy and precision of SUVs across multiple institutions having different PET/CT systems [18][19][20]. Harmonisation in this case means that sites are able to generate SUVs with a comparable and known accuracy and precision in a manner that is feasible for all sites in a multicentre setting.…”

“…Often, use of these new technologies is preferred by the nuclear medicine physicians for visual assessment of the images [16,17]. At the same time use of these new technologies may result in a wider variability (and change) of SUV across different centres [16,19,21]. Moreover, use of the maximum SUV (SUV max ), being the de facto standard in many studies, in combination with these new technologies may even worsen accuracy and precision [19,22].…”

“…The lack of functionality of generating a second data set by simple post-processing on their PET/CT system or display station has probably forced the authors into doing a second time-consuming reconstruction process. Therefore, it would be extremely useful if PET/CT vendors were able to implement additional post-processing functionality as part of their standard reconstruction process [19], which would create an additional post-processed image data set. Preferably, the post-processing functionality could be automatically attached to acquisition and reconstruction protocols upon user request, after which this second data set is automatically generated following a singe image acquisition and reconstruction.…”