Method to Determine the Statistical Technical Variability of SUV Parameters

Abstract Background: Some of the parameters used for the quantification of Positron Emission Tomography (PET) images are the Standardized Uptake Value (SUV)Max, SUVMean and SUVPeak. In order to assess the significance of an increasing or decreasing of these parameters for diagnostic purposes it is relevant to know their standard deviation. The sources of the standard deviation can be divided in biological and technical. In this study we present a method to determine the technical variation of the SUV in PET images.Results: This method was tested on images of a NEMA quality phantom with spheres of various diameters with full-length acquisition time of 150 s per bed position and foreground to background activity ratio of F18-2-fluoro-2-deoxy-D-glucose (FDG) of 10:1. Our method is based on dividing the full-length 150 s acquisition into subsets of shorter time length and reconstructing the images in the subsets. The SUVMax, Mean and Peak were calculated for each reconstructed image in a subset. The coefficient of deviation of the SUV parameters within each subset has then been used to estimate the expected standard deviation between images at 150 s reconstruction length. We report the largest technical variation of the SUV parameters for the smallest sphere, and the smallest variation for the largest sphere. The expected variation at 150 s reconstruction length does not exceed 6% for the smallest sphere and 2% for the largest sphere. Conclusions: With the presented method we are able to determine the technical variation of SUV. The method enables us to evaluate the effect of parameter selection and lesion size on the technical variation, and therefore to evaluate its relevance on the total variation of the SUV value between studies.