The aim of the study was to evaluate the robustness of the calibration procedure against the counting statistics and lesion volumes when using an adaptive thresholding method for the delineation of 2-[18F]fluoro-2-deoxyglucose (18F-FDG)-PET-positive tissue.
Three data sets obtained from physical and simulated images of a phantom containing hot spheres of known volume and contrast were used to study the robustness of the calibration procedure against the counting statistics and range of volumes and contrasts for a given PET model. The mathematical expression of the adaptive thresholding method used corresponds to a linear relationship between the optimal threshold value and the inverse of the local contrast. Robustness was evaluated by testing whether the slopes and intercepts of the linear expression found under two experimental conditions were significantly different (P<0.05).
It was found that the calibration step was not sensitive to the PET device for the studied PET model, nor to the counting statistics for a signal-to-noise ratio higher than 5.7. No statistical difference was found in the calibration step when using a wide range of volumes (0.2–200 ml) and contrasts (2.0–20.6) or more restricted ones (0.43–97.3 ml and 2.0–7.7, respectively). Therefore, a calibration procedure using limited experimental conditions can be applied to a wider range of volumes and contrasts.
These results show that the manufacturer could propose simulated or experimental raw data corresponding to a given PET model with high counting statistics, allowing each clinical center to reconstruct calibration images according to the algorithm parameters used in the clinic.
aLITIS Laboratory EA 4108 – QUANT.I.F, University of Rouen
bDepartment of Nuclear Medicine, Henri Becquerel Centre and Rouen University Hospital, Rouen
cSiemens Medical Solutions, Bobigny
dDepartment of Nuclear Medicine and Medical Imaging Analysis, Amiens University Hospital
eMedical Image Processing Department, University of Picardy Jules Verne, Amiens, France
Correspondence to Isabelle Gardin, PhD, Department of Nuclear Medicine, CHB, 1 rue d’Amiens, 76038 Rouen, Cedex, France Tel: +33 232 082 254; fax: +33 232 082 550; e-mail: firstname.lastname@example.org
Received June 25, 2012
Accepted February 6, 2013