Standard uptake values in whole-body FDG PET: effects of acquisition and processing parameters

摘要

Standard uptake values, SUV, are commonly used semiquantitative parameters in tumor diagnosis, staging and monitoring therapy response. However, their accuracy and reproducibility is affected by the glucose level, length of the uptake period, and body weight and composition. The aim of this study is to evaluate the effects of PET acquisition parameters (count rate, SNR, 2D vs 3D, object geometry) and image reconstruction parameters (Filtered backprojection, (FBP), iterative reconstruction (OSEM), filter selection) on calculated SUVs. The evaluation was done using circular and elliptical cylinders with spherical sources from 0.6-3.5 cm in dia, with sphere to background activity concentration varied from 2:1 to 20:1. Coincidence count rate varied from 5 kcps to 600 kcps. All studies were acquired in 2D and 3D mode, with variable emission (3-10 min) and transmission time durations (2-10 min). Reconstruction was performed with both FBP and OSEM with 2-10 iterations and 8-32 subsets. SUVs were estimated using the average and the maximum count density from ROIs placed in the center of the structure of interest The evaluation was done on the CTI ECAT HR + high resolution PET scanner and the biograph PET/CT LSO system. The variation in the calculated SUVs as a function of selected acquisition and processing parameters in addition to the variations due to patient dependent parameters indicated that distinguishing between benign and malignant disease based on SUVs, and using SUVs as semiquantitative parameters in the follow-up studies has to be interpreted with caution.