Abstract
1204
Objectives: Many factors affect SUV in 18F-FDG PET/CT, There is therefore a need for standardization of SUV. This article evaluated the most important factors related to quantification with SUV measurements, the potential errors in SUV calculation and also used the standardization of procedures to avoid or minimize errors.
Methods: During 18 months, 52 patients referred to our hospital for staging or restaging of malignant tumors were included in this study retrospectively. Among these patients, twenty underwent two 18F-FDG PET/CT examinations for the purpose of therapy monitoring (Table 1). Mean (SD) 18F-FDG dosage was 0.101 (0.015) mCi per Kg of body weight. The delay (SD) between tracer injection and image acquisition was 59.56 (7.89) min in the present study. For the 20 patients underwent two PET/CT scans, mean (SD) post injection delay times was 60.30 (10.42) min and 57.10 (8.06) min for first and second scans respectively, there was no significant difference between them (t test, P>0.05). Mean (SD) glucose level was 5.39 (0.76) mmol/L for all patients with first scan. For the 20 patients underwent two PET/CT scans, mean (SD) glucose level was 4.95 (0.67) mmol/L and 5.43 (0.67) mmol/L for first and second scans respectively, there was significant difference between them (P<0.05). The SULpeak (this is a sphere with a diameter of approximately 1.2 cm to produce a 1 cm3 volume spherical VOI) centering around the hottest point in the tumor foci was determined.
Results: The mean SULmean (SD) for liver and blood pool were 1.80 (0.23) and 1.32 (0.19), respectively for all patients with first scan. In the subset of 20 patients that underwent two PET/CT examinations for therapy monitoring, the mean SULmeam (SD) for liver on PET1 and PET2 images were 1.76 (0.25) and 1.93 (0.28), respectively, there was significant difference (p<0.05). The mean difference value (SD) of liver SULmean between two scans was 0.17 (0.25), from -0.75 to 0.11. The mean SULmeam (SD) for blood pool on PET1 and PET2 images were 1.26 (0.17) and 1.39 (0.18), respectively, there was significant difference (p<0.05). The mean difference value (SD) of bloodpool SULmean between two scans was 0.13 (0.20), from -0.73 to 0.24. For the 52 patients with first scan, the mean SULpeak (SD) was 8.43 (5.90) for all lesions, primary tumour lesions and metastatic lesions were 10.48 (7.26) and 7.12 (4.40), respectively; the mean SULmean (SD) was 6.14 (4.32) for all lesions, primary tumour lesions and metastatic lesions were 7.42 (5.26) and 5.32 (3.38), respectively. For 20 patients underwent both a pre- and post-therapy PET/CT evaluation, overall, 57 lesions were evaluated post-treatment: 20 (14.3 %) primary tumour lesions, 37 (48.8 %) metastatic lesions. When PERCIST was used for interpreting both pre- and post-therapeutic PET examinations (PET1/PET2), 10 patients were considered to have had a CMR, 3 a PMR, 5 were stable and 2 had progressed.
Conclusions: This study evaluated a protocol for standardization of quantitative 18F-FDG whole body PET/CT scans via comprehensive routine quality control while addressing impact factors. The data were successfully introduced for establishing guidelines for China Society of Nuclear Medicine on the topics QC and SUV normalization.