[Clinical diagnostic value of (18)F-FDG PET-CT in incidental finding of focal hypermetabolism focus in the colon and rectum].

OBJECTIVE: To investigate the value of incidental focal (18)F-FDG uptake in the colon and rectum and characteristics of functional anatomic form for differential diagnosis of colorectal benign or malignant diseases. METHODS: Clinical data and images of incidental focal hypermetabolism focus in colon and rectum of 37 individuals undergoing (18)F-FDG PET-CT were analyzed retrospectively. According to the eventual outcomes of pathological examination and clinical follow-up, these cases were divided into four subgroups: malignant disease, benign tumor (including precancerous change), inflammation and physiological uptake. Radioactive uptake level (SUVmax) and change of delayed imaging (RI) of focal hypermetabolism focus were compared between groups. The data analysis was performed using variance analysis. RESULTS: The average SUVmax was 6.3±3.7, 8.8±6.5, 5.2±1.4, and 3.8±0.9 in malignant disease (n=11), benign (precancerous) tumor (n=9), inflammation (n=9) and physiological uptaking (n=8) respectively. The average SUVmax was 7.6±5.6 in benign and malignant tumor, and 4.7±1.5 in inflammation and physiological uptake. The distinction of average SUVmax was not statistically significant between benign and malignant tumor or inflammation and physiological uptake. But it was higher in tumors as compared to inflammation or physiological uptake with a statistically difference (P<0.05). The RI was 0.3±0.2, 0.4±0.1, 0.3±0.2, 0.4±0.2 in above 4 groups respectively, and the differences were not statistically significant. CONCLUSIONS: The incidental focal hypermetabolism focus in the colon the rectum during (18)F-FDG PET-CT may indicate potential colorectal malignant diseases and precancerous lesions. SUVmax value in focal hypermetabolism focus in the colon and rectum can help to distinguish tumor from inflammation or physiological uptake. But there is no diagnostic value for distinguishing malignant disease from benign tumor.

[Transport processes of low-level radioactive liquid effluent of nuclear power station in closed water body].

The transport processes of low-level radioactive liquid effluent of Xianning nuclear power station in the closed water body Fushui Reservoir are simulated using the EFDC model. Six nuclides concentration distribution with different half-lives in the reservoir are analyzed under the condition of 97% guarantee rate incoming water and four-running nuclear power units. The results show that the nuclides concentration distribution is mainly affected by the flow field of the reservoir and the concentration is decided by the half-lives of nuclide and the volume of incoming water. In addition, the influence region is enlarged as increasing of half-life and tends to be stable when the half-life is longer than 5 years. Moreover, the waste water discharged from the outlet of the nuclear power plant has no effect on the water-intake for the outlet located at the upstream of the water-intake and the flow field flows to the dam of the reservoir.