Clinical effects of hyperglycemia on FDG uptake of tumor and brain in patients with suspected cancer.

Objectives: The purpose of this study was to evaluate the effects of hyperglycemia on FDG uptake of the brain, liver, muscle and tumor in clinical situation.Methods: Fifty-seven patients (mean age: 64.8+-8.9, range: 42-79, male : female=40 : 17) who showed blood glucose level more than 200 mg/dl at the time of examination (mean glucose level: 255.5+-69.3, range: 201-666) were included in this retrospective study. All patients received FDG-PET scan for suspected cancer in Kyoto University Hospital from January 2001 to December 2005 and fasted at least 4 hours before PET study. Reasons of hyperglycemia were follows; untreated diabetes: n=5, uncontrolled diabetes: n=32, unknown: n=20. FDG accumulation of the tumor was visually analyzed. SUV of the brain, liver, muscle and tumor were also analyzed.Results: Presence or absence of malignant lesion was confirmed by other modality such as CT, surgery, and clinical follow-up at least 6 month in 49 patients and malignant lesion(s) were finally diagnosed in 35 patients. Twenty eight of 35 patients had positive results by visual analysis (lung cancer: 7, pancreas cancer: 7, liver metastases: 3, lung metastases: 3, hepatocellular carcinoma: 2, bone metastases: 2, etc.) and the average of tumor SUV was 5.7+-2.5. False negative results were observed in 7 cases which consisted of so-called low-FDG-avid tumors (hepatocellular carcinoma: 3, pancreas cancer: 3, small lung metastasis from pancreas cancer: 1) and the average of tumor SUV was 2.7+-0.8. In contrast to relatively stable tumor FDG uptake, brain FDG uptake tended to be lower in this high glucose level (SUV=4.4+-1.1), as compared to that in normoglycemia (SUV=11.8+-2.6). Liver, muscle and tumor FDG uptake didnt show clear correlation with blood glucose level. Specificity, sensitivity and PPV of FDG-PET scan were 67%, 97% and 80% respectively. Conclusions: In spite of high blood glucose level (more than 200 mg/dl),FDG uptake of the tumor maintained enough high level for visual diagnosis in majority of cases, except for the cases of low-FDG-avid tumors, such as hepatocellular carcinoma and pancreas cancer.Society of nuclear medicine 54rd Annual Meetn