FDG PET - ELEVATED PLASMA-GLUCOSE REDUCES BOTH UPTAKE AND DETECTION RATE OF PANCREATIC MALIGNANCIES

The aim of the study was to evaluate the effects of elevated plasma gl ucose levels on tumor detection. Methods: One-hundred and seventy-one fasted patients (100 malignant pancreatic tumors, 46 chronic pancreati tis and 25 patients with other benign pancreatic lesions) were studied with F-18-fluorodeoxyglucose (FDG) PET before planned resective pancr eatic surgery. Nineteen of 171 patients had elevated plasma glucose le vels above 130 mg/dl, and 24 of 171 had diabetes mellitus. Standard up take values (SUVs) with and without glucose correction, tumor-to-muscl e ratios and tumor-to-liver ratios were measured of the pancreatic les ion respective of the area with the highest uptake within the pancreas . The original qualitative PET reports concerning the dignity of the p ancreatic lesion were translated into a five-point malignancy scale. T umor detection rates and SUVs were compared according to plasma glucos e levels above and below 130 mg/dl, the presence of diabetes and by us ing receiver operating characteristic (ROC) analysis. Results: The det ection rates (and mean SUVs) for pancreatic malignancies were 86% and 42% (4.2 and 2.3) if fasted plasma glucose levels were below and above 130 mg/dl, respectively. The sensitivities (and mean SUVs of malignan t tumors) were 83% and 69% (3.3 and 2.5) for patients without and with known diabetes. Areas under ROC curves were nearly equal for glucose corrected SUV and visual qualitative results (0.86 and 0.85), followed by uncorrected SW (0.83), tumor-to-liver ratios (0.80) and tumor-to-m uscle ratios (0.79). SUVs for chronic pancreatitis, muscle and liver h ad a tendency to increase with elevated plasma glucose levels. Conclus ion: Negative PET results of patients with elevated plasma glucose sho uld be interpreted with caution.