(18)FDG-positron emission tomography in pancreatic cancer

Positron emission tomography: Malignant cells present an increased glucose consumption compared to normal pancreatic tissue. Positron emission tomogra phy with F-18 fluoro - D-deoxyglucose is a new imaging tool to in vivo asse ss the amount of glucose metabolism. This method provides metabolic informa tion on tumors rather than morphological information. Methods: In most PET centers a static emission scan of the upper abdomen is performed 45 - 60 minutes after intravenous administration of the radiotra cer. To obtain quantitative parameter an additional transmission scan is ne cessary to correct for attenuation. Today, both visual analysis and semiqua ntitative parameters of glucose consumption as the Standardized Uptake Valu e (SUV) are used for image interpretation. To allow coregistration of the m etabolic PET images and morphological imaging tools as CT or MRI external m arkers may be used. Following exact reorientation both the metabolic inform ation (PET) and the morphologic information (MRI/CT) can be merged in one 3 D data set (image fusion). Results: In our series of patients the sensitivity for PET to detect pancre atic cancer was 85%, the specificity 84%. False negative results were obtai ned in patients with hyperglycemia, false positive results in patients with chronic active pancreatitis. Excluding hyperglycemic patients the sensitiv ity for PET increased to 98%. In a sample statistics of 305 euglycemic pati ents sensitivity, specificity and accuracy were 92%, 79%, and 87%, respecti vely. Image fusion of metabolic (PET) and morphologic data (MRI/CT) can hel p to better localize the focus of increased glucose consumption demonstrate d with PET and to differentiate multifocal cancer from lymph node metastase s. Conclusion: (18)FDG PET is a feasible diagnostic modality to differentiate benign and malignant pancreatic masses when morphological imaging is equivo cal. Image fusion of PET and CT or MRI can combine the advantages of both m odalities in one image - detailed anatomic information combined with accura te metabolic data.