Diagnosis and staging of pancreatic cancer by positron emission tomography

The detection of pancreatic cancer or the discrimination between pancreatic cancer and chronic pancreatitis remains an important diagnostic problem. Several imaging modalities are now used to diagnose pancreatic cancer, including transabdominal ultrasonography (US), contrast-enhanced computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasonography, and selective angiography. None of these six methods is perfect: Each has advantages and disadvantages, and their sensitivity and specificity are in a high range. In 1990 positron emission tomography (PET) was first applied to diagnose pancreatic cancer. This new diagnostic modality is based on functional changes in the pancreatic cancer cells caused by enhanced glucose metabolism. Increased glucose utilization is one of the characteristics of malignantly transformed cells, independent of their origin. The technical development of PET has allowed this new procedure to be used for clinical evaluation. Using 2-(F-18)-fluoro-2-deoxy-D-glucose, PET can identify pancreatic cancer and differentiate pancreatic cancer from chronic pancreatitis with a sensitivity of 85% to 98% and a specificity of 53% to 93%. However, high sensitivity and high specificity are strongly dependent on the tumor stage. At present PET is still experimental and is available only in specialized centers. It may represent a new and noninvasive diagnostic procedure for the detection and the staging of pancreatic cancer. Further clinical studies, especially including patients with early tumor stages (small tumor size), are needed. This review discusses the possibilities and limits of PET and evaluates its importance in the future.