Imaging in Pancreatic Cancer

Abstract

Pancreatic ductal adenocarcinoma is the fifth leading cause of cancer deaths in the Western hemisphere. It represents 90 % of all malignant tumors arising from the pancreatic gland. Early pancreatic cancer often does not cause symptoms and the later symptoms are usually nonspecific and varied. Therefore, pancreatic cancer is often not diagnosed until it is advanced. And despite all the advances in oncological treatments, the overall 5-year-survival rates remain poor (\5 %). On the other hand surgery is still the only curative option but only a minority of cancers is resectable.Therefore the role of the imaging modalities should be to: (a) detect early the pancreatic cancer and (b) stage the tumor and determine if it is locally resectable. DiagnosisThe diagnostic approach usually begins with abdominal ultrasound because it is widely available and noninvasive. Ultrasound (US) may detect pancreatic cancer as an ill-defined hypoechoic mass but usually is performed in order to exclude gallstones, choledocholithiasis, and signs of common bile duct obstruction in patients who are present with abdominal pain and jaundice. The accuracy of US for detection of pancreatic cancer is 50-70 % [1]. However the body habitus, the overlying bowel gas, and the variable operator dependency decrease the sensitivity of the method.CT is the standard imaging modality for accurate diagnosis and staging of pancreatic cancer. The standard protocol for the evaluation of the pancreas consists of two phases after the intravenous administration of contrast media (pancreatic and portal venous phase). During the pancreatic phase or late arterial phase (approximately 30-40 s after the injection of the contrast media) the contrast between the normal parenchyma and the lesion is maximal and also there is sufficient enhancement of the arteries in order to evaluate possible vascular tumor involvement. Portal venous phase is optimal for detecting potential metastatic disease and for the assessing of the peripancreatic veins [2].State-of-the-art protocol with MDCT scanners includes acquisitions with very thin slices (\1 mm) which is crucial for optimizing lesion detection. These isotropic or nearly isotropic data sets are used with postprocessing techniques (MPR, MIP VRT) in order to depict high quality reformatted images. Recent reports have demonstrated the role of reformatted images in the preoperative evaluation of pancreatic cancer regarding the invasion of the peripancreatic vessels and the potential resectability of the pancreatic tumor [3].