Pancreas. Part II: Tumors

Adenocarcinoma is the most common malignant pancreatic tumor, affecting the head in 60-70% of cases. By the time of diagnosis, approximately 80% of tumors are unresectable. Helical CT is very effective in detection and staging of adenocarcinoma, with a sensitivity of 76-92% for detection and an accuracy of 80-90% for staging, but it has limitations in detection of small cancers (<= 2 cm). Multidetector CT (MD CT) has brought substantial improvements with its inherent 3D imaging capability. Mangafodipir-enhanced MRI is a problem-solving tool in the depiction of small cancers following an equivocal CT imaging result. Gadolinium-enhanced 3D gradient-echo MRI is helpful in the assessment of vascular invasion of cancer and in determining the etiology of cystic lesions. Serous cystadenoma is benign, has a lobulated contour and contains innumerable small cysts of 0.1-2 cm in diameter. Mucinous cystic neoplasms are unilocular or multilocular (fewer than six cysts), and the cyst diameter exceeds 2 cm. The presence of solid nodular components should alert the radiologist to suspect cystadenocarcinoma. Neuroendocrine tumors are mostly hypervascular. Diagnosis of insulinoma is a challenge: they are < 2 cm in 90% of cases and mostly hypervascular at CT or MRI. A combination of contrast-enhanced MDCT, MRI, endosonography, and/or somatostatin receptor scintigraphy is used to detect these small tumors. This review summarizes the imaging features of the most common pancreatic tumors and discusses the limitations of CT, MRI and endosonography.