1  Answer C.Coronal image from MR cholangiopancreatography (MRCP) demonstrates dilation of the pancreatic and biliary ducts consistent with the “double-duct” sign. The most common cause is obstruction by pancreatic ductal adenocarcinoma. Other neoplasms of the ampulla, pancreas, and periampullary region such as duodenal carcinoma can also produce the double-duct sign. Benign causes include chronic pancreatitis and ampullary stenosis. Dilation of multiple side branches in addition to the main pancreatic duct, as seen in this case, may or may not be evident.

References: Ahualli J. The double duct sign. Radiology 2007;244(1):314–315.

Lopez Hänninen E, Amthauer H, Hosten N, et al. Prospective evaluation of pancreatic tumors: accuracy of MR imaging with MR cholangiopancreatography and MR angiography. Radiology 2002;224(1):34–41.

2  Answer A.The majority of pancreatic neuroendocrine tumors (NETs) are sporadic, but some are associated with genetic syndromes. About a quarter of tumors are found in patients with multiple endocrine neoplasia type 1 (MEN-1) and are the major cause of mortality. Patients with MEN-1 are predisposed to developing parathyroid adenomas or hyperplasia, pancreatic NETs, and pituitary adenoma (“pa, pa, pi”). Von Hippel-Lindau (VHL) disease is a rare hereditary syndrome with a broad spectrum of clinical features, and pancreatic findings in VHL include simple cysts, NET, serous microcystic cystadenomas, and rarely ductal adenocarcinomas. Two other syndromes, neurofibromatosis type 1 and tuberous sclerosis, have also been linked with pancreatic NETs. Pancreatic lesions are not a feature of MEN-2a or MEN-2b. MEN-2a is associated with medullary thyroid cancer, pheochromocytoma, and parathyroid adenomas (“me, phe, pt”). MEN-2b is associated with medullary thyroid cancer, pheochromocytoma, and neuromas (“me, phe, ne”).

References: Kim KW, Krajewski KM, Nishino M, et al. Update on the management of gastroenteropancreatic neuroendocrine tumors with emphasis on the role of imaging. AJR Am J Roentgenol 2013;201(4):811–824.

Scarsbrook AF, Thakker RV, Wass JA, et al. Multiple endocrine neoplasia: spectrum of radiologic appearances and discussion of a multitechnique imaging approach. Radiographics 2006;26(2):433–451.

3  Answer D.Most patients with acute pancreatitis (AP) can be diagnosed without imaging based on clinical presentation and elevated laboratory values. Serum lipase level is more sensitive than imaging in the diagnosis of acute pancreatitis. Serum insulin levels have no role in diagnosis of AP.

The role of imaging in the setting of uncomplicated AP is primarily to identify cholelithiasis as a treatable cause. Ultrasound is the most appropriate imaging study for this purpose. Cholelithiasis and heavy alcohol consumption together account for about 90% of cases of AP in developed countries. If the diagnosis of AP is equivocal or if worsening symptoms suggest a complication such as necrosis, contrast-enhanced CT scan would be appropriate. MRCP may be helpful in patients with suspected choledocholithiasis or pancreatic duct stone. MRI with contrast may have a secondary role in follow-up of complications of AP in patients with iodinated contrast allergy or young patients who require repeated imaging.

References: ACR Appropriateness Criteria: acute pancreatitis. American College of Radiology website. http://www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/AcutePancreatitis.pdf. Published 1998. Updated 2013. Accessed June 20, 2014.

Shinagare AB, Ip IK, Raja AS, et al. Use of CT and MRI in emergency department patients with acute pancreatitis. Abdom Imaging 2015;40(2):272–277.

4a  Answer B.There is a well-circumscribed mass in the tail of the pancreas on axial CT images, with enhancement greater on the arterial phase than venous phase. This pattern of enhancement indicates a hypervascular neoplasm and is compatible with a pancreatic neuroendocrine tumor (NET). The SPECT image from the ¹¹¹In-octreotide scan shows uptake, confirming NET. (Not all NETs will show uptake, so a negative scan does not exclude NET.) Two additional cases of pancreatic NET are shown below. Large tumors are more likely to be heterogeneous with cystic, necrotic, or calcified components. The NET in the image on the left is heterogeneous and shows a calcification (arrowhead). About 15% of pancreatic NETs are cystic and difficult to differentiate from other cystic pancreatic lesions. A clue to a cystic or necrotic NET is a hypervascular rim (arrows) on the arterial phase image on the right.

A metastasis from renal cell carcinoma is also hypervascular and should be considered in the appropriate clinical setting. Splenules (accessory spleens) can be seen at the pancreatic tail and mimic a NET. Splenules should follow splenic enhancement on all phases. The arterial phase may demonstrate the serpiginous “arciform” or “moiré” sinusoidal enhancement diagnostic of splenic tissue. Splenules show uptake on ^99mTc-sulfur colloid scan or ^99mTc-heat–damaged red blood cell scan. Lymphoma is typically homogeneously hypovascular without arterial enhancement.

References: Lewis RB, Lattin GE, Paal E. Pancreatic endocrine tumors: radiologic-clinicopathologic correlation. Radiographics 2010;30(6):1445–1464.

Raman SP, Hruban RH, Cameron JL, et al. Pancreatic imaging mimics: part 2, pancreatic neuroendocrine tumors and their mimics. AJR Am J Roentgenol 2012;199(2):309–318.

4b  Answer C.Pancreatic neuroendocrine tumors (NETs) may be nonfunctioning or functioning. Nonfunctioning neoplasms can be asymptomatic or present with symptoms of mass effect because of large size at time of diagnosis. Patients with functioning pancreatic NETs may manifest symptoms of hormonal overproduction as listed in the following table, allowing earlier diagnosis when the tumor is small. The most common functioning subtype is insulinoma, accounting for nearly half of functioning pancreatic NETs. Symptoms of hypoglycemia frequently lead to diagnosis of insulinomas at <2 cm.

NETs typically behave indolently. Curative surgical resection or enucleation is the preferred treatment. Metastatic disease to the liver may be managed with radiofrequency ablation or chemoembolization. Other treatment options include somatostatin analogues (such as octreotide), molecular targeted therapies, and chemotherapy.

References: Lewis RB, Lattin GE, Paal E. Pancreatic endocrine tumors: radiologic–clinicopathologic correlation. Radiographics 2010;30(6):1445–1464.

Sahani DV, Bonaffini PA, Fernández-Del Castillo C, et al. Gastroenteropancreatic neuroendocrine tumors: role of imaging in diagnosis and management. Radiology 2013;266(1):38–61.

5  Answer C.Diffuse calcifications, seen throughout the pancreas in this case, are specific for chronic pancreatitis. Chronic alcohol consumption accounts for 70% to 90% of cases of chronic pancreatitis in developed countries. Less common causes are chronic biliary tract disease, hereditary pancreatitis, cystic fibrosis, hyperlipidemia, hypercalcemia (most commonly hyperparathyroidism), medications, and pancreas divisum. Chronic pancreatitis, thought to be an entity distinct from acute pancreatitis, is a disease of prolonged inflammation leading to fibrosis and gland dysfunction. Focal or diffuse pancreatic calcifications are present in half of patients, visible on CT and occasionally on radiographs as shown on the following image from a different patient (arrows).

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