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Pancreatic imaging: inflammation, collections, adenocarcinoma and cystic lesions

In acute pancreatitis CT is not needed for a typical diagnosis, and CT done too early misses necrosis; by Atlanta, fluid and necrotic collections are distinguished by age (4 weeks) and content; in adenocarcinoma the pancreas-protocol CT decides resectability by arterial contact.

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Why it matters in the exam

Diagnosis of acute pancreatitis: two of three — typical pain, lipase above 3 times normal, an imaging finding. Contrast CT is needed when the diagnosis is in doubt or there is no improvement, and is better after 72–96 hours, because earlier the necrosis is not yet visible. Atlanta 2012: interstitial oedematous versus necrotising pancreatitis. Collections: under 4 weeks — acute peripancreatic fluid collection (APFC) or acute necrotic collection (ANC); after 4 weeks with a wall — pseudocyst (fluid only) or walled-off necrosis (with a solid component). Gas within a necrotic collection indicates infection. Vascular complications: pseudoaneurysm (mainly of the splenic artery) and splenic vein thrombosis. On US in acute pancreatitis the pancreas is enlarged and hypoechoic with fluid around it.

Adenocarcinoma: pancreas-protocol CT — pancreatic and portal phases in thin sections. The tumour is hypodense in the pancreatic phase, with a "double duct" (dilated bile duct and pancreatic duct) and atrophy of the upstream pancreas; about 10% are isodense. Resectability (NCCN): resectable — no contact with the coeliac axis, SMA or common hepatic artery, and venous contact of 180° or less without contour deformity; borderline — SMA contact of 180° or less, or reconstructible venous involvement; unresectable — SMA or coeliac contact of more than 180°, or metastases. Autoimmune pancreatitis: a diffusely enlarged "sausage" pancreas without clefts, a hypodense "halo" around it, pancreatic duct narrowing without upstream dilatation, raised IgG4 and response to steroids — it mimics tumour.

Cystic lesions: IPMN communicates with the pancreatic duct; high-risk stigmata — obstructive jaundice with a cyst in the head, an enhancing nodule of 5 mm or more, a main duct of 10 mm or more; worrisome features — a cyst of 3 cm or more, a nodule smaller than 5 mm, a thickened wall, a main duct of 5–9 mm and rapid growth. Serous cystadenoma — older woman, "honeycomb" microcysts with a calcified central scar, benign. Mucinous cystic neoplasm — middle-aged woman, body and tail, a large cyst with peripheral calcification, no duct communication — for resection. SPN — young woman, a solid-cystic mass with haemorrhage. Pseudocyst — a history of pancreatitis. Insulinoma — small and strongly enhancing in the arterial phase; gastrinoma — the "gastrinoma triangle". In pancreas divisum the minor papilla drains the body and tail.

Key points

• CT in pancreatitis — after 72–96 hours, not for a typical diagnosis.
• 4 weeks separate an acute collection from a walled one.
• Adenocarcinoma — hypodense, double duct.
• SMA contact above 180° — unresectable.
• IPMN — communicates with the duct; duct 10 mm or more — high risk.

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Sources

• Revised Atlanta Classification of Acute Pancreatitis, 2012 — Morphological types and peripancreatic collections
• International Consensus Guidelines for the Management of IPMN (Fukuoka), 2017 — High-risk stigmata and worrisome features
• NCCN Guidelines: Pancreatic Adenocarcinoma, 2024 — Resectability criteria on pancreas-protocol CT

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.