Introduction
This topic covers the imaging of the pancreas: which modality to use and why, the radiological picture of acute pancreatitis and its complications, the features of chronic pancreatitis, and the imaging approach to pancreatic cancer, including staging and resectability.
Imaging modalities for the pancreas
The pancreas lies deep in the upper abdomen behind the stomach, so no single modality is ideal for every question. Choice depends on the clinical problem: urgent screening, severity assessment, ductal evaluation or tumour staging.
Acute pancreatitis
Acute pancreatitis is an acute inflammation of the gland caused most often by gallstones and alcohol. Imaging confirms the diagnosis when clinical and laboratory findings are not clear, establishes severity and looks for complications. Ultrasound is the first examination, mainly to look for gallstones and the bile duct. Contrast-enhanced CT is used when the diagnosis is uncertain, when the patient does not improve, or to assess severity and complications. CT done too early (within the first 72 hours) may underestimate necrosis, so it is usually delayed when possible.
- Interstitially oedematous pancreatitis: diffuse gland enlargement with homogeneous enhancement and peripancreatic fat stranding.
- Necrotising pancreatitis: non-enhancing areas of parenchyma, with or without peripancreatic necrosis; quantified as the percentage of gland involved.
- Balthazar CT grading (A to E) estimates severity, from a normal gland (A) to extensive necrosis or abscess with multiple fluid collections (E).
- Acute peripancreatic fluid collection: occurs early, often resolves, and is not a pseudocyst.
- Acute necrotic collection: heterogeneous content with solid debris, which may later become walled-off necrosis.
- Pseudocyst: a fluid collection with a well-defined wall, arising after about four weeks without necrosis.
- Infected necrosis: gas bubbles within a collection or necrosis and clinical deterioration suggest infection; an abscess is a collection with gas and pus.
- Other complications: splenic or portal vein thrombosis, pseudoaneurysm (look for bleeding, especially after intervention), and pleural effusion.