MRI of the pancreas

Normal anatomy on MRCP and topography

During magnetic resonance cholangiopancreatography (MRCP), the normal anatomy of the excretory ducts is visualized in detail. Normally, the main pancreatic duct (Wirsung's duct) merges with the common bile duct and empties into the major duodenal papilla (Vater's papilla). The accessory pancreatic duct (Santorini's duct) opens independently into the minor duodenal papilla.

Topographically, the pancreas is located in the anterior pararenal space (anterior pararenal space). The ascending and descending colon, as well as the duodenum, are located in this same anatomical space.

Differential diagnosis: pancreatitis or cancer

One of the main objectives of MRI is to distinguish focal chronic pancreatitis from adenocarcinoma (adenocarcinoma).

• T1-weighted GRE image with gadolinium: A focal mass (focal mass) in the pancreas is often characterized by reduced contrast enhancement (reduced enhancement). This sign is non-specific, so the ductal system is evaluated for an accurate diagnosis.
• MRCP in chronic pancreatitis: The key marker of a focal inflammatory process (focal inflammatory mass) is the "duct-penetrating sign" (duct-penetrating sign). The main pancreatic duct passes straight through the pathological lesion.
• MRCP in adenocarcinoma: A malignant tumor leads to complete obstruction (complete obstruction) of the main pancreatic duct. The duct abruptly terminates at the border of the mass and does not pass through it.

Features of chronic pancreatitis on MRCP

The chronic inflammatory process leads to structural changes in the ductal system. Tomograms typically reveal:

1. Visualization of a stricture (narrowing), most commonly in the body of the pancreas.
2. Pronounced dilatation (expansion) of the main pancreatic duct and its side branches upstream of the narrowing (upstream).

Clinical rule (Red Flag): When any stricture is detected, it is critically important to rule out a malignant tumor at the site of narrowing.

MRI in pancreatic trauma

In direct blunt abdominal trauma, MRI allows a detailed assessment of the extent of parenchymal and ductal damage:

• Standard T1- and T2-weighted images reveal a hyperintense hematoma within the pancreatic tissue.
• Upon administration of gadolinium contrast, a large parenchymal defect is identified, caused by rupture or fracture (fracture) of the organ.
• Evaluation of the ductal system reveals rupture of the main pancreatic duct. This condition is described as disconnected duct syndrome (disconnected duct syndrome).

Imaging of developmental anomalies

MRI and MRCP allow precise identification of congenital pancreatic malformations, which may be asymptomatic incidental findings in adults:

• Annular pancreas (Annular pancreas): Pancreatic tissue or a fibrous band encircles the descending part of the duodenum. MRCP confirms the diagnosis by visualizing the pancreatic duct ringing the duodenum.
• Agenesis and hypoplasia: Complete agenesis is extremely rare. Hypoplasia or agenesis of the dorsal anlage (dorsal anlage) is significantly more common. On MRI scans, the body and tail of the pancreas are absent, and the duct in the dorsal anlage appears shortened.

Class and exam questions

What else to study on this topic

• Paraduodenal (groove) pancreatitis on MSCT
• Ultrasound and CT in the diagnosis of complications of chronic pancreatitis
• Revised classification of acute pancreatitis (Atlanta, 2008)
• Core-needle biopsy and FNA of pancreatic masses
• Percutaneous drainage of pancreatic abscesses

Other topics in the section "Diagnostic Radiology of the Abdominal Organs"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.