Diagnostic Ultrasound - Abdomen and Pelvis

Pancreatic Ductal Carcinoma
TERMINOLOGY
Synonyms
• Pancreatic ductal adenocarcinoma (PDA), pancreatic cancer
Definitions
• Solid epithelial neoplasm from ductal exocrine pancreas
IMAGING
General Features
• Best diagnostic clue
○ Ill-defined pancreatic mass obstructing pancreatic and
possibly common bile duct (producing "double duct"
sign)
• Location
○ Head (60-70%), body (5-10%), tail (10-15%), multiple
regions or diffuse (22%)
• Size
○ Average diameter: 2-3 cm
• Morphology
○ Accounts for 85-90% of all pancreatic tumors
○ Encases intrapancreatic blood vessels and usually not
resectable for cure at time of presentation
○ Local infiltrative invasion
○ Metastatic involvement of liver, portal hilar nodes,
peritoneum, lungs, pleura, bone
Ultrasonographic Findings
• Grayscale ultrasound
○ Hypoechoic, infiltrative mass
– Pancreatic ductal dilatation
□ > 3 mm upstream from tumor with tortuous
configuration and loss of parallel nature
– Bile duct dilatation
□ Common in pancreatic head carcinoma
□ Obstruction at level of pancreatic head or porta
hepatis, depending on tumor size and regional
adenopathy
□ ±dilatation of cystic duct and gallbladder
(Courvoisier sign)
– Calcification or necrosis/cystic change: Rarely seen
○ Can be small, isoechoic mass, with subtle focal contour
deformity (e.g., in uncinate process)
○ Diffuse glandular tumor involvement can be difficult to
differentiate from acute pancreatitis
○ Secondary findings
– Displacement/encasement of adjacent vascular
structures
– Atrophy or pancreatitis proximal to pancreatic ductal
obstruction
– Ascites due to peritoneal metastasis
– Liver and regional lymph node metastases
• Color Doppler
○ May be helpful in assessing vascular encasement or
venous obstruction
• Endoscopic ultrasound (EUS): Most sensitive test for small
hypoechoic mass in pancreatic head
• Can guide fine-needle aspiration biopsy
Radiographic Findings
• ERCP
○ Pancreatic stricture with upstream dilatation
○ Combined with endoscopic ultrasound for biopsy
○ Allows drainage of obstructed ducts
CT Findings
• CECT
○ Hypoenhancing, poorly defined, infiltrating mass with
secondary signs of
– Obstruction of pancreatic duct and common bile duct
when located in head of pancreas
– Upstream atrophy of pancreas
○ Isodense masses (10-15%) and tumors < 2 cm are more
difficult to detect
– May only see secondary signs with subtle parenchymal
fullness
○ Can detect contiguous organ invasion (duodenum,
stomach, splenic hilum, porta hepatis, mesentery)
○ Distant metastases to liver, peritoneum, regional nodes
• CTA
○ More accurate for detecting vascular involvement
– Abutment (< 180° vessel circumference), encasement
(> 180° vessel circumference), narrowing, or occlusion
– Teardrop-shaped superior mesenteric vein (SMV)
suggests venous invasion
MR Findings
• T1WI
○ Hypointense relative to normal parenchyma due to
fibrous nature of tumor
○ Fat-saturation increases conspicuity
• T2WI
○ Improves detection of ductal dilatation
• T1WI C+
○ Best sequence for delineating mass, which shows limited
enhancement
○ Shows imaging features of vascular encasement and
tumor extension similar to CECT
• MRCP
○ Dilated ducts proximal to obstructing mass
Imaging Recommendations
• Best imaging tool
○ CECT overall accuracy: 86-99%
• Protocol advice
○ CECT should follow pancreas-specific protocol with CT
arteriography
• US often first-line imaging for painless obstructive jaundice
to show level of obstruction
○ Less sensitive than CT or MR for detection of pancreatic
mass or for determining resectability
• EUS used to guide biopsy in setting of ductal obstruction
without mass
○ Increased sensitivity for small lesions < 2 cm that can be
missed on CT
DIFFERENTIAL DIAGNOSIS
Chronic Pancreatitis
• Focal or diffuse atrophy of gland with dilated main
pancreatic duct and bulky calcifications
• May have long segment distal common bile duct stricture
with prestenotic dilatation
Diagnoses: Pancreas
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