Diagnostic Ultrasound - Abdomen and Pelvis

Chronic Pancreatitis
TERMINOLOGY
Abbreviations
• Main pancreatic duct (MPD)
• Common bile duct (CBD)
Definitions
• Progressive, irreversible inflammatory and fibrosing disease
of pancreas
IMAGING
General Features
• Best diagnostic clue
○ Dilated MPD with intraductal calculi
• Location
○ Diffuse or focal involvement of pancreatic parenchyma
• Size
○ Usually atrophic
○ Focal enlargement in 30-40%, especially head; can mimic
adenocarcinoma
• Morphology
○ Inflammatory disease of pancreas characterized by
irreversible damage to morphology & function
○ Pancreatic calcifications
– In 40-60% of patients with alcoholic pancreatitis
– ~ 90% of calcific pancreatitis caused by alcoholism
○ Pseudocyst formation in up to 40%
Ultrasonographic Findings
• Grayscale ultrasound
○ Evaluation by ultrasound alone can be limited
– Calcification/calculi: Posterior shadowing obscures
portions of pancreas and adjacent structures
– Margins are ill-defined and difficult to delineate
○ Gland may be enlarged in early stage of chronic
pancreatitis or during acute on chronic episode;
enlargement may be focal or diffuse
○ Heterogeneous echo pattern
– Hypoechoic: Inflammation
– Hyperechoic: Fibrosis and calcification
○ Dilated MPD (irregular, smooth, or beaded) in up to 90%
○ Pancreatic calcifications
– Intraductal calculi: Deposition of calcium carbonate on
intraductal protein plugs
– Parenchymal calcifications
○ Irregular pancreatic contour
○ Pseudocyst: Unilocular, anechoic & sharply defined
○ Dilatation of common bile duct: 5-10%
– Smooth gradual tapering; distinguish from
adenocarcinoma (abrupt cutoff)
• Color Doppler
○ Portosplenic venous thrombosis: 5%
○ Arterial pseudoaneurysm formation
Radiographic Findings
• Small, irregular calcifications (local or diffuse)
• Gastric distention secondary to duodenal obstruction
Fluoroscopic Findings
• Upper GI
○ Duodenum with thickened irregular mucosal folds
○ Duodenal stricture and proximal dilatation
○ Enlarged papilla of Vater (Poppel papillary sign)
• ERCP
○ Dilated & beaded MPD plus radicals (side branches)
○ MPD filling defects: Intraductal calculi
○ CBD may appear dilated with distal narrowing
CT Findings
• Glandular atrophy, parenchymal calcifications
• Dilated MPD with intraductal calculi
• Intra- and peripancreatic cysts
• Heterogeneous enhancement
• Hypodense focal mass (fibrosis and fat necrosis) with varied
enhancement
MR Findings
• T1WI
○ Decreased signal intensity due to loss of proteinaceous
material
• T2WI FS
○ Pseudocyst, necrotic areas: Hyperintense
○ Gallstones, intraductal calculi: Signal void within ducts
• T1WI C+ FS
○ Heterogeneous enhancement pattern due to
inflammation and fibrosis
○ Vascular thrombosis: Filling defect or occlusion
• MRCP
○ Dilated MPD, usually with smooth tapering
○ Dilated side branch ducts in severe cases
○ Ductal disruption: MPD in continuity with pseudocyst,
bowel, or pleural space
○ CBD may be dilated with smooth distal tapering
Imaging Recommendations
• Best imaging tool
○ EUS for detecting early disease; MRCP, CECT for
morphologic changes
• Protocol advice
○ MRCP best to evaluate dilated MPD and side branches
○ MR with contrast helpful to distinguish tumor from
enlargement related to inflammation
○ CT best to evaluate extent of calcifications and
inflammation related to acute on chronic pancreatitis
DIFFERENTIAL DIAGNOSIS
Infiltrating Pancreatic Carcinoma
• Irregular, heterogeneous, hypoechoic mass
• Abrupt obstruction & dilatation of pancreatic duct
• Regional nodal metastases: Splenic hilum & porta hepatis
• Contiguous organ invasion: Duodenum, stomach, liver,
mesentery
Acute Pancreatitis
• Diffuse/focal parenchymal enlargement
• Hypoechoic echogenicity in inflamed parenchyma
• Pancreatic ductal dilatation uncommon
• Lack of pancreatic calcification
• Peripancreatic edema and fluid collection
Diagnoses: Pancreas
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