How is the operability of pancreatic carcinoma assessed on imaging?

Assessment of Operability in Pancreatic Carcinoma on Imaging

Operability of pancreatic carcinoma is assessed primarily by CT angiography with pancreatic protocol to determine vascular involvement, with tumors classified as resectable (no arterial contact, <180° venous contact), borderline resectable (limited arterial/venous involvement requiring neoadjuvant therapy), or unresectable (>180° arterial contact or distant metastases). 1

Primary Imaging Modality

• Multidetector CT angiography with dedicated pancreatic protocol is the gold standard for assessing operability 2
• Acquire thin (submillimeter) axial sections using dual-phase technique: pancreatic/arterial phase at 40-50 seconds and portal venous phase at 65-70 seconds post-contrast 2, 3
• CT has >90% positive predictive value for determining unresectability but <50% positive predictive value for confirming resectability [1, @15@]

Classification Based on Vascular Involvement

Resectable Disease (15-20% of patients at diagnosis)

Arterial criteria:

• No tumor contact with superior mesenteric artery (SMA), celiac axis, or common hepatic artery 1
• Each vessel must be assessed individually for encasement or abutment 2, 1

Venous criteria:

• No contact with superior mesenteric vein (SMV) or portal vein (PV), OR
• Tumor contact <180° of vessel circumference without vessel deformity, thrombosis, or tear-drop deformation 2, 1

Borderline Resectable Disease

• Limited arterial contact or venous involvement with distortion 1
• Critical pitfall: Do NOT perform upfront surgery on borderline resectable cases - these patients require neoadjuvant therapy first due to high R1 resection risk 1, 2

Locally Advanced/Unresectable Disease

• Tumor contact >180° with SMA or celiac axis 1, 2
• Involvement of celiac axis or SMA defines T4 disease (unresectable) 2
• Arterial involvement >180° predicts unresectability with prohibitive surgical morbidity 1

Additional Imaging Assessment

Tumor characteristics on CT:

• Appears as hypo-attenuating, homogeneous mass with indistinct margins during pancreatic arterial phase 2, 3
• Interruption of biliary duct (±dilatation) specifies tumor extension 2, 3

Metastatic disease evaluation:

• Assess for hepatic metastases, peritoneal nodules, and enlarged retroportal lymph nodes 2
• Extra-pancreatic extension including retroperitoneal structures must be described 2

Complementary Imaging Modalities

MRI indications:

• Problem-solving for CT-indeterminate hepatic lesions (detects occult liver metastases in 10-23% of cases) 1, 4
• Cystic pancreatic neoplasms or biliary anatomy evaluation 2, 1
• Shows equal benefit to CT for staging with no demonstrated superiority 2
• Alternative when IV contrast contraindicated 3

Endoscopic ultrasound (EUS):

• Provides complementary staging information with 90% sensitivity and 86% specificity for predicting resectability 2
• Primary role is tissue acquisition via fine-needle aspiration (95% diagnostic accuracy) 2, 1
• Can sample atypical lymph nodes to detect distant metastases that would contraindicate resection 2
• Should NOT be used routinely to assess vascular involvement - highly operator-dependent and inferior to CT for this purpose 2

Critical Pitfalls to Avoid

• Never place metal biliary stents before complete staging work-up - associated with increased post-operative morbidity; use plastic stents if biliary sepsis present 2
• Avoid percutaneous biopsy in potentially resectable cases - not necessary for surgical candidates 2
• Do not rely on lymph node size alone - EUS has limited value (69% sensitivity, 81% specificity) for detecting metastatic nodes 2
• Recognize that 70-85% of CT-determined resectable tumors actually undergo successful resection, meaning 15-30% have occult unresectable disease discovered at surgery 2, 5

Standardized Reporting

• Use standardized radiology staging reporting templates to ensure complete assessment of all imaging criteria essential for optimal staging 2, 5
• Report tumor size, precise burden, arterial and venous involvement according to TNM classification 2