What is the sensitivity of Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) in cholangiocarcinoma?

Sensitivity of FDG PET in Cholangiocarcinoma

FDG-PET demonstrates limited overall sensitivity of 52% for detecting cholangiocarcinoma, with performance heavily dependent on tumor morphology—sensitivity reaches 85-95% for mass-forming/nodular lesions ≥1 cm but drops dramatically to only 18% for infiltrating-type tumors. 1

Sensitivity by Tumor Type and Location

Mass-Forming/Nodular Cholangiocarcinoma

• Sensitivity is 85-95% for nodular intrahepatic cholangiocarcinoma (iCCA) when the mass is ≥1 cm 1
• One high-quality study reported 92.3% sensitivity (24/26 cases detected) for histologically proven cholangiocarcinoma 2
• Another study confirmed 85% sensitivity specifically for nodular morphology in cholangiocarcinoma 3

Infiltrating/Periductal Cholangiocarcinoma

• Sensitivity plummets to only 18% for infiltrating-type cholangiocarcinoma, making FDG-PET unreliable for this morphology 3
• The 2023 ESMO guidelines note that sensitivity is lower in infiltrating CCA compared to nodular forms 1
• FDG-PET was falsely negative in intrahepatic infiltrating-type cholangiocarcinoma in multiple studies 4

Extrahepatic Cholangiocarcinoma

• Sensitivity for detecting primary extrahepatic cholangiocarcinoma is lower than contrast-enhanced MDCT or MRI (p < 0.001) 5
• The 2023 ESMO guidelines report sensitivity of approximately 80-90% for gallbladder carcinoma or nodular CCA ≥1 cm 1

Performance for Staging

Lymph Node Metastases

• Meta-analyses show FDG-PET has limited sensitivity of only 52% for detecting lymph node metastases with specificity of 91% 1
• Sensitivity for regional lymph node metastases in extrahepatic cholangiocarcinoma is significantly lower than MDCT or MRI 5
• FDG-PET detected regional/hepatoduodenal lymph node metastases in only 2 of 15 cases (13% sensitivity) 2
• However, specificity and positive predictive value for regional lymph nodes are significantly better with FDG-PET compared to MDCT and MRI (all p < 0.001) 5

Distant Metastases

• FDG-PET outperforms CT for detecting distant metastases (88% vs. 79% sensitivity, respectively) 1
• Sensitivity for distant metastases was 70% (7/10 cases) in one study, including peritoneal carcinomatosis and pulmonary metastases 2
• Sensitivity for extrahepatic metastases in gallbladder carcinoma was 50% in eight patients 3

Critical Limitation: Carcinomatosis

• FDG-PET was false negative for carcinomatosis in 3 of 3 patients (0% sensitivity) 3
• Six of eight patients with extrahepatic metastases from gallbladder carcinoma had carcinomatosis, limiting PET utility 3

Important Clinical Caveats

False Positive Results

• False positives occur in primary sclerosing cholangitis (PSC), particularly with acute cholangitis 3
• Poor positive predictive value in patients with PSC, biliary prosthesis, or granulomatous disease 1
• 58% (7/12) of patients showed FDG uptake along biliary stent tracts, creating interpretation challenges 3

Specificity

• Overall specificity is high at 91-93% when excluding confounding conditions 1, 2
• Specificity was 100% in one study when properly accounting for benign biliary lesions 2

Clinical Recommendations from Guidelines

• The 2024 French Association for the Study of the Liver (AFEF) guidelines state that FDG-PET is NOT recommended for primary diagnosis of cholangiocarcinoma 1
• FDG-PET may be useful for identifying nodal metastases, distant metastases, and disease recurrence, but utility for lymph node assessment remains to be fully evaluated 1
• The 2023 ESMO guidelines similarly do not recommend FDG-PET for primary diagnosis 1
• The 2014 Journal of Hepatology guidelines note limited clinical utility of CT/PET for diagnosis of iCCA when CT or MRI has already been performed 1

Practical Algorithm

For suspected cholangiocarcinoma:

1. Use multiphase CT or MRI as first-line imaging (sensitivity 78% for CT, higher specificity with MRI) 1
2. Reserve FDG-PET for detecting distant metastases when curative treatment is being considered 1
3. Do NOT rely on FDG-PET for infiltrating-type tumors, patients with PSC, or those with biliary stents 3
4. Interpret with extreme caution in the presence of acute cholangitis or granulomatous disease 3
5. FDG-PET should not replace tissue diagnosis via biopsy 1