Detection of Primary Malignancy and Metastases with FDG PET/CT in Patients with Cholangiocarcinomas: Lesion-based Comparison with Contrast Enhanced CT

Abstract

The current National Comprehensive Cancer Network (NCCN) Guidelines consider the role of 2-deoxy-2-(18)F-fluoro-d-glucose positron emission tomography/computer tomography (FDG PET/CT) in the evaluation of cholangiocarcinoma (CCA) as "uncertain," and have recommended contrast enhanced computed tomography (CECT) but not FDG PET/CT as a routine imaging test for CCA workup. We set out to compare the diagnostic performance of FDG PET/CT and CECT in patients with CCA. The retrospective study included patients with CCA who underwent FDG PET/CT and CECT within 2-month interval between 2011 and 2013 in our hospital. Lesion-based comparison was conducted. Final diagnoses were made based on the composite clinical and imaging data with minimal 6-month follow-up. A total of 18 patients with 28-paired tests were included. There is a total of 142 true malignant lesions as revealed by the 6-paired pre-treatment and 22-paired post-treatment tests. On a lesion-based analysis, the sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs), and accuracies of PET/CT and CECT for detection of CCA were 96.5%, 55.5%, 97.2%, 50.0%, 94.1% and 62.2%, 66.7%, 96.7%, 10.0%, 62.5%, respectively. FDG PET/CT detected more intrahepatic malignant and extrahepatic metastases; and had significant higher sensitivity, NPV, and accuracy than CECT, while similar in specificity and PPV. No true positive lesion detected on CECT that was missed on PET/CT, and none of the false negative lesions on PET/CT were detected on CECT. Six patients had paired pretreatment tests, and FDG PET/CT results changed planned management in three patients. Our data suggest that FDG PET/CT detect more primary and metastatic lesions and lead to considerable changes in treatment plan in comparison with CECT.

Keywords: 2-deoxy-2-18F-fluoro-d-glucose positron emission tomography/computer tomography; Cholangiocarcinoma; contrast enhanced computed tomography; diagnostic performance; lesion-based comparison.

Figure 1

FDG PET/CT detected more intrahepatic lesions than CECT (a) CECT only detected one conglomerate mass in the left lobe liver (arrow), (b–d) FDG PET/CT (B: CT, C: PET, D: Fused PET/CT) detected the same left lobe lesion (short arrows) and more lesions within the right lobe liver (long arrows)

Figure 2

Patient with early recurrent cholangiocarcinoma detected on FDG PET/CT but not on contrast enhanced CT(CECT) (a) Follow-up CECT performed 3-months after the Y-90 radioembolization (Y90-RE) showed low attenuation, central necrotic left lobe lesions in the region of Y-90 RE, deemed as post-treatment change, (b–d) PET/CT (B: CT; C: PET; D: Fused PET/CT) obtained within 1 week after CECT detected a small focal FDG avid lesion at the peripheral edge of Y-90 RE (arrows), suggestive of early recurrence and was confirmed on follow-up images

Figure 3

Patient with metastatic cholangiocarcinoma detected on FDG PET/CT but not on contrast enhanced CT (CECT) (a) PET/CT MIP image showed multiple hypermetabolic intrahepatic foci and several bone metastases (arrows) (b) CECT only detected the conglomerate right lobe primary lesion in the liver (arrow) (c-e) PET/CT (C: CT; D: PET; E: Fused PET/CT) detected both the primary right lobe lesion (long arrows), and 3 additional small intrahepatic malignant lesions (short arrows). Furthermore, CECT (F, J) failed to detect the bone metastases in the sacrum (F) and left acetabulum (J); while PET/CT (G,K: CT; H,L: PET; I,M: Fused PET/CT) clearly demonstrated the FDG-avid bone metastases (arrows)