Clinical usefulness of 18F-FDG PET-CT for patients with gallbladder cancer and cholangiocarcinoma

Background: Reports concerning the clinical usefulness of ¹⁸F 2-fluoro-2-deoxy-d-glucose integrated positron emission and computed tomography (¹⁸F-FDG PET-CT) for patients with gallbladder cancer and cholangiocarcinoma are relatively scarce. The purpose of this study was to assess the diagnostic value of PET-CT in relation to a conventional imaging modality, multidetector row CT (MDCT), for patients with gallbladder cancer and cholangiocarcinoma. Methods: Ninety-nine patients with suspected gallbladder cancer and cholangiocarcinoma who underwent both PET-CT and MDCT for initial staging were included in our study. The results of these two imaging modalities for evaluating primary tumors, regional lymph nodes and distant metastases were compared with the final diagnoses based on pathological or clinical findings. Results: A maximum standardized uptake value (SUV_max) of 3.65 was found to be the best cutoff value for detecting a malignant tumor. The overall values for the sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs) and the accuracies of PET-CT and MDCT for the detection of a primary tumor were 90.2, 70.6, 93.7, 60.0, 86.9% and 84.2, 70.6, 93.2, 48.0, 81.8%, respectively. PET-CT demonstrated no significant advantage over MDCT for the diagnosis of a primary tumor. PET-CT showed a significantly higher PPV (94.1 vs. 77.5%, P = 0.04) than that found for MDCT in the diagnosis of regional lymph node metastasis. Additionally, PET-CT showed a significantly higher sensitivity (94.7 vs. 63.2%, P = 0.02) than that found for MDCT in the diagnosis of distant metastasis. Conclusions: PET-CT is valuable for detecting regional lymph node involvement and unsuspected distant metastases that are not diagnosed by MDCT.