Background and Objectives: Histopathologically confirmed lymph node metastasis is a prognostic factor in the surgical treatment of biliary tract cancer, however, preoperative diagnosis is still difficult even with computed tomography. FDG-PET has been used for the diagnosis of cancer and metastatic lesions. Herein, we retrospectively evaluated the utility of FDG-PET for detection of lymph node metastasis in biliary tract cancer. Methods: We measured SUVmax at each 190 surgically dissected lymph node area in 36 patients, and compared the values with histopathological diagnosis. The cutoff values for SUVmax were defined from the ROC curve and the mean plus two standard deviations then used for detection of metastatic lymph node and prognostic value, compared with CT diagnosis. Results: The sensitivity, specificity, and positive predictive value of FDG-PET were better than CT diagnosis (86%, 74%, 43% for SUVmax ≥ 2.0, and 37%, 97%, 72% for SUVmax ≥ 2.8, respectively). There was no relationship between SUVmax and CT-determined lymph node dimensions. The presence of SUVmax ≥ 2.8 lymph nodes was an independent determinant of prognosis after surgical treatment. Conclusion: The detection of metastatic lymph nodes by FDG-PETis limited, but better than CT. SUVmax for lymph nodes seems useful for clinical decision-making regarding treatment strategy including surgery.
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