The Diagnostic Contribution of ¹⁸F-FDG PET/CT SCAN in Cancer of BMUO

Objectives: The purpose of this study was to investigate the value of 18F-FDG PET / CT in finding primary tumors in patients with bone metastasis of unknown primary origin (BMUO).

Methods: A total of 223 patients were enrolled from November, 2017 to April, 2018 in the Department of Nuclear Medicine of the First Affiliated Hospital of Zhengzhou University to find the primary tumor for ¹⁸F-FDG PET/CT examination due to the discovery of bone metastases. The patients who found bone metastasis by routine examination were performed ¹⁸F-FDG PET/CT examination to find the primary tumor within 3 days after routine examination. All patients were finally diagnosed by histopathology. The diagnostic efficacy of ¹⁸F-FDG PET/CT to find the primary lesion was calculated by comparing the histopathological results with the ¹⁸F-FDG PET/CT imaging results.

Results: A total of 223 patients were enrolled in this study, including 122 males and 101 females, with a median age of 62 years. Among 223 cases, the primary tumor was found in 205 cases, but 18 cases were not found. ¹⁸F-FDG PET/CT imaging was positive in 203 cases, including 199 true positives and 4 false positives. ¹⁸F-FDG PET/CT imaging was negative in 20 cases, including 14 true negatives and 6 false negatives. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of ¹⁸F-FDG PET/CT in detecting primary tumors in patients with BUMO were 97.1% (199/205), 77.8% (14/18), 91.9% (205/223), 98.0% (199/203), and 17% (14/20) respectively. ¹⁸F-FDG PET/CT detected all previously known metastases and found new metastases in 173 patients.

Conclusions: ¹⁸F-FDG PET/CT, as a non-invasive examination method, is of great value in finding primary tumors in patients with unknown primary tumor bone metastasis. It can be used as the first choice for finding primary lesions. Keywords: ¹⁸F-FDG; PET/CT; BUMO; Diagnosis; Sensitivity; Specificity