18FDG-PET/CT in detection of primary tumors in metastatic carcinoma of unknown primary site

Objectives To evaluate the role of whole body 18F-FDG PET/CT in detection of primary tumors in metastatic carcinoma of unknown primary site

Methods The study population consisted of 45 patients(23 males ,18 females; mean age(49.1%) with cytology or biopsy proven metastatic tumors and negative conventional imaging modalities (CT/MRI/Panendoscopy).Whole body 18F-FDG PET/CT imaging was done for all the patients. Patient data was retrospectively analysed. Histopathology and/clinical follow up was kept as gold standard.

Results Among 45 patients 18F-FDG PET/CT detected primary site in 27 patients and for remaining 18 patients primary site was not localized. Among the 27 patients with positive results, 21(46.6%) patients were true positives and 6 patients were false positives. Among those 18 patients with unidentified primary site the result of 1 patient was false negative and the remaining 17(37.7%) were true negatives. Hence the rate of detection of primary tumors by 18F-FDG PET/CT is 46.6%

Conclusions 18F-FDG PET/CT was found to be a useful diagnostic procedure and has high rate of detection of primary tumors in metastatic carcinoma of unknown primary sit