title: ¹⁸F-Fluorodeoxyglucose positron emission tomography/computed tomography finds answers in cancer patients with increasing tumor markers and negative or equivocal conventional imaging modalities.
abstract: BACKGROUND
  The increase in tumor markers with negative or equivocal conventional imaging modalities represents a serious dilemma in the follow-up of previously treated cancer patients. Positron emission tomography/computed tomography (PET/CT) has emerged as a useful tool in oncological imaging in staging and restaging of most cancers.
  
  
  OBJECTIVE
  This study explored the potential role of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT in the detection and localization of tumor recurrence in cancer patients with increasing serum tumor markers and negative or equivocal conventional imaging modalities.
  
  
  METHODS
  This prospective study was conducted on 105 previously diagnosed and treated cancer patients with different pathologies. All patients were referred for ¹⁸F-FDG PET/CT scans because of increasing tumor markers with negative or equivocal conventional imaging modalities. All patients underwent whole-body ¹⁸F-FDG PET/CT scans. The findings were confirmed by clinical and/or radiological follow-up of at least 12 months and histopathologically whenever possible.
  
  
  RESULTS
  PET/CT detected recurrence and/or metastases in 90 patients (85.7%), including 17 recurrences, 50 metastases, and 23 recurrences and metastases. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of PET/CT scans were 95.7, 100, 100, 73.3, and 96.2%, respectively. These parameters were 95, 100, 100, 69, and 95% for PET scans alone and were 91.5, 100, 100, 57.9, and 92.3% for CT scans alone.
  
  
  CONCLUSIONS
  ¹⁸F-FDG PET/CT is a powerful diagnostic tool in restaging of cancer patients. In most cases, PET/CT provides accurate results and helps resolve the clinical dilemma encountered in oncological patients with increasing serum tumor markers and negative or equivocal findings in conventional imaging modalities.
authors.affiliation: Department of Nuclear Medicine, Cairo University, Cairo, Egypt. afssalem@yahoo.com
authors.forename: Shahenda S
authors.initials: SS
authors.lastname: Salem
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Shahin
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging* / Q000473:pathology; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000473:pathology; D009367:Neoplasm Staging / Q000379:methods; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D014408:Biomarkers, Tumor; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18