title: Recurrent thyroid cancer diagnosis: ROC study of the effect of a high-resolution head and neck 18F-FDG PET/CT scan.
abstract: OBJECTIVE
  (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) has demonstrated significant value in the evaluation of patients with indication of recurrent thyroid cancer with negative conventional workup. The hypothesis of this study was that the addition of a dedicated, high-resolution head and neck scan (HNS) to the standard whole-body scan (WBS) improves the accuracy of the detection and diagnosis of recurrent thyroid cancer.
  
  
  METHODS
  Forty-three consecutive patients suspected for recurrent thyroid cancer, as indicated by increased tumor markers, prospectively underwent a WBS and a HNS with (18)F-FDG PET/CT. The patients were followed up to establish ground truth. A receiver operator characteristic (ROC) study with two observers was conducted to evaluate the impact of the additional HNS on the detection and diagnosis of recurrent thyroid cancer. Indices of performance included the area under the ROC curve (AUC), the number of detected abnormal foci, and the size of the detected foci without and with the HNS images.
  
  
  RESULTS
  ROC results showed that the addition of the HNS to the standard WBS increased the average AUC index of performance from 0.69 to 0.96, a statistically significant difference with a confidence interval (CI) of -0.33 to -0.19. Diagnosis was also improved with the average AUC increasing from 0.79 to 0.87 but differences were not statistically significant (CI, -0.19 to 0.04). Interreader agreement was "good" in the detection task and "excellent" in the diagnostic task. The addition of the HNS increased the number of detected foci in the positive patients by an average of 37%, whereas false-positive detections in the negative patients increased by an average of 10%. Reported average maximum lesion size also increased with the HNS addition by an average of 11%.
  
  
  CONCLUSIONS
  The addition of a high-resolution HNS to the standard whole-body PET/CT imaging improves readers' performance in the detection and diagnosis of recurrent thyroid cancer and could greatly benefit patient care.
authors: Nuclear Medicine Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece; 2nd Department of Radiology, Nuclear Medicine Section, University General Hospital Attikon, School of Medicine, National and Kapodistrian University of Athens, Chaidari, Greece.
authors: Sofia N
authors: SN
authors: Chatziioannou
authors: Nuclear Medicine Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors: Alexandros T
authors: AT
authors: Georgakopoulos
authors: Nuclear Medicine Division, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors: Nikoletta K
authors: NK
authors: Pianou
authors: Endocrine Clinics, Athens, Greece.
authors: Georgia Th
authors: GT
authors: Kafiri
authors: Endocrine Clinics, Athens, Greece.
authors: Spyros N
authors: SN
authors: Pavlou
authors: Department of Medical Instruments Technology, Technological Educational Institute of Athens, Egaleo 12210, Greece. Electronic address: sofiac@bcm.edu.
authors: Maria
authors: M
authors: Kallergi
mesh_terms: D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D015588:Observer Variation; D049268:Positron-Emission Tomography / Q000379:methods*; D012372:ROC Curve; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: FDG; PET/CT, ROC; Thyroid cancer; positron emission tomography