title: Prospective evaluation of (68)Ga-DOTANOC PET-CT in differentiated thyroid cancer patients with raised thyroglobulin and negative (131)I-whole body scan: comparison with (18)F-FDG PET-CT.
abstract: OBJECTIVE
  The purpose of the study was to evaluate the role of (68)Ga-DOTANOC PET-CT in differentiated thyroid cancer (DTC) patients with negative (131)I-whole body scan (WBS) along with serially increasing serum thyroglobulin (Tg), and compare the same with (18)F-FDG PET-CT.
  
  
  METHODS
  Sixty two DTC patients with serially rising Tg levels and negative (131)I-WBS were prospectively enrolled. All patients underwent (68)Ga-DOTANOC PET-CT and (18)F-FDG PET-CT within an interval of two weeks. PET-CT analysis was done on a per-patient basis, location wise and lesion wise. All PET-CT lesions were divided into four categories-local, nodal, pulmonary and skeletal. Histopathology and/or serial serum Tg level, clinical and imaging follow up (minimum-1 year) were used as a reference standard.
  
  
  RESULTS
  Ga-DOTANOC PET-CT demonstrated disease in 40/62 (65 %) patients and (18)F-FDG PET-CT in 45/62 (72 %) patients, with no significant difference on McNemar analysis (p = 0.226). Per-patient sensitivity and specificity of (68)Ga-DOTANOC PET-CT was 78.4 %, 100 %, and for (18)F-FDG PET-CT was 86.3 %, 90.9 %, respectively. Out of 186 lesions detected by both PET-CTs, 121/186 (65 %) lesions were seen on (68)Ga-DOTANOC PET-CT and 168/186 (90.3 %) lesions on (18)F-FDG PET-CT (p < 0.0001). There were 103/186 (55 %) lesions concordant on both. Excellent agreement was noted between (68)Ga-DOTANOC PET-CT and (18)F-FDG PET-CT for detection of local disease (ĸ = 0.92), while moderate agreement was noted for nodal and pulmonary disease (ĸ = 0.67). (68)Ga-DOTANOC PET-CT changed management in 21/62 (34 %) patients and (18)F-FDG PET-CT in 17/62 (27 %) patients.
  
  
  CONCLUSIONS
  Ga-DOTANOC PET-CT is inferior to (18)F-FDG PET-CT on lesion based but not on patient based analysis for detection of recurrent/residual disease in DTC patients with negative WBS scan and elevated serum Tg levels. It can also help in selection of potential candidates for peptide receptor radionuclide therapy.
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India.
authors.forename: Parveen
authors.initials: P
authors.lastname: Kundu
authors.forename: Sneh
authors.initials: S
authors.lastname: Lata
authors.forename: Punit
authors.initials: P
authors.lastname: Sharma
authors.forename: Harmandeep
authors.initials: H
authors.lastname: Singh
authors.forename: Arun
authors.initials: A
authors.lastname: Malhotra
authors.forename: Chandrasekhar
authors.initials: C
authors.lastname: Bal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging; D055815:Young Adult
chemical_list: C504894:68Ga-DOTANOC; D007457:Iodine Radioisotopes; D009942:Organometallic Compounds; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin