title: Increasing the yield of recombinant thyroid-stimulating hormone-stimulated 2-(18-fluoride)-flu-2-deoxy-D-glucose positron emission tomography-CT in patients with differentiated thyroid carcinoma.
abstract: OBJECTIVE
  The aim of this study was to assess the accuracy of recombinant thyroid-stimulating hormone (rTSH)-stimulated 2-(18-fluoride)-flu-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET)-CT in detecting recurrence in patients with differentiated thyroid cancer.
  
  
  METHODS
  Consecutive (18)F-FDG PET-CT scans performed with rTSH stimulation between 2007 and 2010 in patients with a history of papillary or follicular thyroid carcinoma were reviewed. PET-CT findings were correlated with thyroglobulin levels, and histological, clinical and radiological follow-up.
  
  
  RESULTS
  58 rTSH PET-CT scans were performed in 47 patients with a previous thyroidectomy and radioiodine ablation. The only indication for PET-CT was a raised thyroglobulin level in 46 of 58 scans, with the remainder for characterisation of equivocal radiology or staging. 25 (43%) of PET-CT scans were positive for recurrent disease. Histological correlation was available for 21 (36%) scans. The overall sensitivity, specificity, positive predictive value and negative predictive value were 69%, 76%, 72% and 73%, respectively. Median unstimulated thyroglobulin in true-positive scans was 33 µg l(-1) and 2.2 µg l(-1) in the remainder (p=0.12). 4 of 35 (11%) patients with unstimulated thyroglobulin levels <10 µg l(-1) had true-positive scans. Median stimulated thyroglobulin in true-positive scans was 320 µg l(-1), and 10 µg l(-1) in the remainder (p=0.046), with no positive scans with a stimulated thyroglobulin <8 µg l(-1). PET-CT directly influenced patient management in 17/58 (29%) scans.
  
  
  CONCLUSIONS
  rTSH PET-CT is a useful imaging technique for detecting disease recurrence in patients with iodine-resistant differentiated thyroid cancer. Low stimulated thyroglobulin levels are potentially useful in identifying patients unlikely to benefit from a PET-CT scan.
authors.affiliation: Department of Nuclear Medicine, St James's Institute of Oncology, Leeds, UK. robin.prestwich@leedsth.nhs.uk
authors.forename: R J D
authors.initials: RJ
authors.lastname: Prestwich
authors.forename: S
authors.initials: S
authors.lastname: Viner
authors.forename: G
authors.initials: G
authors.lastname: Gerrard
authors.forename: C N
authors.initials: CN
authors.lastname: Patel
authors.forename: A F
authors.initials: AF
authors.lastname: Scarsbrook
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000097:blood / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000097:blood / Q000000981:diagnostic imaging; D002291:Carcinoma, Papillary; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D011994:Recombinant Proteins; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000097:blood / Q000000981:diagnostic imaging*; D057073:Thyrotropin Alfa; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D011994:Recombinant Proteins; D057073:Thyrotropin Alfa; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin