title: The role of ultrasound in the follow-up of children with differentiated thyroid cancer.
abstract: BACKGROUND
  Thyroid cancer is the most common endocrine malignancy with relatively good prognosis in children. However, unlike adults, children usually present with more advanced disease and have a higher local recurrence and distant metastases. Thus surveillance for recurrence is a major goal of long-term follow-up.
  
  
  OBJECTIVE
  This retrospective study evaluates the diagnostic value of ultrasound (US) imaging in the post-therapy surveillance of children with differentiated thyroid cancer.
  
  
  METHODS
  We reviewed the charts of 54 children (40 girls; mean age 14.3 ± 3.6 years) with differentiated thyroid cancer treated with total or near-total thyroidectomy. Forty children (29 girls and 11 boys) who had routine follow-up US examinations (112 studies) were included for the evaluation of US accuracy in the follow-up of pediatric differentiated thyroid cancer. Histopathology, stimulated thyroglobulin determination, post-therapy whole-body iodine scan and clinical follow-up were used as the standards of reference.
  
  
  RESULTS
  Mean period of follow-up was 34 months. The frequency of recurrence was 42% (17/40). Seventeen percent of the children had lung metastases either at presentation or on follow-up. In all cases of lung metastases, stimulated thyroglobulin level was greater than 10 ng/ml. The sensitivity was 85.7%, specificity 89.4%, negative predictive value 94.4% and positive predictive value 75% for US in detecting loco-regional recurrence in follow-up studies of pediatric differentiated thyroid cancer. In 17.3% (18/104) of studies, the results of stimulated thyroglobulin and US were discordant.
  
  
  CONCLUSIONS
  US showed very good sensitivity and specificity and a high negative predictive value for evaluation of loco-regional involvement in follow-up of pediatric differentiated thyroid cancer. Diagnostic whole-body iodine scan is indicated when serum anti-thyroglobulin Ab is high, or in cases of discordant findings between US and stimulated thyroglobulin levels, or when stimulated thyroglobulin levels are >10 ng/ml (to evaluate for lung metastasis).
authors.affiliation: Department of Diagnostic Imaging, Division of Nuclear Medicine, The Hospital for Sick Children, University of Toronto, 555 University Ave., Toronto, ON, Canada, M5G 1X8, reza.vali@sickkids.ca.
authors.forename: Reza
authors.initials: R
authors.lastname: Vali
authors.forename: Marianna
authors.initials: M
authors.lastname: Rachmiel
authors.forename: Jill
authors.initials: J
authors.lastname: Hamilton
authors.forename: Mohamad
authors.initials: M
authors.lastname: El Zein
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wasserman
authors.forename: Danny L
authors.initials: DL
authors.lastname: Costantini
authors.forename: Martin
authors.initials: M
authors.lastname: Charron
authors.forename: Alan
authors.initials: A
authors.lastname: Daneman
mesh_terms: D000293:Adolescent; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D016609:Neoplasms, Second Primary / Q000000981:diagnostic imaging*; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000601:surgery; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D014463:Ultrasonography