title: Thallium bone imaging as an indicator of response and outcome in nonmetastatic primary extremity osteosarcoma.
abstract: OBJECTIVE
  We investigated one 201Tl bone scintigraphy method as a predictor of histologic response and event-free survival (EFS) of nonmetastatic extremity osteosarcoma.
  
  
  METHODS
  We evaluated images of the primary tumor to determine whether they exhibited a donut of avidity for 40 patients enrolled on a single institutional protocol. Participants underwent three serial 201Tl bone scintigraphy studies during preoperative neoadjuvant chemotherapy. Intra- and interobserver variability of the method was assessed, and the presence of the donut of avidity was examined as a predictor of EFS and histologic response.
  
  
  RESULTS
  Fifty-three percent of patients were female and 75% were Caucasian; the median age at diagnosis was 13.5 years. Intraobserver agreement was moderate to very good, ranging from 0.595 to 0.865. Interobserver agreement was moderate to good for all time points, ranging from 0.576 to 0.708. There was a significant difference in EFS among patients with and without the donut-shape at any of the three time points (P = 0.049); patients whose tumors displayed a donutshape had inferior EFS.
  
  
  CONCLUSIONS
  The pattern of donut avidity in extremity OS is a predictor of lower EFS, but does not correlate with histologic response to therapy.
authors.affiliation: Department of Diagnostic Imaging, St. Jude Children's Research Hospital, 332 N. Lauderdale, Memphis, TN 38105-2794, USA. sue.kaste@stjude.org
authors.forename: S C
authors.initials: SC
authors.lastname: Kaste
authors.forename: C
authors.initials: C
authors.lastname: Billips
authors.forename: M
authors.initials: M
authors.lastname: Tan
authors.forename: W H
authors.initials: WH
authors.lastname: Meyer
authors.forename: D M
authors.initials: DM
authors.lastname: Parham
authors.forename: B N
authors.initials: BN
authors.lastname: Rao
authors.forename: C B
authors.initials: CB
authors.lastname: Pratt
authors.forename: B D
authors.initials: BD
authors.lastname: Fletcher
mesh_terms: D000293:Adolescent; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000601:surgery; D003131:Combined Modality Therapy; D005121:Extremities; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D012516:Osteosarcoma / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000601:surgery; D011877:Radionuclide Imaging; D016019:Survival Analysis; D013794:Thallium Radioisotopes; D016896:Treatment Outcome
chemical_list: D013794:Thallium Radioisotopes