title: Incidental thyroid nodules on CT: evaluation of 2 risk-categorization methods for work-up of nodules.
abstract: OBJECTIVE
  Thyroid nodules are common incidental findings on CT, but there are no clear guidelines regarding their further diagnostic work-up. This study compares the performance of 2 risk-categorization methods of selecting CT-detected incidental thyroid nodules for work-up.
  
  
  METHODS
  The 2 categorization methods were method A, based on nodule size ≥10 mm, and method B, a 3-tiered system based on aggressive imaging features, patient age younger than 35 years or nodule size of ≥15 mm. In part 1, the 2 categorization methods were applied to thyroid cancers in the SEER data base of the National Cancer Institute to compare the cancer capture rates and survival. In part two, 755 CT neck scans at our institution were retrospectively reviewed for the presence of ITNs of ≥5 mm, and the same 2 categorization methods were applied to the CT cases to compare the number of patients who would theoretically meet the criteria for work-up. Comparisons of proportions of subjects captured under methods A and B were made by using the McNemar test.
  
  
  RESULTS
  For 84,720 subjects in the SEER data base, methods A and B each captured 74% (62,708/84,720 and 62,586/84,720, respectively) of malignancies. SEER subjects who would not have met the criteria for further work-up by both methods had equally excellent 10-year cause-specific and relative survival of >99%. For part 2, the prevalence of ITNs of ≥5 mm at our institution was 133/755 (18%). The number of ITNs that would be recommended for work-up by method A was 57/133 (43%) compared with 31/133 (23%) for method B (P < .0005).
  
  
  CONCLUSIONS
  Compared with using a 10-mm cutoff, the 3-tiered risk-stratification method identified fewer ITNs for work-up but captured the same proportion of cancers in a national data base and showed no difference in missing high-mortality cancers.
authors.affiliation: Department of Radiology.
authors.forename: X V
authors.initials: XV
authors.lastname: Nguyen
authors.forename: K Roy
authors.initials: KR
authors.lastname: Choudhury
authors.forename: J D
authors.initials: JD
authors.lastname: Eastwood
authors.forename: G H
authors.initials: GH
authors.lastname: Lyman
authors.forename: R M
authors.initials: RM
authors.lastname: Esclamado
authors.forename: J D
authors.initials: JD
authors.lastname: Werner
authors.forename: J K
authors.initials: JK
authors.lastname: Hoang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D015995:Prevalence; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods* / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D016019:Survival Analysis; D015996:Survival Rate; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000401:mortality*; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data*; D055815:Young Adult
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