title: Interobserver variability and diagnostic performance in US assessment of thyroid nodule according to size.
abstract: OBJECTIVE
  To evaluate the interobserver variability for US assessments of thyroid nodules and analyze the diagnostic performances of US assessments in thyroid nodules according to nodule size.
  
  
  METHODS
  This was an IRB-approved retrospective study with waiver of informed consent. A total of 400 surgically-confirmed thyroid nodules were included. Nodules were divided into 4 groups by size; group 1 (nodule size < 5 mm), group 2 (5 mm ≤ nodule size < 10 mm), group 3 (10 mm ≤ nodule size < 20 mm), and group 4 (nodule size ≥ 20 mm). Three experienced (7 - 10 years) radiologists retrospectively reviewed the US images. Agreement of each US descriptor and final US assessment, and diagnostic performances were calculated in each group and compared.
  
  
  RESULTS
  Composition represented substantial or good agreement (k = 0.719 - 0.89). Margin showed the lowest agreement (k = 0.322 - 0.365). Individual kappa values for final assessment according to nodule size were as follows: group 1 (k = 0.674), group 2 (k = 0.596), group 3 (k = 0.674), and group 4 (k = 0.673). Specificity, PPV, and accuracy were significantly different among the groups with different size (p value < 0.05) and lowest in group 1. NPV, specificity, PPV and accuracy except PPV of observer 3 increased with nodule size (p < 0.05).
  
  
  CONCLUSIONS
  Interobserver agreements were relatively good (k = 0.637) in final US assessment regardless of nodule size in experienced radiologists. High false-positive rate was observed in US assessment in nodules less than 5 mm in maximum diameter.
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine.
authors.forename: S J
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine.
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.affiliation: Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Radiology, Busan Paik Hospital, Inje University College of Medicine.
authors.forename: D W
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine.
authors.forename: E J
authors.initials: EJ
authors.lastname: Son
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine.
authors.forename: H S
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Department of Radiology, CHA Bundang Medical Center, CHA University, School of Medicine.
authors.forename: J H
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine.
authors.forename: E-K
authors.initials: EK
authors.lastname: Kim
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine.
authors.forename: H J
authors.initials: HJ
authors.lastname: Moon
authors.affiliation: Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine.
authors.forename: J Y
authors.initials: JY
authors.lastname: Kwak
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D047368:Tumor Burden; D018084:Ultrasonography, Interventional; D055815:Young Adult