title: Positive predictive value and interobserver variability of preoperative staging sonography for thyroid carcinoma.
abstract: OBJECTIVE
  The purpose of this article is to evaluate the positive predictive value (PPV) and interobserver variability of preoperative staging sonography for thyroid carcinoma.
  
  
  METHODS
  Eighty-five patients (median age, 45 years) were included. The T and N staging were classified according to TNM classification. Extrathyroidal extension was defined as contact with the capsule greater than 25% of the perimeter of a malignant lesion or loss of the capsule line. The sonography criteria for lymph node metastases were absence of echogenic fatty hilum, round shape, hyperechogenicity, microcalcifications, cystic change, and peripheral vascularity. The PPV and interobserver variability of two radiologists were calculated.
  
  
  RESULTS
  The mean size of 85 malignancies was 8.6 mm, with 17 that were larger than 10 mm and 68 that were 10 mm or smaller. PPV ranges of sonography by two radiologists were 65-100% for T staging, 44.4-45.5% for multifocality, 71.4-81.8% for bilaterality, 28.6-80% for N1a staging, and 40-100% for N1b staging. In all malignancies, the kappa values were 0.5319 for T staging, 0.7741 for multifocality, 0.8604 for bilaterality, and 0.6793 for N staging. In 17 malignancies larger than 10 mm, the corresponding kappa values were lower (κ = 0.4516, 0.5952, 0.8211, and 0.6364, respectively). In 68 malignancies 10 mm or smaller, the corresponding kappa values showed slight improvements, except for T staging (κ = 0.5016, 0.8413, 0.8721, and 0.6821, respectively).
  
  
  CONCLUSIONS
  The T staging, bilaterality, and N1b staging of preoperative staging sonography showed high PPV. Agreements for T and N staging, multifocality, and bilaterality were moderate, substantial, substantial, and excellent, respectively.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, 120-752 Seoul, Republic of Korea.
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Moon
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Yoon
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
authors.forename: Woong Youn
authors.initials: WY
authors.lastname: Chung
authors.forename: Kee-Hyun
authors.initials: KH
authors.lastname: Nam
authors.forename: Jong Ju
authors.initials: JJ
authors.lastname: Jeong
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015588:Observer Variation; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011446:Prospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D014463:Ultrasonography