title: Positive predictive values of sonographic features of solid thyroid nodule.
abstract: OBJECTIVE
  The purpose of this study was to assess the positive predictive value of the suspicious sonographic features of solid nodules of the thyroid.
  
  
  METHODS
  After approval by our institutional review board, we evaluated 594 sonographically detected nodules on which fine needle aspiration biopsy had been performed from January to December 2005. Among these, pure cystic lesions and inadequate pathologic results were excluded. The remaining 530 solid thyroid nodules were analyzed by two radiologists. Each lesion was classified based on four sonographic features that suggested malignancy: microcalcifications; an irregular or microlobulated margin; marked hypoechogenicity; and a shape that was taller than wide. The sensitivity, specificity, positive predictive value, and negative predictive value of the each sonographic feature were calculated.
  
  
  RESULTS
  Final pathologic results showed that 97 (18.3%) of 530 nodules were malignant. The positive predictive values for malignancy in each sonographic feature were microcalcifications, 38.6% (39/101); an irregular or microlobulated margin, 28.2% (70/248); marked hypoechogenecity, 49.4% (38/77); taller than wide shape, 59.8% (49/82). In terms of relative risk, microcalcification [P<.01, relative risk (RR)=3.115, 95% CI: 1.724-5.628], hypoechogenecity (P<.01, RR=2.510, 95% CI: 1.290-4.881). The shape of nodule which was taller than wide (P<.01, RR=7.624, 95% CI: 4.156-13.986) revealed the highest predictive sonographic finding suggesting malignancy. However, margin is the least significant feature of detection of thyroid malignancy (P=.27, RR=1.395, 95% CI: 0.777-2.505).
  
  
  CONCLUSIONS
  The three sonographic features of solid thyroid nodule, that is, microcalcifications, marked hypoechogenecity, and a taller than wide shape are meaningful findings in the diagnosis of thyroid malignancy. The shape that was taller than wide was the most reliable sonographic feature for predicting malignancy.
authors.affiliation: Department of Diagnostic Radiology, The Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Yoo Jin
authors.initials: YJ
authors.lastname: Hong
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Son
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
authors.forename: Soon Won
authors.initials: SW
authors.lastname: Hong
authors.forename: Hang-Seok
authors.initials: HS
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016606:Thyroid Nodule / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult