title: Diagnostic accuracy and interobserver agreement of Quasistatic Ultrasound Elastography in the diagnosis of thyroid nodules.
abstract: OBJECTIVE
  To assess the best technique and the diagnostic accuracy of Quasistatic Ultrasound Elastography (QUE) in thyroid nodules. Interobserver agreement was also evaluated.
  
  
  METHODS
  A preliminary study of 50 patients with 54 thyroid nodules was performed with quantitative software in order to define the best cut-off value of different imaging methods. All patients underwent total thyroidectomy and histopathology findings served as the standard of reference. Thereafter, 154 nodules in 137 consecutive patients were prospectively evaluated by three operators. Findings at fine-needle aspiration cytology and histopathology (N = 60) served as the standard of reference.
  
  
  RESULTS
  The most accurate technique was the axial peri-intranodular measurement method which achieved an area under the ROC curve of 0.961 (95 %CI 0.848 - 1.00) and had an optimal cut-off value of 3.00. QUE in the differentiation of thyroid nodules showed for operator 1: sensitivity 90 % (95 %CI 73.5 - 97.9 %), specificity 92.7 % (95 %CI 86.7 - 96.6 %), LR+ 12.40 (6.54 - 23.50), LR- 0.11 (0.04 - 0.32) and accuracy 91.4 % (95 %CI 85.4 - 97.3 %); for operator 2: sensitivity 86.7 % (95 %CI 69.3 - 96.2 %), specificity 87.1 % (95 %CI 79.9 - 92.4 %), LR+ 6.72 (4.16 - 10.80), LR- 0.15 (0.06 - 0.38) and accuracy 86.9 % (95 %CI 80.0 - 93.7 %); for operator 3: sensitivity 80 % (95 %CI 61.4 - 92.3 %), specificity 83.9 % (95 %CI 76.2 - 89.9 %), LR+ 4.96 (3.20 - 7.70), LR- 0.24 (0.12 - 0.49) and accuracy 81.9 % (95 %CI 74.0 - 89.9 %). Interobserver agreement values between operator 1 and operator 2 (k = 0.79) (p < 0.05, 95 %CI 0.684 - 0.904), between operator 1 and operator 3 (k = 0.73, 95 %CI: 0.607 - 0.854) and between operator 2 and operator 3 (k = 0.71, 95 %CI: 0.584 - 0.835) were significant.
  
  
  CONCLUSIONS
  QUE provides accurate quantitative evaluation of thyroid nodules with low interobserver variability.
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: V
authors: V
authors: Cantisani
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: P
authors: P
authors: Lodise
authors: Department of Surgical Sciences, "Sapienza" University of Rome, Rome, Italy.
authors: G
authors: G
authors: Di Rocco
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: H
authors: H
authors: Grazhdani
authors: Department of Surgical Sciences, "Sapienza" University of Rome, Rome, Italy.
authors: D
authors: D
authors: Giannotti
authors: Department of Surgical Sciences, "Sapienza" University of Rome, Rome, Italy.
authors: G
authors: G
authors: Patrizi
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: E
authors: E
authors: Medvedyeva
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: M
authors: M
authors: Olive
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: C
authors: C
authors: Fioravanti
authors: Department of Surgical Sciences, "Sapienza" University of Rome, Rome, Italy.
authors: L
authors: L
authors: Giacomelli
authors: Department of Surgical Sciences, "Sapienza" University of Rome, Rome, Italy.
authors: C
authors: C
authors: Chiesa
authors: Department of Surgical Sciences, "Sapienza" University of Rome, Rome, Italy.
authors: A
authors: A
authors: Redler
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: C
authors: C
authors: Catalano
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: F
authors: F
authors: D'Ambrosio
authors: Department of Radiology, "Sapienza" University of Rome, Rome, Italy.
authors: P
authors: P
authors: Ricci
mesh_terms: D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D015331:Cohort Studies; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012984:Software; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D013965:Thyroidectomy; D018084:Ultrasonography, Interventional