title: A threshold value in Shear Wave elastography to rule out malignant thyroid nodules: a reality?
abstract: OBJECTIVE
  To evaluate the ability of a threshold value in ShearWave™ elastography to rule out malignant thyroid nodules while studying its pertinence in association with morphological signs.
  
  
  METHODS
  148 patients (110 women and 38 men; 52.5 y.o. 15.8) referred for surgery of thyroid nodules underwent standard ultrasound as well as elastography. Characteristics of the morphological signs and maximum elastographic index were calculated in relation to histology. Association of morphological signs alone and then of elastography was also evaluated. One hundred and fifty one nodules were studied on a double-blind basis.
  
  
  RESULTS
  297 nodules were studied. Thirty-five cancers were detected (11.6%). Elastographic index was higher in malignant nodules (115 kPa 60.4) than in benign nodules (41 kPa 25.8) (p<0.001, Student's t-test). Cut off value of 66 kPa was the best to discriminate malignant nodules with a sensitivity of 80% (CI 95%, 62.5; 90.9) and a specificity of 90.5% (CI 95%, 86.1; 93.6) (p=0.0001). Association of elastography and morphological ultrasound signs presented a sensitivity of 97% (CI 95%, 83.3; 99.8) and a negative predictive value of 99.5% (CI 95%, 95.6; 99.9). Interobserver reproducibility proved to be excellent with an interclass correlation of 0.97 (CI 95%, 0.96; 0.98) (p<0.001).
  
  
  CONCLUSIONS
  The 66 kPa threshold in Shear Wave elastography is the best ultrasound sign to rule out malignant thyroid nodules. The method is simple, quantitative, reproducible and usable in the study of nodules larger than 3 cm. Progress must still be made in the study of calcified nodules and follicular tumors.
authors.affiliation: Département d'imagerie médicale, Hôpital d'Instruction des Armées St Anne, Bd Saint Anne, BP 20545 Toulon cedex, France. jbveyrieres@hotmail.fr
authors.forename: J-B
authors.initials: JB
authors.lastname: Veyrieres
authors.forename: F
authors.initials: F
authors.lastname: Albarel
authors.forename: J Vaillant
authors.initials: JV
authors.lastname: Lombard
authors.forename: J
authors.initials: J
authors.lastname: Berbis
authors.forename: F
authors.initials: F
authors.lastname: Sebag
authors.forename: C
authors.initials: C
authors.lastname: Oliver
authors.forename: P
authors.initials: P
authors.lastname: Petit
mesh_terms: D000465:Algorithms; D004311:Double-Blind Method; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000503:physiopathology*