title: Use of a curved-array transducer to reduce interobserver variation in sonographic measurement of thyroid volume in healthy adults.
abstract: OBJECTIVE
  Sonographic calculation of thyroid volume is used in the diagnosis and follow-up of thyroid diseases. Since the calculated volume of thyroid lobes is highly influenced by the longest (ie, craniocaudal) diameter, we examined whether using a curved-array transducer as opposed to a linear-array transducer to measure the craniocaudal diameter would reduce interobserver variation.
  
  
  METHODS
  Three sonographers with different levels of expertise each used a 5-12-MHz linear-array transducer and a 2-5-MHz curved-array transducer to measure the craniocaudal diameter of both thyroid lobes of 25 healthy volunteers. On the basis of these measurements, thyroid lobe volumes were calculated. Single-factor analysis of variance was used to evaluate the interobserver variations between the measurements made by all 3 observers as well as between measurements taken by pairs of observers. A p value of less than 0.05 was considered significant.
  
  
  RESULTS
  Using the linear-array transducer to measure the craniocaudal diameter resulted in significant interobserver variation in thyroid volume calculation (p = 0.02), whereas using the convex-array transducer did not. Using either transducer resulted in a highly significant interobserver variation in measurements of the craniocaudal diameter, although the variation was far more pronounced for measurements made with the linear-array transducer (p = 0.0005) than for those made with the curved-array transducer (p = 0.04). For both transducers, the interobserver variations were most pronounced between the most and the least experienced sonographers.
  
  
  CONCLUSIONS
  To avoid significant interobserver variation in calculating thyroid lobe volume, we recommend using a curved-array transducer to measure the craniocaudal diameter of the thyroid lobes.
authors.affiliation: Department of Radiology, University Hospital, Vrije Universiteit Brussel, Laarbeeklaan 101, B-1090 Brussels, Belgium.
authors.forename: Els Y
authors.initials: EY
authors.lastname: Peeters
authors.forename: Wael M
authors.initials: WM
authors.lastname: Shabana
authors.forename: Peter A
authors.initials: PA
authors.lastname: Verbeek
authors.forename: Michel M
authors.initials: MM
authors.lastname: Osteaux
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation