title: 3D ultrasonography is as accurate as low-dose CT in thyroid volumetry.
abstract: OBJECTIVE
  The purpose of this study was to compare thyroid volumetry by three-dimensional mechanically swept ultrasonography (3DmsUS) and low-dose computed tomography (ldCT).
  
  
  METHODS
  30 subjects referred for radioiodine therapy of benign thyroid diseases were subjected to 3DmsUS and ldCT. A prerequisite of 3DmsUS analyses was that the scans had to capture the entire thyroid, excluding therefore cases with a very large volume or retrosternal portions. The 3DmsUS data were transformed into a DICOM format, and volumetry calculations were performed via a multimodal workstation equipped with standard software for cross-sectional imaging. Volume was calculated applying both the ellipsoid model and a manually tracing method. Statistical analyses included 95% confidence intervals (CI) of the means and limits of agreement according to Bland and Altman, the latter including 95% of all expected values.
  
  
  RESULTS
  Volumetric measurements by 3DmsUS and ldCT resulted in very high, significant correlation coefficients, r = 0.997 using the ellipsoid model and r = 0.993 with the manually tracing method. The mean relative differences of the two imaging modalities proved very small (-1.2±4.0% [95% CI -2.62; 0.28] using the ellipsoid model; -1.1±5.2% [95% CI -2.93; 0.80] using the manually tracing method) and the limits of agreement sufficiently narrow (-9.1% to 6.8%; -11.3% to 9.2%, respectively).
  
  
  CONCLUSIONS
  For moderately enlarged thyroids, volumetry with 3DmsUS proved comparable to that of ldCT, irrespective of whether the ellipsoid model or the manually tracing method was applied. Thus, 3DmsUS qualifies as a potential alternative to ldCT, provided that the organ is completely accessible. The use of a standard workstation for cross-sectional imaging with routine software did not prove problematic.
authors.forename: K
authors.initials: K
authors.lastname: Licht
authors.forename: A
authors.initials: A
authors.lastname: Darr
authors.forename: T
authors.initials: T
authors.lastname: Opfermann
authors.forename: T
authors.initials: T
authors.lastname: Winkens
authors.affiliation: Martin Freesmeyer, MD, Clinic of Nuclear Medicine, Jena University Hospital, Bachstraße 18, 07743 Jena, Germany, Tel. +49/(0)36 41/93 32 20, Fax +49/(0)36 41/93 32 44, E-mail: martin.freesmeyer@med.uni-jena.de.
authors.forename: M
authors.initials: M
authors.lastname: Freesmeyer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013959:Thyroid Diseases / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*
keywords: Thyroid gland volume; thyroid gland computed tomography; thyroid gland three-dimensional imaging; thyroid gland ultrasonography; volumetry methods