title: Inter- and intraobserver variability of (semi-)quantitative parameters commonly used in feline thyroid scintigraphy.
abstract: The aim of this study was to assess inter- and intraobserver variability of commonly used semi-quantitative and quantitative parameters in feline thyroid scintigraphy: thyroid to salivary gland ratio (T/S), thyroid to background ratio (T/B) and the percentage technetium pertechnetate uptake for the thyroid glands (%TcUT). These parameters are being used to diagnose thyroid disease and to assess its severity, but may be influenced by operator related factors when processing the images. Additionally, inter- and intraobserver variability of the percentage technetium pertechnetate uptake for the salivary glands was determined (%TcUSG). The study included technetium pertechnetate scans of 100 hyperthyroid cats. Variability within and between three observers was determined using a random effects model and variance components were estimated by the restricted maximum likelihood procedure. The %TcU for the thyroid and salivary glands, as well as the T/S ratio, showed little to no difference in inter- and intraobserver variability, whereas this was clearly present for the T/B ratio. Overall, the T/S ratio and %TcUSG showed a good repeatability and reproducibility with low inter- and intraobserver variabilities. Inter- and intraobserver variability was higher for the %TcUT, however variations were still considered to be acceptable. On the contrary, inter- and intraobserver variability was clearly larger for the T/B ratio. These findings suggest the preferential use of the T/S ratio or %TcU, especially in facilities with a less experienced staff.
authors.affiliation: Department of Medical Imaging, Faculty of Veterinary Medicine, Ghent University (UGent), Ghent, Belgium. Electronic address: veerlevolckaert@gmail.com.
authors.forename: Veerle
authors.initials: V
authors.lastname: Volckaert
authors.affiliation: Department of Medical Imaging, Faculty of Veterinary Medicine, Ghent University (UGent), Ghent, Belgium.
authors.forename: Eva
authors.initials: E
authors.lastname: Vandermeulen
authors.affiliation: Department of Comparative Physiology and Biometrics, Faculty of Veterinary Medicine, Ghent University (UGent), Ghent, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Duchateau
authors.affiliation: Department of Medical Imaging, Faculty of Veterinary Medicine, Ghent University (UGent), Ghent, Belgium.
authors.forename: Jimmy H
authors.initials: JH
authors.lastname: Saunders
authors.affiliation: Department of Medical Imaging, Faculty of Veterinary Medicine, Ghent University (UGent), Ghent, Belgium.
authors.forename: Kathelijne
authors.initials: K
authors.lastname: Peremans
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000000981:diagnostic imaging*; D002415:Cats; D006980:Hyperthyroidism / Q000000981:diagnostic imaging / Q000662:veterinary*; D015588:Observer Variation; D011877:Radionuclide Imaging / Q000379:methods / Q000662:veterinary*; D015203:Reproducibility of Results; D012469:Salivary Glands; D013670:Sodium Pertechnetate Tc 99m / Q000494:pharmacology*; D013961:Thyroid Gland / Q000000981:diagnostic imaging
chemical_list: D013670:Sodium Pertechnetate Tc 99m
keywords: Feline; Hyperthyroidism; Quantification; Scintigraphy; Thyroid