title: Thyroid to salivary ratios determined by technetium-99m pertechnetate imaging in thirty-two euthyroid cats.
abstract: Thyroid to salivary (TS) ratio is the most commonly used scintigraphic parameter for differentiating euthyroid and hyperthyroid cats. Studies to determine the normal TS ratio have been performed in small cat populations. In this study, the TS ratio was determined in 32 cats between 8 and 13 years of age. The study population was documented to be euthyroid based on normal initial and 6-week follow-up serum thyroid concentrations and normal T3 suppression tests. All images were obtained with a low-energy all-purpose collimator between 20 and 40 min after the injection of approximately 111 MBq (3.0 mCi) pertechnetate. Manual regions of interest (ROI) were made of the thyroid and salivary glands of the ventral image A 95% prediction interval based on the natural log of the TS ratio was computed to provide a normal range of 0.48-1.66. This range is similar to previous studies, but suggests a slightly higher upper limit than previously reported.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
authors.forename: Todd D
authors.initials: TD
authors.lastname: Henrikson
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Armbrust
authors.forename: James J
authors.initials: JJ
authors.lastname: Hoskinson
authors.forename: George A
authors.initials: GA
authors.lastname: Milliken
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Wedekind
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Kirk
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Nachreiner
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000000981:diagnostic imaging*; D002415:Cats; D005260:Female; D008297:Male; D011877:Radionuclide Imaging; D012016:Reference Values; D012463:Saliva / Q000737:chemistry*; D013670:Sodium Pertechnetate Tc 99m; D013959:Thyroid Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000662:veterinary*; D013963:Thyroid Hormones / Q000097:blood / Q000378:metabolism*
chemical_list: D013963:Thyroid Hormones; D013670:Sodium Pertechnetate Tc 99m