title: Effect of four sedative and anesthetic protocols on quantitative thyroid scintigraphy in euthyroid cats.
abstract: OBJECTIVE
  To determine the effect of sedation and anesthesia on thyroid and salivary gland uptake of technetium Tc 99m pertechnetate ((99m)TcO(4)) in euthyroid cats.
  
  
  METHODS
  6 euthyroid cats.
  
  
  METHODS
  Thyroid scintigraphy was performed by use of a high-resolution low-energy parallel-hole collimator after IV injection of 117 to 133 MBq (3.16 to 3.59 mCi) of (99m)TcO(4)(-). The procedure was performed 4 times on each cat during different sedative and anesthetic protocols in a rotating schedule as follows: propofol, ketamine-midazolam-atropine, ketaminemidazolam, and medetomidine. Regions of interest were drawn around thyroid and salivary glands and counts corrected for background and decay. Percentage of (99m)TcO(4)(-) uptake in salivary and thyroid glands and thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio were calculated at 20 and 40 minutes. Relative effects of anesthesia and sedation on salivary and thyroid gland (99m)TcO(4)(-) uptake were compared.
  
  
  RESULTS
  Significant differences among sedativeanesthetic protocols were found for thyroid gland (99m)TcO(4)(-) uptake, salivary gland (99m)TcO(4)(-) uptake, and thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio. Thyroid gland (99m)TcO(4)(-) uptake for the ketamine-midazolam protocol at 20 and 40 minutes after (99m)TcO(4)(-) administration was significantly higher than for the propofol protocol. A significant difference in salivary gland(99m) TcO(4)(-) uptake was found between ketamine-midazolam and ketamine-midazolam-atropine protocols at 40 minutes. The thyroid-to-salivary gland (99m)TcO(4)(-) uptake ratio for the ketamine-midazolam protocol was significantly higher at 40 minutes than for propofol or ketamine-midazolam-atropine protocols.
  
  
  CONCLUSIONS
  Sedation and anesthesia have a significant effect on thyroid and salivary gland (99m)TcO(4) uptake in euthyroid cats that may interfere with thyroid scintigraphic image interpretation.
authors.affiliation: Division of Diagnostic Imaging, Department of Clinical, Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 10, NL-3508 TD, Utrecht, The Netherlands.
authors.forename: Irene A
authors.initials: IA
authors.lastname: Schaafsma
authors.forename: Yvonne W E A
authors.initials: YW
authors.lastname: Pollak
authors.forename: Paul Y
authors.initials: PY
authors.lastname: Barthez
mesh_terms: D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002415:Cats; D005260:Female; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D020926:Medetomidine / Q000494:pharmacology; D008874:Midazolam / Q000494:pharmacology; D015742:Propofol / Q000494:pharmacology; D011877:Radionuclide Imaging / Q000662:veterinary*; D019275:Radiopharmaceuticals; D012469:Salivary Glands / Q000033:anatomy & histology / Q000187:drug effects; D013670:Sodium Pertechnetate Tc 99m; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000777:Anesthetics; D006993:Hypnotics and Sedatives; D019275:Radiopharmaceuticals; D007649:Ketamine; D001285:Atropine; D013670:Sodium Pertechnetate Tc 99m; D020926:Medetomidine; D008874:Midazolam; D015742:Propofol