Thyroidal radioisotope uptake in euthyroid cats: a comparison between 131I and 99mTcO4.
Two thyroidal evaluation systems in euthyroid cats (n = 12) were compared. A single, confirmed hyperthyroid cat was included for interest. Firstly, thyroidal uptake of an intravenous bolus of approximately 111 MBq (3 mCi) 99MTcO4 was estimated by using a scintillation camera and calculating the ratio of thyroid to salivary activities at 20 min and 4 h. Thyroid to salivary activity ratios were 1:1 at 20 min and 2:1 at 4 h. Two discrete areas of salivary uptake were identified, namely a parotid/mandibular complex and a more rostral buccal/sublingual complex. These results were compared to radioiodine uptake of an oral dose of approximately 0.925 MBq (25 microCi) 131I using a standard thyroid uptake system, measured at 1, 2, 4, 6, 8, 10, 12, 24 and 48 h after administration. Mean radioiodine thyroidal uptake started at 33% at 1 h, stabilised at 21% between 4 and 24 h, and dropped to 18% at 48 h. There was a significant correlation between the early thyroid:salivary ratio of the parotid/mandibular complex and the radioiodine uptake at 12 h.
Lambrechts
N
N
Department of Companion Animal Medicine and Surgery, Faculty of Veterinary Science, Medical University of South Africa, Medunsa, South Africa.
Jordaan
M M
MM
Pilloy
W J
WJ
van Heerden
J
J
Clauss
R P
RP
D000818:Animals; D002415:Cats; D005260:Female; D007457:Iodine Radioisotopes / Q000378:metabolism; D008297:Male; D011877:Radionuclide Imaging; D013670:Sodium Pertechnetate Tc 99m / Q000378:metabolism; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000378:metabolism; D013997:Time Factors
D007457:Iodine Radioisotopes; D013670:Sodium Pertechnetate Tc 99m