THYROID VOLUMETRIC MEASUREMENT AND QUANTITATIVE THYROID SCINTIGRAPHY IN DOGS

Thyroid volumetric measurement combined with quantitative Tc-99m-perte chnetate thyroid scintigraphy was performed in 62 clinical canine pati ents having suspected thyroid abnormalities. Euthyroid dogs (n = 22) h ad a total thyroid size of 3.60 +/- 1.36 cm(3), the thyroid/salivary g land region of interest (ROI) ratio was 2.01 +/- 0.55, the thyroid/bac kground ROI ratio was 3.86 +/- 0.90, and 20-min thyroid radioactivity uptake was 1.17 +/- 0.71% of the injected dose (I. D.). By Student's u npaired test, thyroid size of the hypothyroid group (n = 36) was not s tatistically different from that of the euthyroid dogs, but all other quantitative data (e.g. thyroid/salivary gland ROT ratio = 1.08 +/- 0. 56, thyroid/background ROI ratio = 2.32 +/- 0.70, and 20-min thyroid r adioactivity uptake = 0.34 +/- 0.22% of the I. D.) were significantly (p < 0.001) lower in hypothyroid than in euthyroid dogs. Evaluating th e above-listed quantitative data of separated thyroid lobes by Student 's paired test, there was no significant difference between the left a nd the right lobe either in the euthyroid or in the hypothyroid group.