QUALITATIVE AND QUANTITATIVE THYROID IMAGING IN FELINE HYPERTHYROIDISM USING TECHNETIUM‐99M AS PERTECHNETATE

Abstract

Thyroid imaging using technetium‐99m as pertechnetate (99mTcO4) was carried out in five healthy, euthyroid and 37 hyperthyroid cats using both pinhole and parallel‐hole collimators. Images of greater resolution, necessary to distinguish bilateral lobe involvement, were obtained using the pinhole collimator. Per cent thyriod 99mTcO4 ‐ uptake was calculated in each cat and was significanly (P < 0.001) higher in hyperthyroid compared with euthyroid cats. In the hyperthyroid cats, per cent thyroid uptake was significantly correlated with serum total thyroxine (T4) and triiodothyronine (T3) Concentrations. Per cent thyroid 99mTcO4 ‐ uptake is increased in feline hyperthyrodism and may be calculated using a pinhole collimator alone at the time of qalitative assessment of the extent of thyroid tissue involvement.