A SIMPLIFIED METHOD FOR MEASURING THYROIDAL UPTAKE OF TECHNETIUM99m USING DIRECTIONAL COUNTING

Abstract

SUMMARY The uptake of technetium-99m (99mTc) by the thyroid was measured 15 min after injection using a directional counting technique. The 'washout' of thyroidal 99mTc after intravenous perchlorate injection was quantitated so that separate measurement of the extrathyroidal activity of 99mTc was unnecessary. In normal subjects the thyroidal uptake was 1·28 ± 0·61% of the administered dose (mean ± 1 s.d.); in primary myxoedema 0·26 ± 0·28%, in simple goitre 2·18 ± 2·10%, in thyrotoxicosis 11·0 ± 5·4%, in hypothyroid patients with Hashimoto's disease 4·50 ± 3·70% and in three patients with Pendred's syndrome the mean uptake was 9·3%. The technique has been evaluated and its advantages as a simple alternative to quantitative scintiscanning are discussed.