TC-99(M)-MIBI SCANNING OF THE THYROID-GLAND IN PATIENTS WITH MARKEDLYDECREASED PERTECHNETATE UPTAKE

Diffusely reduced Tc-99(m)-pertechnetate uptake is a relatively infreq uent but annoying finding that impairs evaluation of the thyroid gland . We studied 32 female patients aged 19-85 years with markedly reduced pertechnetate uptake. The following causes of reduced pertechnetate u ptake were recognized: treatment with iodinated pharmaceuticals (n = 1 5), suppression therapy with T4 (n = 11), subacute thyroiditis (n = 5) and massive tumour replacement (n = 1). Tc-99(m)-MIBI thyroid scintig raphy was performed within 24 h of the pertechnetate study. The result s were correlated with neck ultrasound, serum TSH (n = 25) and surgica l findings in patients who had been operated on. The technique identif ied the following conditions: normally sized thyroids (n = 4), diffuse goitres (n = 8), multinodular goitres (n = 17) and solitary thyroid n odules (n = 3). Moreover, substernal goitres were identified in nine p atients. This condition was confirmed at surgery in seven patients. Ul trasonography was concordant in 29 of 32 patients in terms of thyroid size and structure, but failed to demonstrate substernal thyroid tissu e. Our results suggest that Tc-99(m)-MIBI scintigraphy may contribute to the diagnosis of thyroid pathology and treatment planning in patien ts with diffusely decreased Tc-99(m)-pertechnetate uptake. ((C) 1998 C hapman & Hall Ltd.).