Preclinical [18F]tetrafluoroborate-PET/CT imaging of pituitary gland hyperplasia

Abstract

By blocking of sodium–iodide symporter (NIS) in thyroid gland with potassium perchlorate administered in drinking water to rats for 18 months, we provoke hyperplasia of thyroid which led to thyroid cancer, but also of hyperplasia (benign tumour) of pituitary gland since the lack of thyroid hormones, as a consequence of NIS blockage, hyper-stimulates pituitary in order to produce more thyrotropin stimulating hormone (TSH), the hormone that stimulates thyroid for hormone secretion. There is evidence that hyperplasia of pituitary is provoked by perchlorate or estradiol benzoate in animal models. NIS is expressed in pituitary at the level of about one-tenth of that in thyroid. [18F]tetrafluoroborate ([18F]TFB), which mimics iodine, is a large mononegative anion that binds specifically to NIS. TFB-SUVmax (maximum Standard Uptake Value in the volume of interest, g/mL) in PET is correlated with NIS expression in thyroid.