A New and Superior Adrenal Imaging Agent, 131I-6ß-Iodomethyl-19-Nor-Cholesterol (NP-59): Evaluation in Humans

We have reported tissue distribution studies in rats and dogs with a new adrenal imaging agent, l31I-6s3-iodomethyl–19-nor-cholesterol (NP-59). This agent concentrated five times higher in the adrenal cortex than 13II–19-iodocholesterol without increased concentration in non-adrenal tissues. We now report in 34 patients, the findings on scintigraphy with NP-59 compared with angiograms and/or adrenal vein hormone levels and histopathology, including 13 patients with hypercortisolism, 12 with primary aldosteronism, 2 with low renin hypertension, 5 with catecholamine excess, 1 with a liver metastasis from an aldosterone producing adrenal cortical carcinoma, and 1 with anaplastic adrenal cortical carcinoma. NP-59 adrenal cortical uptake was more rapid and intense and background activity was less prominent, allowing earlier and more definite interpretation of images than was possible with 131 I-19-iodocholesterol.