Disease relevance of ADOSTEROL

• In the presence of normal biochemistry, a concordant NP-59 imaging pattern is diagnostic of a nonhypersecretory benign adrenal adenoma and requires no immediate therapeutic intervention [1].
• The adrenal gland uptake of 131I-6-beta-iodomethyl-19-norcholesterol (NP-59) was calculated using a semioperator-independent computer algorithm in 17 patients with Cushing's syndrome (CS) [2].
• NP-59 adrenal uptake values were 0.20 +/- 0.02%/dose (range, 0.03-0.72), 0.28 +/- 0.04% (range, 0.10-0.65), and 0.14 +/- 0.02%/dose (range, 0.08-0.30) in AA, BAH, and essential hypertension, respectively [3].
• The accuracy of NP-59 scintigraphy ranged from 71% in primary aldosteronism and 75% in euadrenal tumors, to 100% for Cushing's syndrome and hyperandrogenism [4].
• With NP-59, nine of ten tumors were correctly located (90%) , correct distinction between tumor and hyperplasia was possible in 90%, and a locating DS scan was specific for tumor in 90% [5].

High impact information on ADOSTEROL

• Bilateral, symmetric accumulation of NP-59 was seen in 17 patients, in whom the adrenal masses were shown to be metastatic malignancies in 2, and adenomas in 6 (the lesions in these cases being 2 cm or less in diameter), and lesions not truly involving the adrenal in the rest (periadrenal metastases in 4 and pseudoadrenal masses in 5) [6].
• The elevation of adrenal cortical NP-59 uptake in PCO was quantitatively similar to that in women with ACTH-dependent Cushing's syndrome (0.64 +/- 0.11%; P greater than 0.1) [7].
• A significant correlation was found between adrenal gland uptake of NP-59 and urinary aldosterone excretion in AA (r = 0.93; P less than 0.001) and BAH (r = 0.6; P less than 0.01) patients [3].
• These data confirm that adrenal gland accumulation of NP-59 while on dexamethasone suppression can be used to characterize abnormal zona glomerulosa function in PA, in addition to localizing AA and differentiating AA from BAH [3].
• Adrenocortical SPECT using iodine-131 NP-59 [8].

Chemical compound and disease context of ADOSTEROL

• Increased serum cholesterol concentrations are associated with diminished adrenal uptake of NP-59, and in some cases may limit the diagnostic efficacy of adrenal scintigraphy in Cushing's syndrome [9].
• Dexamethasone suppression NP-59 adrenal scintigraphy has been shown to be highly sensitive and specific, and exceeds the efficacy of CT in the differentiation of adenoma and bilateral hyperplasia in primary aldosteronism [10].
• Visualization of adrenocortical carcinoma lung metastases with iodine-131 labeled 6B-iodomethylnorcholesterol (NP-59) [11].
• The relationship of I-131 6 beta-iodomethyl-19-norcholesterol (NP-59) adrenal cortical uptake to indices of androgen secretion in women with hyperandrogenism [12].

Biological context of ADOSTEROL

• However, more than in most nuclear medicine studies, NP-59 imaging requires well-defined indications to be met for it to be efficacious, including the fulfillment of clear clinical, biochemical, and radiographic criteria [4].
• Enterohepatic circulation and distribution of 131I-6 beta-iodomethyl-19-norcholesterol (NP-59) [13].

Anatomical context of ADOSTEROL

• The mean adrenal gland uptake (percentage of administered dose) of NP-59 was 0.74 +/- 0.18% (range, 0.21-2.02%) in CS and was significantly higher than that of normal subjects (0.33 +/- 0.02%) [2].
• The remaining adrenal cortex may be anatomically abnormal after unilateral adrenalectomy and demonstrate compensatory, increased NP-59 uptake in the presence of overall, normal adrenocortical function [14].
• External scanning with NP-59 localized steroid production to the testes, and bilateral orchiectomy was performed [15].
• Scanning the gonads with NP-59 may be a helpful imaging procedure in localizing possible sites for exploratory surgery in certain cases of gonadal neoplasia [16].
• Imaging of the cortex is achieved by iodine-131-labeled iodomethyl nor-cholesterol (NP-59), while adrenal medulla imaging can be successfully accomplished by 131I-metaiodobenzylguanidine (MIBG), which localizes in the adrenergic nerve terminal with norepinephrine [17].

Associations of ADOSTEROL with other chemical compounds

• NP-59 concentrates in steroid hormone synthesizing tissues, enabling scintigraphic localization and characterization of endocrine dysfunction in the adrenal cortex and ovary [4].
• The chemical stabilities of the adrenal-scanning agents, 6beta-iodo-methyl-19-norcholest-5(10)-en-3beta-ol (6-iodomethylnorcholesterol) and 19-iodocholest-5-en-3beta-ol (19-iodocholesterol), and several of their derivatives were examined by 13C nuclear magnetic resonance [18].
• In the course of recovery from o,p' DDD damage, the ability of the adrenal gland to take up NP-59 may be restored before the return of its biosynthetic and secretory functions [19].

Gene context of ADOSTEROL

• This is the case of a large 2 x 1.5 cm adrenal tumor demonstrated on CT scan that was proven biochemically and surgically to be an aldosteronoma and that did not concentrate 6-beta(131I)-iodo-methyl-19-norcholesterol (NP-59) [20].

Analytical, diagnostic and therapeutic context of ADOSTEROL

• Conversely, patients with discordant patterns of NP-59 scintigraphy have lesions that carry a significant risk for malignancy, and the pursuit of a tissue diagnosis is indicated, usually by means of FNA [1].
• In 76 patients, NP-59 uptake lateralized to the abnormal adrenal seen on CT scans (concordant imaging), and in all of these patients, a diagnosis of adenoma was made by needle-aspiration biopsy, adrenalectomy, or extended follow-up with repeat CT scans that were unchanged at 6 months or later [6].
• One-time evaluation with fine-needle aspiration (FNA) and combinations of chemical-shift MRI, noncontrast CT, 131I-6beta-iodomethylnorcholesterol (NP-59) scintigraphy, with or without FNA, in a hypothetical cohort of 1000 patients with incidentally discovered unilateral, nonhypersecretory adrenal masses [21].
• Adrenal scintigraphy was performed using 1 mCi of NP-59 injected intravenously, with gamma camera imaging 5-7 days later [22].
• Both adrenocortical scintigraphy with [131]6beta-iodomethylnorcholesterol (NP-59) and adrenomedullary imaging with 131I or 123I-labelled metaiodobenzylguanidine (MIBG) as function-dependant imaging techniques provide functional metabolic information for lesion characterization [23].

References