title: Diagnostic dilemma of small incidentally discovered adrenal masses: role for 131I-6beta-iodomethyl-norcholesterol scintigraphy.
abstract: Incidentally discovered adrenal masses are detected in 0.35% to 5. 00% of patients imaged with computed tomography (CT) for reasons other than suspected adrenal pathology. Most small adrenal masses are benign, although malignant tumors </= 3 cm in diameter are well described. In the setting of normal adrenal hormonal secretion, the preferential accumulation of 131I-6beta-iodomethyl-norcholesterol (NP59) by adrenocortical tissues allows the distinction of adenomas from other space-occupying or destructive lesions, with diagnostic images being obtained in 100% of lesions > 2 cm. Although some lesions </= 2 cm have yielded nondiagnostic images, the frequency of this phenomenon and thus the utility of NP59 scintigraphy for the evaluation of small adrenal lesions has remained incompletely characterized. Between January 1976 and December 1994 a total of 166 patients with nonhypersecretory unilateral adrenal masses </= 3 cm in maximal diameter, discovered incidentally during CT examinations of the abdomen or chest for reasons other than clinically suspected adrenal disease, were studied with NP59 scintigraphy. Nonhypersecretory masses </= 1 cm, > 1 to </= 2 cm, and > 2 to </= 3 cm yielded diagnostic images in 52%, 89%, and 100% of patients, respectively. Lesions other than adenomas, including malignancies, > 1 to </= 2 cm and > 2 to </= 3 cm were present in 9% and 10% of patients, respectively. These findings emphasize the need to determine the nature of small incidentally discovered adrenal masses whose management may alter patient care and confirm the utility of NP59 scintigraphy to evaluate nonhypersecretory adrenal masses regardless of size.
authors.affiliation: Division of Nuclear Medicine, Department of Internal Medicine, University of Michigan Medical Center, 1500 E. Medical Center Drive, B1G412, Box 28, Ann Arbor, Michigan 48109, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Kloos
authors.forename: M D
authors.initials: MD
authors.lastname: Gross
authors.forename: B
authors.initials: B
authors.lastname: Shapiro
authors.forename: I R
authors.initials: IR
authors.lastname: Francis
authors.forename: M
authors.initials: M
authors.lastname: Korobkin
authors.forename: N W
authors.initials: NW
authors.lastname: Thompson
mesh_terms: D015071:19-Iodocholesterol / Q000031:analogs & derivatives*; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D014057:Tomography, X-Ray Computed
chemical_list: D015071:19-Iodocholesterol; C035501:6-iodomethylcholesterol