Distinguishing benign from malignant euadrenal masses.
OBJECTIVE
To determine the efficacy of 131I-6-beta-iodomethylnorcholesterol (NP-59) adrenal scintigraphy in distinguishing benign from malignant euadrenal masses.


METHODS
Case series of patients with incidentally discovered unilateral, euadrenal masses.


METHODS
Referral-based nuclear medicine clinics at university and affiliated Veterans Administration medical centers.


METHODS
Consecutive sample of 119 euadrenal patients with unilateral adrenal masses discovered on computed tomographic (CT) scans for reasons other than suspected adrenal disease.


METHODS
Adrenal scintiscans done using 1 mCi of NP-59 intravenously, and gamma camera imaging 5 to 7 days later.


RESULTS
Mean lesion diameter was 3.3 +/- 1.9 cm (SD) (95% CI: 2.9 to 3.6 cm). 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. Twenty-six patients had absent or markedly reduced NP-59 uptake in the glands identified as abnormal on CT scans (discordant imaging). These adrenal masses proved to be metastatic malignancies in 19 patients, primary adrenal neoplasms other than adenoma in 4, and adrenal cysts in 3. 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). Sensitivity was 76% (26 of 34 patients; CI, 58% to 88%); specificity, 100% (85 of 85 patients; CI, 95% to 100%), and accuracy, 93% (111 of 119 patients: CI, 88% to 98%).


CONCLUSIONS
Functional NP-59 scintigraphy can be used to accurately and noninvasively characterize many euadrenal masses; concordance of CT and NP-59 scans can be used to exclude the presence of a malignancy or other space-occupying adrenal lesion.
University of Michigan, Ann Arbor.
M D
MD
Gross
B
B
Shapiro
J A
JA
Bouffard
G M
GM
Glazer
I R
IR
Francis
G P
GP
Wilton
F
F
Khafagi
L P
LP
Sonda
D015071:19-Iodocholesterol / Q000031:analogs & derivatives*; D000236:Adenoma / Q000175:diagnosis; D000293:Adolescent; D000302:Adrenal Cortex / Q000000981:diagnostic imaging*; D000307:Adrenal Gland Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002784:Cholesterol / Q000031:analogs & derivatives*; D003560:Cysts / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D014057:Tomography, X-Ray Computed
D007457:Iodine Radioisotopes; D015071:19-Iodocholesterol; C035501:6-iodomethylcholesterol; D002784:Cholesterol