Distinguishing benign from malignant euadrenal masses

Area of Science:

• Nuclear medicine
• Radiology
• Endocrinology

Background:

• Adrenal masses are often discovered incidentally on computed tomographic (CT) scans.
• Distinguishing benign from malignant adrenal masses is crucial for patient management.
• Current diagnostic methods may be invasive or lack specificity.

Purpose of the Study:

• To evaluate the efficacy of 131I-6-beta-iodomethylnorcholesterol (NP-59) adrenal scintigraphy in differentiating benign from malignant adrenal masses.
• To assess the diagnostic accuracy of NP-59 scintigraphy in incidentally discovered adrenal lesions.

Main Methods:

• A case series of 119 patients with incidentally discovered unilateral, euadrenal masses was analyzed.
• Patients underwent adrenal scintigraphy using 1 mCi of NP-59 intravenously, followed by gamma camera imaging 5 to 7 days later.
• Results were correlated with CT findings, needle-aspiration biopsy, adrenalectomy, or extended follow-up.

Main Results:

• NP-59 uptake lateralized to the abnormal adrenal in 76 patients, all diagnosed with adenoma (concordant imaging).
• Absent or reduced NP-59 uptake in abnormal glands (discordant imaging) indicated malignancy in 19 patients, other primary adrenal neoplasms in 4, and cysts in 3.
• The sensitivity, specificity, and accuracy of NP-59 scintigraphy were 76%, 100%, and 93%, respectively.

Conclusions:

• Functional NP-59 scintigraphy is an accurate and noninvasive tool for characterizing euadrenal masses.
• Concordance between CT and NP-59 scans effectively excludes malignancy and other space-occupying adrenal lesions.
• NP-59 scintigraphy aids in the diagnostic workup of incidentally discovered adrenal masses.