Differentiating adrenal adenomas from nonadenomas using (18)F-FDG PET/CT: quantitative and qualitative evaluation

Area of Science:

• Nuclear Medicine
• Radiology
• Oncology

Background:

• Adrenal masses require accurate differentiation between benign adenomas and malignant nonadenomas.
• ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT) is utilized in evaluating various malignancies.

Purpose of the Study:

• To evaluate the efficacy of ¹⁸F-FDG PET/CT in differentiating adrenal adenomas from nonadenomas in patients with suspected malignancy.
• To assess the diagnostic performance of CT attenuation values and standardized uptake values (SUVs) in this differentiation.

Main Methods:

• Fifty-nine adrenal masses underwent coregistered ¹⁸F-FDG PET/CT imaging.
• Two reviewers independently assessed visual ¹⁸F-FDG uptake compared to liver and background.
• CT attenuation values and SUVs of adrenal masses, liver, background, and primary neoplasms were measured and analyzed.

Main Results:

• Unenhanced CT showed adenomas typically <10 HU, while nonadenomas were >10 HU.
• Nonadenomas exhibited significantly higher ¹⁸F-FDG uptake compared to the liver (mean adrenal/liver ratio 2.1) than adenomas (mean ratio 1.0).
• Visually, adrenal mass activity less than the liver was more specific for adenoma, while activity greater than the liver suggested malignancy.

Conclusions:

• Combining unenhanced CT measurements with SUV ratios derived from ¹⁸F-FDG PET/CT enhances the differentiation of adrenal adenomas from nonadenomas.
• Qualitative assessment of ¹⁸F-FDG uptake relative to liver provides valuable information for distinguishing benign from malignant adrenal lesions.