Employing 18F-FDG PET/CT for distinguishing benign from metastatic adrenal masses

Abstract

Background: Metastatic adrenal disease can occur in a wide diversity of malignancies. Distinguishing benign from metastatic adrenal masses in oncologic patients is vital. Objective: To appraise the 18F-FDG PET/CT performance for distinguishing benign from metastatic adrenal masses. Material and methods: In the current prospective study, 21 patients with proven extra-adrenal primary malignancy, having adrenal masses ≥10 mm on the axial CT images of their PET/CT examinations, were enrolled. Positive PET findings for malignancy were considered if the mass showed FDG uptake equivalent to or more prominent than the FDG liver uptake. Alternatively, negative PET findings for malignancy were considered if the mass showed FDG uptake not as much of the FDG liver uptake. Afterward, the obtained results were correlated with serial imaging follow-up or histopathological diagnosis by surgery or percutaneous biopsy as the diagnostic standard of reference. Results: An overall number of 24 adrenal masses was diagnosed. Positive PET/CT results were found in 14 adrenal masses. All were finally considered to be metastases by serial imaging follow-up (n = 8) and histopathological analysis by surgery (n = 1) and percutaneous biopsy (n = 5). Accordingly, no false positive result was obtained. Negative PET/CT results were observed in 10 adrenal masses, 9 of them were finally confirmed to be benign by serial imaging follow-up. The remaining mass was finally confirmed to be metastasis by percutaneous biopsy and hence, it represented the false negative result. 93% sensitivity, 100% specificity and 96% accuracy for identifying adrenal metastases were obtained. Conclusion: 18F-FDG PET/CT is a precise, non invasive modality for distinguishing benign from metastatic adrenal masses in oncologic patients.

Keywords

• 18F-FDG PET/CT
• Extra-adrenal primary malignancy
• Benign
• Metastatic adrenal masses