Objective: The objective of our study was to evaluate the value that PET/CT adds to adrenal protocol CT for characterizing adrenal metastasis in oncologic patients.
Materials and methods: Sixty-eight oncologic patients with 68 adrenal masses underwent both adrenal protocol CT and (18)F-FDG PET/CT. For adrenal protocol CT, metastasis was diagnosed if a mass measured more than 10 HU on unenhanced CT and if the absolute and relative percentage washouts were less than 60% and 40%, respectively. For PET/CT, metastasis was diagnosed if FDG uptake of the lesion was equal to or greater than that of the liver. Diagnostic accuracies were compared between these two imaging modalities.
Results: The accuracy of adrenal protocol CT and PET/CT for a metastatic lesion, defined as a lesion with FDG uptake equal to or higher than that of the liver, was 85.3% (58/68) and 76.5% (52/68), respectively. However, the accuracy of PET/CT increased to 89.7% (61/68) when a lesion with high FDG uptake alone was considered a metastatic lesion. When both adrenal protocol CT and PET/CT were positive for metastasis, the accuracy increased to 91.2% (62/68), but the sensitivity decreased to 70.6% (12/17).
Conclusion: Adding PET/CT to adrenal protocol CT improves the accuracy for adrenal metastasis in oncologic patients when a lesion with high FDG uptake alone is considered metastasis.