Diagnostic and prognostic value of 18F-FDG PET/CT in comparison with morphological imaging in primary adrenal gland malignancies - A multicenter experience

Objective: To evaluate the diagnostic and prognostic role of fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (F-18-FDG PET/CT) in comparison to morphological imaging such as computed tomography in primary adrenal malignancies. Materials and Methods: In this multicenter retrospective study, 68 patients with adrenal malignancy were included. All patients had histologically proven diagnosis of primary adrenal malignancy (adrenocortical carcinoma, malignant pheochromocytoma, neuroblastoma and lymphoma), one whole body F-18-FDG PET/CT scan and one whole-body contrast enhancement computed tomography (CECT) scan acquired within one month and were followed clinically and by performing morphological tests for at least 12 months. Results: Overall sensitivity, specificity, accuracy, positive and negative predictive values for CECT and F-18-FDG PET/CT were respectively, 59%, 100%, 65%, 100%, 27% and 75%, 100%, 82%, 100% and 63%. For adrenocortical carcinomas, F-18-FDG PET/CT showed a better accuracy (93.4%) than CECT (75%). For neuroblastomas F-18-FDG PET/CT also showed better accuracy (70.4%) than CECT (66.7%). For malignant pheochromocytomas F-18-FDG PET/CT and CECT showed the same accuracy (90%). For primary adrenal lymphomas, F-18-FDG PET/CT showed better accuracy (100%) than CECT (74.41%). Kaplan-Mayer curves showed that "histo-types" and "metastases at the last follow-up" were similarly detected for both disease free survival (DFS) and overall survival (OS), while "global F-18-FDG PET/CT" and "presence of metastases at diagnosis" were significant for DFS. Stratifying the sample by the presence or absence of metastases at diagnosis, standardized uptake value (SUVmax) was a significant prognostic factor for DFS when metastases were absent (Wald test=7.035, P=0.008). Conclusion: Our multicenter study demonstrated that F-18-FDG PET/CT better than CECT diagnosed adrenal malignancies achieving also a good prognostic performance. Therefore management algorithms should include F-18-FDG PET/CT.