Abstract
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Objectives Bilateral adrenal masses or bilaterally increased FDG metabolism usually suggest other ethiologies such as primary adrenal hyperplasia and more rare primary adrenal neoplasms mostly seen in particular syndromes.The aim of this study is to retrospectively review a rather large number of oncologic PET/CT studies to find out the frequency of adrenal hypermetabolism and to make differential diagnosis based on other modalities.
Methods A total of 448 oncologic FDG PET/CT studies in 407 patients in about 3-year-period were included.All patients had confirmed malignancy. The images were retrospectively reviewed by 2 experienced nuclear medicine physicians and correlated to histopathology, CT and/or MR findings.Both visual and quantitative analysis were used for interpretation.
Results Among all patients 27/407 (7%) showed adrenal hypermetabolism on FDG PET/CT, where 20/27 (74%) were found to be malignant and 7/27(26%) benign.Adrenal metastates were unilateral in 18/20 (90%) while bilateral in 2 (10%) patients.All metastatic sites were confirmed by other modalities (2 by histopathology and 18 by CT and/or MRI). Among benign adrenal hypermetabolism, 6/7 (86%) was due to adenoma where 1/7(14%) was lipoma, confirmed by radiology. Adenomas were bilateral in just 1/7 (14%) patient. Mean SUVmax value of malignant adrenal hypermetabolism was significantly higher than that of benign adrenal FDG uptake (p<0,05).Only 3/7 (43%) patients with benign uptake showed higher intensity than liver while all malignant FDG uptake values were higher compared to liver SUVmean
Conclusions The intensity of adrenal uptake compared to liver SUVmean, uni/bilateral pattern and the primary diagnosis may be the key parameters which lead to correct differential diagnosis, based on confirmation by some other methods