RT Journal Article SR Electronic T1 18F-FDG PET in Characterizing Adrenal Lesions Detected on CT or MRI JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1795 OP 1799 VO 42 IS 12 A1 Mijin Yun A1 Woojin Kim A1 Naheel Alnafisi A1 Lester Lacorte A1 Sunyoung Jang A1 Abass Alavi YR 2001 UL http://jnm.snmjournals.org/content/42/12/1795.abstract AB The purpose of this study was to evaluate the ability of 18F-FDG PET to characterize adrenal lesions in patients with proven or suspected cancers. Methods: A retrospective analysis was performed on 50 adrenal lesions in 41 patients, whose PET scans were done to evaluate the primary or metastatic disease. CT had shown 50 adrenal lesions in 41 patients and MRI had revealed 13 lesions in 10 patients. There were 34 patients with proven malignancy (28 lung cancer, 3 thyroid cancer, 2 colorectal cancer, and 1 lymphoma) and 7 with lung nodules. Of the 50 lesions, 18 were eventually determined to be malignant either by histopathology (n = 7) or by follow-up (n = 11). The remaining 32 lesions were proven or assumed to be benign by histopathology (n = 4) or clinical follow-up (n = 28). Unlike previously published reports, PET was interpreted as positive if the uptake was equal to or greater than that of the liver. Results: No malignant lesion yielded a negative result on PET. Most lesions (13/18) showed significantly higher FDG uptake than that of the liver. In the remaining 5 lesions (2 metastases from neuroendocrine tumor, 2 early metastases, and 1 necrotic metastasis), FDG uptake was equal to or slightly higher than that of the liver. Of the 32 benign lesions, there were 2 lesions with uptake equal to or slightly higher than that of the liver, 3 with uptake less than the liver but more than the background, and 27 with uptake of the background. MRI identified 3 of the 13 lesions as false-positives but FDG PET correctly identified all 3 as benign. The other 10 adrenal lesions accurately diagnosed by MRI were also characterized by PET. FDG PET for characterization of adrenal lesions showed a sensitivity of 100%, a specificity of 94%, and an accuracy of 96%. Conclusion: FDG PET showed excellent diagnostic performance in differentiating adrenal lesions detected on CT or MRI. Because FDG PET has the additional advantage of evaluating the primary lesions as well as metastases, it could be cost-effective and the modality of choice for the characterization of adrenal lesions, especially in patients with malignancy.