| Abstract: |
Background: Pheochromocytomas and paragangliomas (PPGLs) are rare tumors of the adrenal medulla and extra-adrenal sympathetic chromaffin tissues; their anatomical and functional imaging are critical to guiding treatment decisions. This study aimed to compare the sensitivity and specificity of 18F-fluorodeoxyglucose positron emission tomography with computed tomography ( 18F-FDG PET/CT) for tumor localization and staging of PPGLs with that of conventional imaging by [ 123I]- metaiodobenzylguanidine single photon emission CT ( 123I-MIBG SPECT), CT, and magnetic resonance imaging (MRI). Methods: A total of 216 patients (106 men, 110 women, aged 45.2 ± 14.9 years) with suspected PPGL underwent CT or MRI, 18F-FDG PET/CT, and 123I-MIBG SPECT/CT. Sensitivity and specificity were measured as endpoints and compared by the McNemar test, using two-sided P values only. Results: Sixty (28%) of patients had nonmetastatic PPGL, 95 (44%) had metastatic PPGL, and 61 (28%) were PPGL negative. For nonmetastatic tumors, the sensitivity of 18F-FDG was similar to that of 123I-MIBG but less than that of CT/MRI (sensitivity of 18F-FDG = 76.8%; of 123I-MIBG = 75.0%; of CT/MRI = 95.7%; 18F-FDG vs 123I-MIBG: difference = 1.8%, 95% confidence interval [CI] = 214.8% to 14.8%, P = .210; 18F-FDG vs CT/MRI: difference = 18.9%, 95% CI = 9.4% to 28.3%, P < .001). The specificity was 90.2% for 18F-FDG, 91.8% for 123I-MIBG, and 90.2% for CT/MRI. 18F-FDG uptake was higher in succinate dehydrogenase complex- and von Hippel-Lindau syndrome-related tumors than in multiple endocrine neoplasia type 2 (MEN2) related tumors. For metastases, sensitivity was greater for 18F-FDG and CT/MRI than for 123I-MIBG (sensitivity of 18F-FDG = 82.5%; of 123I-MIBG = 50.0%; of CT/MRI = 74.4%; 18F-FDG vs 123I-MIBG: difference = 32.5%, 95% CI = 22.3% to 42.5%, P < .001; CT/MRI vs 123I-MIBG: difference =24.4%, 95% CI = 11.3% to 31.6%, P < .001). For bone metastases, 18F-FDG was more sensitive than CT/MRI (sensitivity of 18F-FDG = 93.7%; of CT/MRI = 76.7%; difference = 17.0%, 95% CI = 4.9% to 28.5%, P = .013). Conclusions: Compared with 123I-MIBG SPECT and CT/MRI, both considered gold standards for PPGL imaging, metastases were better detected by 18F-FDG PET. 18F-FDG PET provides a high specificity in patients with a biochemically established diagnosis of PPGL. |
