Compared to 123I-MIBG SPECT/CT, 18F-DOPA PET/CT provides accurate tumor extent in patients with extra-adrenal paraganglioma

AIM: The aim of this study was to compare the accuracy of 123I-MIBG SPECT/CT with that of 18F-DOPA PET/CT for staging extra-adrenal paragangliomas (PGLs) using both functional and anatomical images (i.e., combined cross-sectional imaging) as the reference standards.

METHODS: Three men and seven women (age range 26-73 years) with anatomical and/or histologically proven disease were included in this study. Three patients had either metastatic head-and-neck paragangliomas (HNPGLs) or multifocal PGL, and seven patients had nonmetastatic disease. Comparative evaluation included morphological imaging with CT, functional imaging with 18F-DOPA PET, and 123I-MIBG imaging including SPECT/CT. Imaging results were analyzed on a per-patient and per-lesion basis.

RESULTS: On a per-patient basis, 18F-DOPA PET's detection rate for both nonmetastatic and metastatic/multifocal disease was 100%, whereas that of planar 123I-MIBG imaging alone was 10.0% and that of 123I-MIBG SPECT/CT was 20.0%. Overall, on a per-lesion basis, 18F-DOPA PET showed a sensitivity of 69.2% (McNemar p < 0.001) compared with anatomical imaging. Sensitivity of planar 123I-MIBG scintigraphy was 5.6%, and that of SPECT/CT was 11.1% (McNemar p < 0.0001). Overall, 18F-DOPA PET identified 18 lesions, and anatomical imaging identified 26 lesions; planar 123IMIBG imaging identified only 1 lesion, and SPECT/CT, 2 lesions.

CONCLUSION: 18F-DOPA PET is more sensitive than is 123I-MIBG imaging, including SPECT/CT, for staging HNPGL. Combined functional and anatomical imaging (PET/CT) is indicated to exclude metastatic disease in extra-adrenal PGL.