Functional imaging in paragangliomas with 18F DOPA PET/CT and 123I MIBG SPECT/CT imaging

Objectives We compared functional imaging modalities in the diagnosis and staging of paragangliomas (PGLs), using 18F-DOPA PET/CT (diagnostic CT) and 123I-MIBG imaging, including SPECT/CT (“low dose” CT). Diagnostic CT imaging referred as reference standard.

Methods Three male and eight female patients (age range 26 to 73 years) with anatomical and/or histologically proven disease were included in this study. Three patients were either suffering from metastatic head and neck paragangliomas (HNPGLs) or multifocal PGLs and eight patients from nonmetastastic disease. Comparative evaluation included diagnostic imaging with CT, functional imaging with 18F-DOPA PET and 123I-MIBG imaging. Imaging results were analyzed on a per lesion basis.

Results On a per lesion basis, 18F-DOPA showed a sensitivity of 67.9% and a specificity of 100% (McNemar p<0.01), when compared with anatomical imaging. Sensitivity and specificity of 123I-MIBG was 7.1% (McNemar p<0.0001), and 100% and that of SPECT/CT 10.7% and 66.7% (McNemar p<0.0001), respectively. Overall, 18F-DOPA PET identified 19 lesions, anatomical imaging identified 28 lesions, and 123I-MIBG imaging identified only 2 lesions and SPECT/CT 3 lesions.

Conclusions Both, 18F-DOPA PET and 123I-MIBG SPECT/CT imaging, achieve excellent to moderate specificity. 18F-DOPA PET is more sensitive than planar 123I-MIBG imaging including SPECT/CT, providing valuable clinical information for staging of paragangliomas.