Functional imaging in paragangliomas with 68Ga-DOTA-TOC PET/CT and 123I-MIBG SPECT/CT imaging

Objectives We compared functional imaging modalities in the staging of both metastatic and non-metastatic paragangliomas (PGLs), using 68Ga-DOTA-TOC PET/CT (diagnostic CT) and 123I-MIBG scintigraphy, 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 morphological imaging with CT, functional imaging with 68Ga-DOTA-TOC PET and 123I-MIBG imaging. Imaging results were analyzed on a per patient and on a per lesion basis.

Results On a per-patient basis, 68Ga-DOTA-TOC PET showed a sensitivity of 100%, 18.2% for 123I-MIBG imaging and 27.3% for SPECT/CT, respectively. The overall sensitivity of 68Ga-DOTA-TOC PET on a per lesion basis was 100% (McNemar p<0.5) and that of 123I-MIBG imaging was only 7.1% (McNemar p<0.0001) and of SPECT/CT was 10.7 % (McNemar p<0.0001), respectively. Both, 68Ga-DOTA-TOC PET and anatomical imaging, identified 28 lesions. 123I-MIBG imaging identified only 2 lesions and SPECT/CT 3 lesions. Two additional lesions were detected by 68Ga DOTA TOC PET, but negative in both, 123I MIBG and CT imaging.

Conclusions Our analysis in this patient cohort indicates that 68Ga-DOTA-TOC PET is superior to 123I-MIBG imaging, including SPECT/CT, providing valuable information for pretherapeutic staging of paragangliomas, particularly in surgically inoperable tumors or multifocal/malignant disease.