68Ga-DOTATOC PET/CT provides accurate tumour extent in patients with extraadrenal paraganglioma compared to 123I-MIBG SPECT/CT

The aim of this study was to compare the accuracy of I-123-MIBG SPECT/CT with that of Ga-68-DOTATOC PET/CT for staging extraadrenal paragangliomas (PGL) using both functional and anatomical images (i.e. combined cross-sectional imaging) as the reference standards. The study included three men and seven women (age range 26 to 73 years) with anatomical and/or histologically proven disease. Three patients had either metastatic head and neck PGL (HNPGL) or multifocal extraadrenal PGL, and seven patients had nonmetastatic extraadrenal disease. Comparative evaluation included morphological imaging with CT, functional imaging with Ga-68-DOTATOC PET, and I-123-MIBG imaging. The imaging results were analysed on a per-patient and on a per-lesion basis. On a per-patient basis, the detection rate of Ga-68-DOTATOC PET was 100 %, whereas that of planar I-123-MIBG imaging was 10.0 % and with SPECT/CT 20.0 % for both nonmetastatic and metastatic/multifocal extraadrenal PGL. On a per-lesion basis, the overall sensitivity of Ga-68-DOTATOC PET was 100 % (McNemar p < 0.5), that of planar I-123-MIBG imaging was 3.4 % (McNemar p < 0.001) and that of SPECT/CT was 6.9 % (McNemar p < 0.001). Both Ga-68-DOTATOC PET and anatomical imaging identified 27 lesions. Planar I-123-MIBG imaging identified only one lesion, and SPECT/CT two lesions. Two additional lesions were detected by Ga-68-DOTATOC PET but not by either I-123-MIBG or CT imaging. Our analysis in this patient cohort indicated that Ga-68-DOTATOC PET/CT is superior to I-123-MIBG SPECT/CT, particularly in head and neck and bone lesions, and provides valuable information for staging extraadrenal PGL, particularly in patients with surgically inoperable tumours or multifocal/malignant disease.