68Ga-DOTATOC PET/CT in the localization of head and neck paraganglioma compared with 18F-DOPA PET/CT and 123I-MIBG SPECT/CT

Abstract

Purpose: ¹⁸F-Fluoro-L-dihydroxyphenylalanine (¹⁸F-DOPA) PET offers high sensitivity and specificity in the imaging of non-malignant head and neck paraganglioma (HNPGL) but lower sensitivity in metastatic disease of these neuroendocrine tumours (NET). In contrast to the radiotracer ¹⁸F-DOPA, both ¹²³I-meta-iodo-benzylguanidine (¹²³I-MIBG) and ⁶⁸Ga-DOTA-Tyr3-octreotide (⁶⁸Ga-DOTA-TOC) offer valuable clinical information on norepinephrine and somatostatin (SST) receptor status for planning ¹³¹I-MIBG and radionuclide peptide therapy (PRRT), respectively. Therefore, we compared ⁶⁸Ga-DOTA-TOC and ¹⁸F-DOPA PET/CT with ¹²³I-MIBG planar and SPECT/CT imaging, for the detection of HNPGL. Combined cross-sectional imaging was the reference standard.

Methods: A total of 3 men and 7 women (age range 22 to 73 years) with anatomical and/or histologically proven HNPGL were included in this study. Of these patients, 3 patients had metastatic HNPGL. Comparative evaluation included morphological imaging with CT and functional imaging with ⁶⁸Ga-DOTA-TOC and ¹⁸F-DOPA PET, including ¹²³I-MIBG imaging. The imaging results were analysed on a per-patient and per-lesion basis.

Results: On a per-patient analysis, the detection rate of both ⁶⁸Ga-DOTA-TOC PET/CT and ¹⁸F-DOPA PET/CT was 100%, that of planar ¹²³I-MIBG imaging 10.0% and that of SPECT/CT 20.0%. On a per-lesion basis and in reference to diagnostic CT, the sensitivity of ⁶⁸Ga-DOTA-TOC PET/CT was 100% (McNemar, P < 0.5), that of ¹⁸F-DOPA PET/CT was 66.7% (McNemar, P < 0.01), that of planar ¹²³I-MIBG imaging was 3.7% (McNemar, P < 0.0001), and that of SPECT/CT was 7.4% (McNemar, P < 0.0001) in HNPGL. Overall, ⁶⁸Ga-DOTA-TOC PET identified 29 lesions and anatomical imaging identified 27 lesions. ¹⁸F-DOPA PET identified 18 lesions, whereas planar ¹²³I-MIBG imaging identified 1 lesion and SPECT/CT 2 lesions.

Conclusion: ⁶⁸Ga-DOTA-TOC PET/CT is superior for imaging, non-malignant and metastatic HNPGL compared to ¹⁸F-DOPA PET/CT and planar ¹²³I-MIBG imaging, including SPECT/CT, particularly in bone lesions. Combined functional/anatomical imaging (⁶⁸Ga-DOTA-TOC PET/CT) enables excellent delineation of tumour extent in these rare tumour entities. Compared to ¹²³I-MIBG scintigraphy, ⁶⁸Ga-DOTA-TOC PET appears far more useful for planning radionuclide therapy in patients with surgically inoperable tumours or metastatic disease.

Keywords: (123)I-MIBG; (18)F-DOPA; (68)Ga-DOTA-TOC; Head and neck paraganglioma; PET; SPECT/CT.