Quantification of [68Ga]DOTANOC PET
[68Ga]DOTANOC ([68Ga]DOTA-NaI-octreotide) is a somatostatin analogue which binds to subtypes 2, 3 and 5 of somatostatin receptors (SSTR2, SSTR3, and SSTR5, respectively) (Wild et al., 2005). The receptor binding profile is wider than with some other related ligands, which may be advantageous for tumour imaging, because neuroendocrine tumours (NETs) may express different SSTR subtypes (Wild et al., 2013). Minor disadvantage is that this may prevent using traditional compartmental modelling for quantitative analysis. Graphical analysis methods may still be valid, but currently [68Ga]DOTANOC PET studies are analysed using only semiquantitative methods, mainly SUV.
Somatostatin receptor imaging is not specific to NETs; for example some lymphomas express SSTRs (Ruuska et al., 2018). [68Ga]DOTANOC PET offers good diagnostic accuracy in head and neck paraganglioma (Sharma et al., 2013) and pheochromocytoma (Sharma et al., 2014). [68Ga]DOTANOC has prognostic value in non-functional pancreatic NETs (Majala et al., 2019).
Activate inflammatory cells can overexpress SSTRs, especially SSTR2A. Cardiac sarcoidosis can be detected using [68Ga]DOTANOC (Gormsen et al., 2019). In patients with idiopathic pulmonary fibrosis (IPF), [68Ga]DOTANOC uptake is high in pathologic lung regions, and only slightly increased in nonspecific interstitial pneumonia (Ambrosini et al., 2010).
[68Ga]DOTANOC is excreted mainly to urine, causing kidneys to receive the highest absorbed doses (Pettinato et al., 2008). Gender, age, and diabetes influence the biodistribution of [68Ga]DOTANOC (Leisser et al., 2019).
Retrieving input function from [68Ga]DOTANOC studies is relatively easy, because correction for radioactive metabolites is not necessary. If arterial blood curve is measured from dynamic PET image (IDIF), it needs to be converted to plasma, which can be done using haematocrit because [68Ga]DOTANOC does not pass red blood cell membranes. Alternatively, arterial blood curve can be directly used as model input, in which case the results are biased by the blood-plasma conversion factor.
Quantitative methods have not yet been validated for the analysis of [68Ga]DOTANOC PET. Oncological imaging is usually performed in multiple bed positions, preventing precise measurement of tissue kinetics. Therefore simple semiquantitative methods like SUV are recommended. Static whole-body scan is started ∼1 h after [68Ga]DOTANOC administration (Majala et al., 2019).
Pettinato C, Sarnelli A, Di Donna M, Civollani S, Nanni C, Montini G, Di Pierro D, Ferrari M, Marengo M, Bergamini C. 68Ga-DOTANOC: biodistribution and dosimetry in patients affected by neuroendocrine tumors. Eur J Nucl Med Mol Imaging 2008; 35(1): 72-79. doi: 10.1007/s00259-007-0587-y.
Ruuska T, Escalante YR, Vaittinen S, Gardberg M, Kiviniemi A, Marjamäki P, Kemppainen J, Jyrkkiö S, Minn H. Somatostatin receptor expression in lymphomas: a source of false diagnosis of neuroendocrine tumor at 68Ga-DOTANOC PET/CT imaging. Acta Oncol. 2018; 57(2): 283-289. doi: 10.1080/0284186X.2017.1342864.
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Wild D, Mäcke HR, Waser B, Reubi JC, Ginj M, Rasch H, Müller-Brand J, Hofmann M. 68Ga-DOTANOC: a first compound for PET imaging with high affinity for somatostatin receptor subtypes 2 and 5. Eur J Nucl Med Mol Imaging 2005; 32(6): 724. doi: 10.1007/s00259-004-1697-4.
Updated at: 2022-01-03
Created at: 2014-01-20
Written by: Vesa Oikonen