Quantification of [68Ga]DOTANOC PET

[68Ga]DOTANOC is a somatostatin analog which binds to subtypes 2, 3 and 5 of somatostatin receptors (SSTR2, SSTR3, and SSTR5, respectively). 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. 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 analyzed using only semiquantitative methods, mainly SUV.

Somatostatin receptor imaging is not specific to NETs; for example some lymphomas express SSTRs (Ruuska et al., 2018).

Arterial plasma

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.

Receptor binding

Quantitative methods have not yet been validated for the analysis of [68Ga]DOTANOC PET. Therefore simple semiquantitative methods like SUV are recommended.

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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.

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.

Wild D, Bomanji JB, Benkert P, Maecke H, Ell PJ, Reubi JC, Caplin ME. Comparison of 68Ga-DOTANOC and 68Ga-DOTATATE PET/CT within patients with gastroenteropancreatic neuroendocrine tumors. J Nucl Med. 2013; 54(3): 364-372.

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.

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Created at: 2014-01-20
Updated at: 2018-06-13
Written by: Vesa Oikonen