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). [68Ga]DOTANOC has prognostic value in non-functional pancreatic NETs (Majala 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).
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Updated at: 2020-01-17
Created at: 2014-01-20
Written by: Vesa Oikonen