Correlations between [ 68 Ga]Ga-DOTA-TOC Uptake and Absorbed Dose from [ 177 Lu]Lu-DOTA-TATE

The aim of this paper was to investigate correlations between pre- therapeutic [ Ga]Ga-DOTA-TOC uptake and absorbed dose to tumours from therapy with [ Lu]Lu-DOTA-TATE. This retrospective study included 301 tumours from 54 GEP-NET patients. The tumours were segmented on pre-therapeutic [ Ga]Ga-DOTA-...

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Bibliographic Details
Published in:	Cancers 2023-02, Vol.15 (4), p.1134
Main Authors:	Bruvoll, Ragnar, Blakkisrud, Johan, Mikalsen, Lars Tore, Connelly, James, Stokke, Caroline
Format:	Article
Language:	eng
Subjects:	[177Lu]Lu-DOTA-TATE [68Ga]Ga-DOTA-TOC Cell surface Computed tomography Dosimetry Medical imaging Neuroendocrine tumors Patients peptide receptor radionuclide therapy PET/CT Positron emission tomography Prediction models Radiation Radiation therapy Single photon emission computed tomography Somatostatin Somatostatin receptors SPECT/CT Tumors Variance analysis
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Summary:	The aim of this paper was to investigate correlations between pre- therapeutic [ Ga]Ga-DOTA-TOC uptake and absorbed dose to tumours from therapy with [ Lu]Lu-DOTA-TATE. This retrospective study included 301 tumours from 54 GEP-NET patients. The tumours were segmented on pre-therapeutic [ Ga]Ga-DOTA-TOC PET/CT, and post-therapy [ Lu]Lu-DOTA-TATE SPECT/CT images, using a fixed 40% threshold. The SPECT/CT images were used for absorbed dose calculations by assuming a linear build-up from time zero to day one, and mono-exponential wash-out after that. Both SUV and SUV were measured from the PET images. A linear absorbed-dose prediction model was formed with SUV as the independent variable, and the accuracy was tested with a split 70-30 training-test set. Mean SUV and SUV from [ Ga]Ga-DOTA-TOC PET was 24.0 (3.6-84.4) and 41.0 (6.7-146.5), and the mean absorbed dose from [ Lu]Lu-DOTA-TATE was 26.9 Gy (2.4-101.9). A linear relationship between SUV and [ Lu]Lu-DOTA-TATE activity concentration at 24 h post injection was found (R = 0.44, < 0.05). In the prediction model, a root mean squared error and a mean absolute error of 1.77 and 1.33 Gy/GBq, respectively, were found for the test set. There was a high inter- and intra-patient variability in tumour measurements, both for [ Ga]Ga-DOTA-TOC SUVs and absorbed doses from [ Lu]Lu-DOTA-TATE. Depending on the required accuracy, [ Ga]Ga-DOTA-TOC PET imaging may estimate the [ Lu]Lu-DOTA-TATE uptake. However, there could be a high variance between predicted and actual absorbed doses.
ISSN:	2072-6694 2072-6694