Can the Standardized Uptake Values derived from Diagnostic 68Ga-DOTATATE PET/CT Imaging Predict the Radiation Dose delivered to the Metastatic Liver NET Lesions on 177Lu-DOTATATE Peptide Receptor Radionuclide Therapy?

ABSTRACT Introduction Neuroendocrine neoplasms express somatostatin receptors, enabling the use of somatostatin analogs for molecular imaging, when labeled with the positron-emitter 68Ga for receptor positron emission tomography/computed tomography (PET/CT), and targeted radionuclide therapy, when labeled with beta-emitters, e.g. 90Y and 177Lu. Aim To investigate if 68Ga-DOTATATE PET-derived standardized uptake values (SUV) correlate with the dose delivered to the liver lesions following 177Lu-DOTATATE radionuclide therapy in patients with neuroendocrine neoplasms. Materials and methods Twelve adult (8M: 4F; mean age: 55.9 ± 14.5 years; range: 23-78 years) patients with documented neuroendocrine tumor (NET) disease and liver metastases were enrolled in the study. Ten patients were subjected to 68Ga-DOTATATE and one patient each underwent 68Ga-DOTATOC and 68Ga-DOTANOC diagnostic PET/CT imaging. Subsequently, on the basis of positive PET/CT scan findings for the metastatic NET disease, all these patients were subjected to peptide receptor radionuclide therapy (PRRNT) with 177Lu-DOTATATE. The reconstructed PET/CT data was used to calculate the SUVs on the identifiable liver lesions. The scintigraphic data acquired (anterior and posterior whole body images) following therapeutic doses of 177Lu-DOTATATE were subjected to the quantitative analysis (HERMES workstation and OLINDA/EXM software) to calculate the dose delivered to the hepatic lesions. Results The initial results of this preliminary study indicate poor correlation between SUV and the tumor dose and the linear regression analysis provided R2 values which explained only a small fraction of the total variance. Conclusion The SUVs derived from 68Ga-DOTA-peptide PET/CT images should be used with caution for the prediction of tumor dose on 177Lu-DOTA-peptide therapy as there are large intra- and interpatient variability. Further studies with large numbers of patients are warranted to establish such a correlation between SUV, tumor dose and the response assessment. How to cite this article Singh B, Prasad V, Schuchardt C, Kulkarni H, Baum RP. Can the Standardized Uptake Values derived from Diagnostic 68Ga-DOTATATE PET/CT Imaging Predict the Radiation Dose delivered to the Metastatic Liver NET Lesions on 177Lu-DOTATATE Peptide Receptor Radionuclide Therapy? J Postgrad Med Edu Res 2013;47(1):7-13.