RT Journal Article
SR Electronic
T1 Tumor-to-blood ratio for assessment of somatostatin receptor density in neuroendocrine tumors using <sup>68</sup>Ga-DOTATOC and <sup>68</sup>Ga-DOTATATE
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.119.228072
DO 10.2967/jnumed.119.228072
A1 Ilan, Ezgi
A1 Velikyan, Irina
A1 Sandström, Mattias
A1 Sundin, Anders
A1 Lubberink, Mark
YR 2019
UL http://jnm.snmjournals.org/content/early/2019/07/02/jnumed.119.228072.abstract
AB PET/CT with 68Ga-DOTA-somatostatin analogs has been tested for therapy monitoring in patients with neuroendocrine tumors (NETs). However, standardized uptake values (SUV) in tumors do not correlate with the net influx rate (Ki), as a representation of the somatostatin receptor (SSTR) expression. In this study, tumor-to-blood-ratio (TBR) was evaluated as an alternative tool for semi-quantitative assessment of 68Ga-DOTATOC and 68Ga-DOTATATE tumor uptake and as a therapy monitoring tool for patients with NETs. Methods: Twenty-two NET patients underwent a 45-min dynamic PET/CT scan after injection of 68Ga-DOTATOC and/or 68Ga-DOTATATE. Ki was determined using the Patlak method and TBR was calculated for the 40-45 min time interval. Results: A linear relation was found between Ki and TBR, with a square of Pearson correlation (R2) of 0.98 and 0.93 for 68Ga-DOTATOC and 68Ga-DOTATATE, respectively. Conclusion: High correlation was found between Ki and TBR. Hence, TBR reflects SSTR density more accurately than SUV and is suggested as the preferred metrics for semi-quantitative assessment of 68Ga-DOTATOC and 68Ga-DOTATATE tumor uptake.