PT - JOURNAL ARTICLE AU - Guillaume P. Nicolas AU - Nils Schreiter AU - Felix Kaul AU - John Uiters AU - Hakim Bouterfa AU - Jens Kaufmann AU - Tobias E. Erlanger AU - Richard Cathomas AU - Emanuel Christ AU - Melpomeni Fani AU - Damian Wild TI - Sensitivity Comparison of <sup>68</sup>Ga-OPS202 and <sup>68</sup>Ga-DOTATOC PET/CT in Patients with Gastroenteropancreatic Neuroendocrine Tumors: A Prospective Phase II Imaging Study AID - 10.2967/jnumed.117.199760 DP - 2018 Jun 01 TA - Journal of Nuclear Medicine PG - 915--921 VI - 59 IP - 6 4099 - http://jnm.snmjournals.org/content/59/6/915.short 4100 - http://jnm.snmjournals.org/content/59/6/915.full SO - J Nucl Med2018 Jun 01; 59 AB - Radiolabeled somatostatin (sst) receptor agonists are integral to the diagnosis of gastroenteropancreatic neuroendocrine tumors (NETs), but detection rates, especially of liver metastases, remain limited even with PET/CT. 68Ga-OPS202 (68Ga-NODAGA-JR11; NODAGA = 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid and JR11 = Cpa-c(dCys-Aph(Hor)-dAph(Cbm)-Lys-Thr-Cys)-dTyr-NH2)), a novel radiolabeled sst receptor antagonist with a high affinity for the sst2 receptor, has the potential to perform better than sst receptor agonists. Here, we present the results of the phase II component of a phase I/II study that evaluated the sensitivity of 68Ga-OPS202, compared with the reference compound, 68Ga-DOTATOC (an sst receptor agonist), in PET imaging. Methods: Patients received a single 150-MBq intravenous injection of 68Ga-DOTATOC (15 μg of peptide) and 2 single 150-MBq intravenous injections of 68Ga-OPS202 (15 μg of peptide at visit 1 and 50 μg at visit 2). Whole-body PET/CT acquisitions were performed 1 h after injection on the same calibrated PET/CT scanner. Diagnostic efficacy measures were compared against contrast medium–enhanced CT or MRI as the gold standard. Two independent masked experts read the scans, and both outcomes were combined for analysis. Results: Twelve consecutive patients with low- or intermediate-grade gastroenteropancreatic NETs took part in this prospective study. Image contrast for matched malignant liver lesions was significantly higher for the 68Ga-OPS202 scans than for the 68Ga-DOTATOC scan: the median of the mean tumor-to-background SUVmax ratios were significantly higher for 15 and 50 μg of 68Ga-OPS202 (5.3 and 4.3, with interquartile ranges of 2.9–5.7 and 3.4–6.3 and P values of 0.004 and 0.008) than for 68Ga-DOTATOC (1.9, with an interquartile range of 1.4–2.9). The higher tumor-to-background ratio of 68Ga-OPS202 resulted not only in a higher detection rate of liver metastases but also in a significantly higher lesion-based overall sensitivity with the antagonist than with 68Ga-DOTATOC: 94% and 88% for 50 and 15 μg of 68Ga-OPS202, respectively, and 59% for 15 μg of 68Ga-DOTATOC (P &lt; 0.001). Positive predictive values for 68Ga-OPS202 PET/CT and 68Ga-DOTATOC PET/CT were similar (∼98%). There were no significant differences in image contrast, sensitivity, or positive predictive values between the 2 68Ga-OPS202 peptide doses, indicating a high reproducibility. Conclusion: Preliminary diagnostic efficacy data from this phase II study indicate that 68Ga-OPS202 has high sensitivity for the detection of gastroenteropancreatic NETs. Further studies in larger patient populations are warranted.