TY - JOUR T1 - Pilot Comparison of <sup>68</sup>Ga-RM2 PET and <sup>68</sup>Ga-PSMA-11 PET in Patients with Biochemically Recurrent Prostate Cancer JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 557 LP - 562 DO - 10.2967/jnumed.115.168393 VL - 57 IS - 4 AU - Ryogo Minamimoto AU - Steven Hancock AU - Bernadette Schneider AU - Frederick T. Chin AU - Mehran Jamali AU - Andreas Loening AU - Shreyas Vasanawala AU - Sanjiv Sam Gambhir AU - Andrei Iagaru Y1 - 2016/04/01 UR - http://jnm.snmjournals.org/content/57/4/557.abstract N2 - Glu-NH-CO-NH-Lys-(Ahx)-[68Ga(HBED-CC)] (68Ga-PSMA-11) is a PET tracer that can detect prostate cancer relapses and metastases by binding to the extracellular domain of PSMA. 68Ga-labeled DOTA-4-amino-1-carboxymethyl-piperidine-d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 (68Ga-RM2) is a synthetic bombesin receptor antagonist that targets gastrin-releasing peptide receptors. We present pilot data on the biodistribution of these PET tracers in a small cohort of patients with biochemically recurrent prostate cancer. Methods: Seven men (mean age ± SD, 74.3 ± 5.9 y) with biochemically recurrent prostate cancer underwent both 68Ga-PSMA-11 PET/CT and 68Ga-RM2 PET/MRI scans. SUVmax and SUVmean were recorded for normal tissues and areas of uptake outside the expected physiologic biodistribution. Results: All patients had a rising level of prostate-specific antigen (mean ± SD, 13.5 ± 11.5) and noncontributory results on conventional imaging. 68Ga-PSMA-11 had the highest physiologic uptake in the salivary glands and small bowel, with hepatobiliary and renal clearance noted, whereas 68Ga-RM2 had the highest physiologic uptake in the pancreas, with renal clearance noted. Uptake outside the expected physiologic biodistribution did not significantly differ between 68Ga-PSMA-11 and 68Ga-RM2; however, 68Ga-PSMA-11 localized in a lymph node and seminal vesicle in a patient with no abnormal 68Ga-RM2 uptake. Abdominal periaortic lymph nodes were more easily visualized by 68Ga-RM2 in two patients because of lack of interference by radioactivity in the small intestine. Conclusion: 68Ga-PSMA-11 and 68Ga-RM2 had distinct biodistributions in this small cohort of patients with biochemically recurrent prostate cancer. Additional work is needed to understand the expression of PSMA and gastrin-releasing peptide receptors in different types of prostate cancer. ER -