PT  - JOURNAL ARTICLE
AU  - Minamimoto, Ryogo
AU  - Hancock, Steven
AU  - Schneider, Bernadette
AU  - Chin, Frederick T.
AU  - Jamali, Mehran
AU  - Loening, Andreas
AU  - Vasanawala, Shreyas
AU  - Gambhir, Sanjiv Sam
AU  - Iagaru, Andrei
TI  - Pilot Comparison of <sup>68</sup>Ga-RM2 PET and <sup>68</sup>Ga-PSMA-11 PET in Patients with Biochemically Recurrent Prostate Cancer
AID  - 10.2967/jnumed.115.168393
DP  - 2016 Apr 01
TA  - Journal of Nuclear Medicine
PG  - 557--562
VI  - 57
IP  - 4
4099  - http://jnm.snmjournals.org/content/57/4/557.short
4100  - http://jnm.snmjournals.org/content/57/4/557.full
SO  - J Nucl Med2016 Apr 01; 57
AB  - 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.