title: Pilot Comparison of ⁶⁸Ga-RM2 PET and ⁶⁸Ga-PSMA-11 PET in Patients with Biochemically Recurrent Prostate Cancer.
abstract: Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBED-CC)] ((68)Ga-PSMA-11) is a PET tracer that can detect prostate cancer relapses and metastases by binding to the extracellular domain of PSMA. (68)Ga-labeled DOTA-4-amino-1-carboxymethyl-piperidine-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 ((68)Ga-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 (68)Ga-PSMA-11 PET/CT and (68)Ga-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. (68)Ga-PSMA-11 had the highest physiologic uptake in the salivary glands and small bowel, with hepatobiliary and renal clearance noted, whereas (68)Ga-RM2 had the highest physiologic uptake in the pancreas, with renal clearance noted. Uptake outside the expected physiologic biodistribution did not significantly differ between (68)Ga-PSMA-11 and (68)Ga-RM2; however, (68)Ga-PSMA-11 localized in a lymph node and seminal vesicle in a patient with no abnormal (68)Ga-RM2 uptake. Abdominal periaortic lymph nodes were more easily visualized by(68)Ga-RM2 in two patients because of lack of interference by radioactivity in the small intestine.
  
  
  CONCLUSIONS
  (68)Ga-PSMA-11 and (68)Ga-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.
authors.affiliation: Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University, Stanford, California Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, Stanford, California.
authors.forename: Ryogo
authors.initials: R
authors.lastname: Minamimoto
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, California; and.
authors.forename: Steven
authors.initials: S
authors.lastname: Hancock
authors.affiliation: Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, Stanford, California.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Schneider
authors.affiliation: Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, Stanford, California.
authors.forename: Frederick T
authors.initials: FT
authors.lastname: Chin
authors.affiliation: Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University, Stanford, California Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, Stanford, California.
authors.forename: Mehran
authors.initials: M
authors.lastname: Jamali
authors.affiliation: Department of Radiology, Stanford University, Stanford, California.
authors.forename: Andreas
authors.initials: A
authors.lastname: Loening
authors.affiliation: Department of Radiology, Stanford University, Stanford, California.
authors.forename: Shreyas
authors.initials: S
authors.lastname: Vasanawala
authors.affiliation: Molecular Imaging Program at Stanford, Department of Radiology, Stanford University, Stanford, California.
authors.forename: Sanjiv Sam
authors.initials: SS
authors.lastname: Gambhir
authors.affiliation: Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Stanford University, Stanford, California aiagaru@stanford.edu.
authors.forename: Andrei
authors.initials: A
authors.lastname: Iagaru
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004492:Edetic Acid / Q000031:analogs & derivatives; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007421:Intestine, Small / Q000000981:diagnostic imaging / Q000378:metabolism; D008198:Lymph Nodes / Q000000981:diagnostic imaging; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D009842:Oligopeptides; D009942:Organometallic Compounds; D010865:Pilot Projects; D049268:Positron-Emission Tomography / Q000379:methods*; D017430:Prostate-Specific Antigen / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D019275:Radiopharmaceuticals; D012469:Salivary Glands / Q000000981:diagnostic imaging / Q000378:metabolism; D012669:Seminal Vesicles / Q000000981:diagnostic imaging; D014018:Tissue Distribution; D051598:Whole Body Imaging
chemical_list: C582579:BAY 86-7548; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid; D017430:Prostate-Specific Antigen
keywords: 68Ga; PET/CT; PET/MRI; PSMA; RM2; prostate cancer