title: Anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid: physiologic uptake patterns, incidental findings, and variants that may simulate disease.
abstract: Anti-1-amino-3-(18)F-fluorocyclobutane-1-carboxylic acid ((18)F-FACBC) is a synthetic amino acid analog PET radiotracer undergoing clinical trials for the evaluation of prostate and other cancers. We aimed to describe common physiologic uptake patterns, incidental findings, and variants in patients who had undergone (18)F-FACBC PET.
  
  
  METHODS
  Sixteen clinical trials involving 611 (18)F-FACBC studies from 6 centers, which included dosimetry studies on 12 healthy volunteers, were reviewed. Qualitative observations of common physiologic patterns, incidental uptake, and variants that could simulate disease were recorded and compared with similar observations in studies of the healthy volunteers. Quantitative analysis of select data and review of prior published reports and observations were also made.
  
  
  RESULTS
  The liver and pancreas demonstrated the most intense uptake. Moderate salivary and pituitary uptake and variable mild to moderate bowel activity were commonly visualized. Moderate bone marrow and mild muscle activity were present on early images, with marrow activity decreasing and muscle activity increasing with time. Brain and lungs demonstrated activity less than blood pool. Though (18)F-FACBC exhibited little renal excretion or bladder uptake during the clinically useful early imaging time window, mild to moderate activity might accumulate in the bladder and interfere with evaluation of adjacent prostate bed and seminal vesicles in 5%-10% of patients. Uptake might also occur from benign processes such as infection, inflammation, prostatic hyperplasia, and metabolically active benign bone lesions such as osteoid osteoma.
  
  
  CONCLUSIONS
  Common physiologic uptake patterns were similar to those noted in healthy volunteers. The activity in organs followed the presence of amino acid transport and metabolism described with other amino acid-based PET radiotracers. As with other PET radiotracers such as (18)F-FDG, focal nonphysiologic uptake may represent incidental malignancy. Uptake due to benign etiologies distinct from physiologic background also occurred and could lead to misinterpretations if the reader is unaware of them.
authors.affiliation: Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia dschust@emory.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Schuster
authors.affiliation: Department of Nuclear Medicine, Policlinico S. Orsola, University of Bologna, Bologna, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Nanni
authors.affiliation: Department of Nuclear Medicine, Policlinico S. Orsola, University of Bologna, Bologna, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Fanti
authors.affiliation: Research Center, Nihon Medi-Physics Co., Ltd., Chiba, Japan.
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Oka
authors.affiliation: Research Center, Nihon Medi-Physics Co., Ltd., Chiba, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okudaira
authors.affiliation: Department of Diagnostic Radiology, Kitasato University School of Medicine, Kitasato, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Department of Radiology, Oncology and Radiation Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Jens
authors.initials: J
authors.lastname: Sörensen
authors.affiliation: GE Healthcare, Life Sciences, Imaging R&D, Uppsala, Sweden.
authors.forename: Rikard
authors.initials: R
authors.lastname: Owenius
authors.affiliation: Molecular Imaging Program, National Cancer Institute, Bethesda, Maryland.
authors.forename: Peter
authors.initials: P
authors.lastname: Choyke
authors.affiliation: Molecular Imaging Program, National Cancer Institute, Bethesda, Maryland.
authors.forename: Baris
authors.initials: B
authors.lastname: Turkbey
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway; and Department of Nuclear Medicine and PET-Center, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Trond V
authors.initials: TV
authors.lastname: Bogsrud
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway; and.
authors.forename: Tore
authors.initials: T
authors.lastname: Bach-Gansmo
authors.affiliation: Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia.
authors.forename: Raghuveer K
authors.initials: RK
authors.lastname: Halkar
authors.affiliation: Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia.
authors.forename: Jonathon A
authors.initials: JA
authors.lastname: Nye
authors.affiliation: Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia.
authors.forename: Oluwaseun A
authors.initials: OA
authors.lastname: Odewole
authors.affiliation: Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia.
authors.forename: Bital
authors.initials: B
authors.lastname: Savir-Baruch
authors.affiliation: Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia.
authors.forename: Mark M
authors.initials: MM
authors.lastname: Goodman
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D002264:Carboxylic Acids / Q000493:pharmacokinetics; D002490:Central Nervous System / Q000000981:diagnostic imaging; D003503:Cyclobutanes / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods* / Q000592:standards; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012015:Reference Standards; D015203:Reproducibility of Results
chemical_list: D002264:Carboxylic Acids; D003503:Cyclobutanes; D019275:Radiopharmaceuticals; C117460:fluciclovine F-18
keywords: 18F-FACBC; physiologic uptake; positron emission tomography