title: 11C-L-methyl methionine dynamic PET/CT of skeletal muscle: response to protein supplementation compared to L-[ring13C6] phenylalanine infusion with serial muscle biopsy.
abstract: OBJECTIVE
  The objective of this study was to determine if clinical dynamic PET/CT imaging with11C-L-methyl-methionine (11C-MET) in healthy older women can provide an estimate of tissue-level post-absorptive and post-prandial skeletal muscle protein synthesis that is consistent with the more traditional method of calculating fractional synthesis rate (FSR) of muscle protein synthesis from skeletal muscle biopsies obtained during an infusion of L-[ring13C6] phenylalanine (13C6-Phe).
  
  
  METHODS
  Healthy older women (73 ± 5 years) completed both dynamic PET/CT imaging with11C-MET and a stable isotope infusion of13C6-Phe with biopsies to measure the skeletal muscle protein synthetic response to 25 g of a whey protein supplement. Graphical estimation of the Patlak coefficient Kifrom analysis of the dynamic PET/CT images was employed as a measure of incorporation of 11 C-MET in the mid-thigh muscle bundle.
  
  
  RESULTS
  Post-prandial values [mean ± standard error of the mean (SEM)] were higher than post-absorptive values for both Ki(0.0095 ± 0.001 vs. 0.00785 ± 0.001 min-1, p < 0.05) and FSR (0.083 ± 0.008 vs. 0.049 ± 0.006%/h, p < 0.001) in response to the whey protein supplement. The percent increase in Kiand FSR in response to the whey protein supplement was significantly correlated (r = 0.79, p = 0.015).
  
  
  CONCLUSIONS
  Dynamic PET/CT imaging with11C-MET provides an estimate of the post-prandial anabolic response that is consistent with a traditional, invasive stable isotope, and muscle biopsy approach. These results support the potential future use of11C-MET imaging as a non-invasive method for assessing conditions affecting skeletal muscle protein synthesis.
authors.affiliation: Department of Nutrition and Metabolism and Center for Recovery, Physical Activity and Nutrition (CeRPAN), University of Texas Medical Branch, Galveston, 77573, USA.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Arentson-Lantz
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: Isra H
authors.initials: IH
authors.lastname: Saeed
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA, 94143, USA.
authors.forename: Lynda A
authors.initials: LA
authors.lastname: Frassetto
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, CA, 94143, USA.
authors.forename: Umesh
authors.initials: U
authors.lastname: Masharani
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: Roy J
authors.initials: RJ
authors.lastname: Harnish
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: Youngho
authors.initials: Y
authors.lastname: Seo
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: Henry F
authors.initials: HF
authors.lastname: VanBrocklin
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: Randall A
authors.initials: RA
authors.lastname: Hawkins
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: Carina
authors.initials: C
authors.lastname: Mari-Aparici
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: Miguel H
authors.initials: MH
authors.lastname: Pampaloni
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA.
authors.forename: James
authors.initials: J
authors.lastname: Slater
authors.affiliation: Department of Nutrition and Metabolism and Center for Recovery, Physical Activity and Nutrition (CeRPAN), University of Texas Medical Branch, Galveston, 77573, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Paddon-Jones
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, Box 0946, San Francisco, CA, 94143-0946, USA. thomas.lang@ucsf.edu.
authors.forename: Thomas F
authors.identifier: http://orcid.org/0000-0002-3720-8038
authors.initials: TF
authors.lastname: Lang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002247:Carbon Isotopes; D005260:Female; D006801:Humans; D008715:Methionine / Q000031:analogs & derivatives; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*; D010649:Phenylalanine; D000072078:Positron Emission Tomography Computed Tomography; D019518:Postprandial Period; D019275:Radiopharmaceuticals; D055948:Sarcopenia / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D013848:Thigh / Q000000981:diagnostic imaging / Q000473:pathology; D000067816:Whey Proteins / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D019275:Radiopharmaceuticals; D000067816:Whey Proteins; D010649:Phenylalanine; D008715:Methionine; C038344:methionine methyl ester
keywords: FSR; Human; Muscle protein synthesis; PET/CT