title: Direct comparison of radiation dosimetry of six PET tracers using human whole-body imaging and murine biodistribution studies.
abstract: OBJECTIVE
  We investigated the whole-body biodistributions and radiation dosimetry of five (11)C-labeled and one (18)F-labeled radiotracers in human subjects, and compared the results to those obtained from murine biodistribution studies.
  
  
  METHODS
  The radiotracers investigated were (11)C-SA4503, (11)C-MPDX, (11)C-TMSX, (11)C-CHIBA-1001, (11)C-4DST, and (18)F-FBPA. Dynamic whole-body positron emission tomography (PET) was performed in three human subjects after a single bolus injection of each radiotracer. Emission scans were collected in two-dimensional mode in five bed positions. Regions of interest were placed over organs identified in reconstructed PET images. The OLINDA program was used to estimate radiation doses from the number of disintegrations of these source organs. These results were compared with the predicted human radiation doses on the basis of biodistribution data obtained from mice by dissection.
  
  
  RESULTS
  The ratios of estimated effective doses from the human-derived data to those from the mouse-derived data ranged from 0.86 to 1.88. The critical organs that received the highest absorbed doses in the human- and mouse-derived studies differed for two of the six radiotracers. The differences between the human- and mouse-derived dosimetry involved not only the species differences, including faster systemic circulation of mice and differences in the metabolism, but also measurement methodologies.
  
  
  CONCLUSIONS
  Although the mouse-derived effective doses were roughly comparable to the human-derived doses in most cases, considerable differences were found for critical organ dose estimates and pharmacokinetics in certain cases. Whole-body imaging for investigation of radiation dosimetry is desirable for the initial clinical evaluation of new PET probes prior to their application in subsequent clinical investigations.
authors: Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1 Naka-cho, Itabashi-ku, Tokyo 173-0022, Japan. sakata@pet.tmig.or.jp
authors: Muneyuki
authors: M
authors: Sakata
authors: Keiichi
authors: K
authors: Oda
authors: Jun
authors: J
authors: Toyohara
authors: Kenji
authors: K
authors: Ishii
authors: Tadashi
authors: T
authors: Nariai
authors: Kiichi
authors: K
authors: Ishiwata
mesh_terms: D000328:Adult; D000818:Animals; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011849:Radioactive Tracers; D011874:Radiometry; D014018:Tissue Distribution; D051598:Whole Body Imaging; D055815:Young Adult
chemical_list: D011849:Radioactive Tracers