title: Longitudinal observation of [11C]4DST uptake in turpentine-induced inflammatory tissue.
abstract: BACKGROUND
  Longitudinal changes of 4'-[methyl-(11)C]thiothymidine ([(11)C]4DST) uptake were evaluated in turpentine-induced inflammation.
  
  
  METHODS
  Turpentine (0.1 ml) was injected intramuscularly into the right hind leg of male Wistar rats. Longitudinal [(11)C]4DST uptake was evaluated by the tissue dissection method at 1, 2, 4, 7, and 14 days after turpentine injection (n=5). The tumor selectivity index was calculated using the previously published biodistribution data in C6 glioma-bearing rats. Dynamic PET scan was performed on day 4 when maximum [(11)C]4DST uptake was observed during the longitudinal study. Histopathological analysis and Ki-67 immunostaining were also performed.
  
  
  RESULTS
  The uptake of [(11)C]4DST in inflammatory tissue was significantly increased on days 2-4 after turpentine injection, and then decreased. On day 14, tracer uptake returned to the day 1 level. The maximum SUV of inflamed muscle was 0.6 and was 3 times higher than that of the contralateral healthy muscle on days 2-4 after turpentine injection. However, tumor selectivity index remains very high (>10) because of the low inflammation uptake. A dynamic PET scan showed that the radioactivity in inflammatory tissues peaked at 5 min after [(11)C]4DST injection, and then washed out until 20 min. At intervals >20 min, radioactivity levels were constant and double that of healthy muscle. The changes in Ki-67 index were paralleled with those of [(11)C]4DST uptake, indicating cell proliferation-dependent uptake of [(11)C]4DST in inflammatory tissues.
  
  
  CONCLUSIONS
  In our animal model, low but significant levels of [(11)C]4DST uptake were observed in subacute inflammation.
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 1-1 Naka-cho, Itabashi-ku, Tokyo 173-0022, Japan. toyohara@pet.tmig.or.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Toyohara
authors.forename: Muneyuki
authors.initials: M
authors.lastname: Sakata
authors.forename: Keiichi
authors.initials: K
authors.lastname: Oda
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishii
authors.forename: Kiichi
authors.initials: K
authors.lastname: Ishiwata
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002250:Carbon Radioisotopes; D049109:Cell Proliferation / Q000187:drug effects; D007249:Inflammation / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D049268:Positron-Emission Tomography; D051381:Rats; D017208:Rats, Wistar; D013936:Thymidine / Q000031:analogs & derivatives* / Q000378:metabolism; D013997:Time Factors; D014425:Turpentine / Q000494:pharmacology*
chemical_list: D002250:Carbon Radioisotopes; D019394:Ki-67 Antigen; C024529:5-((methylthio)methyl)-2'-deoxyuridine; D013936:Thymidine; D014425:Turpentine