title: Measurement of tumor hypoxia in spontaneous canine sarcomas.
abstract: We used positron emission tomography (PET) with [18F]fluoromisonidazole ([18F]FMISO) to study tumor hypoxia in six dogs with spontaneous sarcomas. The tumors were regarded as hypoxic if [18F]FMISO uptake exceeded normal tissue radioactivity by 40% (tumor/muscle ratio > 1.4) or if kinetic analysis indicated a positive [18F]FMISO tissue influx rate (Ki > 0) by a Patlak plot. Using these criteria, we found hypoxia in a fibrosarcoma grade II, an undifferentiated sarcoma, and an ostoeosarcoma, but not in a fibrosarcoma grade I, another osteosarcoma, and a myxosarcoma. In three animals, the tumor oxygen partial pressure (pO2) was also measured invasively using Eppendorf needle electrodes. In these cases, the Eppendorf measurements were confirmed by the [18F]FMISO PET results. In addition, [15O]H2O PET was performed in four dogs in order to assess tumor perfusion. Comparisons of the [18F]FMISO with [15O]H2O PET images in two cases showed that tumor hypoxia occurred in the tumor center with low perfusion, whereas perfusion was heterogeneous in a nonhypoxic tumor.
authors.affiliation: Section of Diagnostic Imaging and Radiation Oncology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland. matthias.bruehlmeier@ksa.ch
authors.forename: Matthias
authors.initials: M
authors.lastname: Bruehlmeier
authors.forename: Barbara
authors.initials: B
authors.lastname: Kaser-Hotz
authors.forename: Roger
authors.initials: R
authors.lastname: Achermann
authors.forename: Carla Rohrer
authors.initials: CR
authors.lastname: Bley
authors.forename: Melanie
authors.initials: M
authors.lastname: Wergin
authors.forename: Pius A
authors.initials: PA
authors.lastname: Schubiger
authors.forename: Simon M
authors.initials: SM
authors.lastname: Ametamey
mesh_terms: D000818:Animals; D001785:Blood Gas Monitoring, Transcutaneous; D004283:Dog Diseases / Q000378:metabolism*; D004285:Dogs; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics; D000860:Hypoxia / Q000378:metabolism / Q000662:veterinary*; D008920:Misonidazole / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D049268:Positron-Emission Tomography; D011838:Radiation-Sensitizing Agents / Q000493:pharmacokinetics*; D012509:Sarcoma / Q000145:classification / Q000378:metabolism / Q000662:veterinary*
chemical_list: D005462:Fluorine Radioisotopes; D011838:Radiation-Sensitizing Agents; C031843:fluoromisonidazole; D008920:Misonidazole