RESUMO
Many of the particles currently suspended in the martian atmosphere are magnetic, with an average saturation magnetization of about 4 A. m2/kg (amperes times square meters per kilogram). The particles appear to consist of claylike aggregates stained or cemented with ferric oxide (Fe2O3); at least some of the stain and cement is probably maghemite (gamma-Fe2O3). The presence of the gamma phase would imply that Fe2+ ions leached from the bedrock, passing through a state as free Fe2+ ions dissolved in liquid water. These particles could be a freeze-dried precipitate from ground water poured out on the surface. An alternative is that the magnetic particles are titanomagnetite occurring in palagonite and inherited directly from a basaltic precursor.
Assuntos
Meio Ambiente Extraterreno , Magnetismo , Marte , Atmosfera , Compostos Férricos , Óxido Ferroso-Férrico , Ferro , Minerais , Óxidos , Silicatos , ÁguaAssuntos
Doenças Ósseas/diagnóstico por imagem , Osso e Ossos/diagnóstico por imagem , Transplante de Rim , Adulto , Doenças Ósseas/etiologia , Doenças Ósseas/patologia , Osso e Ossos/patologia , Feminino , Humanos , Falência Renal Crônica/terapia , Masculino , Pessoa de Meia-Idade , Osteonecrose/etiologia , Osteoporose/etiologia , Prednisona/efeitos adversos , Cintilografia , Diálise Renal , Transplante HomólogoAssuntos
Osso e Ossos/metabolismo , Distúrbio Mineral e Ósseo na Doença Renal Crônica/metabolismo , Difosfatos/metabolismo , Falência Renal Crônica/metabolismo , Transplante de Rim , Diálise Renal , Adulto , Humanos , Falência Renal Crônica/terapia , Pessoa de Meia-Idade , Prednisona/efeitos adversos , Contagem Corporal TotalRESUMO
To compare 99mTc-polyphosphate and 18F for use in orthopedics, 79 patients were examined with both. Fifty cases were suitable for analysis. While the extraskeletal uptake of 18F was found to be negligible, 99mTc-polyphosphate may accumulate considerably in pathologic soft tissue, e.g., in soft-tissue tumors and in inflamed synovial tissue. This soft-tissue Tc accumulation may obscure the osseus uptake, notably in the examination of joint regions, commonly the regions of interest in orthopedics. After simultaneous administration of both agents, quantitative measurements were performed on specimens of bone and synovial tissue from diseased joints in human patients and in rabbits. The uptake of 99mTc-polyphosphate in synovial tissue was shown to be about seven times that of 18F, while their uptakes in bone were equal. In short, 99mTc-polyphosphate, a valuable tracer in general, is hardly the agent of choice in orthopedics.
