RESUMEN
Irregularly structured brain tumors, such as glioblastomas, challenge attempts to visualize and quantify their three dimensional structure. Magnetic resonance imaging (MRI) represents one tool for attempting to noninvasively track tumor size. MR images demonstrate widely varying perceived tumor margins. In addition, adjunct therapies, such as the administration of steroids, greatly affect the volumes perceived in images formed by certain pulse sequences. In this study tumors were grown in 15 dogs and the tumor size tracked for a period of time. The dogs were placed on dexamethasone for a week and another series of scans was obtained. No other therapies were provided. The data for visualized tumor size are provided for T1, T2, and proton density. Weighted images are provided and the relationships between the scans are discussed.
Asunto(s)
Barrera Hematoencefálica , Neoplasias Encefálicas/diagnóstico , Medios de Contraste/farmacocinética , Glioma/diagnóstico , Aumento de la Imagen/métodos , Imagen por Resonancia Magnética , Neoplasias Experimentales/diagnóstico , Compuestos Organometálicos/farmacocinética , Ácido Pentético/análogos & derivados , Animales , Biopsia , Neoplasias Encefálicas/tratamiento farmacológico , Protocolos Clínicos , Dexametasona/farmacología , Modelos Animales de Enfermedad , Perros , Gadolinio DTPA , Glioma/tratamiento farmacológico , Aumento de la Imagen/instrumentación , Modelos Lineales , Imagen por Resonancia Magnética/instrumentación , Imagen por Resonancia Magnética/métodos , Neoplasias Experimentales/tratamiento farmacológico , Variaciones Dependientes del Observador , Ácido Pentético/farmacocinética , Percepción del TamañoRESUMEN
The erythropoietin (EPO) response to anemia was assessed for 244 subjects aged 1-64 years (mean 45.2 years) and 121 subjects aged 65-94 years (mean 68.3 years). Subjects included non-anemic individuals as well as those with anemia of various etiologies, excluding renal disease and pregnancy. Significant inverse correlations between serum immunoreactive EPO and hematocrit were noted for both groups. Regression lines failed to show a significantly lower slope or y-intercept for older compared to younger subjects. EPO levels were not significantly lower for older compared to younger subjects when controlled for hematocrit level. These results suggest that the EPO response to anemia in older subjects is similar to that of younger subjects.
Asunto(s)
Envejecimiento/sangre , Anemia/sangre , Eritropoyetina/sangre , Hematócrito , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Envejecimiento/inmunología , Anemia/etiología , Anemia/inmunología , Niño , Preescolar , Enfermedad Crónica , Humanos , Lactante , Recién Nacido , Persona de Mediana Edad , Trastornos Nutricionales/complicacionesRESUMEN
The evaluation of tumor size by neurodiagnostic imaging is an important tool in determining disease progression or treatment efficacy. Apparent tumor size on any single slice image is sensitive to tumor shape and slice orientation. Volumetric measurements which use multiple, stacked images attenuate that sensitivity and can provide insights into tumor architecture. Volumetric measurements were made of induced canine gliomas using three common MR imaging protocols and with and without a contrast agent. Comparisons of the volumes described by each technique are made.
