RESUMO
A 44-year-old man was brought unconscious to the emergency room; he was believed to have suffered anoxic brain damage probably due to carbon monoxide poisoning. Computerized tomography with contrast enhancement helped establish the diagnosis and was correlated with the subsequent clinical improvement of the patient.
Assuntos
Intoxicação por Monóxido de Carbono/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Adulto , Encéfalo/diagnóstico por imagem , Diagnóstico Diferencial , Humanos , Masculino , Intensificação de Imagem Radiográfica , Tomografia Computadorizada por Raios X/métodosRESUMO
The effects of Poisson noise on three estimates of ejection fraction made from left-ventricular time-activity curves have been investigated. All three methods are based on a sinusoidal model of left-ventricular volume changes. The first, developed by Schelbert et al., overestimates the ejection fraction for low-activity levels and low ejection fractions. The second estimate, which is merely a first-order correction for the contribution of Poisson noise to the first estimate, appears to be more accurate when both estimators are applied to simulated time-activity curves, and the resulting ejection fractions are compared. A third, "maximum likelihood" estimator, when applied to the same data, is apparently more accurate than the first two.