RESUMO
PURPOSE: To evaluate the imaging performance characteristics of four multidetector-row helical computed tomography (CT) and assess improvement in volume coverage speed over that with single multidetector-row helical CT. MATERIALS AND METHODS: The section-sensitivity profile and image noise of a four multidetector-row scanner were measured with phantom scans and compared with predictions from theoretic models. Nominal section thickness ranged from 1.25 to 10.00 mm, beam collimation from 1.25 to 5.00 mm, and table speed from 3.75 to 30.00 mm per rotation. Image artifacts with four and single multidetector-row helical CT were compared in both a phantom study and a subjective rating analysis of clinical images. RESULTS: Compared with single multidetector-row helical CT, the volume coverage speed of four multidetector-row helical CT (range, 3.75-30.00 mm per rotation) is at least twice as fast as that with single multidetector-row helical CT (1.0-10.0 mm per rotation) with fully comparable image quality or, in many cases, three times as fast with diagnostically comparable image quality. CONCLUSION: Compared with single multidetector-row helical CT, four multidetector-row helical CT provides a two- to threefold improvement in volume coverage speed with comparable diagnostic image quality.
Assuntos
Processamento de Imagem Assistida por Computador/métodos , Intensificação de Imagem Radiográfica/métodos , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Artefatos , Desenho de Equipamento , Estudos de Avaliação como Assunto , Feminino , Previsões , Humanos , Processamento de Imagem Assistida por Computador/instrumentação , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Variações Dependentes do Observador , Pelve/diagnóstico por imagem , Imagens de Fantasmas , Intensificação de Imagem Radiográfica/instrumentação , Radiografia Abdominal , Radiografia Torácica , Rotação , Estatística como Assunto , Fatores de Tempo , Tomografia Computadorizada por Raios X/instrumentaçãoRESUMO
Progress in helical CT acquisition and processing over the last 5 years has lead to new applications and new requirements. Recent progress to meet these requirements is discussed in this article. The potential of future acquisition developments and their potential to further import application are explored.
Assuntos
Previsões , Tecnologia Radiológica/tendências , Tomografia Computadorizada por Raios X/tendências , Apresentação de Dados , Fluoroscopia/métodos , Humanos , Processamento de Imagem Assistida por Computador/instrumentação , Processamento de Imagem Assistida por Computador/métodos , Processamento de Imagem Assistida por Computador/tendências , Intensificação de Imagem Radiográfica/instrumentação , Intensificação de Imagem Radiográfica/métodos , Tomografia Computadorizada por Raios X/instrumentação , Tomografia Computadorizada por Raios X/métodosRESUMO
Platelet aggregation and thromboxane B2 (TXB2) production induced by arachidonic acid (AA) or Adenosine diphosphate (ADP) were studied by turbidimetry and radioimmunoassay in rabbits. 3,4,5-tri-hydroxystibene-3-beta-mono-D-glucoside (PD) 6.7-107.2 mumol/L inhibited platelet aggregation and the production of TXB2 as well. The inhibitions by PD were dose-dependent: 48-90% (AA-induced) and 43-69% (ADP-induced) for platelet aggregation; 50-87% (AA-induced) and 43-68% (ADP-induced) for TXB2. There were positive correlations between the inhibition of platelet aggregation and production of TXB2.