RESUMEN
Contrast-enhanced magnetic resonance angiography (CE MR angiography) has benefited from advancements in MR imaging speed, pulse sequence design, and dedicated equipment and algorithms for its performance. These improvements have greatly expanded the number of options available to the operator and enabled the application of CE MR angiography to a broader range of clinical applications. In this article, the various timing options, pulse sequence innovations, and contrast administration concerns related to clinical CE MR angiography are reviewed. Pertinent issues related to multiphase and multistation bolus chase CE MR angiography also will be discussed.
Asunto(s)
Medios de Contraste , Gadolinio , Aumento de la Imagen/métodos , Angiografía por Resonancia Magnética/métodos , HumanosRESUMEN
In this pilot study, using a standard 40 mL gadolinium (Gd) chelate contrast dose, dual-rate (first 20 mL at 0.5 mL/sec; remaining 20 mL at 1.5 mL/sec) and fixed-rate (entire 40 mL dose at either 0.7 mL/sec or 2.0 mL/sec) injection schemes for multistation, bolus-chase magnetic resonance angiography (MRA) were compared in normal volunteers. Signal-to-noise ratio, contrast-to-noise ratio, and physician preference were determined for nine arterial segments. At the terminal station (calf), the dual-rate contrast injection improved arterial signal and contrast compared with both fixed-rate injection schemes and improved subjective vessel appearance compared with the 2.0 mL/sec, but not the 0.7 mL/sec, fixed-rate scheme.
Asunto(s)
Medios de Contraste , Gadolinio , Angiografía por Resonancia Magnética/métodos , Adulto , Análisis de Varianza , Arterias/anatomía & histología , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Proyectos Piloto , Intensificación de Imagen Radiográfica , Valores de Referencia , Sensibilidad y Especificidad , Factores de TiempoRESUMEN
Bolus chase 3-dimensional MR angiography (3D MRA) is a recent development that extends the effective field of view for arterial imaging from the typical single 40-50 cm to over 100 cm. This technique is well suited for imaging long vascular territories such as the lower extremity. Bolus chase peripheral 3D MRA is achieved with overlapping 3D gradient-echo scans during the arterial transit of a single intravenous injection of gadolinium-chelate contrast media. This technique can depict the arteries from the infrarenal aorta to the ankles in less than 2 minutes. The initial experiences with bolus chase peripheral MRA using an automated algorithm that controls both table translation and 3D data acquisition are described. Suggestions for future refinements to the technique are also discussed.
Asunto(s)
Medios de Contraste/administración & dosificación , Gadolinio/administración & dosificación , Aumento de la Imagen/métodos , Angiografía por Resonancia Magnética/métodos , Enfermedades Vasculares Periféricas/diagnóstico , Algoritmos , Análisis de Fourier , Humanos , Inyecciones IntravenosasRESUMEN
Magnetic resonance (MR) imaging is a reliable tool for the depiction of the thoracic aorta. By combining traditional T1-weighted spin echo pulse sequences with newer MR angiography techniques, MR imaging can provide both the structural and functional information necessary to manage most thoracic aortic abnormalities. This article reviews the various MR pulse sequences germane to aortography, highlighting their technical considerations and clinical applications. Newer MR techniques for vascular imaging are also introduced.
