Improvement of vessel visibility in time-of-flight MR angiography of the brain.
J Magn Reson Imaging
; 27(6): 1362-70, 2008 Jun.
Article
em En
| MEDLINE
| ID: mdl-18504756
ABSTRACT
PURPOSE:
To improve vessel visibility in time-of-flight MR angiography (TOF-MRA) by careful consideration of coil choice, coil position, and frequency offset and profile of the nonspatially selective chemical shift selective (CHESS) presaturation pulse. MATERIALS ANDMETHODS:
The effects of both the CHESS and the excitation radiofrequency (RF) pulses on flow signal and signals from stationary substances were evaluated by changing the spatial area where RF pulses were applied to upstream flow in a flow phantom and in human subjects. The difference between the eight-channel phased-array receive-only coil and the transmit-receive coil was evaluated.RESULTS:
The CHESS pulse suppresses the flow signal over a wider frequency range than the signals from stationary substances, especially when using the body coil for transmission. Even without presaturation pulse, the excitation pulse slightly suppressed the flow signal. Adjusting the position of the transmit-receive coil relative to the head improved these TOF-MRA images. The results were better than those obtained with the eight-channel coil.CONCLUSION:
The excitation and the nonspatially selective CHESS pulses degraded the flow signal. Our results suggest that reduced spatial extent of RF pulse application to upstream flow can improve image quality of TOF-MRA. This result can be implemented on conventional scanners.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Encéfalo
/
Aumento da Imagem
/
Artérias Cerebrais
/
Angiografia por Ressonância Magnética
/
Imagens de Fantasmas
Limite:
Adult
/
Female
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Humans
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Male
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Middle aged
Idioma:
En
Revista:
J Magn Reson Imaging
Assunto da revista:
DIAGNOSTICO POR IMAGEM
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Estados Unidos