Steady-state functional MRI using spoiled small-tip fast recovery imaging.
Magn Reson Med
; 73(2): 536-43, 2015 Feb.
Article
en En
| MEDLINE
| ID: mdl-24619593
ABSTRACT
PURPOSE:
To determine whether a recently proposed steady-state magnetic resonance imaging (MRI) sequence, "small-tip fast recovery" (STFR), can be used for functional brain imaging. Compared to existing functional MRI (fMRI) based on T2*-contrast and long echo time, STFR has the potential for high-resolution imaging with reduced B0 artifacts such as geometric distortions, blurring, or local signal dropout.METHODS:
We used Monte Carlo Bloch simulations to calculate the voxel-averaged steady-state signal during rest and activation, for blood oxygen level dependent (BOLD) and STFR. STFR relies on a tailored "tip-up" radiofrequency pulse to align the spins with the longitudinal axis after each data readout segment, and here we performed proof-of-concept in vivo STFR fMRI experiments using a tip-up pulse tailored to a two-dimensional region-of-interest in motor cortex. Experiments were performed on multiple subjects to test reliability of the functional activation maps.RESULTS:
Bloch simulations predict a detectable functional signal that depends mainly on intravoxel dephasing, and only weakly on spin diffusion. STFR produces similar activation maps and signal change as BOLD in finger-tapping experiments, and shows reliability comparable to BOLD.CONCLUSION:
STFR can produce functional contrast (even with short TE), and is a potential alternative to long-TE ( T2*) fMRI. The functional contrast arises primarily from the interaction between T2*-like dephasing and the tailored tip-up pulse, and not from spin diffusion.Palabras clave
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Algoritmos
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Mapeo Encefálico
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Imagen por Resonancia Magnética
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Interpretación de Imagen Asistida por Computador
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Corteza Motora
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Movimiento
Tipo de estudio:
Diagnostic_studies
/
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
Magn Reson Med
Asunto de la revista:
DIAGNOSTICO POR IMAGEM
Año:
2015
Tipo del documento:
Article
País de afiliación:
Estados Unidos