Ultra-high resolution blood volume fMRI and BOLD fMRI in humans at 9.4â¯T: Capabilities and challenges.
Neuroimage
; 178: 769-779, 2018 09.
Article
em En
| MEDLINE
| ID: mdl-29890330
ABSTRACT
Functional mapping of cerebral blood volume (CBV) changes has the potential to reveal brain activity with high localization specificity at the level of cortical layers and columns. Non-invasive CBV imaging using Vascular Space Occupancy (VASO) at ultra-high magnetic field strengths promises high spatial specificity but poses unique challenges in human applications. As such, 9.4â¯T B1+ and B0 inhomogeneities limit efficient blood tagging, while the specific absorption rate (SAR) constraints limit the application of VASO-specific RF pulses. Moreover, short T2* values at 9.4â¯T require short readout duration, and long T1 values at 9.4â¯T can cause blood-inflow contaminations. In this study, we investigated the applicability of layer-dependent CBV-fMRI at 9.4â¯T in humans. We addressed the aforementioned challenges by combining multiple technical advancements temporally alternating pTx B1+ shimming parameters, advanced adiabatic RF-pulses, 3D-EPI signal readout, optimized GRAPPA acquisition and reconstruction, and stability-optimized RF channel combination. We found that a combination of suitable advanced methodology alleviates the challenges and potential artifacts, and that VASO fMRI provides reliable measures of CBV change across cortical layers in humans at 9.4â¯T. The localization specificity of CBV-fMRI, combined with the high sensitivity of 9.4â¯T, makes this method an important tool for future studies investigating cortical micro-circuitry in humans.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Processamento de Imagem Assistida por Computador
/
Encéfalo
/
Mapeamento Encefálico
/
Imageamento por Ressonância Magnética
/
Volume Sanguíneo Cerebral
Limite:
Humans
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article