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The spatial and temporal characteristics of the apparent-diffusion-coefficient-dependent fMRI signal changes during visual stimulation.

Abstract：

:The blood oxygenation level dependent (BOLD) contrast has been commonly used to detect fMRI signal. The majority of the BOLD signals are believed to arise from the venous and capillary networks. However, only those from the capillaries are spatially close to the neuronal activities, while the signals from large veins could be distant, rendering the overall localization inaccurate. In recent years, an alternative contrast using arterial spin labeled (ASL) perfusion imaging techniques has been proposed for predominant capillary sensitivity. Such acquisition methods, however, are intrinsically limited in temporal resolution and spatial coverage. Another contrast mechanism, free of such constraints, is based on the apparent diffusion coefficient (ADC) changes during brain activation using isotropic diffusion weighting. It has been shown that these changes are synchronized with brain activation and that they, as a whole, temporally precede BOLD activation, suggesting significant upstream arterial contribution. Moreover, the spatial overlaps between the upstream ADC and downstream BOLD activations are shown to be more localized in the capillaries, which are the temporal and spatial middle ground. In this paper, we sought to further investigate the temporal and spatial characteristics of ADC contrast with additional arterial signal suppression. Also, a pixel-based evaluation was performed in conjunction with the averaged global assessment. It was found that in addition to the known spatial discrepancy and global timing advance compared to the BOLD signal, the ADC activation endured significant temporal heterogeneities. Such fine spatial and temporal assessment could help characterize the exact signal sources of ADC contrast, and ultimately achieve exclusive capillary sensitivity.

journal_name

J Neural Eng

journal_title

Journal of neural engineering

authors

Song AW,Gangstead SL

doi

10.1088/1741-2560/1/1/005

subject

Has Abstract

pub_date

2004-03-01 00:00:00

pages

32-8

issue

eissn

1741-2560

issn

1741-2552

pii

S1741-2560(04)74398-0

journal_volume

pub_type

临床试验,杂志文章

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The spatial and temporal characteristics of the apparent-diffusion-coefficient-dependent fMRI signal changes during visual stimulation.