Dinâmica da alteração perfusional induzida por estado de apnéia utilizando fMRI / Dynamic of brain perfusion changes induced by breath-holding fMRI.

AUTOR(ES)

Katia Cristine Andrade

DATA DE PUBLICAÇÃO

2006

RESUMO

The BOLD (Blood Oxygenation Level Dependent) signal, is the most used contrast mechanism of the so called functional Magnetic Resonance Imaging (fMRI). Although it indirectly measures neuronal activity, its response is directly related to cerebral blood flow (CBF), Cerebral Metabolic Rate of Oxygen (CMRO2) and Cerebral Blood Volume (CBV) and can be, in principle, used to map cerebral perfusion. Thus, the main purpose of this study was to investigate, quantitatively, some aspects of perfusional alterations in the human brain. These changes were mapped by changes in the BOLD signal as a result of a global and uniform stimulation: hypercapnia induced by breath holding paradigms. Magnetic resonance images were acquired in a 1.5 T scanner (Siemens, Magneton Vision) with EPI-BOLD fMRI sequences. It was analyzed the BOLD dependency on breath holding duration and differences on the BOLD signal due the employed breath holding techniques: breath holding after expiration or after inspiration. The regional variability of the BOLD signal propagation was also studied. Moreover, the signal was used to construct maps based on CBV information. It was possible to gain information about the BOLD signal behavior that respond to PaO2 and PaCO2 alterations. Besides, it was demonstrated its regional variations sensibility, which can be correlated with arterial reactivity or the rest CBV of this arteries. It was also possible acquire information about the temporal characteristics of CBF changes induced by hypercapnia across brain regions as well as the identification of cortical areas that were responsible to the voluntary breathing. Finally, the B-CBV maps that used the BOLD con-trast were able to reflect CBV information, although, it is necessary the study of other parameters that can influence the signal.

ASSUNTO(S)

fmri perfusion perfusão bold bold fmri

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