Effects of cardiac gating on fMRI of the human auditory system

Guimaraes et al. (1998) showed that sound-evoked fMRI activation in the auditory midbrain was significantly improved by a method which reduces image signal variability associated with cardiac-related brainstem motion. The method, cardiac gating, synchronizes image acquisition to a constant phase of the cardiac cycle. Since that study, several improvements to auditory fMRI have been made, and it is unclear whether cardiac gating still yields worthwhile benefits. The present study re-evaluated the effects of cardiac gating for detecting fMRI activation with current auditory fMRI standards. In 11 experiments, we directly compared fMRI activation for images acquired with a fixed repetition time (ungated) vs. those acquired by triggering image acquisition (gated) to the oxygen saturation at the fingertip (SpO2), an indirect measure of cardiac activity. Three of these experiments compared the effects of gating with the Sp02 signal vs. gating with the R-wave of the electrocardiogram (ECG). fMRI activation was routinely detected at all levels of the auditory pathway from the cochlear nucleus to the auditory cortex. Compared to ungated acquisitions, cardiac gating with the SpO2 reduced image signal variability in all centers of the auditory system and increased the magnitude of activation in the inferior colliculus (p < 0.01) and medial geniculate body (p < 0.1).

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Dykstra, Andrew R. (Andrew Richard)

Advisor dc:contributor.advisor

• Jennifer R. Melcher and Louis D. Braida.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/45852

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/45852