A comparison of signal instability in 2D and 3D EPI resting-state fMRI

Ute Goerke, Harald E. Möller, David G. Norris, Christian Schwarzbauer

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Spatiotemporally structured noise, such as physiological noise, is a potential source of artifacts in functional magnetic resonance imaging (fMRI) and is the main limiting factor for the detection of small blood oxygen level-dependent (BOLD) signal variations. fMRI was employed to detect low-frequency BOLD signal fluctuations, which are thought to be related to spontaneous neuronal activity in the resting human brain. The sensitivity to noise, that is, signal variations of non-BOLD origin, was investigated for two- (2D) and three-dimensional (3D) imaging techniques. Incomplete relaxation between subsequent scans increases the level of temporally and spatially correlated signal variations originating from physiological and/or systemic noise. Although inflow effects are suspected to be reduced in 3D echo-planar imaging (EPI) compared with multi-slice 2D EPI, the noise level was higher in the 3D technique. The noise level in 3D fMRI experiments was significantly increased by instabilities of the transverse steady-state magnetization as the repetition time was of the order of T2. By implementing radiofrequency spoiling, temporal signal fluctuations and erroneous inter-regional correlation in connectivity maps were diminished to a level present in data sets acquired with 2D EP1.

Original languageEnglish (US)
Pages (from-to)534-542
Number of pages9
JournalNMR in biomedicine
Volume18
Issue number8
DOIs
StatePublished - Dec 2005

Keywords

  • Functional connectivity
  • Physiological noise
  • Signal stability
  • Steady-state magnetization

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