Multiecho segmented EPI with z-shimmed background gradient compensation (MESBAC) pulse sequence for fMRI. Magn Reson Med 2002 Aug;48(2):312-21
Date
09/05/2002Pubmed ID
12210940DOI
10.1002/mrm.10219Scopus ID
2-s2.0-0036328751 (requires institutional sign-in at Scopus site) 25 CitationsAbstract
A MultiEcho Segmented EPI with z-shimmed BAckground gradient Compensation (MESBAC) pulse sequence is proposed and validated for functional MRI (fMRI) study in regions suffering from severe susceptibility artifacts. This sequence provides an effective tradeoff between spatial and temporal resolution and reduces image distortion and signal dropout. The blood oxygenation level-dependent (BOLD)-weighted fMRI signal can be reliably obtained in the region of the orbitofrontal cortex (OFC). To overcome physiological motion artifacts during prolonged multisegment EPI acquisition, two sets of navigator echoes were acquired in both the readout and phase-encoding directions. Ghost artifacts generally produced by single-shot EPI acquisition were eliminated by separately placing the even and odd echoes in different k-space trajectories. Unlike most z-shim methods that focus on increasing temporal resolution for event-related functional brain mapping, the MESBAC sequence simultaneously addresses problems of image distortion and signal dropout while maintaining sufficient temporal resolution. The MESBAC sequence will be particularly useful for pharmacological and affective fMRI studies in brain regions such as the OFC, nucleus accumbens, amygdala, parahippocampus, etc.
Author List
Li Z, Wu G, Zhao X, Luo F, Li SJMESH terms used to index this publication - Major topics in bold
AdultArtifacts
Brain Mapping
Cerebral Cortex
Cerebrovascular Circulation
Echo-Planar Imaging
Humans
Magnetic Resonance Imaging
Psychomotor Performance
Smell
