Multi‐gradient echo with susceptibility inhomogeneity compensation (MGESIC): Demonstration of fMRI in the olfactory cortex at 3.0 T

Short image acquisition times and sensitivity to magnetic susceptibility favor the use of gradient echo imaging methods in functional MRI (fMRI). However, magnetic susceptibility effects attributed to air‐tissue interfaces also lead to severe signal loss in images of the large inferior frontal and lateral temporal cortices of the human brain, which renders these regions inaccessible to fMRI. The signal loss is caused by the local field gradients in the slice selection direction. A multigradient echo with magnetic susceptibility inhomogeneity compensation method (MGESIC) is proposed to overcome this problem. The MGESIC method effectively corrects the susceptibility artifacts and maintains the advantages of gradient echo methods to both BOLD sensitivity and fast image acquisition. The effectiveness of the MGESIC method is demonstrated by fMRI experimental results within the olfactory cortex.

[1]  A. Damasio,et al.  Olfactory dysfunction in man: Anatomical and behavioral aspects , 1982, Brain and Cognition.

[2]  J. Frahm,et al.  Direct FLASH MR imaging of magnetic field inhomogeneities by gradient compensation , 1988, Magnetic resonance in medicine.

[3]  J. Felmlee,et al.  Proton MR chemical shift imaging using double and triple phase contrast acquisition methods. , 1989, Journal of computer assisted tomography.

[4]  S. Riederer,et al.  Analysis of T2 limitations and off‐resonance effects on spatial resolution and artifacts in echo‐planar imaging , 1990, Magnetic resonance in medicine.

[5]  Yong Man Ro,et al.  Reduction of susceptibility artifact in gradient‐echo imaging , 1992, Magnetic resonance in medicine.

[6]  Alan C. Evans,et al.  Functional localization and lateralization of human olfactory cortex , 1992, Nature.

[7]  Ravi S. Menon,et al.  Intrinsic signal changes accompanying sensory stimulation: functional brain mapping with magnetic resonance imaging. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[8]  R. Turner,et al.  Functional mapping of the human visual cortex at 4 and 1.5 tesla using deoxygenation contrast EPI , 1993, Magnetic resonance in medicine.

[9]  J C Gore,et al.  Functional brain imaging at 1.5 T using conventional gradient echo MR imaging techniques. , 1993, Magnetic resonance imaging.

[10]  E C Wong,et al.  Processing strategies for time‐course data sets in functional mri of the human brain , 1993, Magnetic resonance in medicine.

[11]  J. Frahm,et al.  Functional MRI of human brain activation at high spatial resolution , 1993, Magnetic resonance in medicine.

[12]  R. Ordidge,et al.  Assessment of relative brain iron concentrations using T2‐weighted and T2*‐weighted MRI at 3 Tesla , 1994, Magnetic resonance in medicine.

[13]  L R Schad,et al.  Functional 2D and 3D magnetic resonance imaging of motor cortex stimulation at high spatial resolution using standard 1.5 T imager. , 1994, Magnetic resonance imaging.

[14]  Jean A. Tkach,et al.  2D and 3D high resolution gradient echo functional imaging of the brain: Venous contributions to signal in motor cortex studies , 1994, NMR in biomedicine.

[15]  T. Ebner,et al.  Spatial patterns of functional activation of the cerebellum investigated using high field (4 T) MRI , 1994, NMR in biomedicine.

[16]  R T Constable,et al.  Functional MR imaging using gradient‐echo echo‐planar imaging in the presence of large static field inhomogeneities , 1995, Journal of magnetic resonance imaging : JMRI.

[17]  N J Pelc,et al.  Artifacts and signal loss due to flow in the presence of Bo inhomogeneity , 1996, Magnetic resonance in medicine.