Magnetization transfer (MT) asymmetry around the water resonance in human cervical spinal cord |
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| Authors: | Man‐Cheuk Ng PhD Jun Hua MSc Yong Hu PhD Keith D Luk MD PhD Edmund Y Lam PhD |
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| Institution: | 1. Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam, Hong Kong;2. Russell H. Morgan Department of Radiology and Radiological Sciences, Division of MR Research, Johns Hopkins University, Baltimore, Maryland, USA;3. F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA;4. Department of Orthopedics and Traumatology, University of Hong Kong, Pokfulam, Hong Kong |
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| Abstract: | Purpose To demonstrate the presence of magnetization transfer (MT) asymmetry in human cervical spinal cord due to the interaction between bulk water and semisolid macromolecules (conventional MT), and the chemical exchange dependent saturation transfer (CEST) effect. Materials and Methods MT asymmetry in the cervical spinal cord (C3/C4–C5) was investigated in 14 healthy male subjects with a 3T magnetic resonance (MR) system. Both spin‐echo (SE) and gradient‐echo (GE) echo‐planar imaging (EPI) sequences, with low‐power off‐resonance radiofrequency irradiation at different frequency offsets, were used. Results Our results show that the z‐spectrum in gray/white matter (GM/WM) is asymmetrical about the water resonance frequency in both SE‐EPI and GE‐EPI, with a more significant saturation effect at the lower frequencies (negative frequency offset) far away from water and at the higher frequencies (positive offset) close to water. These are attributed mainly to the conventional MT and CEST effects respectively. Furthermore, the amplitude of MT asymmetry is larger in the SE‐EPI sequence than in the GE‐EPI sequence in the frequency range of amide protons. Conclusion Our results demonstrate the presence of MT asymmetry in human cervical spinal cord, which is consistent with the ones reported in the brain. J. Magn. Reson. Imaging 2009;29:523–528. © 2009 Wiley‐Liss, Inc. |
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| Keywords: | magnetization transfer asymmetry CEST APT spinal cord |
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