Mechanisms of normal appearing corpus callosum injury related to pericallosal T1 lesions in multiple sclerosis using directional diffusion tensor and 1H MRS imaging
- 1Magnetic Resonance Science Center, Department of Radiology, University of California, San Francisco, CA, USA
- 2UCSF Multiple Sclerosis Center, Department of Neurology, University of California, San Francisco, CA, USA
- Correspondence to: Dr J Oh Magnetic Resonance Science Center, Department of Radiology, Box 0946, University of California, San Francisco, 185 Berry St, Suite 350, San Francisco, CA 94107, USA; joonmimrsc.ucsf.edu
- Received 10 February 2004
- Accepted 23 April 2004
- Revised 12 April 2004
Abstract
Objectives: To investigate the extent of tissue damage in a region of normal appearing corpus callosum (NACC) for different forms of multiple sclerosis (MS) using diffusion tensor and proton magnetic resonance (MR) spectroscopic imaging.
Methods: A total of 47 patients with MS and 15 controls were included. Regions of interest from the NACC were manually segmented using high resolution anatomical images. Diffusion tensor eigenvalues and metabolite ratio of N-acetyl-aspartate (NAA) to creatine/phosphocreatine (Cr) were calculated in the NACC region.
Results: Increased apparent diffusion coefficients (ADCs) and decreased anisotropy were observed in the NACC for patients with MS relative to the control subjects. These resulted from increased diffusion tensor eigenvalues perpendicular to the maximum diffusion direction. The NAA:Cr ratio was decreased in the NACC for patients with MS relative to the control subjects. Significant correlations between pericallosal T1 lesion load and MR modalities in the NACC were observed for patients with relapsing remitting/secondary progressive MS (RR/SPMS), but not for patients with primary progressive MS (PPMS).
Conclusion: This study provides further insight into changes in the ADC and diffusion anisotropy based on the diffusion tensor eigenvalues for patients with MS. The changes in the diffusion tensor eigenvalues and NAA:Cr ratio in the NACC for patients with RR/SPMS suggest axonal injury and/or dysfunction induced by wallerian degeneration. The lack of correlation between these variables in the NACC and focal MS lesions for patients with PPMS further supports intrinsic differences related to tissue injury between these subtypes of MS.
- ADC, apparent diffusion coefficient
- 3D SPGR, three dimensional spoiled gradient echo
- CSF, cerebrospinal fluid
- Cr, creatine/phosphocreatine
- EDSS, Expanded Disability Status Scale
- FLAIR, fluid attenuated inversion recovery
- 1H MRSI, proton magnetic resonance spectroscopic imaging
- MS, multiple sclerosis
- NAA, N-acetyl-aspartate
- NAWM, normal appearing white matter
- PPMS, primary progressive MS
- SPMS, secondary progressive MS
- ROI, region of interest
- RRMS, relapsing remitting MS
Footnotes
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This study was supported in part by National Multiple Sclerosis Society grant RG2655B6/1 and National Institute of Health grant R01 NS39529.
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Dr J Oh is a National Multiple Sclerosis Society Postdoctoral Fellowship awardee.
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Competing interests: none declared
