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Lin TH, Spees WM, Chiang CW, Trinkaus K, Cross AH, Song SK. Diffusion fMRI detects white-matter dysfunction in mice with acute optic neuritis. Neurobiol Dis 2014; 67:1-8. [PMID: 24632420 PMCID: PMC4035476 DOI: 10.1016/j.nbd.2014.02.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 02/18/2014] [Accepted: 02/25/2014] [Indexed: 12/14/2022] Open
Abstract
Optic neuritis is a frequent and early symptom of multiple sclerosis (MS). Conventional magnetic resonance (MR) techniques provide means to assess multiple MS-related pathologies, including axonal injury, demyelination, and inflammation. A method to directly and non-invasively probe white-matter function could further elucidate the interplay of underlying pathologies and functional impairments. Previously, we demonstrated a significant 27% activation-associated decrease in the apparent diffusion coefficient of water perpendicular to the axonal fibers (ADC⊥) in normal C57BL/6 mouse optic nerve with visual stimulation using diffusion fMRI. Here we apply this approach to explore the relationship between visual acuity, optic nerve pathology, and diffusion fMRI in the experimental autoimmune encephalomyelitis (EAE) mouse model of optic neuritis. Visual stimulation produced a significant 25% (vs. baseline) ADC⊥ decrease in sham EAE optic nerves, while only a 7% (vs. baseline) ADC⊥ decrease was seen in EAE mice with acute optic neuritis. The reduced activation-associated ADC⊥ response correlated with post-MRI immunohistochemistry determined pathologies (including inflammation, demyelination, and axonal injury). The negative correlation between activation-associated ADC⊥ response and visual acuity was also found when pooling EAE-affected and sham groups under our experimental criteria. Results suggest that reduction in diffusion fMRI directly reflects impaired axonal-activation in EAE mice with optic neuritis. Diffusion fMRI holds promise for directly gauging in vivo white-matter dysfunction or therapeutic responses in MS patients.
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Affiliation(s)
- Tsen-Hsuan Lin
- Department of Physics, Washington University, St. Louis, MO 63130, USA
| | - William M Spees
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Chia-Wen Chiang
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kathryn Trinkaus
- Department of Biostatistics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Anne H Cross
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sheng-Kwei Song
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Kou Z, VandeVord PJ. Traumatic white matter injury and glial activation: from basic science to clinics. Glia 2014; 62:1831-55. [PMID: 24807544 DOI: 10.1002/glia.22690] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 03/27/2014] [Accepted: 04/23/2014] [Indexed: 12/15/2022]
Abstract
An improved understanding and characterization of glial activation and its relationship with white matter injury will likely serve as a novel treatment target to curb post injury inflammation and promote axonal remyelination after brain trauma. Traumatic brain injury (TBI) is a significant public healthcare burden and a leading cause of death and disability in the United States. Particularly, traumatic white matter (WM) injury or traumatic axonal injury has been reported as being associated with patients' poor outcomes. However, there is very limited data reporting the importance of glial activation after TBI and its interaction with WM injury. This article presents a systematic review of traumatic WM injury and the associated glial activation, from basic science to clinical diagnosis and prognosis, from advanced neuroimaging perspective. It concludes that there is a disconnection between WM injury research and the essential role of glia which serve to restore a healthy environment for axonal regeneration following WM injury. Particularly, there is a significant lack of non-invasive means to characterize the complex pathophysiology of WM injury and glial activation in both animal models and in humans. An improved understanding and characterization of the relationship between glia and WM injury will likely serve as a novel treatment target to curb post injury inflammation and promote axonal remyelination.
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Affiliation(s)
- Zhifeng Kou
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan; Department of Radiology, Wayne State University, Detroit, Michigan
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Hori M, Tsutsumi S, Yasumoto Y, Ito M, Suzuki M, Tanaka FS, Kyogoku S, Nakamura M, Tabuchi T, Fukunaga I, Suzuki Y, Kamagata K, Masutani Y, Aoki S. Cervical spondylosis: Evaluation of microstructural changes in spinal cord white matter and gray matter by diffusional kurtosis imaging. Magn Reson Imaging 2014; 32:428-32. [PMID: 24602824 DOI: 10.1016/j.mri.2014.01.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 01/20/2014] [Accepted: 01/24/2014] [Indexed: 12/13/2022]
Abstract
INTRODUCTION We investigated microstructural changes in the spinal cord, separately for white matter and gray matter, in patients with cervical spondylosis by using diffusional kurtosis imaging (DKI). METHODS We studied 13 consecutive patients with cervical myelopathy (15 affected sides and 11 unaffected sides). After conventional magnetic resonance (MR) imaging, DKI data were acquired by using a 3T MR imaging scanner. Values for fractional anisotropy (FA), apparent diffusion coefficient (ADC), and mean diffusional kurtosis (MK) were calculated and compared between unaffected and affected spinal cords, separately for white matter and gray matter. RESULTS Tract-specific analysis of white matter in the lateral funiculus showed no statistical differences between the affected and unaffected sides. In gray matter, only MK was significantly lower in the affected spinal cords than in unaffected spinal cords (0.60±0.18 vs. 0.73±0.13, P=0.0005, Wilcoxon's signed rank test). CONCLUSIONS MK values in the spinal cord may reflect microstructural changes and gray matter damage and can potentially provide more information beyond that obtained with conventional diffusion metrics.
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Affiliation(s)
- Masaaki Hori
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan.
| | - Satoshi Tsutsumi
- Department of Neurological Surgery, Juntendo University Urayasu Hospital, Chiba, Japan
| | - Yukimasa Yasumoto
- Department of Neurological Surgery, Juntendo University Urayasu Hospital, Chiba, Japan
| | - Masanori Ito
- Department of Neurological Surgery, Juntendo University Urayasu Hospital, Chiba, Japan
| | - Michimasa Suzuki
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Fumine S Tanaka
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Shinsuke Kyogoku
- Department of Radiology, Juntendo University Urayasu Hospital, Chiba, Japan
| | | | | | - Issei Fukunaga
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan; Department of Health Science, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Yuriko Suzuki
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan; Philips Electronics Japan, Tokyo, Japan
| | - Koji Kamagata
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | | | - Shigeki Aoki
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
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White matter organization in relation to upper limb motor control in healthy subjects: exploring the added value of diffusion kurtosis imaging. Brain Struct Funct 2013; 219:1627-38. [PMID: 23760816 DOI: 10.1007/s00429-013-0590-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 05/31/2013] [Indexed: 01/14/2023]
Abstract
Diffusion tensor imaging (DTI) characterizes white matter (WM) microstructure. In many brain regions, however, the assumption that the diffusion probability distribution is Gaussian may be invalid, even at low b values. Recently, diffusion kurtosis imaging (DKI) was suggested to more accurately estimate this distribution. We explored the added value of DKI in studying the relation between WM microstructure and upper limb coordination in healthy controls (N = 24). Performance on a complex bimanual tracking task was studied with respect to the conventional DTI measures (DKI or DTI derived) and kurtosis metrics of WM tracts/regions carrying efferent (motor) output from the brain, corpus callosum (CC) substructures and whole brain WM. For both estimation models, motor performance was associated with fractional anisotropy (FA) of the CC-genu, CC-body, the anterior limb of the internal capsule, and whole brain WM (r s range 0.42-0.63). Although DKI revealed higher mean, radial and axial diffusivity and lower FA than DTI (p < 0.001), the correlation coefficients were comparable. Finally, better motor performance was associated with increased mean and radial kurtosis and kurtosis anisotropy (r s range 0.43-0.55). In conclusion, DKI provided additional information, but did not show increased sensitivity to detect relations between WM microstructure and bimanual performance in healthy controls.
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