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Shengkwei Song - One of the best experts on this subject based on the ideXlab platform.
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quantifying white matter tract diffusion parameters in the presence of increased extra fiber cellularity and vasogenic edema
NeuroImage, 2014Co-Authors: Chiawen Chiang, Kathryn Trinkaus, Anne H Cross, Yong Wang, Peng Sun, Tsenhsuan Lin, Shengkwei SongAbstract:The effect of extra-fiber structural and pathological components confounding diffusion tensor imaging (DTI) computation was quantitatively investigated using data generated by both Monte-Carlo simulations and tissue phantoms. Increased extent of vasogenic edema, by addition of various amount of gel to fixed normal mouse trigeminal nerves or by increasing non-restricted isotropic diffusion tensor components in Monte-Carlo simulations, significantly decreased fractional anisotropy (FA) and increased Radial Diffusivity, while less significantly increased axial Diffusivity derived by DTI. Increased cellularity, mimicked by graded increase of the restricted isotropic diffusion tensor component in Monte-Carlo simulations, significantly decreased FA and axial Diffusivity with limited impact on Radial Diffusivity derived by DTI. The MC simulation and tissue phantom data were also analyzed by the recently developed diffusion basis spectrum imaging (DBSI) to simultaneously distinguish and quantify the axon/myelin integrity and extra-fiber diffusion components. Results showed that increased cellularity or vasogenic edema did not affect the DBSI-derived fiber FA, axial or Radial Diffusivity. Importantly, the extent of extra-fiber cellularity and edema estimated by DBSI correlated with experimentally added gel and Monte-Carlo simulations. We also examined the feasibility of applying 25-direction diffusion encoding scheme for DBSI analysis on coherent white matter tracts. Results from both phantom experiments and simulations suggested that the 25-direction diffusion scheme provided comparable DBSI estimation of both fiber diffusion parameters and extra-fiber cellularity/edema extent as those by 99-direction scheme. An in vivo 25-direction DBSI analysis was performed on experimental autoimmune encephalomyelitis (EAE, an animal model of human multiple sclerosis) optic nerve as an example to examine the validity of derived DBSI parameters with post-imaging immunohistochemistry verification. Results support that in vivo DBSI using 25-direction diffusion scheme correctly reflect the underlying axonal injury, demyelination, and inflammation of optic nerves in EAE mice.
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optic nerve diffusion tensor imaging parameters and their correlation with optic disc topography and disease severity in adult glaucoma patients and controls
Journal of Glaucoma, 2014Co-Authors: Sidney T Chang, Kathryn Trinkaus, Shengkwei Song, Melike Pekmezci, Stella N Arthur, Edward M BarnettAbstract:Purpose: To evaluate optic nerve diffusion tensor imaging (DTI) parameters in glaucoma patients and controls, and to correlate DTI parameters with the rim area obtained with Heidelberg retina tomography (HRT) and with the severity of glaucomatous damage using the Glaucoma Staging System. Design: Pilot study. Methods: Twenty-seven patients with glaucoma and 12 control subjects underwent DTI and HRT imaging. Main outcome measures included: fractional anisotropy, mean Diffusivity, axial Diffusivity, Radial Diffusivity, HRT rim area, and Glaucoma Staging System stage. Results: In group comparison, mean Diffusivity (1.33 vs. 0.91 mu m(2)/ms, P = 0.0002), axial Diffusivity (1.70 vs. 1.43 mu m(2)/ms, P = 0.036), and Radial Diffusivity (1.24 vs. 0.71 mu m(2)/ms, P 0.05). Conclusions: DTI may be a useful technique for detection and evaluation of glaucomatous damage in the optic nerve, particularly for patients in whom conventional imaging and perimetry are not possible. Future studies are needed to evaluate how DTI parameters change longitudinally with glaucomatous damage within the visual pathways and address cerebrospinal fluid partial volume effects in diffusion tensor quantification, especially for patients with advanced glaucoma stage.
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improved in vivo diffusion tensor imaging of human cervical spinal cord
NeuroImage, 2013Co-Authors: Joshua S Shimony, Robert T Naismith, Tammie L S Benzinger, Kathryn Trinkaus, Anne H Cross, Eric C Klawiter, Abraham Z Snyder, Shengkwei SongAbstract:We describe a cardiac gated high in-plane resolution axial human cervical spinal cord diffusion tensor imaging (DTI) protocol. Multiple steps were taken to optimize both image acquisition and image processing. The former includes slice-by-slice cardiac triggering and individually tiltable slices. The latter includes (i) iterative 2D retrospective motion correction, (ii) image intensity outlier detection to minimize the influence of physiological noise, (iii) a non-linear DTI estimation procedure incorporating non-negative eigenvalue priors, and (iv) tract-specific region-of-interest (ROI) identification based on an objective geometry reference. Using these strategies in combination, Radial Diffusivity (λ(⊥)) was reproducibly measured in white matter (WM) tracts (adjusted mean [95% confidence interval]=0.25 [0.22, 0.29] μm(2)/ms), lower than previously reported λ(⊥) values in the in vivo human spinal cord DTI literature. Radial Diffusivity and fractional anisotropy (FA) measured in WM varied from rostral to caudal as did mean translational motion, likely reflecting respiratory motion effect. Given the considerable sensitivity of DTI measurements to motion artifact, we believe outlier detection is indispensable in spinal cord diffusion imaging. We also recommend using a mixed-effects model to account for systematic measurement bias depending on cord segment.
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increased Radial Diffusivity in spinal cord lesions in neuromyelitis optica compared with multiple sclerosis
Multiple Sclerosis Journal, 2012Co-Authors: Eric C Klawiter, Robert T Naismith, Tammie L S Benzinger, Joshua S Shimony, Kathryn Trinkaus, Shengkwei Song, Samantha Lancia, Abraham Z Snyder, Anne H CrossAbstract:Background:Multiple sclerosis (MS) and neuromyelitis optica (NMO) both affect spinal cord with notable differences in pathology.Objective:Determine the utility of diffusion tensor imaging (DTI) to differentiate the spinal cord lesions of NMO from MS within and outside T2 lesions.Methods:Subjects greater than or equal to 12 months from a clinical episode of transverse myelitis underwent a novel transaxial cervical spinal cord DTI sequence. Ten subjects with NMO, 10 with MS and 10 healthy controls were included.Results:Within T2 affected white matter regions, Radial Diffusivity was increased in both NMO and MS compared with healthy controls (p<0.001, respectively), and to a greater extent in NMO than MS (p<0.001). Axial Diffusivity was decreased in T2 lesions in both NMO and MS compared with controls (p<0.001, p=0.001), but did not differ between the two diseases. Radial Diffusivity and fractional anisotropy within white matter regions upstream and downstream of T2 lesions were different from controls in ea...
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Radial Diffusivity predicts demyelination in ex vivo multiple sclerosis spinal cords
NeuroImage, 2011Co-Authors: Eric C Klawiter, Robert T Naismith, Kathryn Trinkaus, Anne H Cross, Shengkwei Song, Hsiaofang Liang, Matthew D Budde, Robert E Schmidt, Tammie L S BenzingerAbstract:Objective Correlation of diffusion tensor imaging (DTI) with histochemical staining for demyelination and axonal damage in multiple sclerosis (MS) ex vivo human cervical spinal cords.
Anne H Cross - One of the best experts on this subject based on the ideXlab platform.
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quantifying white matter tract diffusion parameters in the presence of increased extra fiber cellularity and vasogenic edema
NeuroImage, 2014Co-Authors: Chiawen Chiang, Kathryn Trinkaus, Anne H Cross, Yong Wang, Peng Sun, Tsenhsuan Lin, Shengkwei SongAbstract:The effect of extra-fiber structural and pathological components confounding diffusion tensor imaging (DTI) computation was quantitatively investigated using data generated by both Monte-Carlo simulations and tissue phantoms. Increased extent of vasogenic edema, by addition of various amount of gel to fixed normal mouse trigeminal nerves or by increasing non-restricted isotropic diffusion tensor components in Monte-Carlo simulations, significantly decreased fractional anisotropy (FA) and increased Radial Diffusivity, while less significantly increased axial Diffusivity derived by DTI. Increased cellularity, mimicked by graded increase of the restricted isotropic diffusion tensor component in Monte-Carlo simulations, significantly decreased FA and axial Diffusivity with limited impact on Radial Diffusivity derived by DTI. The MC simulation and tissue phantom data were also analyzed by the recently developed diffusion basis spectrum imaging (DBSI) to simultaneously distinguish and quantify the axon/myelin integrity and extra-fiber diffusion components. Results showed that increased cellularity or vasogenic edema did not affect the DBSI-derived fiber FA, axial or Radial Diffusivity. Importantly, the extent of extra-fiber cellularity and edema estimated by DBSI correlated with experimentally added gel and Monte-Carlo simulations. We also examined the feasibility of applying 25-direction diffusion encoding scheme for DBSI analysis on coherent white matter tracts. Results from both phantom experiments and simulations suggested that the 25-direction diffusion scheme provided comparable DBSI estimation of both fiber diffusion parameters and extra-fiber cellularity/edema extent as those by 99-direction scheme. An in vivo 25-direction DBSI analysis was performed on experimental autoimmune encephalomyelitis (EAE, an animal model of human multiple sclerosis) optic nerve as an example to examine the validity of derived DBSI parameters with post-imaging immunohistochemistry verification. Results support that in vivo DBSI using 25-direction diffusion scheme correctly reflect the underlying axonal injury, demyelination, and inflammation of optic nerves in EAE mice.
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improved in vivo diffusion tensor imaging of human cervical spinal cord
NeuroImage, 2013Co-Authors: Joshua S Shimony, Robert T Naismith, Tammie L S Benzinger, Kathryn Trinkaus, Anne H Cross, Eric C Klawiter, Abraham Z Snyder, Shengkwei SongAbstract:We describe a cardiac gated high in-plane resolution axial human cervical spinal cord diffusion tensor imaging (DTI) protocol. Multiple steps were taken to optimize both image acquisition and image processing. The former includes slice-by-slice cardiac triggering and individually tiltable slices. The latter includes (i) iterative 2D retrospective motion correction, (ii) image intensity outlier detection to minimize the influence of physiological noise, (iii) a non-linear DTI estimation procedure incorporating non-negative eigenvalue priors, and (iv) tract-specific region-of-interest (ROI) identification based on an objective geometry reference. Using these strategies in combination, Radial Diffusivity (λ(⊥)) was reproducibly measured in white matter (WM) tracts (adjusted mean [95% confidence interval]=0.25 [0.22, 0.29] μm(2)/ms), lower than previously reported λ(⊥) values in the in vivo human spinal cord DTI literature. Radial Diffusivity and fractional anisotropy (FA) measured in WM varied from rostral to caudal as did mean translational motion, likely reflecting respiratory motion effect. Given the considerable sensitivity of DTI measurements to motion artifact, we believe outlier detection is indispensable in spinal cord diffusion imaging. We also recommend using a mixed-effects model to account for systematic measurement bias depending on cord segment.
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increased Radial Diffusivity in spinal cord lesions in neuromyelitis optica compared with multiple sclerosis
Multiple Sclerosis Journal, 2012Co-Authors: Eric C Klawiter, Robert T Naismith, Tammie L S Benzinger, Joshua S Shimony, Kathryn Trinkaus, Shengkwei Song, Samantha Lancia, Abraham Z Snyder, Anne H CrossAbstract:Background:Multiple sclerosis (MS) and neuromyelitis optica (NMO) both affect spinal cord with notable differences in pathology.Objective:Determine the utility of diffusion tensor imaging (DTI) to differentiate the spinal cord lesions of NMO from MS within and outside T2 lesions.Methods:Subjects greater than or equal to 12 months from a clinical episode of transverse myelitis underwent a novel transaxial cervical spinal cord DTI sequence. Ten subjects with NMO, 10 with MS and 10 healthy controls were included.Results:Within T2 affected white matter regions, Radial Diffusivity was increased in both NMO and MS compared with healthy controls (p<0.001, respectively), and to a greater extent in NMO than MS (p<0.001). Axial Diffusivity was decreased in T2 lesions in both NMO and MS compared with controls (p<0.001, p=0.001), but did not differ between the two diseases. Radial Diffusivity and fractional anisotropy within white matter regions upstream and downstream of T2 lesions were different from controls in ea...
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Radial Diffusivity predicts demyelination in ex vivo multiple sclerosis spinal cords
NeuroImage, 2011Co-Authors: Eric C Klawiter, Robert T Naismith, Kathryn Trinkaus, Anne H Cross, Shengkwei Song, Hsiaofang Liang, Matthew D Budde, Robert E Schmidt, Tammie L S BenzingerAbstract:Objective Correlation of diffusion tensor imaging (DTI) with histochemical staining for demyelination and axonal damage in multiple sclerosis (MS) ex vivo human cervical spinal cords.
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rostrocaudal analysis of corpus callosum demyelination and axon damage across disease stages refines diffusion tensor imaging correlations with pathological features
Journal of Neuropathology and Experimental Neurology, 2010Co-Authors: Mingqiang Xie, Kathryn Trinkaus, Anne H Cross, Shengkwei Song, Matthew D Budde, Jennifer E Tobin, Chin I Chen, Dennis P Mcdaniel, Regina C. ArmstrongAbstract:Non-invasive assessment of the progression of axon damage is important for evaluating disease progression and developing neuroprotective interventions in multiple sclerosis (MS) patients. We examined the cellular responses correlated with diffusion tensor imaging (DTI)-derived axial (λ||) and Radial (λ⊥) Diffusivity values throughout acute (4 weeks) and chronic (12 weeks) stages of demyelination and after 6 weeks of recovery using the cuprizone demyelination of the corpus callosum model in C57BL/6 and Thy1-YFP-16 mice. The rostro-caudal progression of pathologic alterations in the corpus callosum enabled spatially and temporally defined correlations of pathological features with DTI measurements. During acute demyelination, microglial/macrophage activation was most extensive and axons exhibited swellings, neurofilament dephosphorylation, and reduced diameters. Axial Diffusivity values decreased in the acute phase but did not correlate with axonal atrophy during chronic demyelination. In contrast, Radial Diffusivity increased with the progression of demyelination but did not correlate with myelin loss or astrogliosis. Unlike other animals models with progressive neurodegeneration and axon loss, the acute axon damage did not progress to discontinuity or loss of axons even after a period of chronic demyelination. Correlations of reversible axon pathology, demyelination, microglia/macrophage activation, and astrogliosis with regional axial and Radial Diffusivity measurements will facilitate the clinical application of DTI in MS patients.
Regina C. Armstrong - One of the best experts on this subject based on the ideXlab platform.
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reduced axonopathy and enhanced remyelination after chronic demyelination in fibroblast growth factor 2 fgf2 null mice differential detection with diffusion tensor imaging
Journal of Neuropathology and Experimental Neurology, 2011Co-Authors: Jennifer E Tobin, Shengkwei Song, Mingqiang Xie, Regina C. ArmstrongAbstract:Chronic central nervous system demyelinating diseases result in long-term disability because of limited remyelination capacity and cumulative damage to axons. Corpus callosum demyelination in mice fed cuprizone provides a reproducible model of chronic demyelination in which the demyelinating agent can be removed to test modifications that promote recovery and to develop noninvasive neuroimaging techniques for monitoring changes in myelin and axons. We used the cuprizone model in mice with genetic deletion of fibroblast growth factor 2 ( Fgf2 ) to determine the impact of FGF2 on axon pathology and remyelination after chronic demyelination. We also evaluated the ability of quantitative magnetic resonance diffusion tensor imaging (DTI) to distinguish the corresponding pathological changes in axons and myelin during the progression of demyelination and remyelination. During the recovery period after chronic demyelination, Fgf2 -null mice exhibited enhanced remyelination that was detected using DTI measures of Radial Diffusivity and confirmed by electron microscopic analysis of the proportion of remyelinated axons. Ultrastructural analysis also demonstrated reduced axonal atrophy in chronically demyelinated Fgf2 -null versus wild-type mice. This difference in axon atrophy was further demonstrated as reduced immunohistochemical detection of neurofilament dephosphorylation in Fgf2 -null mice. Diffusion tensor imaging axial and Radial Diffusivity measures did not differentiate Fgf2 -null mice from wild-type mice to correlate with changes in axonal atrophy during chronic demyelination. Overall, these findings demonstrate that attenuation of FGF2 signaling promotes neuroprotection of axons and remyelination, suggesting that FGF2 is an important negative regulator of recovery after chronic demyelination.
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rostrocaudal analysis of corpus callosum demyelination and axon damage across disease stages refines diffusion tensor imaging correlations with pathological features
Journal of Neuropathology and Experimental Neurology, 2010Co-Authors: Mingqiang Xie, Kathryn Trinkaus, Anne H Cross, Shengkwei Song, Matthew D Budde, Jennifer E Tobin, Chin I Chen, Dennis P Mcdaniel, Regina C. ArmstrongAbstract:Non-invasive assessment of the progression of axon damage is important for evaluating disease progression and developing neuroprotective interventions in multiple sclerosis (MS) patients. We examined the cellular responses correlated with diffusion tensor imaging (DTI)-derived axial (λ||) and Radial (λ⊥) Diffusivity values throughout acute (4 weeks) and chronic (12 weeks) stages of demyelination and after 6 weeks of recovery using the cuprizone demyelination of the corpus callosum model in C57BL/6 and Thy1-YFP-16 mice. The rostro-caudal progression of pathologic alterations in the corpus callosum enabled spatially and temporally defined correlations of pathological features with DTI measurements. During acute demyelination, microglial/macrophage activation was most extensive and axons exhibited swellings, neurofilament dephosphorylation, and reduced diameters. Axial Diffusivity values decreased in the acute phase but did not correlate with axonal atrophy during chronic demyelination. In contrast, Radial Diffusivity increased with the progression of demyelination but did not correlate with myelin loss or astrogliosis. Unlike other animals models with progressive neurodegeneration and axon loss, the acute axon damage did not progress to discontinuity or loss of axons even after a period of chronic demyelination. Correlations of reversible axon pathology, demyelination, microglia/macrophage activation, and astrogliosis with regional axial and Radial Diffusivity measurements will facilitate the clinical application of DTI in MS patients.
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demyelination increases Radial Diffusivity in corpus callosum of mouse brain
NeuroImage, 2005Co-Authors: Shengkwei Song, Anne H Cross, Regina C. Armstrong, Jun E. Yoshino, Shiowjiuan Lin, Shuwei SunAbstract:Myelin damage, as seen in multiple sclerosis (MS) and other demyelinating diseases, impairs axonal conduction and can also be associated with axonal degeneration. Accurate assessments of these conditions may be highly beneficial in evaluating and selecting therapeutic strategies for patient management. Recently, an analytical approach examining diffusion tensor imaging (DTI) derived parameters has been proposed to assess the extent of axonal damage, demyelination, or both. The current study uses the well-characterized cuprizone model of experimental demyelination and remyelination of corpus callosum in mouse brain to evaluate the ability of DTI parameters to detect the progression of myelin degeneration and regeneration. Our results demonstrate that the extent of increased Radial Diffusivity reflects the severity of demyelination in corpus callosum of mouse brain affected by cuprizone treatment. Subsequently, Radial Diffusivity decreases with the progression of remyelination. Furthermore, Radial Diffusivity changes were specific to the time course of changes in myelin integrity as distinct from axonal injury, which was detected by betaAPP immunostaining and shown to be most extensive prior to demyelination. Radial Diffusivity offers a specific assessment of demyelination and remyelination, as distinct from acute axonal damage.
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demyelination increases Radial Diffusivity in corpus callosum of mouse brain
NeuroImage, 2005Co-Authors: Shengkwei Song, Anne H Cross, Regina C. Armstrong, Jun E. Yoshino, Tuan Q LeAbstract:Abstract Myelin damage, as seen in multiple sclerosis (MS) and other demyelinating diseases, impairs axonal conduction and can also be associated with axonal degeneration. Accurate assessments of these conditions may be highly beneficial in evaluating and selecting therapeutic strategies for patient management. Recently, an analytical approach examining diffusion tensor imaging (DTI) derived parameters has been proposed to assess the extent of axonal damage, demyelination, or both. The current study uses the well-characterized cuprizone model of experimental demyelination and remyelination of corpus callosum in mouse brain to evaluate the ability of DTI parameters to detect the progression of myelin degeneration and regeneration. Our results demonstrate that the extent of increased Radial Diffusivity reflects the severity of demyelination in corpus callosum of mouse brain affected by cuprizone treatment. Subsequently, Radial Diffusivity decreases with the progression of remyelination. Furthermore, Radial Diffusivity changes were specific to the time course of changes in myelin integrity as distinct from axonal injury, which was detected by βAPP immunostaining and shown to be most extensive prior to demyelination. Radial Diffusivity offers a specific assessment of demyelination and remyelination, as distinct from acute axonal damage.
Kathryn Trinkaus - One of the best experts on this subject based on the ideXlab platform.
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quantifying white matter tract diffusion parameters in the presence of increased extra fiber cellularity and vasogenic edema
NeuroImage, 2014Co-Authors: Chiawen Chiang, Kathryn Trinkaus, Anne H Cross, Yong Wang, Peng Sun, Tsenhsuan Lin, Shengkwei SongAbstract:The effect of extra-fiber structural and pathological components confounding diffusion tensor imaging (DTI) computation was quantitatively investigated using data generated by both Monte-Carlo simulations and tissue phantoms. Increased extent of vasogenic edema, by addition of various amount of gel to fixed normal mouse trigeminal nerves or by increasing non-restricted isotropic diffusion tensor components in Monte-Carlo simulations, significantly decreased fractional anisotropy (FA) and increased Radial Diffusivity, while less significantly increased axial Diffusivity derived by DTI. Increased cellularity, mimicked by graded increase of the restricted isotropic diffusion tensor component in Monte-Carlo simulations, significantly decreased FA and axial Diffusivity with limited impact on Radial Diffusivity derived by DTI. The MC simulation and tissue phantom data were also analyzed by the recently developed diffusion basis spectrum imaging (DBSI) to simultaneously distinguish and quantify the axon/myelin integrity and extra-fiber diffusion components. Results showed that increased cellularity or vasogenic edema did not affect the DBSI-derived fiber FA, axial or Radial Diffusivity. Importantly, the extent of extra-fiber cellularity and edema estimated by DBSI correlated with experimentally added gel and Monte-Carlo simulations. We also examined the feasibility of applying 25-direction diffusion encoding scheme for DBSI analysis on coherent white matter tracts. Results from both phantom experiments and simulations suggested that the 25-direction diffusion scheme provided comparable DBSI estimation of both fiber diffusion parameters and extra-fiber cellularity/edema extent as those by 99-direction scheme. An in vivo 25-direction DBSI analysis was performed on experimental autoimmune encephalomyelitis (EAE, an animal model of human multiple sclerosis) optic nerve as an example to examine the validity of derived DBSI parameters with post-imaging immunohistochemistry verification. Results support that in vivo DBSI using 25-direction diffusion scheme correctly reflect the underlying axonal injury, demyelination, and inflammation of optic nerves in EAE mice.
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optic nerve diffusion tensor imaging parameters and their correlation with optic disc topography and disease severity in adult glaucoma patients and controls
Journal of Glaucoma, 2014Co-Authors: Sidney T Chang, Kathryn Trinkaus, Shengkwei Song, Melike Pekmezci, Stella N Arthur, Edward M BarnettAbstract:Purpose: To evaluate optic nerve diffusion tensor imaging (DTI) parameters in glaucoma patients and controls, and to correlate DTI parameters with the rim area obtained with Heidelberg retina tomography (HRT) and with the severity of glaucomatous damage using the Glaucoma Staging System. Design: Pilot study. Methods: Twenty-seven patients with glaucoma and 12 control subjects underwent DTI and HRT imaging. Main outcome measures included: fractional anisotropy, mean Diffusivity, axial Diffusivity, Radial Diffusivity, HRT rim area, and Glaucoma Staging System stage. Results: In group comparison, mean Diffusivity (1.33 vs. 0.91 mu m(2)/ms, P = 0.0002), axial Diffusivity (1.70 vs. 1.43 mu m(2)/ms, P = 0.036), and Radial Diffusivity (1.24 vs. 0.71 mu m(2)/ms, P 0.05). Conclusions: DTI may be a useful technique for detection and evaluation of glaucomatous damage in the optic nerve, particularly for patients in whom conventional imaging and perimetry are not possible. Future studies are needed to evaluate how DTI parameters change longitudinally with glaucomatous damage within the visual pathways and address cerebrospinal fluid partial volume effects in diffusion tensor quantification, especially for patients with advanced glaucoma stage.
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improved in vivo diffusion tensor imaging of human cervical spinal cord
NeuroImage, 2013Co-Authors: Joshua S Shimony, Robert T Naismith, Tammie L S Benzinger, Kathryn Trinkaus, Anne H Cross, Eric C Klawiter, Abraham Z Snyder, Shengkwei SongAbstract:We describe a cardiac gated high in-plane resolution axial human cervical spinal cord diffusion tensor imaging (DTI) protocol. Multiple steps were taken to optimize both image acquisition and image processing. The former includes slice-by-slice cardiac triggering and individually tiltable slices. The latter includes (i) iterative 2D retrospective motion correction, (ii) image intensity outlier detection to minimize the influence of physiological noise, (iii) a non-linear DTI estimation procedure incorporating non-negative eigenvalue priors, and (iv) tract-specific region-of-interest (ROI) identification based on an objective geometry reference. Using these strategies in combination, Radial Diffusivity (λ(⊥)) was reproducibly measured in white matter (WM) tracts (adjusted mean [95% confidence interval]=0.25 [0.22, 0.29] μm(2)/ms), lower than previously reported λ(⊥) values in the in vivo human spinal cord DTI literature. Radial Diffusivity and fractional anisotropy (FA) measured in WM varied from rostral to caudal as did mean translational motion, likely reflecting respiratory motion effect. Given the considerable sensitivity of DTI measurements to motion artifact, we believe outlier detection is indispensable in spinal cord diffusion imaging. We also recommend using a mixed-effects model to account for systematic measurement bias depending on cord segment.
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increased Radial Diffusivity in spinal cord lesions in neuromyelitis optica compared with multiple sclerosis
Multiple Sclerosis Journal, 2012Co-Authors: Eric C Klawiter, Robert T Naismith, Tammie L S Benzinger, Joshua S Shimony, Kathryn Trinkaus, Shengkwei Song, Samantha Lancia, Abraham Z Snyder, Anne H CrossAbstract:Background:Multiple sclerosis (MS) and neuromyelitis optica (NMO) both affect spinal cord with notable differences in pathology.Objective:Determine the utility of diffusion tensor imaging (DTI) to differentiate the spinal cord lesions of NMO from MS within and outside T2 lesions.Methods:Subjects greater than or equal to 12 months from a clinical episode of transverse myelitis underwent a novel transaxial cervical spinal cord DTI sequence. Ten subjects with NMO, 10 with MS and 10 healthy controls were included.Results:Within T2 affected white matter regions, Radial Diffusivity was increased in both NMO and MS compared with healthy controls (p<0.001, respectively), and to a greater extent in NMO than MS (p<0.001). Axial Diffusivity was decreased in T2 lesions in both NMO and MS compared with controls (p<0.001, p=0.001), but did not differ between the two diseases. Radial Diffusivity and fractional anisotropy within white matter regions upstream and downstream of T2 lesions were different from controls in ea...
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Radial Diffusivity predicts demyelination in ex vivo multiple sclerosis spinal cords
NeuroImage, 2011Co-Authors: Eric C Klawiter, Robert T Naismith, Kathryn Trinkaus, Anne H Cross, Shengkwei Song, Hsiaofang Liang, Matthew D Budde, Robert E Schmidt, Tammie L S BenzingerAbstract:Objective Correlation of diffusion tensor imaging (DTI) with histochemical staining for demyelination and axonal damage in multiple sclerosis (MS) ex vivo human cervical spinal cords.
Robert T Naismith - One of the best experts on this subject based on the ideXlab platform.
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improved in vivo diffusion tensor imaging of human cervical spinal cord
NeuroImage, 2013Co-Authors: Joshua S Shimony, Robert T Naismith, Tammie L S Benzinger, Kathryn Trinkaus, Anne H Cross, Eric C Klawiter, Abraham Z Snyder, Shengkwei SongAbstract:We describe a cardiac gated high in-plane resolution axial human cervical spinal cord diffusion tensor imaging (DTI) protocol. Multiple steps were taken to optimize both image acquisition and image processing. The former includes slice-by-slice cardiac triggering and individually tiltable slices. The latter includes (i) iterative 2D retrospective motion correction, (ii) image intensity outlier detection to minimize the influence of physiological noise, (iii) a non-linear DTI estimation procedure incorporating non-negative eigenvalue priors, and (iv) tract-specific region-of-interest (ROI) identification based on an objective geometry reference. Using these strategies in combination, Radial Diffusivity (λ(⊥)) was reproducibly measured in white matter (WM) tracts (adjusted mean [95% confidence interval]=0.25 [0.22, 0.29] μm(2)/ms), lower than previously reported λ(⊥) values in the in vivo human spinal cord DTI literature. Radial Diffusivity and fractional anisotropy (FA) measured in WM varied from rostral to caudal as did mean translational motion, likely reflecting respiratory motion effect. Given the considerable sensitivity of DTI measurements to motion artifact, we believe outlier detection is indispensable in spinal cord diffusion imaging. We also recommend using a mixed-effects model to account for systematic measurement bias depending on cord segment.
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increased Radial Diffusivity in spinal cord lesions in neuromyelitis optica compared with multiple sclerosis
Multiple Sclerosis Journal, 2012Co-Authors: Eric C Klawiter, Robert T Naismith, Tammie L S Benzinger, Joshua S Shimony, Kathryn Trinkaus, Shengkwei Song, Samantha Lancia, Abraham Z Snyder, Anne H CrossAbstract:Background:Multiple sclerosis (MS) and neuromyelitis optica (NMO) both affect spinal cord with notable differences in pathology.Objective:Determine the utility of diffusion tensor imaging (DTI) to differentiate the spinal cord lesions of NMO from MS within and outside T2 lesions.Methods:Subjects greater than or equal to 12 months from a clinical episode of transverse myelitis underwent a novel transaxial cervical spinal cord DTI sequence. Ten subjects with NMO, 10 with MS and 10 healthy controls were included.Results:Within T2 affected white matter regions, Radial Diffusivity was increased in both NMO and MS compared with healthy controls (p<0.001, respectively), and to a greater extent in NMO than MS (p<0.001). Axial Diffusivity was decreased in T2 lesions in both NMO and MS compared with controls (p<0.001, p=0.001), but did not differ between the two diseases. Radial Diffusivity and fractional anisotropy within white matter regions upstream and downstream of T2 lesions were different from controls in ea...
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Radial Diffusivity predicts demyelination in ex vivo multiple sclerosis spinal cords
NeuroImage, 2011Co-Authors: Eric C Klawiter, Robert T Naismith, Kathryn Trinkaus, Anne H Cross, Shengkwei Song, Hsiaofang Liang, Matthew D Budde, Robert E Schmidt, Tammie L S BenzingerAbstract:Objective Correlation of diffusion tensor imaging (DTI) with histochemical staining for demyelination and axonal damage in multiple sclerosis (MS) ex vivo human cervical spinal cords.
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Radial Diffusivity in remote optic neuritis discriminates visual outcomes
Neurology, 2010Co-Authors: Robert T Naismith, Junqian Xu, Nhial T Tutlam, Kathryn Trinkaus, Anne H Cross, Shengkwei SongAbstract:Objective: Diffusion tensor imaging (DTI) quantifies Brownian motion of water within tissue. The goal of this study was to test whether, following a remote episode of optic neuritis (ON), breakdown of myelin and axons within the optic nerve could be detected by alterations in DTI parameters, and whether these alterations would correlate with visual loss. Methods: Seventy subjects with a history of ON ≥6 months prior underwent DTI of the optic nerves, assessment of visual acuities (VA) and contrast sensitivities (CS), and laboratory measures of visual evoked potentials (VEP) and optical coherence tomography (OCT). Results: Radial Diffusivity (RD) correlated with visual acuity (r = −0.61), Pelli-Robson CS (r = −0.60), 5%CS (r = 0.61), OCT (r = −0.78), VEP latency (r = 0.61), and VEP amplitude (r = −0.46). RD differentiated the unaffected fellow nerves from affected nerves in all visual outcome categories. RD also discriminated nerves with recovery to normal from mild visual impairment, and those with mild impairment from profound visual loss. RD differentiated healthy controls from both clinically affected nerves and unaffected fellow nerves after ON. RD differentiated all categories of 5%CS outcomes, and all categories of Pelli-Robson CS with the exception of normal recovery from mildly affected. Conclusions: Increased optic nerve Radial Diffusivity (RD) detected by diffusion tensor imaging (DTI) was associated with a proportional decline in vision after optic neuritis. RD can differentiate healthy control nerves from both affected and unaffected fellow nerves. RD can discriminate among categories of visual recovery within affected eyes. Optic nerve injury as assessed by DTI was corroborated by both optical coherence tomography and visual evoked potentials.
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disability in optic neuritis correlates with diffusion tensor derived directional diffusivities
Neurology, 2009Co-Authors: Robert T Naismith, Junqian Xu, Nhial T Tutlam, A Z Snyder, Tammie L S Benzinger, Joshua S Shimony, J Shepherd, Kathryn Trinkaus, Anne H Cross, Shengkwei SongAbstract:Objective: To determine the potential of directional diffusivities from diffusion tensor imaging (DTI) to predict clinical outcome of optic neuritis (ON), and correlate with vision, optical coherence tomography (OCT), and visual evoked potentials (VEP). Methods: Twelve cases of acute and isolated ON were imaged within 30 days of onset and followed prospectively. Twenty-eight subjects with a remote clinical history of ON were studied cross-sectionally. Twelve healthy controls were imaged for comparison. DTI data were acquired at 3T with a surface coil and 1.3 × 1.3 × 1.3 mm 3 isotropic voxels. Results: Normal DTI parameters (mean ± SD, μm 2 /ms) were axial Diffusivity = 1.66 ± 0.18, Radial Diffusivity = 0.81 ± 0.26, apparent diffusion coefficient (ADC) = 1.09 ± 0.21, and fractional anisotropy (FA) = 0.43 ± 0.15. Axial Diffusivity decreased up to 2.5 SD in acute ON. The decrease in axial Diffusivity at onset correlated with visual contrast sensitivity 1 month ( r = 0.59) and 3 months later ( r = 0.65). In three subjects followed from the acute through the remote stage, Radial Diffusivity subsequently increased to >2.5 SD above normal, as did axial Diffusivity and ADC. In remote ON, Radial Diffusivity correlated with OCT ( r = 0.81), contrast sensitivity ( r = 0.68), visual acuity ( r = 0.56), and VEP ( r = 0.54). Conclusion: In acute and isolated demyelination, axial Diffusivity merits further investigation as a predictor of future clinical outcome. Diffusion parameters are dynamic in acute and isolated optic neuritis, with an initial acute decrease in axial Diffusivity. In remote disease, Radial Diffusivity correlates with functional, structural, and physiologic tests of vision.
