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Herrera SL, Sheft M, Mercredi ME, Buist R, Matsuda KM, Martin M. Axon diameter inferences in the human corpus callosum using oscillating gradient spin echo sequences. Magn Reson Imaging 2021; 85:64-70. [PMID: 34662703 DOI: 10.1016/j.mri.2021.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/30/2021] [Accepted: 10/12/2021] [Indexed: 10/20/2022]
Abstract
Previous methods used to infer axon diameter distributions using magnetic resonance imaging (MRI) primarily use single diffusion encoding sequences such as pulsed gradient spin echo (PGSE) and are thus sensitive to axons of diameters >5 μm. We applied oscillating gradient spin echo (OGSE) sequences to study human axons in the 1-2 μm range in the corpus callosum, which include the majority of axons constituting cortical connections. The ActiveAx model was applied to calculate the fitted mean effective diameter for axons (AxD) and was compared with values found using histology. Axon diameters from histological data were calculated using three different datasets; true diameters (minimum diameter), a combination of minimum and maximum diameters, and diameters measured across a consistent diffusion direction. The AxD estimates from MRI were 1.8 ± 0.1 μm to 2.34 ± 0.04 μm with an average of 2.0 ± 0.2 μm for the ActiveAx model. The histology AxD values were 1.43 ± 0.02 μm when using the true minimum axon diameters, 5.52 ± 0.02 μm when using the combination of minimum and maximum axon diameters, and 2.20 ± 0.02 μm when collecting measurements across a consistent diffusion direction. This experiment demonstrates the first known usage of OGSE to calculate axon diameters in the human corpus callosum on a 1-2 μm scale. The importance for the model to account for axonal orientation dispersion is indicated by histological results which more closely match the MRI model results depending on the direction of axon diameter measurements. These initial steps using this non-invasive imaging method can be applied to future methodology to develop in vivo axon diameter measurements in human brain tissue.
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Affiliation(s)
| | - Maxina Sheft
- Physics, University of Winnipeg, Canada; Biomedical Engineering, Georgia Institute of Technology, United States of America.
| | | | | | - Kant M Matsuda
- Pathology, Robert Wood Johnson (RWJ) Medical School, Rutgers University, United States of America
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Herrera SL, Mercredi ME, Buist R, Martin M. Inferring diameters of spheres and cylinders using interstitial water. MAGMA 2018; 31:609-620. [PMID: 29869134 DOI: 10.1007/s10334-018-0685-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 04/06/2018] [Accepted: 04/19/2018] [Indexed: 11/25/2022]
Abstract
OBJECT Most early methods to infer axon diameter distributions using magnetic resonance imaging (MRI) used single diffusion encoding sequences such as pulsed gradient spin echo (SE) and are thus sensitive to axons of diameters > 5 μm. We previously simulated oscillating gradient (OG) SE sequences for diffusion spectroscopy to study smaller axons including the majority constituting cortical connections. That study suggested the model of constant extra-axonal diffusion breaks down at OG accessible frequencies. In this study we present data from phantoms to test a time-varying interstitial apparent diffusion coefficient. MATERIALS AND METHODS Diffusion spectra were measured in four samples from water packed around beads of diameters 3, 6 and 10 μm; and 151 μm diameter tubes. Surface-to-volume ratios, and diameters were inferred. RESULTS The bead pore radii estimates were 0.60±0.08 μm, 0.54±0.06 μm and 1.0±0.1 μm corresponding to bead diameters ranging from 2.9±0.4 μm to 5.3±0.7 μm, 2.6±0.3 μm to 4.8±0.6 μm, and 4.9±0.7 μm to 9±1 μm. The tube surface-to-volume ratio estimate was 0.06±0.02 μm-1 corresponding to a tube diameter of 180±70 μm. CONCLUSION Interstitial models with OG inferred 3-10 μm bead diameters from 0.54±0.06 μm to 1.0±0.1 μm pore radii and 151 μm tube diameters from 0.06±0.02 μm-1 surface-to-volume ratios.
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Affiliation(s)
- Sheryl L Herrera
- Physics and Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
| | - Morgan E Mercredi
- Physics and Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Richard Buist
- Radiology, University of Manitoba, Winnipeg, MB, R3E 0T6, Canada
| | - Melanie Martin
- Physics and Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
- Physics, University of Winnipeg, Winnipeg, MB, R3B 2E9, Canada
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Herrera SL, Palmer VL, Whittaker H, Smith BC, Kim A, Schellenberg AE, Thiessen JD, Buist R, Del Bigio MR, Martin M. Damage to the optic chiasm in myelin oligodendrocyte glycoprotein-experimental autoimmune encephalomyelitis mice. Magn Reson Insights 2014; 7:23-31. [PMID: 25520558 PMCID: PMC4226389 DOI: 10.4137/mri.s19750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 09/30/2014] [Accepted: 10/02/2014] [Indexed: 12/19/2022]
Abstract
Optic chiasm lesions in myelin oligodendrocyte glycoprotein (MOG)–experimental autoimmune encephalomyelitis (EAE) mice were characterized using magnetic resonance imaging (MRI) and validated using electron microscopy (EM). MR images were collected from 3 days after induction to remission, approximately 20 days after induction. Hematoxylin and eosin, solochrome cyanin–stained sections, and EM images were obtained from the optic chiasms of some mice approximately 4 days after disease onset when their scores were thought to be the highest. T2-weighted imaging and apparent diffusion coefficient map hyperintensities corresponded to abnormalities in the optic chiasms of EAE mice. Mixed inflammation was concentrated at the lateral surface. Degeneration of oligodendrocytes, myelin, and early axonal damage were also apparent. A marked increase in chiasm thickness was observed. T2-weighted and diffusion-weighted MRI can detect abnormalities in the optic chiasms of MOG-EAE mice. MRI is an important method in the study of this model toward understanding optic neuritis.
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Affiliation(s)
- Sheryl L Herrera
- Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Vanessa L Palmer
- Biomedical Engineering Program, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Heather Whittaker
- Biopsychology Program, University of Winnipeg, Winnipeg, Manitoba, Canada
| | | | - Annie Kim
- Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Angela E Schellenberg
- Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada. ; General Surgery, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jonathan D Thiessen
- Imaging Program, Lawson Health Research Institute, London, Ontario, Canada. ; Medical Biophysics, Western University, London, Ontario, Canada
| | - Richard Buist
- Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | - Melanie Martin
- Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada. ; Biomedical Engineering Program, University of Manitoba, Winnipeg, Manitoba, Canada. ; Physics, University of Winnipeg, Winnipeg, Manitoba, Canada. ; Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada. ; Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
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Kastyak-Ibrahim MZ, Di Curzio DL, Buist R, Herrera SL, Albensi BC, Del Bigio MR, Martin M. Neurofibrillary tangles and plaques are not accompanied by white matter pathology in aged triple transgenic-Alzheimer disease mice. Magn Reson Imaging 2013; 31:1515-21. [PMID: 23993791 DOI: 10.1016/j.mri.2013.06.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 06/12/2013] [Accepted: 06/26/2013] [Indexed: 01/27/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is the most common cause of dementia in aging populations. Although senile plaques and neurofibrillary tangles are well-established hallmarks of AD, changes in cerebral white matter correlate with cognitive decline and may increase the risk of the development of dementia. We used the triple transgenic (3xTg)-AD mouse model of AD, previously used to show that white matter changes precede plaque formation, to test the hypothesis that MRI detectable changes occur in the corpus callosum, external capsule and the fornix. T2-weighted and diffusion tensor magnetic resonance imaging and histological stains were employed to assess white matter in older (11-17months) 3xTg-AD mice and controls. We found no statistically significant changes in white matter between 3xTg-AD mice and controls, despite well-developed neurofibrillary tangles and beta amyloid immunoreactive plaques. Myelin staining was normal in affected mice. These data suggest that the 3xTg-AD mouse model does not develop MRI detectable white matter changes at the ages we examined.
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Affiliation(s)
- Marzena Z Kastyak-Ibrahim
- Department of Physics, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, R3B 2E9, Canada.
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Thiessen JD, Vincent TJ, Herrera SL, Martin M. Diffusion Tensor Metric Measurements as a Function of Diffusion Time in the Rat Central Nervous System. Magn Reson�Insights 2012. [DOI: 10.4137/mri.s10692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
MRI and Monte Carlo simulated data of pulsed gradient spin echo experiments were used to study the effects of diffusion time, gradient strength and b-value on diffusion tensor (DT) metrics using real and simulated fixed rat spines. Radial (λ⊥) in grey matter and simulation data, axial (λ||) in both grey and white matter in fixed rat spinal cords and mean diffusivity in all tissues showed a significant decrease with diffusion time at b = 1 μm2/ms. All diffusivities significantly decreased with b-value at g = 116 mT/m and at Δeff = 23 ms. The fractional anisotropy (FA) significantly increased with diffusion time at b = 1 μm2/ms in the simulation data and grey matter. FA significantly increased in white matter and simulation data and significantly decreased in grey matter with b-value at g = 116 mT/m and at Δeff = 23 ms. These data suggest that DTI metrics are highly dependent on pulse sequence parameters.
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Affiliation(s)
- Jonathan D. Thiessen
- Department of Physics and Astronomy, University of Manitoba
- Department of Radiology, University of Manitoba
| | | | | | - Melanie Martin
- Department of Physics and Astronomy, University of Manitoba
- Department of Physics, University of Winnipeg
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