Twice‐refocused stimulated echo diffusion imaging: Measuring diffusion time dependence at constant T 1 weighting

2019 ◽  
Vol 83 (5) ◽  
pp. 1741-1749
Author(s):  
Jan Martin ◽  
Sebastian Endt ◽  
Andreas Wetscherek ◽  
Tristan Anselm Kuder ◽  
Arnd Doerfler ◽  
...  
Keyword(s):  
Time Dependence ◽  
Diffusion Imaging ◽  
Diffusion Time ◽  
Stimulated Echo

scholarly journals Relevance of time‐dependence for clinically viable diffusion imaging of the spinal cord

2018 ◽  
Vol 81 (2) ◽  
pp. 1247-1264 ◽  
Author(s):  
Francesco Grussu ◽  
Andrada Ianuş ◽  
Carmen Tur ◽  
Ferran Prados ◽  
Torben Schneider ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Time Dependence ◽  
Diffusion Imaging

scholarly journals Investigation of field and diffusion time dependence of the diffusion-weighted signal at ultrahigh magnetic fields

2013 ◽  
Vol 26 (10) ◽  
pp. 1251-1257 ◽  
Author(s):  
Nicolas Kunz ◽  
Stéphane V. Sizonenko ◽  
Petra S. Hüppi ◽  
Rolf Gruetter ◽  
Yohan van de Looij
Keyword(s):  
Magnetic Fields ◽  
Time Dependence ◽  
Diffusion Time ◽  
Diffusion Weighted ◽  
Ultrahigh Magnetic Fields ◽  
And Diffusion

scholarly journals Electron microscopy 3-dimensional segmentation and quantification of axonal dispersion and diameter distribution in mouse brain corpus callosum

2018 ◽  
Author(s):  
Hong-Hsi Lee ◽  
Katarina Yaros ◽  
Jelle Veraart ◽  
Jasmine Pathan ◽  
Feng-Xia Liang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Corpus Callosum ◽  
Time Dependence ◽  
Mouse Brain ◽  
Fiber Orientation ◽  
Diffusion Mri ◽  
Orientation Distribution ◽  
Diffusion Time ◽  
3 Dimensional ◽  
Axonal Diameter

AbstractTo model the diffusion MRI signal in brain white matter, general assumptions have been made about the microstructural properties of axonal fiber bundles, such as the axonal shape and the fiber orientation dispersion. In particular, axons are modeled by perfectly circular cylinders with no diameter variation within each axon, and their directions obey a specific orientation distribution. However, these assumptions have not been validated by histology in 3-dimensional high-resolution neural tissue. Here, we reconstructed sequential scanning electron microscopy images in mouse brain corpus callosum, and introduced a semi-automatic random-walker (RaW) based algorithm to rapidly segment individual intra-axonal spaces and myelin sheaths of myelinated axons. Confirmed with a conventional machine-learning-based interactive segmentation method, our semi-automatic algorithm is reliable and less time-consuming. Based on the segmentation, we calculated histological estimates of size-related (e.g., inner axonal diameter, g-ratio) and orientation-related (e.g., Fiber orientation distribution and its rotational invariants, dispersion angle) quantities, and simulated how these quantities would be observed in actual diffusion MRI experiments by considering diffusion time-dependence. The reported dispersion angle is consistent with previous 2-dimensional histology studies and diffusion MRI measurements, though the reported diameter is larger than those in other mouse brain studies. Our results show that the orientation-related metrics have negligible diffusion time-dependence; however, inner axonal diameters demonstrate a non-trivial time-dependence at diffusion times typical for clinical and preclinical use. In other words, the fiber dispersion estimated by diffusion MRI modeling is relatively independent, while the "apparent" axonal size estimated by axonal diameter mapping potentially depends on experimental MRI settings.

scholarly journals Diffusion‐time dependence of diffusional kurtosis in the mouse brain

2020 ◽  
Vol 84 (3) ◽  
pp. 1564-1578 ◽  
Author(s):  
Manisha Aggarwal ◽  
Matthew D. Smith ◽  
Peter A. Calabresi
Keyword(s):  
Time Dependence ◽  
Mouse Brain ◽  
Diffusion Time
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