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Diffusion tensor MR microscopy of tissues with low diffusional anisotropy Cover

Diffusion tensor MR microscopy of tissues with low diffusional anisotropy

Radiology and Oncology
Volume 50 (2016): Issue 2 (June 2016)
By: Franci Bajd,  Carlos Mattea,  Siegfried Stapf and  Igor Sersa  
Open Access
|Apr 2016
Figures & tables

Figures & Tables

A simulation flowchart for analysis of selected commonly used and random/isotropic diffusion sensitizing gradients (DSG) configurations.
Simulated two dimensional maps of D̅2 (DA signal - to - [SNR]), D̅3 (DA, SNR) - D̅1 (DA, SNR), and fractional anisotropy (FA)(DA, SNR) for four representative, commonly used diffusion sensitizing gradients (DSG) configurations from Table 1 (#1, #8, #13 and #16).
Panels on the left show simulated average values of diffusion tensor eigenvalues D1,D2 and D3 (A), of average diffusion constant ADC(C) and of fractional anisotropy FA(E) as a function of condition number 1<CN<104 for random diffusion sensitizing gradients (DSG) configurations. Panels on the right (B,D,F) display the zoomed left-side panels for condition numbers in the range 1<CN<10. Solid-line curves (E,F) correspond to best fits of the model function [Eq. 12] to the simulated data. The graphical insert in panel (A) illustrates the selected random DSG configuration with NDSG = 220.
Characteristic values of the simulated correlations between FA and condition number(CN)for random diffusion sensitizing gradients (DSG) configurations as a function of NDSG: maximal, average and minimal values of FA (A), best fit parameters αFA, κFA and fit quality R2(B). The arrow designates a crossover, at which apparent fractional anisotropy drops below fractional anisotropy FA ~0.01. The graphical insert in panel A illustrates the selected random DSG configuration with NDSG = 220.
Simulated average fractional anisotropy FA (solid symbols) and the corresponding condition number CN(void symbols) as a function of NDSG for random (blue symbols) and isotropic (red symbols) diffusion sensitizing gradients (DSG) configurations. The graphical insert illustrates a distribution of DSG directions in a random and an isotropic DSG configuration with NDSG = 200.
The results of numerical simulations with three different fractional anisotropy (FA) values: 0, 0.1, and 0.3 for isotropic (FA = 0) vs. anisotropic (FA = 0.1, 0.3) case.
Experimental 1D DT-MRM results of the cone-shaped water phantom: 2D MR image of the phantom with the corresponding signal-to-noise ratio (SNR) 1D profile along the phantom axis (top left) and stack plots of the diffusion tensor quantities (D1, D2, D3, average diffusion coefficient [ADC] and FA) as 1D profiles as a function of NDSG. Isotropic diffusion sensitizing gradients (DSG) configurations were used. The white dotted curve depicts the region with noticeably reduced fractional anisotropy.
Experimental DT-MRM results of articular cartilage-on-bone samples in a form of 2D maps of D1, D2, D3, average diffusion coefficient (ADC) and fractional anisotropy (FA). The maps were obtained with a spatial resolution of either 78 μm (A) or 156 μm (B). Solid white boxes indicate three different ROI regions for signal-to-noise ratio (SNR) determination, while dashed white lines encircle droplets of liquid expelled from the cartilage tissue. White arrows denote the compression zone.

A list of the analyzed commonly used diffusion sensitizing gradients (DSG) configurations in DTI, adopted from12, along with the corresponding values of NDSG, condition number(CN) and P_

#Scheme nameNDSG[1]CN[1]P[%]
1Tetrahedral69.14816.53
2Cond 665.98414.19
3Decahedral102.74810.70
4Jones noniso72.56012.13
5Dual-gradient62.00011.44
6Jones 10101.6249.67
7Jones 20201.6158.10
8Jones 30301.5947.16
9Papadakis121.5879.29
10Jones 661.58311.04
11Muthupallai61.58111.11
12Tetraortho71.52710.68
13DSM 661.32311.41
14DSM 10101.32410.02
15DSM 20201.6688.43
16DSM 30301.4307.45
17DSM 40401.4016.87

Average values of average diffusion coefficient (ADC) and fractional anisotropy (FA) in three different regions of an uncompressed and compressed cartilage sample obtained with two different spatial resolutions

 Higher resolution (78 μm)Lower resolution (156 μm)
 ADC [10−9 m2/s]FA[1]ADC [10−9 m2/s]FA[1]
Uncompressed cartilage0.99±0.130.27±0.131.12±0.140.14±0.08
Compression zone0.63±0.420.87±0.271.01±0.820.82±0.23
Liquid droplet1.35±0.110.24±0.061.34±0.190.11±0.04
DOI: https://doi.org/10.1515/raon-2016-0018 | Journal eISSN: 1581-3207 | Journal ISSN: 1318-2099
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Language: English
Page range: 175 - 187
Submitted on: Aug 27, 2015
Accepted on: Feb 8, 2016
Published on: Apr 3, 2016
Published by: Association of Radiology and Oncology
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
microscopy,
diffusion tensor imaging,
anisotropy,
signal-to-noise ratio,
cartilage
Related subjects:
Medicine,
Clinical medicine,
Internal medicine,
Haematology, oncology,
Radiology

© 2016 Franci Bajd, Carlos Mattea, Siegfried Stapf, Igor Sersa, published by Association of Radiology and Oncology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 50 (2016): Issue 2 (June 2016)
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