Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue Microstructure
In this article, we consider how differing approaches that characterize biological microstructure with diffusion weighted magnetic resonance imaging intersect. Without geometrical boundary assumptions, there are techniques that make use of power law behavior which can be derived from a generalized d...
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| Format: | Article |
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MDPI AG
2021-08-01
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| Series: | Mathematics |
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| Online Access: | https://www.mdpi.com/2227-7390/9/16/1871 |
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| author | Matt G. Hall Carson Ingo |
| author_facet | Matt G. Hall Carson Ingo |
| author_sort | Matt G. Hall |
| collection | DOAJ |
| description | In this article, we consider how differing approaches that characterize biological microstructure with diffusion weighted magnetic resonance imaging intersect. Without geometrical boundary assumptions, there are techniques that make use of power law behavior which can be derived from a generalized diffusion equation or intuited heuristically as a time dependent diffusion process. Alternatively, by treating biological microstructure (e.g., myelinated axons) as an amalgam of stick-like geometrical entities, there are approaches that can be derived utilizing convolution-based methods, such as the spherical means technique. Since data acquisition requires that multiple diffusion weighting sensitization conditions or <i>b</i>-values are sampled, this suggests that implicit mutual information may be contained within each technique. The information intersection becomes most apparent when the power law exponent approaches a value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfrac><mn>1</mn><mn>2</mn></mfrac></semantics></math></inline-formula>, whereby the functional form of the power law converges with the explicit stick-like geometric structure by way of confluent hypergeometric functions. While a value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfrac><mn>1</mn><mn>2</mn></mfrac></semantics></math></inline-formula> is useful for the case of solely impermeable fibers, values that diverge from <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfrac><mn>1</mn><mn>2</mn></mfrac></semantics></math></inline-formula> may also reveal deep connections between approaches, and potentially provide insight into the presence of compartmentation, exchange, and permeability within heterogeneous biological microstructures. All together, these disparate approaches provide a unique opportunity to more completely characterize the biological origins of observed changes to the diffusion attenuated signal. |
| first_indexed | 2024-03-10T08:38:09Z |
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| issn | 2227-7390 |
| language | English |
| last_indexed | 2024-03-10T08:38:09Z |
| publishDate | 2021-08-01 |
| publisher | MDPI AG |
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| series | Mathematics |
| spelling | doaj.art-79e062cc8ecf4fd48249d75ef088f0ef2023-11-22T08:33:10ZengMDPI AGMathematics2227-73902021-08-01916187110.3390/math9161871Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue MicrostructureMatt G. Hall0Carson Ingo1National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UKDepartment of Neurology, Northwestern University, Chicago, IL 60611, USAIn this article, we consider how differing approaches that characterize biological microstructure with diffusion weighted magnetic resonance imaging intersect. Without geometrical boundary assumptions, there are techniques that make use of power law behavior which can be derived from a generalized diffusion equation or intuited heuristically as a time dependent diffusion process. Alternatively, by treating biological microstructure (e.g., myelinated axons) as an amalgam of stick-like geometrical entities, there are approaches that can be derived utilizing convolution-based methods, such as the spherical means technique. Since data acquisition requires that multiple diffusion weighting sensitization conditions or <i>b</i>-values are sampled, this suggests that implicit mutual information may be contained within each technique. The information intersection becomes most apparent when the power law exponent approaches a value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfrac><mn>1</mn><mn>2</mn></mfrac></semantics></math></inline-formula>, whereby the functional form of the power law converges with the explicit stick-like geometric structure by way of confluent hypergeometric functions. While a value of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfrac><mn>1</mn><mn>2</mn></mfrac></semantics></math></inline-formula> is useful for the case of solely impermeable fibers, values that diverge from <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mfrac><mn>1</mn><mn>2</mn></mfrac></semantics></math></inline-formula> may also reveal deep connections between approaches, and potentially provide insight into the presence of compartmentation, exchange, and permeability within heterogeneous biological microstructures. All together, these disparate approaches provide a unique opportunity to more completely characterize the biological origins of observed changes to the diffusion attenuated signal.https://www.mdpi.com/2227-7390/9/16/1871diffusion MRIfractional calculuspower lawspherical deconvolutionspherical meansbiological microstructure |
| spellingShingle | Matt G. Hall Carson Ingo Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue Microstructure Mathematics diffusion MRI fractional calculus power law spherical deconvolution spherical means biological microstructure |
| title | Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue Microstructure |
| title_full | Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue Microstructure |
| title_fullStr | Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue Microstructure |
| title_full_unstemmed | Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue Microstructure |
| title_short | Half Way There: Theoretical Considerations for Power Laws and Sticks in Diffusion MRI for Tissue Microstructure |
| title_sort | half way there theoretical considerations for power laws and sticks in diffusion mri for tissue microstructure |
| topic | diffusion MRI fractional calculus power law spherical deconvolution spherical means biological microstructure |
| url | https://www.mdpi.com/2227-7390/9/16/1871 |
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