The Project The Project Molecular Molecular Diffusion in MRI Diffusion in MRI Technical application of Technical application of tracking fiber tracking fiber (Tractografía) (Tractografía) investigator: Martha Liliana Mora V. investigator: Martha Liliana Mora V. e:mail:martha.mora@ur jc.es
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The Project Molecular The Project Molecular Diffusion in MRIDiffusion in MRI
Technical application of tracking Technical application of tracking fiber (Tractografía)fiber (Tractografía)
investigator: Martha Liliana Mora V.investigator: Martha Liliana Mora V.
5. Implementation of Methods. (proof in the software)5. Implementation of Methods. (proof in the software)
6 .The Objective of this visit Brigham and women´s 6 .The Objective of this visit Brigham and women´s hospital – Harvard Medical School.hospital – Harvard Medical School.
6.16.1 Collaboration with the group of BWH's work in publications.Collaboration with the group of BWH's work in publications.
6.2 Training in the acquisition, processing, analysis, and application of 6.2 Training in the acquisition, processing, analysis, and application of Diffusion Tensor Imaging.Diffusion Tensor Imaging.
6.3 6.3 Future works with the group of BWH. – HMS.Future works with the group of BWH. – HMS.
Molecular Diffusion in MRIMolecular Diffusion in MRI
Stejskal, E. O., and Tanner, J.E. Spin-diffusion measurements: spin echoes Stejskal, E. O., and Tanner, J.E. Spin-diffusion measurements: spin echoes in the presence of a time-dependent field gradientin the presence of a time-dependent field gradient. J. Chem. Phys. 42, 288-92. . J. Chem. Phys. 42, 288-92. (1965).(1965).
Difusión en imagen de resonancia magnética.Difusión en imagen de resonancia magnética. It was introduced for LeBihan en It was introduced for LeBihan en 1985. Art. – Le Bihan D, Breton E. Imagerie de diffusion in vivo par résonance 1985. Art. – Le Bihan D, Breton E. Imagerie de diffusion in vivo par résonance magnétique nucléaire. CR Acad Sci Paris 1985;301:1109-1112.magnétique nucléaire. CR Acad Sci Paris 1985;301:1109-1112.
Difusion Tensor by Basser et al (Mattiello J. Le Bihan) Diffusion tensor echo-Difusion Tensor by Basser et al (Mattiello J. Le Bihan) Diffusion tensor echo-planar imaging of human brain. In proceedings of the SMRMplanar imaging of human brain. In proceedings of the SMRM, Estimation of the , Estimation of the effective self-diffusion tensor from the NMR spin echo. J. Magn. Reson 1994;effective self-diffusion tensor from the NMR spin echo. J. Magn. Reson 1994;
Diffusion Tensor Imaging: Concepts and Applications;Diffusion Tensor Imaging: Concepts and Applications; (Denis Le Bihan, Jean (Denis Le Bihan, Jean Francois Mangin, Cyril Poupon, Chris A. Clark. Journal of Magnetic Resonance Francois Mangin, Cyril Poupon, Chris A. Clark. Journal of Magnetic Resonance Imaging (2001).Imaging (2001).
Molecular Diffusion in MRIMolecular Diffusion in MRI
1.1. State of the art.State of the art. Diffusion Tensor Imaging – Image Acquisition and Processing Tools.Diffusion Tensor Imaging – Image Acquisition and Processing Tools. Surgical Surgical
Planning Laboratory, Technical Report # 354. Martha E. Shenton, Ph.D., Marek Planning Laboratory, Technical Report # 354. Martha E. Shenton, Ph.D., Marek Kubicki, M.D., Ph.D., Robert W. McCarley, M.D. Kubicki, M.D., Ph.D., Robert W. McCarley, M.D.
An Analysis Tools for Quantification of Diffusion Tensor MRI DataAn Analysis Tools for Quantification of Diffusion Tensor MRI Data. Hae-Jeong . Hae-Jeong Park, Martha E. Shenton, Carl-Fredrik Westin. Division of Nuclear Medicine, Dept. Park, Martha E. Shenton, Carl-Fredrik Westin. Division of Nuclear Medicine, Dept. of Diagnostic Radiology, Yonsei University, Colege of Medicine, Shinchon-dong, of Diagnostic Radiology, Yonsei University, Colege of Medicine, Shinchon-dong, Seodaemun-gu, Seoul 120-749, Korea. Laboratory of Mathematics in Imaging, Seodaemun-gu, Seoul 120-749, Korea. Laboratory of Mathematics in Imaging, Dept. of Radiology, Brigham and Women’s Hospital Harvard Medical School Dept. of Radiology, Brigham and Women’s Hospital Harvard Medical School Boston – USA.Boston – USA.
DTI and MTR abnormalities in schizophrenia: Analysis of white matter DTI and MTR abnormalities in schizophrenia: Analysis of white matter integrity.integrity.
M. Kubicki et al. Neuroimagen 25 (2005) 1109-1118. M. Kubicki et al. Neuroimagen 25 (2005) 1109-1118.
1.1. State of the art.State of the art. P. Perona and J. Malik. Scale-space and edge detection using
anisotropic diffusion. IEEE Transactions on Pattern Analysis and Machine Intelligence, 12(7):629-639,July 1990.
J. Weickert. Theoretical foundations of anisotropic diffusion in image processing. Computing Supplement, 11:221-236, 1996.
J. Weickert. A review of nonlinear diffusion ltering. Scale-Space Theory in Computer Vision, Lecture Notes in Comp. Science (Springer, Berlin), 1252:3-28,1997. Invited Paper.
L. Alvarez, P.L. Lions, and J.M. Morel. Image selective smoothing and edge detection by nonlinear diffusion (II). SIAM Journal of Numerical Analysis, 29:845-866,1992.
Molecular Diffusion in MRIMolecular Diffusion in MRI
4.1 Algorithm RF Inhomogeneity Correction Algorithm in MRI.4.1 Algorithm RF Inhomogeneity Correction Algorithm in MRI. Publication: Juan A. Hernandez, Martha L. Mora, Emanuele Schiavi, and
Pablo Toharia. ISBMDA 2004, LNCS 3337, pp. 1–8, 2004. Publisher: Springer-Verlag Berlin Heidelberg 2004
Molecular Diffusion in MRIMolecular Diffusion in MRIMethods.Methods.4.2 Algorithm Image Registration Classification.4.2 Algorithm Image Registration Classification.
Registration criteria.Registration criteria.- Quantitative measure of a “good match”.Quantitative measure of a “good match”.- Focus on intensity based measures.
Spatial transform type- Allowable mapping from one image to another.
Optimization algorithm used- Optimize transform parameters w.r.t to measure.
Image interpolation method- Value of image at non-grid position
Encapsulates the mapping of points and vectors from an “input” space to an “output” space.
Provides a variety of transforms from simple translation, rotation and scaling to general affine and kernel transforms.
Forward versus inverse mapping Parameters and Jacobians
Molecular Diffusion in MRIMolecular Diffusion in MRI
Molecular Diffusion in MRIMolecular Diffusion in MRI Methods.Methods. 4.2 Algorithm Image Registration Classification.4.2 Algorithm Image Registration Classification.
Forward and Inverse Mappings: Relationship between points of two images can be expressed in two ways: – Forward Pixel of input image mapped onto the output image – Inverse Output pixels are mapped back onto the input image Encapsulates the mapping of points and vectors from an “input” space to an
“output” space. Provides a variety of transforms from simple translation, rotation and
scaling to general affine and kernel transforms. Forward versus inverse mapping Parameters and Jacobians
Molecular Diffusion in MRIMolecular Diffusion in MRI
• The derivative of the image with respect to the variable is written The derivative of the image with respect to the variable is written
• For vector-valued images , we have andFor vector-valued images , we have and
The derivation of a scalar image with respect to its spatial coordinates is The derivation of a scalar image with respect to its spatial coordinates is called the image gradient and is noted by :called the image gradient and is noted by :
4.3 Algorithm Diffusion Isotropy - divergence – based PDE
A major generalization of divergence-based equations has been recently proposed by Weickert.
he considered image pixels as chemical concentrations diffusing with respect to some physical laws (Fick Law and continuity equations) and proposed a very generic equation:
This is justied by the fact that spectral elements of diffusion tensors are the important data that provide signicant structural informations : • For DT-MRI images, the diagonal matrix measures the water molecule velocity in the brain fibers, while the tensor orientation provides important clues to the structure and geometric organization of these fibers.
• Significant physiological values can also be computed from: - Mean diffusivity :
Molecular Diffusion in MRIMolecular Diffusion in MRI
Methods.Methods.
4.2 Algorithm DTI – Multiresolution Approximations and Their Associated 4.2 Algorithm DTI – Multiresolution Approximations and Their Associated Wavelets.Wavelets.
• There is a class of DWT that can be implemented using extremely efficient There is a class of DWT that can be implemented using extremely efficient algorithms. [Aldroubi - S.Mallat]. algorithms. [Aldroubi - S.Mallat].
• These types of wavelet transforms are associated with mathematical These types of wavelet transforms are associated with mathematical structures called multiresolution approximations of (MRA).structures called multiresolution approximations of (MRA).
• A multiresolution approximation of is a set of spaces that are A multiresolution approximation of is a set of spaces that are generated by dilating and translating a single function .generated by dilating and translating a single function .
Molecular Diffusion in MRIMolecular Diffusion in MRI
Methods. Methods. Multiresolution Approximations and Their Associated Wavelets.Multiresolution Approximations and Their Associated Wavelets.
Where are the dilations (or reductions) and translations ofWhere are the dilations (or reductions) and translations of
The function called the scaling function. Moreover, for fixed the set The function called the scaling function. Moreover, for fixed the set
is requered to form an unconditional basis of .is requered to form an unconditional basis of .
If the funcctions form an orthogonal basis of . Then we call If the funcctions form an orthogonal basis of . Then we call an orthogonal scaling function.an orthogonal scaling function.
• The spaces are required to satisfy the additional properties:
Molecular Diffusion in MRIMolecular Diffusion in MRI
Methods. 4.2 Methods. 4.2 Multiresolution Approximations and Their Associated Wavelets.Multiresolution Approximations and Their Associated Wavelets.
Properties (i) – (iv), the scaling function that is used to generated the MRA cannot Properties (i) – (iv), the scaling function that is used to generated the MRA cannot be chosen arbitrarily. be chosen arbitrarily.
In fact since and since In fact since and since
.. Conclude that the generating function must be a linear combinationConclude that the generating function must be a linear combination
of the basis :of the basis :
This last relation is often called the two-scale relation or the refinement equation, and This last relation is often called the two-scale relation or the refinement equation, and the sequence is the generating sequence which is crucial in the implementation the sequence is the generating sequence which is crucial in the implementation of the DWT associated with multiresolutions.of the DWT associated with multiresolutions.
)(t
01 VV 01
2/1 )()2/(2 VtandVt
)2/(2 2/1 t
0Vofzkkt
zk
ktkht )(22/ 2/1
)(kh
Molecular Diffusion in MRIMolecular Diffusion in MRI