Diffusion tensor imaging

Federal government websites often end in. The site is secure. Diffusion tensor imaging DTI is a promising method for characterizing microstructural changes or differences with neuropathology and treatment.

At the time the article was last revised Rohit Sharma had no financial relationships to ineligible companies to disclose. Diffusion tensor imaging DTI is an MRI technique that uses anisotropic diffusion to estimate the axonal white matter organization of the brain. Fiber tractography FT is a 3D reconstruction technique to assess neural tracts using data collected by diffusion tensor imaging. Diffusion-weighted imaging DWI is based on the measurement of thermal Brownian motion of water molecules. Within cerebral white matter, water molecules tend to diffuse more freely along the direction of axonal fascicles rather than across them.

Diffusion tensor imaging

Federal government websites often end in. The site is secure. Diffusion tensor magnetic resonance imaging DTI is a relatively new technology that is popular for imaging the white matter of the brain. The goal of this review is to give a basic and broad overview of DTI such that the reader may develop an intuitive understanding of this type of data, and an awareness of its strengths and weaknesses. We have tried to include equations for completeness but they are not necessary for understanding the paper. Wherever possible, pointers will be provided to more in-depth technical articles or books for further reading. We especially recommend the new diffusion MRI textbook [ 1 ], the introductory paper on fiber tracts and tumors [ 2 ], the white matter atlas book [ 3 ], and the review of potential pitfalls in DTI analysis [ 4 ]. In the rest of this article we will address basic questions about DTI the what, why, and how of DTI , followed by a discussion of issues in interpretation of DTI, and finally an overview of more advanced diffusion imaging methods and future directions. The diffusion tensor was originally proposed for use in magnetic resonance imaging MRI by Peter Basser in [ 5 , 6 ]. Prior to the introduction of the diffusion tensor model, to measure anisotropic diffusion the orientation of the axons in a tissue sample had to be known, so only fixed samples such as the axon of the giant squid could be scanned [ 10 ]. The introduction of the diffusion tensor model allowed, for the first time, a rotationally invariant description of the shape of water diffusion. The invariance to rotation was crucial because it enabled application of the DTI method to the complex anatomy of the fiber tracts in the human brain [ 11 ]. Note however, that the diffusion tensor is not able to fully describe crossing of the fiber tracts [ 12 , 13 ].

Diffusion and perfusion magnetic resonance imaging: Applications to functional MRIch.

Functional MRI is a noninvasive diagnostic test that measures small changes in blood flow as a person performs tasks while in the MRI scanner. It detects the brain in action e. It has an advantage over other imaging studies that focus only on the structure of the brain. Diffusion tensor imaging DTI detects the white matter fibers that connect different parts of the brain. These imaging studies help to map specific brain areas before surgery.

Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Strong gradient systems can improve the signal-to-noise ratio of diffusion MRI measurements and enable a wider range of acquisition parameters that are beneficial for microstructural imaging. The diffusion MRI data were preprocessed to correct for gradient nonlinearity, eddy currents, and susceptibility induced distortions. The MGH Connectome Diffusion Microstructure Dataset CDMD may serve as a test bed for the development of new data analysis methods, such as fiber orientation estimation, tractography and microstructural modelling. Barbara Hollunder, Jill L. Ostrem, … Andreas Horn. Zizhen Yao, Cindy T.

Diffusion tensor imaging

Advanced magnetic resonance MR neuroimaging modalities are becoming more available and useful as their value in the diagnosis and prognosis of central nervous system diseases is more fully studied and understood. Specifically, diffusion tensor imaging DTI has become increasingly studied and utilized in recent years. It has become incorporated by many radiologists into routine clinical practice, with most research performed on traumatic brain injury TBI. DTI is a variant of diffusion-weighted imaging DWI that utilizes a tissue water diffusion rate for image production.

Gl homes

Xu, D. Zhang, Y. Fibers with oblique orientation are represented with colors originating from the combination of the three primary colors:. Quantity Measurement Reference axon packing density pyramidal tract Error! Thus, low FA values may suggest decreased fiber density, reduced myelination of fiber tracts or less directionally coherent organization of fibers within a voxel. Diffusion tensor estimation requires high b -values e. Check for errors and try again. Zhu, T. DWI directly visualizes the ischemic necrosis in cerebral infarction in the form of a cytotoxic edema, [38] appearing as a high DWI signal within minutes of arterial occlusion. Neuroimage 23 Suppl.

The precise characterization of cerebral thrombi prior to an interventional procedure can ease the procedure and increase its success. This study investigates how well cerebral thrombi can be characterized by computed tomography CT , magnetic resonance MR and histology, and how parameters obtained by these methods correlate with each other as well as with the interventional procedure and clinical parameters. Cerebral thrombi of 25 patients diagnosed by CT with acute ischemic stroke were acquired by mechanical thrombectomy and, subsequently, scanned by a high spatial-resolution 3D MRI including T 1 -weighted imaging, apparent diffusion coefficient ADC , T 2 mapping and then finally analyzed by histology.

Journal of molecular neuroscience. In certain clinical situations, this can generate contrast between an area of pathology and the surrounding healthy tissue. Also shown top row, middle is a mapping of the major eigenvector orientation to colors. Rapid isotropic diffusion mapping without susceptibility artifacts: whole brain studies using diffusion-weighted single-shot STEAM MR imaging. With DTI analysis it is possible to infer, in each voxel, properties such as the molecular diffusion rate [Mean Diffusivity MD or Apparent Diffusion Coefficient ADC ], the directional preference of diffusion [Fractional Anisotropy FA ], the axial diffusion rate along the main axis of diffusion , and radial rate of diffusion in the transverse direction diffusivity. Diffusion MR imaging: an important tool in the assessment of brain tumors. With no diffusion present, the change in nuclear magnetization over time is given by the classical Bloch equation. Neuroradiology 46, — New York: Dover Publications; Traditionally, in diffusion-weighted imaging DWI , three gradient-directions are applied, sufficient to estimate the trace of the diffusion tensor or 'average diffusivity', a putative measure of edema. Automated methods for atlas-based tractography segmentation, that use prior knowledge to select trajectories, have also been developed [ 63 , 60 , 64 , 65 , 66 , 67 , 68 ].