The use of diffusion tractography to characterize a corpus. Article clinical impact of diffusion tensor imaging. Tractography is performed using data from diffusion mri. Diffusion tensor imaging dti tractographyloyola medicine.
Diffusion tensor imaging dti infers the trajectory and location of large white. First, a brief explanation of the basic physics of diffusion weighted imaging dwi and apparent diffusion coefficient adc mapping is provided. The diffusion tensor can be represented as an ellipsoid, where a proton at the center of the voxel has an equal probability of diffusing to any point in that ellipsoid. Diffusion tensor mr imaging and fiber tractography. Diffusion tensor imaging delivers crucial information. Diffusion tensor imaging dti is a variation on the theme of dwi, which quantifies water motion in three orthogonal dimensions and, therefore, is better able to capture the anisotropic tendencies of diffusion in highly organized tissues, such as cerebral white matter. In this study, diffusion tensor tractography dtt was used to investigate the correlation between fractionalanisotropy fa values and the number of fibers in the cingulum and uf in patients with and without cognitive impairment. Diffusion tensor tractography, which requires approximately 5 minutes to scan and is easily processed with commercially available software, is practical and easily integrated into the armamentarium of techniques of the highend neurooriented clinical practice. Recent advances in mri techniques have resulted in the development of diffusion tensor dt imaging. Posts include stepbystep processing and tractography tutorials. Does diffusion tensor imagingbased tractography at 3 months. For example, one can determine the location of the corticospinal tract or the thalamocortical tract with the help of syngo dti tractography. Dti studio one of the first packages by susumu moris lab at hopkins and widely used for roi analysis. A testing framework for fiber tractography limin kevin xu.
Diffusion tensor imaging dti is the most widely used method for. In this paper we proposed an automated approach for reconstructing nine brainstem fiber trajectories. Jun 26, 20 diffusion mri is a promising noninvasive technique for assessing the microstructural characteristics of white matter wm tracts. Listing a study does not mean it has been evaluated by the u.
Diffusion tensor magnetic resonance tractography of the brain. Visualization of peripheral nerve degeneration and. How i tricked my brain to like doing hard things dopamine detox duration. Open source diffusion mri software for brain cancer. What is the best program for analyzing diffusion tensor. Preoperative planning with combination of tractography and functional mri. Promising results that strengthen the concept of tractography guided targeting of. At the age of 3 months, diffusion tensor imagingbased tractography of the corticospinal tracts was performed along with assessment of the movement repertoire.
An overview of current methods for quantitative analysis of dti data and fiber tractography in clinical research is also provided. Thirteen patients with extracerebral lesions 11 benign meningiomas and 2 benign cysts underwent magnetic resonance diffusion tensor imaging and diffusion tensor tractography of the cst using fiber assignment by continuous tractography. Regular diffusionweighted dw imaging produces images based on only the sum or average of the eigenvalues. Application of diffusion tensor imaging and tractography in epilepsy surgery the safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Repeatability of quantitative metrics derived from mr. Diffusion tensor im aging dti is currentl y the most sensiti ve mr technique utilized to assess white matter i n tegrity. Diffusion weighted imaging dwi is based on the measurement of thermal brownian motion of water molecules. Open source diffusion mri software for brain cancer research. This principal axis often corresponds to anatomic features such as white matter tracts or fascial planes. The vast majority of diffusion tractography studies to date have focused on connections of particular brain areas, performing detailed comparisons with knowledge from invasive studies in macaque monkeys, using particular connections to predict or explain particular neural responses, or relating particular connections to particular behavioral. However, it is now known that the tensor model is insensitive to the complex fiber architectures found in the vast majority of voxels in the human brain. To demonstrate the utility of diffusion tensor imaging and tractography in two patients with brownsequard syndrome after penetrating. A testing framework for fiber tractography langping kevin wei.
Diffusion tensor tractography dtt produces a threedimensional. We describe slicerdmri, a software suite that enables visualization and analysis of dmri for neuroscientific studies and patientspecific anatomic assessment. This is followed by an overview of the additional information that can be derived from the. It is a noninvasive method, with unparalleled sensitivity to water movements within the architecture of the tissues that uses existing mri technology. Comparing a diffusion tensor and nontensor approach to. Diffusion tensor tractography dtt refers to the analysis and reconstruction of the data obtained by dti, by which the orientation of nerve fibers can be followed to trace specific neural pathways, such as that of the corticospinal tract in the brain or the spinal cord conturo et al. Diffusion tensor imaging and fibre tracking in cervical spondylotic myelopathy. Neuroimaging studies using diffusion tensor imaging dti have shown increased diffusivity e. What is the best program for analyzing diffusion tensor imaging data. Diffusion tensor analysis diffusion tensor tractographic images were computed using the volume one and dtv ii sr software masutani et al.
Tensor imaging and tractography are diffusion based mr techniques for advanced functional imaging of brain white matter. In such a case, the relative mobility of the molecules from the origin has a shape different from a sphere. Information on diffusion tensor imaging dti basics, tractography, analysis, visualization tools, lectures and tutorials. Evaluation of brainstem pathways with diffusion tensor imaging dti. Diffusion tensor magnetic resonance tractography dti of the brain uses magnetic resonance technology to track bundles of nerve fibers in the white matter of the brain. It allows the mapping of the diffusion process of molecules, mainly water, in biological tissues, in vivo and noninvasively. Principles of diffusion tensor imaging and its applications to basic neuroscience research. Dti tractography siemens healthineers united kingdom. Stereotactic diffusion tensor imaging tractography for gamma knife radiosurgery.
Brain sciences free fulltext characteristics of the. Diffusion tensor imaging tractography, or dti tractography, is an mri magnetic resonance imaging technique that measures the rate of water diffusion between cells to understand and create a map of the bodys internal structures. Interactive diffusion tensor tractography visualization for. Jan 17, 2006 tensor imaging and tractography are diffusion based mr techniques for advanced functional imaging of brain white matter.
Diffusion tensor imaging dti comprises a group of techniques where calculated eigenvalues. The three diagonal elements dxx, dyy, dzz represent diffusion coefficients measured along each of the principal x, y and z laboratory axes. Slicerdmri has been successfully applied in multiple studies of the human brain in health and disease, and here, we especially focus. Diffusion tensor magnetic resonance imaging dti allows to decode the mobility of water molecules in cerebral tissue, which is highly directional along myelinated fibers. Dsi studio includes dti, dsi, qball and fiber tracking by isaac tsengs lab in taiwan. The second half of the article focuses on technical considerations specific to diffusion tensor imaging dti and fiber tractography, including optimizing the bvalues, the number and orientations of diffusion weighted acquisitions, as well as the fiber tracking parameters. A substantial improvement in image resolution can be achieved with highangle diffusion magnetic resonance imaging and atlasbased fiber tracking to provide detailed trajectories. These include streamline fiber tracking technique, diffusion tensor deflection. Recent studies have demonstrated diffusion tensor imaging tractography of cranial nerves cns. Stereotactic diffusion tensor imaging tractography for. Diffusion spectrum mri tractography reveals the presence of a.
Diffusion tensor imaging dti is an mri technique that uses anisotropic diffusion to estimate the axonal white matter organization of the brain. Magnetic resonance imaging diffusion tensor tractography. A novel technique, diffusion spectrum mri tractography dsi tractography, was thus used to image myofiber architecture in normal and infarcted myocardium. Diffusion weighted imaging dwi le bihan and breton, 1985. Slicerdmri has been successfully applied in multiple studies of the human brain in health and disease, and here, we. Dwi is a routine protocol in most institutions that perform neuroimaging. The tensor matrix is diagonally symmetric dij dji with six degrees of freedom ie, only six of the tensor matrixs nine entries are independent and so the matrix is fully determined by these six parameters, such that a minimum of six diffusionencoded. The emphasis is on optimizing these technical factors for stateoftheart diffusionweighted imaging and diffusion tensor imaging dti based on the best available evidence in the literature. Validation of diffusion tensor imaging tractography to. There have been a number of tractography techniques developed in the past that simulate the basic structure of nerve fiber tracts in the brain. Spatial and angular resolution, however, is limited with this modality. Diffusion tensor tractography of brainstem fibers and its application.
Diffusion tensor imagingbased fiber tracking of the drtt may help to define the target for dbs to treat tremor depending on the accuracy of the tractography results. As such, this technique is a unique probe for in vivo characterization of. The utility of diffusion tensor imaging tractography for postoperative evaluation of a patient with hemispherotomy performed for intractable epilepsy. Dti is based on a mathematical description the tensor of the 3d shape. Diffusion tensor tractography of the injured thoracic spinal cord. Pdf diffusion tensor mr imaging and fiber tractography. Since the introduction of the diffusion mri tensor. Diffusionbased tractography atlas of the human acoustic. Test retest reproducibility of white matter parcellation using diffusion mri tractography fiber clustering. The role of dwi, diffusion tensor imaging, and motor assessment in predicting unilateral motor deficits were compared by calculating the positive and negative predictive values for each. Specifically, diffusion mri tractography can reconstruct the major wm tracts faithful to the known wm anatomy, allowing mapping of the brains structural connectivity in vivo basser et al. However, for most applications, many more images are usually required to boost snr to acceptable levels. Fan zhang, ye wu, isaiah norton, yogesh rathi, alexandra j golby, and lauren j odonnell.
The procedure was invented approximately 20 years ago, and many areas of the country are just beginning to see dti available in their area. Dti diffusion tensor imaging is an imaging method that grew out of and is part of mri. Anisotropy imaging can also provide information about ordered white matter wm tracts such as directional. Diffusion tensor tractography of brainstem fibers and its. Diffusion tensor imaging dti questions and answers in mri. Unlike diffusion tensor imaging, dsi tractography resolves multiple myofiber populations per voxel, thus generating accurate 3d tractograms, which we present in the myocardium for the first. Probabilistic diffusion tractography and graph theory. Diffusion tensor tractography in cerebral white matter. Diffusion tractography of the fornix in schizophrenia. Apr 19, 2019 weinstein d, kindlmann g, tensorlines le 1999 advectiondiffusion based propagation through diffusion tensor fields. Fortunately an ideal frame of reference for viewing the diffusion tensor exists and can be determined using measurements obtained from any frame of reference. Jul 14, 2015 right corticopontocerebellar axonal loss was demonstrated by specific diffusion tensor imaging software for tractography in 2011 d as compared to 2007 c. Diffusion mri dmri is the only noninvasive method for mapping white matter connections in the brain.
By integrating the direction of highest water diffusion through the tissue, dti tractography enables a noninvasive dissection of brain fiber bundles. Notwithstanding this significant limitation, physical phantoms, as with software phantoms, have been used to infer under which conditions the diffusion tensor and qspace methods are reliable on the voxel scale. Visualization of cranial nerves using highdefinition fiber. Diffusion tensor imaging dti based tractography has been used to demonstrate functionally relevant differences in white matter pathway status after stroke.
If the water diffuses in a medium with barriers, the diffusion will be uneven, which is termed anisotropic diffusion. In general, software phantoms are created by designing a true trajectory, choosing the sample orientation relative to the simulated frame of reference, assuming a diffusion profile, simulating a diffusionweighted signal, adding noise, and finally reconstructing the simulated track using the tractography method under interrogation. Diffusion gives a comprehensive overview of available software, analyzing methods and research possibilities. Diffusion tensor imaging dti and tractography for assessment of renal allograft dysfunction k. This shape is often modeled as an ellipsoid, and the. Early in the development of dti based tractography, a number of researchers pointed out a flaw in the diffusion tensor model. Dti uses mri technology to analyze the movement of water molecules in the white matter of the brain.
Fiber tractography ft is a 3d reconstruction technique to assess neural tracts using data collected by diffusion tensor imaging. Diffusion tensor imaging dtibased tractography has become an integral. Figure 2 demonstrates the extraction of nerve fibers from dti data and figure 3 illustrates both the front view and side. Diffusion tensor tractography in children with sensory. Statistical analysis of fiber bundles using multitensor.
Oct 29, 2015 application of diffusion tensor imaging and tractography in epilepsy surgery the safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Jun 29, 2018 diffusion weighted imaging dwi is a wellestablished magnetic resonance imaging mri method for diagnosing cerebral ischemia. Diffusion tensor imaging in musculoskeletal disorders. In this section, we provide a brief background on the two tensor tractography algorithm malcolm et al. The glial fibrillary acidic proteinderived tracts were.
Diffusion tensor imaging dti fiber tracking imagilys. The correlation between cognitive function, and the. Diffusion tensor imaging and fiber tractography of human. Dtk is a complete software package that does reconstruction, fiber tracking, analysis and visualization. Testretest reproducibility of white matter parcellation. Diffusion tensor imaging of white matter and correlates to. Although quantitative evaluation of diffusion tensor imaging dti data. Diffusion based tractography enables the graphical reconstruction of the white matter pathways in the brain and spinal cord of living humans. This optimal coordinate system is based upon the diffusion ellipsoid, whose main axis is parallel to the principal diffusion direction within a voxel. To permit a direct comparison, diffusion tensor tractography was subsequently performed in 2d fig. The direct fixed and variable costs of dti with mr tractography were determined prospectively with time and motion analysis in a 1.
Manual for clinical language tractography springerlink. An ellipsoid diffusion tensor water molecules move in physical brownian motion t time. Full text diffusion tensor imaging and tractography in. Budzik jf, balbi v, le thuc v, duhamel a, assaker r, cotten a. Galanski 5 1 radiology, hannover medical school, hannover, germany, 2 general, abdominal and transplant surgery, hannover medical school, 3 nephrology, hannover. The three diagonal elements d xx, d yy, d zz represent diffusion coefficients measured along each of the principal x, y and z laboratory axes. In this study, a monte carlo simulation was used to investigate the impact of snr, tensor anisotropy, and diffusion tensor encoding directions on the accuracy of six tractography algorithms. Diffusion tensor imaging dti is a sensitive, noninvasive method of mapping and characterizing the microstructural properties and macroscopic organization of white matter tissues in the brain. Dt imaging is sensitive to the diffusion of water molecules and can analyze the direction of diffusion, revealing the orientation of the white matter tracts. Comparison of parameter threshold combinations for diffusion. Paired ttests and the following calculation of the effect size measure. Figure 2 demonstrates the extraction of nerve fibers from dti data and figure 3. Diffusion based mri tractography allows invivo and noninvasive characterization of white matter architecture of the human brain.
Many studies have examined the relationship between cognition, and the cingulum and uncinate fasciculus uf. It is unfortunately not common practice in diffusion imaging research to report on observed head motion of the participants in the scanner. This study focused on diffusion tensor imaging dti of white matter in a large sample of pae participants that allowed us to examine correlations with behavioral outcomes. Diffusion tensor tractography in cerebral white matter intechopen. It can not only handle diffusion tensor data but can also process high angular resolution diffusion imaging hardi data as well as diffusion spectrum imaging dsi data and qball imaging data.
Providing background on the tools, methods and software to effectively analyze dti data. The cst was reconstructed and assessed by comparing the ipsilateral and unaffected contralateral fibers. Diffusion tensor tractography dtt produces a threedimensional representation in which data are displayed on a colored map obtained from the anisotropy of water molecules in the cwm tracts. In vivo diffusion tensor magnetic resonance tractography of. To estimate the diffusion tensor, one needs dwis with high bvalues along at least 6 noncollinear directions in addition to a lowb dwi or a t2weighted b 0 smm 2 image. Noninvasive procedure to detect central nervous system abnormalities. Diffusionbased tractography in neurological disorders. The eigenvalues and eigenvectors are then used to process scalar indices and, in some studies, tractography analysis. This technique uses magnetic resonance imaging and software that is configured to detect water diffusion in the brain. For example, one can determine the location of the corticospinal tract or the thalamocortical tract with the help of dti tractography. Diffusion weighted magnetic resonance imaging dwi or dwmri is the use of specific mri sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in mr images. There is a large number of variety of software for dti analysis.
Fractional anisotropy fa is a value that measures changes in water diffusion, which can occur if the cwm tracts are displaced, disrupted, or infiltrated. Diffusion tensor magnetic resonance tractography of the. Diffusion tensor imaging and tractography in brownsequard. To determine the total direct costs fixed and variable costs of diffusion tensor imaging dti and mr tractography reconstruction of the brain. The free water diffusion is termed isotropic diffusion. However, identification of these tracts has been elusive, with relatively few in vivo human studies to date. By contrast, probabilistic tractography applies streamline construction of diffusion fiber tracks with attention to the directionality of water molecule movements, and thus constructs track density td maps, which may provide new perspective regarding underlying white matter microstructural changes calamante et al. Dti diffusion tensor imaging tractography uses diffusion tensor data and allows 3d visualization of specific white matter tracts. Anisotropy imaging can also provide information about ordered white. Regular diffusion weighted dw imaging produces images based on only the sum or average of the eigenvalues. Published on dec 12, 20 diffusion tensor tractography is a noninvasive imaging technique that can track neuronal fibre pathways or tracts in a. Application of diffusion tensor imaging and tractography. Diffusion tensor imaging dti, and a new postprocessing method, fiber tractography, provides a unique opportunity to visualize and to quantify entire trajectories of fiber bundles, such as the fornix, in vivo.
Khalil c, hancart c, le thuc v, chantelot c, chechin d, cotten a. This technique has many potential clinical applications, including the investigation of stroke, multiple sclerosis, epilepsy, neurodegenerative diseases, and spinal cord disorders, and it enables hypotheses to be tested that could not previously be. Pdf cost analysis of diffusion tensor imaging and mr. Itkimplemented algorithm, followed by manual inspection and correction as. Diffusion tensor tractography demonstration of partially. A superior method to model diffusion in complex materials is to use the diffusion tensor, a 3 x 3 array of numbers corresponding to diffusion rates in each combination of directions. Diffusion spectrum mri tractography reveals the presence. Evaluation of brainstem pathways with diffusion tensor imaging dti and tractography may provide insights into pathophysiologies associated with dysfunction of key brainstem circuits. Application of diffusion tensor imaging and tractography in. Dec 26, 2018 diffusion toolkit and trackvis software 17 were used for tensor reconstruction and fiber tracking by a deterministic method using fiber assignment by continuous tracking.
Fiber tractography is an important field of study related to dti. The tensor analysis assumes that there is a single ellipsoid in each imaging voxel as if all of the axons traveling through a voxel traveled in exactly the same direction. Toward standardized evaluation of diffusion tensor imaging tractography for neurosurgery sonia pujol. Diffusion tensor tractography how is diffusion tensor. Components of the human connectome project diffusion.