Fiber Tracking Techniques Research Articles

The structural–functional connectome and the default mode network of the human brain

An emerging field of human brain imaging deals with the characterization of the connectome, a comprehensive global description of structural and functional connectivity within the human brain. However, the question of how functional and structural connectivity are related has not been fully answered yet. Here, we used different methods to estimate the connectivity between each voxel of the cerebral cortex based on functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) data in order to obtain observer-independent functional–structural connectomes of the human brain. Probabilistic fiber-tracking and a novel global fiber-tracking technique were used to measure structural connectivity whereas for functional connectivity, full and partial correlations between each voxel pair's fMRI-timecourses were calculated. For every voxel, two vectors consisting of functional and structural connectivity estimates to all other voxels in the cortex were correlated with each other. In this way, voxels structurally and functionally connected to similar regions within the rest of the brain could be identified. Areas forming parts of the ‘default mode network’ (DMN) showed the highest agreement of structure–function connectivity. Bilateral precuneal and inferior parietal regions were found using all applied techniques, whereas the global tracking algorithm additionally revealed bilateral medial prefrontal cortices and early visual areas. There were no significant differences between the results obtained from full and partial correlations. Our data suggests that the DMN is the functional brain network, which uses the most direct structural connections. Thus, the anatomical profile of the brain seems to shape its functional repertoire and the computation of the whole-brain functional–structural connectome appears to be a valuable method to characterize global brain connectivity within and between populations.

Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases

Diffusion tensor imaging (DTI) techniques provide information on the microstructural processes of the cerebral white matter (WM) in vivo. The present applications are designed to investigate differences of WM involvement patterns in different brain diseases, especially neurodegenerative disorders, by use of different DTI analyses in comparison with matched controls. DTI data analysis is performed in a variate fashion, i.e. voxelwise comparison of regional diffusion direction-based metrics such as fractional anisotropy (FA), together with fiber tracking (FT) accompanied by tractwise fractional anisotropy statistics (TFAS) at the group level in order to identify differences in FA along WM structures, aiming at the definition of regional patterns of WM alterations at the group level. Transformation into a stereotaxic standard space is a prerequisite for group studies and requires thorough data processing to preserve directional inter-dependencies. The present applications show optimized technical approaches for this preservation of quantitative and directional information during spatial normalization in data analyses at the group level. On this basis, FT techniques can be applied to group averaged data in order to quantify metrics information as defined by FT. Additionally, application of DTI methods, i.e. differences in FA-maps after stereotaxic alignment, in a longitudinal analysis at an individual subject basis reveal information about the progression of neurological disorders. Further quality improvement of DTI based results can be obtained during preprocessing by application of a controlled elimination of gradient directions with high noise levels. In summary, DTI is used to define a distinct WM pathoanatomy of different brain diseases by the combination of whole brain-based and tract-based DTI analysis.

Early registration of diffusion tensor images for group tractography of dystonia patients

To make a group comparison of diffusion tensor imaging (DTI) results of dystonia patients and controls to reveal occult pathology. We propose using an early registration method that produces sharper group images and enables us to do group tractography. Twelve dystonia patients manifesting the disease, seven nonmanifesting dystonia mutation carriers (DYT1 and DYT6 gene mutations), and eight age-matched normal control subjects were imaged for a previous study. Early and late registration methods for DTI were compared. An early registration technique for a super set was proposed, in which the diffusion-weighted images were registered to a template, gradient vectors were reoriented for each subject, and they were combined into a super set before tensor calculation. The super set included images from all subjects and was useful for group comparisons. We used results obtained from the early registration of a super set for group analysis of tracts using the deterministic fiber-tracking technique. In dystonia mutation carriers, we detected fewer fibers in the cerebello-thalamo-cortical pathways. This result agrees well with the findings of a previous study that utilized a probabilistic tractography method and demonstrated that gene carriers have less fiber tracts in the disease-involved pathway. This analysis visualized group level white matter fractional anisotropy and tract differences between dystonia patients and controls, and can be useful in understanding the pathophysiology of other nonfocal white matter diseases.

Diffusion tensor imaging–based fiber tracking for prediction of the position of the facial nerve in relation to large vestibular schwannomas

The reliable preoperative visualization of facial nerve location in relation to vestibular schwannoma (VS) would allow surgeons to plan tumor removal accordingly and may increase the safety of surgery. In this prospective study, the authors attempted to validate the reliability of facial nerve diffusion tensor (DT) imaging-based fiber tracking in a series of patients with large VSs. Furthermore, the authors evaluated the potential of this visualization technique to predict the morphological shape of the facial nerve (tumor compression-related flattening of the nerve). Diffusion tensor imaging and anatomical images (constructive interference in steady state) were acquired in a series of 22 consecutive patients with large VSs and postprocessed with navigational software to obtain facial nerve fiber tracking. The location of the cerebellopontine angle (CPA) part of the nerve in relation to the tumor was recorded during surgery by the surgeon, who was blinded to the results of the fiber tracking. A correlative analysis was performed of the imaging-based location of the nerve compared with its in situ position in relation to the VS. Fibers corresponding to the anatomical location and course of the facial nerve from the brainstem to the internal auditory meatus were identified with the DT imaging-based fiber tracking technique in all 22 cases. The location of the CPA segment of the facial nerve in relation to the VS determined during surgery corresponded to the location of the fibers, predicted by the DT imaging-based fiber tracking, in 20 (90.9%) of the 22 patients. No DT imaging-based fiber tracking correlates were found with the 2 morphological types of the nerve (compact or flat). The current study of patients with large VSs has shown that the position of the facial nerve in relation to the tumor can be predicted reliably (in 91%) using DT imaging-based fiber tracking. These are preliminary results that need further verification in a larger series.

Microsurgical and tractographic anatomical study of insular and transsylvian transinsular approach

This study is to define the operative anatomy of the insula with emphasis on the transsylvian transinsular approach. The anatomy was studied in 15 brain specimens, among five were dissected by use of fiber dissection technique; diffusion tensor imaging of 10 healthy volunteers was obtained with a 1.5-T MR system. The temporal stem consists mainly of the uncinate fasciculus, inferior occipitofrontal fasciculus, Meyer’s loop of the optic radiation and anterior commissure. The transinsular approach requires an incision of the inferior limiting sulcus. In this procedure, the fibers of the temporal stem can be interrupted to various degrees. The fiber dissection technique is a very relevant and reliable method for neurosurgeons to study the details of brain anatomic features. The DTI fiber tracking technique can identify the fiber tracts of the temporal stem. Moreover, it will also help further functional study of human insula.

A role of diffusion tensor imaging fiber tracking in deep brain stimulation surgery: DBS of the dentato-rubro-thalamic tract (drt) for the treatment of therapy-refractory tremor

Deep brain stimulation (DBS) can alleviate tremor of various origins. A number of regions are targeted. In recent work our group was able to show the involvement of the dentato-rubro-thalamic tract (drt) in tremor control with fiber tracking techniques. Here we report for the first time the successful use of magnetic resonance tractography in combination with traditional landmark-based targeting techniques to perform the implantation of a bilateral DBS system in a patient with dystonic head tremor. We report on a 37-year-old female with long-standing pure head tremor from myoclonus dystonia. She was identified as a candidate for thalamic DBS. The use of head fixation in a stereotactic frame would blur target symptoms (head tremor) during surgery and was therefore avoided. Her dentate-rubro-thalamic tracts were visualized with preoperative diffusion tensor imaging (DTI) and tractography, and then directly targeted stereotactically with DBS electrodes. Three months after implantation, tremor control was excellent (>90%). A close evaluation of the active electrode contact positions revealed clear involvement of the drt. This is the first time that direct visualization of fiber tracts has been employed for direct targeting and successful movement disorder tremor surgery. In the reported case, additional knowledge about the position of the drt, which previously has been shown to be a structure for modulation to achieve tremor control, led to a successful implantation of a DBS system, although there was a lack of intra-operatively testable tremor symptoms. In concordance with studies in optogenetic neuromodulation, fiber tracts are the emerging target structures for DBS. The routine integration of DTI tractography into surgical planning might be a leading path into the future of DBS surgery and will add to our understanding of the pathophysiology of movement disorders. Larger study populations will have to prove these concepts in future research.

Regionally Specific White Matter Disruptions of Fornix and Cingulum in Schizophrenia

Limbic circuitry disruptions have been implicated in the psychopathology and cognitive deficits of schizophrenia, which may involve white matter disruptions of the major tracts of the limbic system, including the fornix and the cingulum. Our study aimed to investigate regionally specific abnormalities of the fornix and cingulum in schizophrenia using diffusion tensor imaging (DTI). We determined the fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) profiles along the fornix and cingulum tracts using a fibertracking technique and a brain mapping algorithm, the large deformation diffeomorphic metric mapping (LDDMM), in the DTI scans of 33 patients with schizophrenia and 31 age-, gender-, and handedness-matched healthy controls. We found that patients with schizophrenia showed reduction in FA and increase in RD in bilateral fornix, and increase in RD in left anterior cingulum when compared to healthy controls. In addition, tract-based analysis revealed specific loci of these white matter differences in schizophrenia, that is, FA reductions and AD and RD increases occur in the region of the left fornix further from the hippocampus, FA reductions and RD increases occur in the rostral portion of the left anterior cingulum, and RD and AD increases occur in the anterior segment of the left middle cingulum. In patients with schizophrenia, decreased FA in the specific loci of the left fornix and increased AD in the right cingulum adjoining the hippocampus correlated with greater severity of psychotic symptoms. These findings support precise disruptions of limbic-cortical integrity in schizophrenia and disruption of these structural networks may contribute towards the neural basis underlying the syndrome of schizophrenia and clinical symptomatology.

Impact of fMRI-guided advanced DTI fiber tracking techniques on their clinical applications in patients with brain tumors

Impact of fMRI-guided advanced DTI fiber tracking techniques on their clinical applications in patients with brain tumors

In Vivo Mapping of Microstructural Somatotopies in the Human Corticospinal Pathways

The human corticospinal pathway is organized in a body-centric (i.e., somatotopic) manner that begins in cortical cell bodies and is maintained in the axons as they project through the midbrain on their way to spinal motor neurons. The subcortical segment of this somatotopy has been described using histological methods on non-human primates but only coarsely validated from lesion studies in human patient populations. Using high definition fiber tracking (HDFT) techniques, we set out to provide the first in vivo quantitative description of the midbrain somatotopy of corticospinal fibers in humans. Multi-shell diffusion imaging and deterministic fiber tracking were used to map white matter bundles that originate in the neocortex, navigate complex fiber crossings, and project through the midbrain. These fiber bundles were segmented into premotor (dorsal premotor, ventral premotor, and supplementary motor area) and primary motor sections based on the cortical origin of each fiber streamline. With HDFT, we were able to reveal several unique corticospinal patterns, including the cortical origins of ventral premotor fibers and small (∼ 1-2 mm) shifts in the midbrain location of premotor versus primary motor cortex fibers. More importantly, within the relatively small diameter of the pyramidal tracts (∼ 5 mm), we were able to map and quantify the direction of the corticospinal somatotopy. These results show how an HDFT approach to white matter mapping provides the first in vivo, quantitative mapping of subcortical corticospinal topographies at resolutions previously only available with postmortem histological techniques.

Cellular-level diffusion tensor microscopy and fiber tracking in mammalian nervous tissue with direct histological correlation

Magnetic resonance imaging techniques have literally revolutionized neuroimaging with an unprecedented ability to explore tissue structure and function. Over the last three decades, the sensitivity and array of imaging techniques available have improved providing ever finer structural information and more sensitive functional techniques. Among these methods, diffusion imaging techniques have facilitated the generation of fiber-tract maps of the brain enabling an examination of issues related to brain structure and neural connectivity. Despite the potential utility of the techniques described, validation has not yet been achieved on biological samples. Recently, using newly developed surface microcoils on small samples at high magnetic fields, we demonstrated the ability of MR microscopy to image individual neurons in mammalian brain tissue. In the present work, we combine MR microscopy with the highest resolution (15 μm) fiber tracking yet reported and demonstrate the accuracy of the fiber tract maps with direct histological validation. Thus it becomes possible to delineate fiber structure in tissues at the cellular level. A semi-quantitative approach was used to estimate the cell overlap fraction (cOF) and fiber tract overlap fraction (tOF), with cOFs of 94%, 92% and 100%, and tOFs of 84%, 86% and 100%, in rat cervical, rat lumbar, and pig spinal cord tissue, respectively. These methods provide a way to directly validate fiber tracking techniques with histology so that contemporary tracking techniques may be compared and refined using the microstructural details of a biological template as a ground truth.

Genetic white matter fiber tractography with global optimization

Diffusion tensor imaging (DTI) tractography is a novel technique that can delineate the trajectories between cortical region of the human brain non-invasively. In this paper, a novel DTI based white matter fiber tractography using genetic algorithm is presented. Adapting the concepts from evolutionary biology which include selection, recombination and mutation, globally optimized fiber pathways are generated iteratively. Global optimality of the fiber tracts is evaluated using Bayes decision rule, which simultaneously considers both the fiber geometric smoothness and consistency with the tensor field. This global optimality assigns the tracking fibers great immunity to random image noise and other local image artifacts, thus avoiding the detrimental effects of cumulative noise on fiber tracking. Experiments with synthetic and in vivo human DTI data have demonstrated the feasibility and robustness of this new fiber tracking technique, and an improved performance over commonly used probabilistic fiber tracking.

Impact of fMRI-guided advanced DTI fiber tracking techniques on their clinical applications in patients with brain tumors

White matter tractography based on diffusion tensor imaging has become a well-accepted non-invasive tool for exploring the white matter architecture of the human brain in vivo. There exist two main key obstacles for reconstructing white matter fibers: firstly, the implementation and application of a suitable tracking algorithm, which is capable of reconstructing anatomically complex fascicular pathways correctly, as, e.g., areas of fiber crossing or branching; secondly, the definition of an appropriate tracking seed area for starting the reconstruction process. Large intersubject, anatomical variations make it difficult to define tracking seed areas based on reliable anatomical landmarks. An accurate definition of seed regions for the reconstruction of a specific neuronal pathway becomes even more challenging in patients suffering from space occupying pathological processes as, e.g., tumors due to the displacement of the tissue and the distortion of anatomical landmarks around the lesion. To resolve the first problem, an advanced tracking algorithm, called advanced fast marching, was applied in this study. The second challenge was overcome by combining functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) in order to perform fMRI-guided accurate definition of appropriate seed areas for the DTI fiber tracking. In addition, the performance of the tasks was controlled by a MR-compatible power device. Application of this combined approach to eight healthy volunteers and exemplary to three tumor patients showed that it is feasible to accurately reconstruct relevant fiber tracts belonging to a specific functional system. fMRI-guided advanced DTI fiber tracking has the potential to provide accurate anatomical and functional information for a more informed therapeutic decision making.

Investigation on the Structure of Ventricular Mass Using Magnetic Resonance Diffusion Tensor Imaging

The 3-dimensional arrangement of the ventricular mass remains controversial. In this study, we used magnetic resonance diffusion tensor imaging (MRDTI) in an attempt to determine whether the ventricular mass is arranged in the form of a helical ventricular myocardial band (HVMB) and what the geometrical features of the HVMB are in postmortem pig hearts. Ten pig hearts were harvested from the slaughterhouse, and their whole-body MR images were obtained. The data were obtained via DTI by single-shot echo planar imaging and sensitivity encoding. The pig hearts were scanned with single-shot echo planar imaging and sensitivity-encoding scans (TE/TRZ78.5/10000 ms) with diffusion-sensitized gradients (b = 800 s/mm2) along 6 directions. Color-coded imaging and fiber-tracking techniques were used to investigate the arrangement of the fibers of ventricular mass on a GE Healthcare Advantage Workstation (Microsoft Windows). Color-coded images showed that the ventricular wall in each section was uniformly divided into 3 layers (subendocardial, middle, and subepicardial) in all samples. Fiber tracking showed that the subendocardial layer ran obliquely from base to apex, turned a circle, and transformed into the middle layer at the apex, and then ran obliquely upward. The ventricular mass was arranged in the form of double-helical coils. The crossing angle between subendocardial layer and middle layer was nearly vertical. Results of our investigation with MRDTI support the theory of Torrent-Guasp et al that the ventricular mass is arranged in the form of an HVMB.

Fiber tracking of white matter integrity connecting the mediodorsal nucleus of the thalamus and the prefrontal cortex in schizophrenia: A diffusion tensor imaging study

The goal of this study was to detect abnormalities in white matter integrity connecting the mediodorsal nucleus of the thalamus and the prefrontal cortex using fiber-tracking technique. Diffusion tensor imaging was acquired in 20 patients with schizophrenia and 20 normal comparison subjects. Fiber tracking was performed on the anterior thalamic peduncle, and the tractography was used to determine the cross-sectional area, mean fractional anisotropy, and standard deviation of fractional anisotropy for every step separately in the right and left hemispheres. Compared with normal subjects, patients showed a significant reduction in the cross-sectional area of the left anterior thalamic peduncle. There were no significant differences for the mean fractional anisotropy bilaterally between the two groups, but significant differences for the standard deviation of fractional anisotropy in both hemispheres. Reduction in the cross-sectional area of the left anterior thalamic peduncle suggests the presence of the failure of left-hemisphere lateralization. In schizophrenic patients a significant increase of the standard deviation of fractional anisotropy raise the possibility that the inhomogeneity of white matter integrity, which is densely or sparsely distributed by site. These findings might provide further evidence for disruption of white matter integrity between the thalamus and the prefrontal cortex in schizophrenia.

Fiber-Tracking Techniques Can Predict the Degree of Neurologic Impairment for Periventricular Leukomalacia

Preterm or low birth weight infants display a greater propensity for white matter injury caused by hypoxic-ischemic encephalopathy in the perinatal period. Such episodes can result in periventricular leukomalacia, which may substantially influence later brain development. Noninvasive methods of assessing the severity of injury at the earliest stage of life have not yet been established. We used diffusion tensor imaging to evaluate sensorimotor fibers in periventricular leukomalacia. Region-of-interest measurements and tractography-based measurements were performed for 10 patients with periventricular leukomalacia. The mean age of the patients was 19 +/- 9.5 months (range: 9-41 months). Motor functions were assessed at a mean age of 28 +/- 14.5 months. Measured fractional anisotropy values of the motor tract were significantly higher in all mild periventricular leukomalacia cases than in severe cases. A fractional anisotropy cutoff value of <0.5 was useful for predicting severe periventricular leukomalacia. Region-of-interest measurements were less sensitive, compared with tractography-based measurements. Fiber-tracking techniques can provide information on the pathophysiologic features of motor disability in patients with periventricular leukomalacia. Early screening of patients with a history of asphyxia may facilitate early intervention (eg, rehabilitation), to achieve better motor function.

Intersubject variability in the analysis of diffusion tensor images at the group level: fractional anisotropy mapping and fiber tracking techniques

Diffusion tensor imaging (DTI) provides comprehensive information about quantitative diffusion and connectivity in the human brain. Transformation into stereotactic standard space is a prerequisite for group studies and requires thorough data processing to preserve directional inter-dependencies. The objective of the present study was to optimize technical approaches for this preservation of quantitative and directional information during spatial normalization in data analyses at the group level. Different averaging methods for mean diffusion-weighted images containing DTI information were compared, i.e., region of interest-based fractional anisotropy (FA) mapping, fiber tracking (FT) and corresponding tractwise FA statistics (TFAS). The novel technique of intersubject FT that takes into account directional information of single data sets during the FT process was compared to standard FT techniques. Application of the methods was shown in the comparison of normal subjects and subjects with defined white matter pathology (alterations of the corpus callosum). Fiber tracking was applied to averaged data sets and showed similar results compared with FT on single subject data. The application of TFAS to averaged data showed averaged FA values around 0.4 for normal controls. The values were in the range of the standard deviation for averaged FA values for TFAS applied to single subject data. These results were independent of the applied averaging technique. A significant reduction of the averaged FA values was found in comparison to TFAS applied to data from subjects with defined white matter pathology (FA around 0.2). The applicability of FT techniques in the analysis of different subjects at the group level was demonstrated. Group comparisons as well as FT on group averaged data were shown to be feasible. The objective of this work was to identify the most appropriate method for intersubject averaging and group comparison which incorporates intersubject variability of the directional information.

Reconstruction and Visualization of Fiber and Laminar Structure in the Normal Human Heart from Ex Vivo Diffusion Tensor Magnetic Resonance Imaging (DTMRI) Data

The human heart is composed of a helical network of muscle fibers organized to form sheets that are separated by cleavage planes responsible for the orthotropic mechanical properties of cardiac muscle. The purpose of this study is the reconstruction and visualization of these structures in 3 dimensions. Anisotropic least square filtering followed by fiber and sheet tracking techniques were applied to diffusion tensor magnetic resonance imaging data of the excised human heart. Fibers were reconstructed using the first eigenvectors of the diffusion tensors. The sheets were reconstructed using the second and third eigenvectors and visualized as surfaces. The fibers are shown to lie in sheets that have transmural structure, which correspond to histologic studies published in the literature. Quantitative measurements show that the sheets as appose to the fibers are organized into laminar orientations without dominant populations. A visualization algorithm was developed to demonstrate the complex 3-dimensional orientation of the fibers and sheets in human myocardium.

Gray and normal-appearing white matter in multiple sclerosis: an MRI perspective

Besides focal white matter lesions, multiple sclerosis brain tissue also displays abnormalities in the gray matter and the normal-appearing white matter. Recent advances in magnetic resonance imaging studies of both types of tissue are discussed. Herein, normal-appearing white matter abnormalities are being found in quantitative magnetic resonance investigations, consistent with a limited degree of axonal damage and/or demyelination, and an increase of glial cells, but the specific nature of the histopathological changes underlying the quantitative magnetic resonance abnormalities remains unclear. Gray matter studies have demonstrated that much of the disease process remains undetected by conventional magnetic resonance imaging. Although newly developed techniques, such as 3D double-inversion recovery, may greatly improve detection of cortical pathology, it remains important to investigate the resultant effects on the cortical tissue alongside this, by studying integrity of normal-appearing cortical tissue through quantitative magnetic resonance studies, as well as the net neurodegenerative effect through measurements of cortical thickness and cortical atrophy (rates). To improve our understanding of normal-appearing white and gray matter changes, their mutual relations, and their relations to clinical changes, further in vivo magnetic resonance imaging studies are required. Specifically, it is proposed that more spatially specific investigations, ideally utilizing subject-specific anatomical information from, for example, diffusion fiber-tracking techniques, could be used to gain more insight into the relations between normal-appearing white matter changes, cortical changes, magnetic resonance visible focal-lesions, and physical and cognitive deficits.

White Matter Tractography by Means of Turboprop Diffusion Tensor Imaging

White matter fiber-tractography by means of diffusion tensor imaging (DTI) is a noninvasive technique that provides estimates of the structural connectivity of the brain. However, conventional fiber-tracking methods using DTI are based on echo-planar image acquisitions (EPI), which suffer from image distortions and artifacts due to magnetic susceptibility variations and eddy currents. Thus, a large percentage of white matter fiber bundles that are mapped using EPI-based DTI data are distorted, and/or terminated early, while others are completely undetected. This severely limits the potential of fiber-tracking techniques. In contrast, Turboprop imaging is a multiple-shot gradient and spin-echo (GRASE) technique that provides images with significantly fewer susceptibility and eddy current-related artifacts than EPI. The purpose of this work was to evaluate the performance of fiber-tractography techniques when using data obtained with Turboprop-DTI. All fiber pathways that were mapped were found to be in agreement with the anatomy. There were no visible distortions in any of the traced fiber bundles, even when these were located in the vicinity of significant magnetic field inhomogeneities. Additionally, the Turboprop-DTI data used in this research were acquired in less than 19 min of scan time. Thus, Turboprop appears to be a promising DTI data acquisition technique for tracing white matter fibers.

Fiber tracking by diffusion tensor imaging in corticospinal tract stroke: Topographical correlation with clinical symptoms

Fiber tracking of the white matter using diffusion tensor imaging is a new imaging technique to visualize the integrity of the white matter. This study investigated the capability of this technique to localize the lacunar infarctions, particularly with respect to the body parts affected, by correlating the location of the lesion with the clinical symptoms topographically. Twenty-seven patients with capsular and pericapsular small acute infarctions underwent diffusion tensor imaging and subsequent fiber tracking of the corticospinal tract (CST). According to the lesion topography with regard to the CST, the infarctions were classified into four types: (1) the anterior type ( n = 9) involving the anterior part of the CST, (2) the central type ( n = 9) involving the middle or whole part of the CST, (3) the posterior type ( n = 5) involving the posterior part of the CST and (4) the intact type ( n = 4) not involving the CST. Motor weakness of the face, upper extremities and lower extremities was found at 100%, 67% and 44%, respectively in the anterior type, at 89%, 100% and 89%, respectively in the central type and at 20%, 80% and 100%, respectively in the posterior type. The intact type was not associated with motor weakness. In conclusion, the fiber tracking technique of the CST enables the specific localization of capsular and pericapsular infarctions with regard to the body parts affected. These results also confirm the topographical accuracy of the fiber tracking of the CST.