scholarly journals Subdivision of Superior Longitudinal Fasciculus in Human Neonatal Brain

2021 ◽  
Author(s):  
Wenjia Liang ◽  
Qiaowen Yu ◽  
Wenjun Wang ◽  
Thijs Dhollander ◽  
Emmanuel Suluba ◽  
...  
Keyword(s):  
Diffusion Tensor ◽  
Morphological Characteristics ◽  
Fiber Morphology ◽  
Neonatal Brain ◽  
Superior Longitudinal Fasciculus ◽  
Functional Roles ◽  
Spherical Deconvolution ◽  
Anatomical Basis ◽  
Comparison Results ◽  
Human Connectome Project

Abstract The superior longitudinal fasciculus (SLF) is a complex associative tract comprising of three distinct subdivisions in the fronto-parietal cortex, each presenting different anatomical connectivity and different functional roles. However, the subdivision of SLF was hampered by limitations of data quality and tractography methods, and many studies on white matter development often consider the SLF as a single entity. The exact anatomical trajectory and developmental status of each sub-bundle of the human SLF in neonatal period remain poorly understood. In this work, we investigated the morphological characteristics and maturation degree of SLF each branch using the diffusion MRI (dMRI) data of 40 healthy term neonates from the Developing Human Connectome Project (dHCP) database. An advanced single shell 3-tissue constrained spherical deconvolution (SS3T-CSD) algorithm was used to ensure the successful separation of the SLF three branches (SLF I, SLF II and SLF III). In addition, diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) parameters values of the three subcomponents of SLF were measured quantitatively. The fiber morphology and connectivity of SLF sub-bundles in neonatal brain were nicely revealed in our study. Furthermore, the comparison results of parameters values supported that the maturation of SLF three segments was heterochronic. Further multiple comparison results indicated that the dorsal SLF II was less mature than the ventral SLF III and the former may involve in higher-level cognitive functions. Our findings can provide new anatomical basis for early diagnosis and treatment of related diseases caused by aberrant development of SLF.

Microsurgical Anatomy of the Vertical Rami of the Superior Longitudinal Fasciculus: An Intraparietal Sulcus Dissection Study

2018 ◽  
Vol 16 (2) ◽  
pp. 226-238 ◽  
Author(s):  
Alejandro Monroy-Sosa ◽  
Jonathan Jennings ◽  
Srikant Chakravarthi ◽  
Melanie B Fukui ◽  
Juanita Celix ◽  
...  
Keyword(s):  
Parietal Lobe ◽  
Diffusion Tensor ◽  
Dorsal Stream ◽  
Microsurgical Anatomy ◽  
Superior Longitudinal Fasciculus ◽  
Human Connectome Project ◽  
Lateral Extent ◽  
Dti Tractography ◽  
Tractography Data ◽  
Diffusion Tensor Imaging Dti

Abstract BACKGROUND A number of vertical prolongations of the superior longitudinal fasciculus, which we refer to as the vertical rami (Vr), arise at the level of the supramarginal gyrus, directed vertically toward the parietal lobe. OBJECTIVE To provide the first published complete description of the white matter tracts (WMT) of the Vr, their relationship to the intraparietal and parieto-occipital sulci (IPS-POS complex), and their importance in neurosurgical approaches to the parietal lobe. METHODS Subcortical dissections of the Vr and WMT of the IPS were performed. Findings were correlated with a virtual dissection using high-resolution diffusion tensor imaging (DTI) tractography data derived from the Human Connectome Project. Example planning of a transparietal, transsulcal operative corridor is demonstrated using an integrated neuronavigation and optical platform. RESULTS The Vr were shown to contain component fibers of the superior longitudinal fasciculus (SLF)-II and SLF-III, with contributions from the middle longitudinal fasciculus merging into the medial bank of the IPS. The anatomic findings correlated well with DTI tractography. The line extending from the lateral extent of the POS to the IPS marks an ideal sulcal entry point that we have termed the IPS-POS Kassam-Monroy (KM) Point, which can be used to permit a safe parafascicular surgical trajectory to the trigone. CONCLUSION The Vr are a newly conceptualized group of tracts merging along the banks of the IPS, mediating connectivity between the parietal lobe and dorsal stream/SLF. We suggest a refined surgical trajectory to the ventricular atrium utilizing the posterior third of the IPS, at or posterior to the IPS-POS Point, in order to mitigate risk to the Vr and its considerable potential for postsurgical morbidity.

scholarly journals An atlas of white matter anatomy, its variability, and reproducibility based on Constrained Spherical Deconvolution of diffusion MRI

2021 ◽  
Author(s):  
Ahmed M. Radwan ◽  
Stefan Sunaert ◽  
Kurt G. Schilling ◽  
Maxime Descoteaux ◽  
Bennett A. Landman ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Mri ◽  
Diffusion Tensor ◽  
Single Subject ◽  
Constrained Spherical Deconvolution ◽  
Spherical Deconvolution ◽  
Pyramidal Tracts ◽  
Human Connectome Project ◽  
Subject Specific ◽  
Virtual Dissection

Virtual dissection of white matter (WM) using diffusion MRI tractography is confounded by its poor reproducibility. Despite the increased adoption of advanced reconstruction models, early region-of-interest driven protocols based on diffusion tensor imaging (DTI) remain the dominant reference for virtual dissection protocols. Here we bridge this gap by providing a comprehensive description of typical WM anatomy reconstructed using a reproducible automated subject-specific parcellation-based approach based on probabilistic constrained-spherical deconvolution (CSD) tractography. We complement this with a WM template in MNI space comprising 68 bundles, including all associated anatomical tract selection labels and associated automated workflows. Additionally, we demonstrate bundle inter- and intra-subject variability using 40 (20 test-retest) datasets from the human connectome project (HCP) and 5 sessions with varying b-values and number of b-shells from the single-subject Multiple Acquisitions for Standardization of Structural Imaging Validation and Evaluation (MASSIVE) dataset. The most reliably reconstructed bundles were the whole pyramidal tracts, primary corticospinal tracts, whole superior longitudinal fasciculi, frontal, parietal and occipital segments of the corpus callosum and middle cerebellar peduncles. More variability was found in less dense bundles, e.g., the first segment of the superior longitudinal fasciculus, fornix, dentato-rubro-thalamic tract (DRTT), and premotor pyramidal tract. Using the DRTT as an example, we show that this variability can be reduced by using a higher number of seeding attempts. Overall inter-session similarity was high for HCP test-retest data (median weighted-dice = 0.963, stdev = 0.201 and IQR = 0.099). Compared to the HCP-template bundles there was a high level of agreement for the HCP test-retest data (median weighted-dice = 0.747, stdev = 0.220 and IQR = 0.277) and for the MASSIVE data (median weighted-dice = 0.767, stdev = 0.255 and IQR = 0.338). In summary, this WM atlas provides an overview of the capabilities and limitations of automated subject-specific probabilistic CSD tractography for mapping white matter fasciculi in healthy adults. It will be most useful in applications requiring a highly reproducible parcellation-based dissection protocol, as well as being an educational resource for applied neuroimaging and clinical professionals.

Segmentation of corpus callosum based on tensor fuzzy clustering algorithm

2021 ◽  
pp. 1-14
Author(s):  
Yujia Qu ◽  
Yuanjun Wang
Keyword(s):  
Corpus Callosum ◽  
Fuzzy Clustering ◽  
Clustering Algorithm ◽  
Diffusion Tensor ◽  
Region Of Interest ◽  
Midsagittal Plane ◽  
Fuzzy Clustering Algorithm ◽  
Human Connectome Project ◽  
Clustering Center ◽  
Fixed Region

BACKGROUND: The corpus callosum in the midsagittal plane plays a crucial role in the early diagnosis of diseases. When the anisotropy of the diffusion tensor in the midsagittal plane is calculated, the anisotropy of corpus callosum is close to that of the fornix, which leads to blurred boundary of the segmentation region. OBJECTIVE: To apply a fuzzy clustering algorithm combined with new spatial information to achieve accurate segmentation of the corpus callosum in the midsagittal plane in diffusion tensor images. METHODS: In this algorithm, a fixed region of interest is selected from the midsagittal plane, and the anisotropic filtering algorithm based on tensor is implemented by replacing the gradient direction of the structural tensor with an eigenvector, thus filtering the diffusion tensor of region of interest. Then, the iterative clustering center based on K-means clustering is used as the initial clustering center of tensor fuzzy clustering algorithm. Taking filtered diffusion tensor as input data and different metrics as similarity measures, the neighborhood diffusion tensor pixel calculation method of Log Euclidean framework is introduced in the membership function calculation, and tensor fuzzy clustering algorithm is proposed. In this study, MGH35 data from the Human Connectome Project (HCP) are tested and the variance, accuracy and specificity of the experimental results are discussed. RESULTS: Segmentation results of three groups of subjects in MGH35 data are reported. The average segmentation accuracy is 97.34%, and the average specificity is 98.43%. CONCLUSIONS: When segmenting the corpus callosum of diffusion tensor imaging, our method cannot only effective denoise images, but also achieve high accuracy and specificity.

scholarly journals Anatomy and white matter connections of the orbitofrontal gyrus

2018 ◽  
Vol 128 (6) ◽  
pp. 1865-1872 ◽  
Author(s):  
Joshua D. Burks ◽  
Andrew K. Conner ◽  
Phillip A. Bonney ◽  
Chad A. Glenn ◽  
Cordell M. Baker ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Diffusion Imaging ◽  
Internal Capsule ◽  
Ground Truth ◽  
Outcome Evaluation ◽  
Anterior Cingulate ◽  
Anatomical Dissection ◽  
Visual Spatial ◽  
Human Connectome Project

OBJECTIVEThe orbitofrontal cortex (OFC) is understood to have a role in outcome evaluation and risk assessment and is commonly involved with infiltrative tumors. A detailed understanding of the exact location and nature of associated white matter tracts could significantly improve postoperative morbidity related to declining capacity. Through diffusion tensor imaging–based fiber tracking validated by gross anatomical dissection as ground truth, the authors have characterized these connections based on relationships to other well-known structures.METHODSDiffusion imaging from the Human Connectome Project for 10 healthy adult controls was used for tractography analysis. The OFC was evaluated as a whole based on connectivity with other regions. All OFC tracts were mapped in both hemispheres, and a lateralization index was calculated with resultant tract volumes. Ten postmortem dissections were then performed using a modified Klingler technique to demonstrate the location of major tracts.RESULTSThe authors identified 3 major connections of the OFC: a bundle to the thalamus and anterior cingulate gyrus, passing inferior to the caudate and medial to the vertical fibers of the thalamic projections; a bundle to the brainstem, traveling lateral to the caudate and medial to the internal capsule; and radiations to the parietal and occipital lobes traveling with the inferior fronto-occipital fasciculus.CONCLUSIONSThe OFC is an important center for processing visual, spatial, and emotional information. Subtle differences in executive functioning following surgery for frontal lobe tumors may be better understood in the context of the fiber-bundle anatomy highlighted by this study.

scholarly journals Evaluating the performance of 3-tissue constrained spherical deconvolution pipelines for within-tumor tractography

2019 ◽  
Author(s):  
Hannelore Aerts ◽  
Thijs Dhollander ◽  
Daniele Marinazzo
Keyword(s):  
White Matter ◽  
Tumor Tissue ◽  
Diffusion Tensor ◽  
Orientation Distribution ◽  
Constrained Spherical Deconvolution ◽  
Spherical Deconvolution ◽  
Fiber Orientation Distribution ◽  
Tissue Compartments ◽  
Diffusion Tensor Imaging Dti ◽  
Single Shell

AbstractThe use of diffusion MRI (dMRI) for assisting in the planning of neurosurgery has become increasingly common practice, allowing to non-invasively map white matter pathways via tractography techniques. Limitations of earlier pipelines based on the diffusion tensor imaging (DTI) model have since been revealed and improvements were made possible by constrained spherical deconvolution (CSD) pipelines. CSD allows to resolve a full white matter (WM) fiber orientation distribution (FOD), which can describe so-called “crossing fibers”: complex local geometries of WM tracts, which DTI fails to model. This was found to have a profound impact on tractography results, with substantial implications for presurgical decision making and planning. More recently, CSD itself has been extended to allow for modeling of other tissue compartments in addition to the WM FOD, typically resulting in a 3-tissue CSD model. It seems likely this may improve the capability to resolve WM FODs in the presence of infiltrating tumor tissue. In this work, we evaluated the performance of 3-tissue CSD pipelines, with a focus on within-tumor tractography. We found that a technique named single-shell 3-tissue CSD (SS3T-CSD) successfully allowed tractography within infiltrating gliomas, without increasing existing single-shell dMRI acquisition requirements.

Brain Structure Alterations in Hemifacial Spasm: A Diffusion Tensor Imaging Study

2020 ◽  
pp. 155005942097925
Author(s):  
Jian Zhang ◽  
Qingyang Yu ◽  
Peng Gu ◽  
Hongtao Sun ◽  
Fei Yuan ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
Hemifacial Spasm ◽  
Diffusion Tensor ◽  
Imaging Study ◽  
Poor Sleep ◽  
Poor Sleep Quality ◽  
Superior Longitudinal Fasciculus ◽  
Activity Dependent ◽  
Diffusion Tensor Imaging Study ◽  
Diffusion Tensor Imaging Dti

This study examined white matter integrity in patients with left-sided hemifacial spasm (HFS) using diffusion tensor imaging (DTI). Thirty-six patients with left-sided HFS (mean age 53.24 ± 8.16 years) and 36 healthy volunteers (mean age 53.92 ± 7.73 years) were recruited. Tract-based spatial statistics (TBSS) analysis revealed significantly increased fractional anisotropy (FA) of bilateral superior longitudinal fasciculus in HFS patients ( P < 0.05, family-wise error corrected), with trends for radial diffusivity to decrease. We inferred that the results may be associated with poor sleep quality, impairment in visuospatial construction, and activity-dependent increases in myelination in HFS patients. Furthermore, the FA value of left superior longitudinal fasciculus showed a positive correlation with HFS duration ( r = 0.352, P = .041) and spasm severity ( r = 0.416, P = .014). However, the alteration of medial diffusivity and axial diffusivity were not found in bilateral superior longitudinal fasciculus between groups. These findings suggest FA changes of superior longitudinal fasciculus reflected by TBSS analysis may provide valuable insights into the diagnosis of HFS.

scholarly journals Carbon Fiber Production from Electrospun Sulfur Free Softwood Lignin Precursors

2017 ◽  
Vol 12 (4) ◽  
pp. 155892501701200 ◽  
Author(s):  
Samira Aslanzadeh ◽  
Behzad Ahvazi ◽  
Yaman Boluk ◽  
Cagri Ayranci
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
Structural Characteristics ◽  
Morphological Characteristics ◽  
Carbonization Temperature ◽  
Purification Process ◽  
Fiber Morphology ◽  
Heating Rates ◽  
Fiber Production

In this study, a sulfur-free softwood lignin (SFSL) was electrospun to form bead-free fibers. The fibers were evaluated as potential precursors for carbon fiber production. Higher heating rates of thermostabilization caused afused fiber morphology. The lignin purification process also affected the quality of the SFSL-based carbon fibers. Therefore, the yield, morphological characteristics, structural characteristics, electrical conductivity and mechanical properties of the carbon fibers were evaluated. At higher carbonization temperatures crystalline carbon fibers were formed. As a result, as the carbonization temperature increased, the conductivity of SFSL-based carbon fibers also increased.

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