scholarly journals Bundle-Specific Axon Diameter Index as a New Contrast to Differentiate White Matter Tracts

2021 ◽  
Vol 15 ◽  
Author(s):  
Muhamed Barakovic ◽  
Gabriel Girard ◽  
Simona Schiavi ◽  
David Romascano ◽  
Maxime Descoteaux ◽  
...  
Keyword(s):  
White Matter ◽  
Internal Capsule ◽  
Mean Value ◽  
Axon Diameter ◽  
Posterior Limb ◽  
Weighted Magnetic Resonance Imaging ◽  
The Central Nervous System ◽  
Index Value ◽  
White Matter Connectivity

In the central nervous system of primates, several pathways are characterized by different spectra of axon diameters. In vivo methods, based on diffusion-weighted magnetic resonance imaging, can provide axon diameter index estimates non-invasively. However, such methods report voxel-wise estimates, which vary from voxel-to-voxel for the same white matter bundle due to partial volume contributions from other pathways having different microstructure properties. Here, we propose a novel microstructure-informed tractography approach, COMMITAxSize, to resolve axon diameter index estimates at the streamline level, thus making the estimates invariant along trajectories. Compared to previously proposed voxel-wise methods, our formulation allows the estimation of a distinct axon diameter index value for each streamline, directly, furnishing a complementary measure to the existing calculation of the mean value along the bundle. We demonstrate the favourable performance of our approach comparing our estimates with existing histologically-derived measurements performed in the corpus callosum and the posterior limb of the internal capsule. Overall, our method provides a more robust estimation of the axon diameter index of pathways by jointly estimating the microstructure properties of the tissue and the macroscopic organisation of the white matter connectivity.

Abstract TP75: Normal Appearing White Matter Integrity and Motor Impairment Severity in Acute Ischemic Stroke

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Carson Ingo ◽  
Chen Lin ◽  
James Higgins ◽  
Yurany Arevalo ◽  
Shyam Prabhakaran
Keyword(s):  
Ischemic Stroke ◽  
White Matter ◽  
Acute Ischemic Stroke ◽  
Motor Function ◽  
Motor Impairment ◽  
Internal Capsule ◽  
Posterior Limb ◽  
Normal Appearing White Matter ◽  
Stroke Group ◽  
Microstructural Integrity

Introduction: The effect of white matter hyperintensities (WMH) as measured by fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging on functional impairment and recovery after ischemic stroke has been investigated thoroughly. However, there has been growing interest to investigate normal-appearing white matter (NAWM) microstructural integrity following ischemic stroke onset with techniques such as diffusion tensor imaging (DTI). Methods: 52 patients with acute ischemic stroke and 36 without stroke were evaluated with a DTI and FLAIR imaging protocol and clinically assessed for severity of motor impairment using the Motricity Index within 72 hours of suspected symptom onset. Results: There were widespread decreases in fractional anisotropy (FA) and increases in mean diffusivity (MD) and radial diffusivity (RD) for the acute stroke group compared to the non-stroke group. As shown in the abstract figure with the blue voxels, there was a significant positive association between FA and motor function and a significant negative association between MD/RD and motor function. The NAWM regions of interest that were most sensitive to the Motricity Index were the anterior/posterior limb of the internal capsule in the infarcted hemisphere and the splenium of the corpus callosum, external capsule, posterior limb/retrolenticular part of the internal capsule, superior longitudinal fasciculus, and cingulum (hippocampus) of the intra-/contralateral hemisphere. Conclusion: The microstructural integrity of NAWM is a significant parameter to identify neural differences not only between those individuals with and without acute ischemic stroke, but also correlated with severity of acute motor impairment.

scholarly journals Large-Scale Evidence for an Association Between Peripheral Inflammation and White Matter Free Water in Schizophrenia and Healthy Individuals

2020 ◽  
Author(s):  
Maria A Di Biase ◽  
Andrew Zalesky ◽  
Suheyla Cetin-Karayumak ◽  
Yogesh Rathi ◽  
Jinglei Lv ◽  
...  
Keyword(s):  
White Matter ◽  
Large Scale ◽  
Interleukin 2 ◽  
Free Water ◽  
Markers Of Inflammation ◽  
Brain White Matter ◽  
Inflammatory Processes ◽  
Weighted Magnetic Resonance Imaging

Abstract Introduction Clarifying the role of neuroinflammation in schizophrenia is subject to its detection in the living brain. Free-water (FW) imaging is an in vivo diffusion-weighted magnetic resonance imaging (dMRI) technique that measures water molecules freely diffusing in the brain and is hypothesized to detect inflammatory processes. Here, we aimed to establish a link between peripheral markers of inflammation and FW in brain white matter. Methods All data were obtained from the Australian Schizophrenia Research Bank (ASRB) across 5 Australian states and territories. We first tested for the presence of peripheral cytokine deregulation in schizophrenia, using a large sample (N = 1143) comprising the ASRB. We next determined the extent to which individual variation in 8 circulating pro-/anti-inflammatory cytokines related to FW in brain white matter, imaged in a subset (n = 308) of patients and controls. Results Patients with schizophrenia showed reduced interleukin-2 (IL-2) (t = −3.56, P = .0004) and IL-12(p70) (t = −2.84, P = .005) and increased IL-6 (t = 3.56, P = .0004), IL-8 (t = 3.8, P = .0002), and TNFα (t = 4.30, P < .0001). Higher proinflammatory signaling of IL-6 (t = 3.4, P = .0007) and TNFα (t = 2.7, P = .0007) was associated with higher FW levels in white matter. The reciprocal increases in serum cytokines and FW were spatially widespread in patients encompassing most major fibers; conversely, in controls, the relationship was confined to the anterior corpus callosum and thalamic radiations. No relationships were observed with alternative dMRI measures, including the fractional anisotropy and tissue-related FA. Conclusions We report widespread deregulation of cytokines in schizophrenia and identify inflammation as a putative mechanism underlying increases in brain FW levels.

Disturbed thalamocortical connectivity in unaffected relatives of schizophrenia patients with a high genetic loading

2019 ◽  
Vol 53 (9) ◽  
pp. 889-895 ◽  
Author(s):  
Kang Ik K Cho ◽  
Minah Kim ◽  
Youngwoo Bryan Yoon ◽  
Junhee Lee ◽  
Tae Young Lee ◽  
...  
Keyword(s):  
White Matter ◽  
Fractional Anisotropy ◽  
Orbitofrontal Cortex ◽  
First Episode ◽  
Healthy Controls ◽  
Degree Relative ◽  
Episode Psychosis ◽  
Weighted Magnetic Resonance Imaging ◽  
White Matter Connectivity ◽  
Genetic Loading

Objectives: Alterations in thalamocortical anatomical connectivity, specifically the connection between the orbitofrontal cortex and thalamus, have been frequently reported in schizophrenia and are suggested to contribute to the pathophysiology of schizophrenia. The connectivity of the thalamocortical white matter in unaffected relatives of schizophrenia patients was compared to that of healthy controls. Methods: The unaffected relative group was defined as asymptomatic family members who had at least one first-degree relative with schizophrenia and one or more other affected first- to third-degree relatives. A total of 35 unaffected relatives and 34 healthy controls underwent diffusion-weighted and T1-weighted magnetic resonance imaging to examine the white matter connectivity between the thalamus and orbitofrontal cortex using probabilistic tractography. Results: After controlling for age and sex, the unaffected relatives exhibited significantly reduced fractional anisotropy values for the left thalamo-orbitofrontal tract compared to that of healthy controls, F(1, 65) = 6.93, p = 0.011, effect size partial η2 = 0.10. However, there was no association between the Genetic Liability Score and fractional anisotropy in the left thalamo-orbitofrontal tracts. Conclusion: Our findings in the unaffected relatives of schizophrenia patients, which are in line with the alterations reported in schizophrenia, first-episode psychosis and clinical high risk for psychosis, highlight a possible genetic contribution to the proposed biomarker of altered thalamocortical connectivity.

Microsurgical Anatomy of the White Matter Tracts in Hemispherotomy

2014 ◽  
Vol 10 (2) ◽  
pp. 305-324 ◽  
Author(s):  
Baris Kucukyuruk ◽  
Kaan Yagmurlu ◽  
Necmettin Tanriover ◽  
Mustafa Uzan ◽  
Albert L. Rhoton
Keyword(s):  
White Matter ◽  
Anterior Commissure ◽  
Posterior Part ◽  
Internal Capsule ◽  
Epileptic Seizures ◽  
Microsurgical Anatomy ◽  
Subcortical Structures ◽  
Posterior Edge ◽  
White Matter Tracts ◽  
Posterior Limb

Abstract BACKGROUND: Hemispherotomy is a surgical procedure performed for refractory epileptic seizures due to wide hemispheric damage. OBJECTIVE: To describe the microanatomy of the white matter tracts transected in a hemispherotomy and the relationship of the surgical landmarks used during the intraventricular callosotomy. METHODS: The cortical and subcortical structures were examined in 32 hemispheres. RESULTS: Incision of the temporal stem along the inferior limiting sulcus crosses the insulo-opercular fibers, uncinate, inferior occipitofrontal and middle longitudinal fasciculi, anterior commissure, and optic and auditory radiations. The incision along the superior limiting sulcus transects insulo-opercular fibers and the genu and posterior limb of internal capsule. The incision along the anterior limiting sulcus crosses the insulo-opercular fibers, anterior limb of the internal capsule, anterior commissure, and the anterior thalamic bundle. The disconnection of the posterior part of the corpus callosum may be incomplete if the point at which the last cortical branch of the anterior cerebral artery (ACA) turns upward and disappears from the view through the intraventricular exposure is used as the landmark for estimating the posterior extent of the callosotomy. This ACA branch turns upward before reaching the posterior edge of the splenium in 85% of hemispheres. The falx, followed to the posterior edge of the splenium, is a more reliable landmark for completing the posterior part of an intraventricular callosotomy. CONCLUSION: The fiber tracts disconnected in hemispherotomy were reviewed. The falx is a more reliable guide than the ACA in completing the posterior part of the intraventricular callosotomy.

scholarly journals The multicellular interplay of microglia in health and disease: lessons from leukodystrophy

2021 ◽  
Vol 14 (8) ◽  
Author(s):  
Woutje M. Berdowski ◽  
Leslie E. Sanderson ◽  
Tjakko J. van Ham
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
White Matter ◽  
Genetic Disorders ◽  
Brain Dysfunction ◽  
Brain Diseases ◽  
Human Patient ◽  
The Central Nervous System ◽  
The Impact

ABSTRACT Microglia are highly dynamic cells crucial for developing and maintaining lifelong brain function and health through their many interactions with essentially all cellular components of the central nervous system. The frequent connection of microglia to leukodystrophies, genetic disorders of the white matter, has highlighted their involvement in the maintenance of white matter integrity. However, the mechanisms that underlie their putative roles in these processes remain largely uncharacterized. Microglia have also been gaining attention as possible therapeutic targets for many neurological conditions, increasing the demand to understand their broad spectrum of functions and the impact of their dysregulation. In this Review, we compare the pathological features of two groups of genetic leukodystrophies: those in which microglial dysfunction holds a central role, termed ‘microgliopathies’, and those in which lysosomal or peroxisomal defects are considered to be the primary driver. The latter are suspected to have notable microglia involvement, as some affected individuals benefit from microglia-replenishing therapy. Based on overlapping pathology, we discuss multiple ways through which aberrant microglia could lead to white matter defects and brain dysfunction. We propose that the study of leukodystrophies, and their extensively multicellular pathology, will benefit from complementing analyses of human patient material with the examination of cellular dynamics in vivo using animal models, such as zebrafish. Together, this will yield important insight into the cell biological mechanisms of microglial impact in the central nervous system, particularly in the development and maintenance of myelin, that will facilitate the development of new, and refinement of existing, therapeutic options for a range of brain diseases.

scholarly journals Patients With Chronic Migraine Without History of Medication Overuse Are Characterized by a Peculiar White Matter Fiber Bundle Profile

2020 ◽  
Author(s):  
Gianluca Coppola ◽  
Antonio Di Renzo ◽  
Emanuele Tinelli ◽  
Barbara Petolicchio ◽  
Cherubino Di Lorenzo ◽  
...  
Keyword(s):  
White Matter ◽  
Chronic Migraine ◽  
Diffusion Tensor ◽  
Internal Capsule ◽  
Posterior Limb ◽  
History Of ◽  
The Right ◽  
Normal White Matter ◽  
Microstructural Integrity ◽  
The Brain

Abstract Background: We investigated intracerebral fiber bundles using a tract-based spatial statistics (TBSS) analysis of diffusion tensor imaging (DTI) datato investigate microstructural integrity in patients with episodic (MO) and chronic migraine (CM).Methods: We performed DTI in 19 patients with MO within interictal periods, 18 patients with CM without any history of drug abuse, and 18 healthy controls (HCs) using a 3T magnetic resonance imaging scanner. We calculated diffusion metrics, including fractional anisotropy (FA), axial diffusion (AD), radial diffusion (RD), and mean diffusion (MD).Results: TBSS revealed no significant differences in the FA, MD, RD, and AD maps between the MO and HC groups. In comparison to the HC group, theCM group exhibited widespread increased RD (bilateral superior [SCR] and posterior corona radiata [PCR], bilateral genu of the corpus callosum [CC], bilateral posterior limb of internal capsule [IC], bilateral superior longitudinal fasciculus [LF]) and MD values (tracts of the right SCR and PCR, right superior LF, and right splenium of the CC). In comparison to theMO group, theCM group showed decreased FA (bilateral SCR and PCR, bilateral body of CC, right superior LF, right forceps minor) and increased MD values (bilateral SCR and right PCR, right body of CC, right superior LF, right splenium of CC, and right posterior limb of IC). Conclusion: Our results suggest that chronic migraine can be associated withthe widespread disruption of normal white matter integrity in the brain.

scholarly journals Magnetic resonance imaging and magnetic resonance venography features in heat stroke: a case report

2019 ◽  
Author(s):  
Lizhi Cao ◽  
Juan Wang ◽  
Yaxuan Gao ◽  
Yumei Liang ◽  
Jinhua Yan ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Heat Stroke ◽  
Internal Capsule ◽  
Subcortical White Matter ◽  
Magnetic Resonance Venography ◽  
Resonance Imaging ◽  
Posterior Limb ◽  
External Capsule

Abstract Background: Heat stroke (HS) is a critical illness that can cause multiple organ dysfunction, including damage to the central nervous system (CNS), which can be life-threatening in severe cases. Brain lesions in patients with HS who present with CNS damage have been rarely reported before, and they usually vary in different cases, hence, patients with such lesions may present a clinical challenge in terms of diagnosis and management. Cerebral venous thrombosis (CVT) is a rare cause of stroke that mostly affects young individuals and children. The pathogenesis of brain damage caused by HS is complex, and CVT may be involved in the pathogenesis of HS with CNS damage. In this manuscript, we have reported a case of a patient with HS having CVT with symmetrical lesions in the bilateral putamen, posterior limb of the internal capsule, external capsule, insular lobe, and subcortical white matter in the brain. Case presentation: We encountered a 48-year-old man who presented with HS in the summer season. During admission, he had a high body temperature and was in coma and shock. Then, he developed rhabdomyolysis syndrome, acute kidney and liver damage, electrolyte imbalance, and acid–base balance disorders, and his D-dimer level was elevated. After several days of anti-shock treatment, the patient’s level of consciousness improved. However, he experienced a decline in vision. Cerebral magnetic resonance imaging (MRI) showed symmetrical lesions in the bilateral posterior limb of the internal capsule, putamen, external capsule, insula, and subcortical white matter, and cerebral magnetic resonance venography (MRV) showed the development of CVT. Therefore, anti-coagulation treatment was provided. After timely clinical intervention, the symptoms of the patient gradually improved. Conclusions: This case showed that HS can cause CVT. Therefore, cerebral MRI findings in HS must be assessed; in addition, early MRV can help in the diagnosis of the disease, which can effectively improve prognosis.

scholarly journals MRI and MRV features of a patient with Heat Stroke: a case report

2019 ◽  
Author(s):  
Lizhi Cao ◽  
Juan Wang ◽  
Yaxuan Gao ◽  
Yumei Liang ◽  
Jinhua Yan ◽  
...  
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
Venous Thrombosis ◽  
Cerebral Venous Thrombosis ◽  
Heat Stroke ◽  
Internal Capsule ◽  
Subcortical White Matter ◽  
Posterior Limb ◽  
External Capsule ◽  
The Brain

Abstract Background Heat stroke (HS) is a critical illness that can cause multiple organ dysfunction including damage to the central nervous system (CNS), which can be life-threatening in severe cases. The brain image lesions of HS patient with CNS damage has been rarely reported before and usually variable in different cases, causing confusing to doctors when encounter these patients in the clinic. Cerebral venous thrombosis (CVT) is a rare cause of stroke that mostly affects young people and children. The pathogenesis of brain damage caused by HS is complex, CVT may be involved in the pathogenesis of HS with CNS damage. In this manuscript, we report a case of HS with CVT with symmetrical lesions in the bilateral putamen,posterior limb of internal capsule,external capsule, insula lobe, and subcortical white matter inside the brain. Case presentation We introduced a 48-year-old man who suffered from HS in the hot summer. At the time of admission, he showed high body temperature, coma and shock. Later, he had laboratory evidence of rhabdomyolysis syndrome, acute kidney and liver damage, electrolyte imbalance, acid-base balance disorders, and high D-dimer levels. After several days of anti-shock treatment, his level of consciousness has improved but his vision has declined. The cerebral magnetic resonance imaging (MRI) showed symmetrical lesions of the bilateral posterior limb of internal capsule,putamen,external capsule and insula, and subcortical white matter, and cerebral magnetic resonance venography (MRV) showed the formation of deep cerebral venous thrombosis (DCVT). Therefore, the anti-coagulation treatment was given to patient. After timely clinical intervention, the symptom of the patient was gradually improved. Conclusions The case shows that HS can cause CVT. Therefore, we believe that when we need to identify the cerebral MRI findings of HS, early MRV can greatly help the diagnosis of the disease, and can effectively improve the prognosis.

Diffusion tensor imaging in neonatal encephalopathy: a systematic review

2019 ◽  
Vol 105 (5) ◽  
pp. 480-488 ◽  
Author(s):  
Megan Dibble ◽  
Mary Isabel O'Dea ◽  
Tim Hurley ◽  
Angela Byrne ◽  
Gabrielle Colleran ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Diffusion Tensor ◽  
Neurodevelopmental Outcome ◽  
Internal Capsule ◽  
Adverse Outcomes ◽  
Restricted Diffusion ◽  
Neonatal Encephalopathy ◽  
White Matter Tracts ◽  
Posterior Limb

Background and objectiveDiffusion tensor imaging (DTI) during the first few days of life can be used to assess brain injury in neonates with neonatal encephalopathy (NE) for outcome prediction. The goal of this review was to identify specific white matter tracts of interest that can be quantified by DTI as being altered in neonates with this condition, and to investigate its potential prognostic ability.MethodsSearches of Medline and the Cochrane Database of Systematic Reviews were conducted to identify studies with diffusion data collected in term-born neonates with NE.Results19 studies were included which described restricted diffusion in encephalopathic neonates as compared with healthy controls, with the posterior limb of the internal capsule and the genu and splenium of the corpus callosum identified as particular regions of interest. Restricted diffusion was related to adverse outcomes in the studies that conducted a follow-up of these infants.ConclusionsObtaining diffusion measures in these key white matter tracts early in life before pseudonormalisation can occur can not only identify the extent of the damage but also can be used to examine the effectiveness of treatment and to predict neurodevelopmental outcome.

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