Subcortical White Matter Tracts Research Articles

NIMG-39. THE “RESECTABILITY INDEX” AS A NOVEL OBJECTIVE PREDICTOR OF SURVIVAL FOR PATIENTS WITH ADULT-TYPE DIFFUSE GLIOMAS

Abstract Extent of resection (EOR) is a strong prognostic factor for patients with adult-type diffuse gliomas. Whole brain tractography (WBT) allows visualization of tumors in relation to functional subcortical white matter tracts connecting eloquent cortex. We developed a preoperative metric, the resectability index (RI), to estimate tumor resectability based on pre-resection volume (PRV) and unresectable tumor volume (UTV). We explore if RI predicts progression-free survival (PFS) and overall survival (OS). We retrospectively reviewed the charts of consecutive patients with adult-type diffuse gliomas resected from 2013-2020. Only patients with pre-operative DTI MRIs were included. UTV was the total overlapping volume of tumor with functionally significant tracts (corticospinal, arcuate, optic, fornix) and deep structures (basal ganglia, thalamus, brainstem). RI was (PRV-UTV)/PRV. Seventy-nine patients were included with an average age of 56 years at time of surgery. Glioblastoma was the most common histology (68%). Tumors were located in the left hemisphere (LH) (48%), right hemisphere (RH) (39%), and bilateral hemispheres or midline (BHM) (13%). EOR for LH, RH, and BHM tumors was 0.8, 0.91, and 0.29, respectively (P = 0.1^7). RI for LH, RH, and BHM tumors was 0.86, 0.912, and 0.44, respectively (P = 0.00021). Cox regression was used to model PFS and OS based on age, preoperative KPS, WHO grade, EOR, and RI. Age, recurrent status, bilaterality, residual tumor volume (RTV) and UTV predicted PFS (CI = 1.01 – 1.06, P = 0.002). For OS, UTV and RI were more strongly predictive than RTV or EOR. In a Cox regression model consisting only of preoperative variables, RI was independently predictive of OS. RI is a novel metric with potential efficacy for preoperative survival prognostication in patients with diffuse gliomas. RI may enable neurosurgeons to provide HGG patients with more accurate information about expected benefits of surgical intervention than is currently possible. RI will also enable more valid comparisons of HGG patient cohorts treated at different institutions.

THE IMPACT OF THE FRONTAL ASLANT TRACT ON POST-OPERATIVE OUTCOMES IN GLIOMA SURGERY

Abstract AIMS The frontal aslant tract (FAT) has a role in speech and language functions and visual-motor activities. It is also not clear whether location of FAT relative to gliomas affects post-operative motor and language outcomes. Our hypothesis is FAT protects the cortico-spinal tract and other subcortical white matter tracts involved in speech. METHOD We conducted a retrospective cohort study. We used electronic patient records to search for all patients who had frontal tumours resected between Jan 2018 and August 2022. We included all adult patients (>18 years) with gliomas located in the SMA region and dorsal premotor cortex who had pre-op diffusion tensor imaging and underwent debulking / resection surgery. The patients were divided into 3 groups based on the location of the tumour relative to FAT. In group 1 patients had tumours located anterior to FAT, in group 2 patients had tumours infiltrating FAT and in group 3 patients had tumours located posterior to FAT. Our outcome measure was new post-operative language or motor deficit. RESULTS Our search yielded 197 patients, of these 43 fulfilled the inclusion criteria. Sixteen patients were included in group 1, 9 patients included in group 2 and 18 included in group 3. Pre-operative motor deficit was significantly more common in patients with tumours posterior to FAT (p=0.046). Post-operative motor deficit at hospital discharge was also more common on this group of patients (p=0.048). At 6 months follow up there was no significant difference post-operative motor and language deficits between the groups but there was a trend towards worse motor outcomes in patients with tumour located posterior to FAT. CONCLUSION There is a suggestion motor outcomes are worse in tumours located posterior to FAT. This can be considered when counselling patients for surgery with tumours related to FAT.

Surgical Management for Primary Intracerebral Hemorrhage.

The incidence of primary intracerebral hemorrhage (ICH) is increasing, particularly in younger patients, in part, because of increased prescription of anticoagulants. The ICH incidence rate from 2016 to 2018 in the United States was nearly 79 per 100,000 person-years and as high as 367 per 100,000 person-years among those 75 years or older. Worldwide, ICH comprises 28% of all new strokes, but a higher disease burden than ischemic stroke because of its higher morbidity and mortality. While mortality seems to be decreasing, functional outcomes are not improving. After negative trials of open surgical evacuation, recent trials of medical management strategies including intensive blood pressure control and prothrombotic agents intended to reduce hematoma expansion failed to demonstrate efficacy. Concomitantly, continued interest in minimally invasive surgical approaches arose from appreciation of secondary iatrogenic injury incurred to subcortical white matter tracts from open surgical techniques. A positive trial of minimally invasive surgery for lobar hemorrhage has recently been reported, bringing new optimism and demanding a reconsideration of surgical management of ICH. In this narrative review, we summarize the landmark studies, review recent literature, and consider the outstanding questions surrounding surgical management of ICH.

Facilitating complete resection of intrinsic motor cortex glioma with titration of high-frequency cortico-subcortical mapping train count informed by navigated transcranial magnetic stimulation: illustrative case.

The dilemma of neuro-oncological surgery involving suspected eloquent cortex is to maximize the extent of resection while minimizing neurological morbidity, referred to as the "onco-functional balance." Diffuse lower-grade gliomas are capable of infiltrating or displacing neural function within cortical regions and subcortical white matter tracts, which can render classical anatomic associations of eloquent function misleading. This study employed presurgical navigated transcranial magnetic stimulation (nTMS) to determine the motor eloquence of a diffuse lower-grade glioma at the superior frontal gyrus extending and intrinsic to the primary motor cortex in a 45-year-old female. Positive nTMS findings were confirmed intraoperatively with high-frequency direct cortico-subcortical stimulation (HF-DCS). Modification of the HF-DCS train count from train-of-five to train-of-two permitted resection beyond classic anatomical boundaries and conventional HF-DCS safe stopping criteria. Anatomical correlates of function can inaccurately inform the surgical management of diffuse lower-grade glioma, which represents the utmost opportunity for progression-free survival. Integrating an individually tailored nTMS-DCS surgical strategy contributed to complete resection, negating the requirement for adjuvant therapy. Serial nTMS follow-up may assist with the characterization of tumor-induced functional reorganization. https://thejns.org/doi/10.3171/CASE24197.

Dissociation of Broca's area from Broca's aphasia in patients undergoing neurosurgical resections.

Broca's aphasia is a syndrome of impaired fluency with retained comprehension. The authors used an unbiased algorithm to examine which neuroanatomical areas are most likely to result in Broca's aphasia following surgical lesions. Patients were prospectively evaluated with standardized language batteries before and after surgery. Broca's area was defined anatomically as the pars opercularis and triangularis of the inferior frontal gyrus. Broca's aphasia was defined by the Western Aphasia Battery language assessment. Resections were outlined from MRI scans to construct 3D volumes of interest. These were aligned using a nonlinear transformation to Montreal Neurological Institute brain space. A voxel-based lesion-symptom mapping (VLSM) algorithm was used to test for areas statistically associated with Broca's aphasia when incorporated into a resection, as well as areas associated with deficits in fluency independent of Western Aphasia Battery classification. Postoperative MRI scans were reviewed in blinded fashion to estimate the percentage resection of Broca's area compared to areas identified using the VLSM algorithm. A total of 289 patients had early language evaluations, of whom 19 had postoperative Broca's aphasia. VLSM analysis revealed an area that was highly correlated (p < 0.001) with Broca's aphasia, spanning ventral sensorimotor cortex and supramarginal gyri, as well as extending into subcortical white matter tracts. Reduced fluency scores were significantly associated with an overlapping region of interest. The fluency score was negatively correlated with fraction of resected precentral, postcentral, and supramarginal components of the VLSM area. Broca's aphasia does not typically arise from neurosurgical resections in Broca's area. When Broca's aphasia does occur after surgery, it is typically in the early postoperative period, improves by 1 month, and is associated with resections of ventral sensorimotor cortex and supramarginal gyri.

Usability of mixed reality in awake craniotomy planning

Purpose This study aimed to describe our institutional use of a commercially available mixed reality viewer within a multi-disciplinary planning workflow for awake craniotomy surgery and to report an assessment of its usability. Materials and methods Three Tesla MRI scans, including 32-direction diffusion tensor sequences, were reconstructed with BrainLab Elements auto-segmentation software. Magic Leap mixed reality viewer headsets were registered to a shared virtual viewing space to display image reconstructions. System Usability Scale was used to assess the usability of the mixed reality system. Results The awake craniotomy planning workflow utilises the mixed reality viewer to facilitate a stepwise discussion through four progressive anatomical layers; the skin, cerebral cortex, subcortical white matter tracts and tumour with surrounding vasculature. At each stage relevant members of the multi-disciplinary team review key operative considerations, including patient positioning, cortical and subcortical speech mapping protocols and surgical approaches to the tumour. The mixed reality system was used for multi-disciplinary awake craniotomy planning in 10 consecutive procedures over a 5-month period. Ten participants (2 Anaesthetists, 5 Neurosurgical trainees, 2 Speech therapists, 1 Neuropsychologist) completed System Usability Scale assessments, reporting a mean score of 71.5. Feedback highlighted the benefit of being able to rehearse important steps in the procedure, including patient positioning and anaesthetic access and visualising the testing protocol for cortical and subcortical speech mapping. Conclusions This study supports the use of mixed reality for multidisciplinary planning for awake craniotomy surgery, with an acceptable degree of usability of the interface. We highlight the need to consider the requirements of non-technical, non-neurosurgical team members when involving mixed reality activities.

Giant Cell Arteritis of the Superior Mesenteric Artery Presenting With Wernicke Encephalopathy From Thiamine Deficiency

Objective N/A. Background Giant cell arteritis (GCA) is one of the most common systemic vasculitides in adults over the age of 50 with incidence ranging from 15 to 35 per 100,000 individuals. The disorder is often included in the differential diagnosis of maladies producing atypical facial pain, headache, visual loss, amaurosis fugax, jaw pain, elevated inflammatory markers, and anemia. GCA is typically known to affect cranial arteries with physical exam findings of tenderness to palpation of the temporal arteries and cranial neuropathies. Clinical diagnosis is further supported by new headache, temporal artery abnormality, elevated ESR (= 50 mm/h), and abnormal artery biopsy. Design/Methods N/A. Results A 68-year-old female with history of primary generalized seizures presented to clinic with a 6-week history of paroxysms of acute confusional episodes, the inability to arise from a seated position due to lower extremity weakness bilaterally, alterations of consciousness without loss of consciousness, severe anorexia, and weight loss. MRI with contrast including Axial FLAIR/T2/Diffusion revealed bilateral pan-lobar cortical and subcortical atrophy with ex-vacuo ventriculomegaly and mild leukoaraiosis in the subcortical white matter tracts. PET-CT body revealed linear uptake involving the aortic root, extending into subclavian arteries bilaterally with segmental involvement of proximal common carotids, and extending inferiorly to the level of the common iliac arteries and the mesenteric arteries. Temporal artery biopsy revealed presence of granulomas with multinucleated giant cells. Serology panel revealed pan hypovitaminoses in Vitamins A, B1, B6, B12, and D. Conclusions Traditional GCA workup initially resulted inconclusive for the patient, whose condition deteriorated as the patient's altered mental status and dizziness spells continued unremittingly. This case highlights the link between large vessel vasculitis and malabsorption syndromes, with the involvement of the superior mesenteric artery, a medium sized vessel, in GCA previously unrecognized. Furthermore, this case is a superb example of multiple etiologies of treatable causes of reversible dementia.

Usability of Mixed Reality in Awake Craniotomy Planning

Abstract AIMS This study aimed to describe our institutional use of a commercially available mixed reality viewer within a multi-disciplinary planning workflow for awake craniotomy surgery and to report an assessment of its usability. METHOD Three Tesla MRI scans, including 32-direction diffusion tensor sequences, were reconstructed with BrainLab Elements auto-segmentation software. Magic Leap mixed reality viewer headsets were registered to a shared virtual viewing space to display image reconstructions. System Usability Scale was used to assess the usability of the mixed reality system. RESULTS The awake craniotomy planning workflow utilises the mixed reality viewer to facilitate a stepwise discussion through four progressive anatomical layers; skin, cerebral cortex, subcortical white matter tracts and tumour with surrounding vasculature. At each stage relevant members of the multi-disciplinary team reviewed key operative considerations, including patient positioning, cortical and subcortical speech mapping protocols and surgical approaches to the tumour. The mixed reality system was used in 10 consecutive awake craniotomy procedures over a 5-month period. Ten participants (2 Anaesthetists, 5 Neurosurgical trainees, 2 Speech therapists, 1 Neuropsychologist) completed System Usability Scale assessments, reporting a mean score of 71.5. Feedback highlighted the benefit of being able to rehearse important steps in the procedure, including patient positioning and anaesthetic access and visualising the testing protocol for cortical and subcortical speech mapping. CONCLUSION This study supports the use of mixed reality for multi-disciplinary planning for awake craniotomy surgery, with an acceptable degree of interface usability. We highlight the need to consider the requirements of non-technical, non-neurosurgical team members when involving mixed reality activities.

Functional Approaches to the Surgery of Brain Gliomas.

In the surgery of gliomas, recent years have witnessed unprecedented theoretical and technical development, which extensively increased indication to surgery. On one hand, it has been solidly demonstrated the impact of gross total resection on life expectancy. On the other hand, the paradigm shift from classical cortical localization of brain function towards connectomics caused by the resurgence of awake surgery and the advent of tractography has permitted safer surgeries focused on subcortical white matter tracts preservation and allowed for surgical resections within regions, such as Broca's area or the primary motor cortex, which were previously deemed inoperable. Furthermore, new asleep electrophysiological techniques have been developed whenever awake surgery is not an option, such as operating in situations of poor compliance (including paediatric patients) or pre-existing neurological deficits. One such strategy is the use of intraoperative neurophysiological monitoring (IONM), enabling the identification and preservation of functionally defined, but anatomically ambiguous, cortico-subcortical structures through mapping and monitoring techniques. These advances tie in with novel challenges, specifically risk prediction and the impact of neuroplasticity, the indication for tumour resection beyond visible borders, or supratotal resection, and most of all, a reappraisal of the importance of the right hemisphere from early psychosurgery to mapping and preservation of social behaviour, executive control, and decision making.Here we review current advances and future perspectives in a functional approach to glioma surgery.

Anatomy and White Matter Connections of the Middle Frontal Gyrus

The middle frontal gyrus (MFG) is involved in attention, working memory, and language-related processing. A detailed understanding of the subcortical white matter tracts connected within the MFG can facilitate improved navigation of white matter lesions in and around this gyrus and explain the postoperative morbidity after surgery. We aimed to characterize the fiber tracts within the MFG according to their connection to neuroanatomic structures through the use of diffusion spectrum imaging-based fiber tractography and validate the findings by gross anatomic dissection for qualitative visual agreement. Tractography analysis was completed using diffusion imaging data from 10 healthy, adult subjects enrolled in the Human Connectome Project. We assessed the MFG as a whole component according to its fiber connectivity with other neural regions. Mapping was completed on all tracts within both hemispheres, with the resultant tract volumes used to calculate a lateralization index. A modified Klingler technique was used on 10 postmortem dissections to demonstrate the location and orientation of the major tracts. Two major connections of the MFG were identified: the superior longitudinal fasciculus, which connects the MFG to parts of the inferior parietal lobule, posterior temporal lobe, and lateral occipital cortex; and the inferior fronto-occipital fasciculus, which connected the MFG to the lingual gyrus and cuneus. Intra- and intergyral short association, U-shaped fibers were also identified. Subcortical white matter pathways integrated within the MFG include the superior longitudinal fasciculus and inferior fronto-occipital fasciculus. The MFG is implicated in a variety of tasks involving attention and memory, making it an important cortical region. The postoperative neurologic outcomes related to surgery in and around the MFG could be clarified in the context of the anatomy of the fiber bundles highlighted in the present study.

488 Understanding astrocyte responses to perinatal white matter injury and their role in disease pathogenesis

White matter injury (WMI) is a complication of preterm birth and a major cause of long-term neurological morbidity. The disease is characterized by reactive microgliosis and astrocytosis, defective oligodendrocyte maturation, and in severe cases, neuronal death. Reactive astrocytes are known to play important roles in the pathogenesis of many diseases, in some cases favoring repair and in others contributing to neurodegeneration. The specific nature of astrocyte reactivity after WMI remains obscure. Here we report the results of experiments aimed to define astrocyte polarization after white matter injury and its contribution to disease outcomes. WMI was induced in 2 day-old rat pups using a combination of hypoxic-ischemic and inflammatory insults. We used immunopanning to purify astrocytes from brains of injured and control rats. mRNA isolated from these cells was used for microfluidic qRT-PCR analysis of a panel of known markers of reactive astrocyte subtypes. In situ hybridization was used to define the spatial distribution of the reactive astrocytes within the rodent brain. In situ hybridization experiments demonstrate the presence of inflammatory reactive astrocytes in subcortical white matter tracts after WMI in our rodent disease model. qRT-PCR using mRNA from pre- and post-injury astrocytes reveals the temporal regulation of astrocyte reactivity over time after injury. Ongoing experiments using transgenic mice aim to modulate the astrocyte response to WMI and to quantify consequent changes in disease outcomes. We demonstrate the formation of inflammatory reactive astrocytes in a rodent model of WMI and present work in progress to characterize the astrocyte response in perinatal WMI. Should ongoing experiments demonstrate that the formation of inflammatory astrocytes is a pivotal step in WMI pathophysiology, this finding will open the door to new therapeutic strategies for the treatment of WMI.

Grey and white matter network disruption is associated with sensory deficits after stroke

Somatosensory deficits after ischaemic stroke are common and can occur in patients with lesions in the anterior parietal cortex and subcortical nuclei. It is less clear to what extent damage to white matter tracts within the somatosensory system may contribute to somatosensory deficits after stroke. We compared the roles of cortical damage and disruption of subcortical white matter tracts as correlates of somatosensory deficit after ischaemic stroke.Clinical and imaging data were assessed in incident stroke patients. Somatosensory deficits were measured using a standardized somatosensory test. Remote effects were quantified by projecting the MRI-based segmented stroke lesions onto a predefined atlas of white matter connectivity. Direct ischaemic damage to grey matter was computed by lesion overlap with grey matter areas. The association between lesion impact scores and sensory deficit was assessed statistically.In 101 patients, median sensory score was 188/193 (97.4%). Lesion volume was associated with somatosensory deficit, explaining 23.3% of variance. Beyond this, the stroke-induced grey and white matter disruption within a subnetwork of the postcentral, supramarginal, and transverse temporal gyri explained an additional 14% of the somatosensory outcome variability. On mutual comparison, white matter network disruption was a stronger predictor than grey matter damage.Ischaemic damage to both grey and white matter are structural correlates of acute somatosensory disturbance after ischaemic stroke. Our data suggest that white matter integrity of a somatosensory network of primary and secondary cortex is a prerequisite for normal processing of somatosensory inputs and might be considered as an additional parameter for stroke outcome prediction in the future.

Minimally invasive tubular corticotomy using “Dandy cannula-glove technique” for trans-cortical approaches to the ventricular lesions. Technical note

Access to deep-seated intraventricular lesions frequently requires a focal corticotomy to allow adequate exposure of the affected area. This is necessary to create a surgical corridor to the lesion. However, this may lead to iatrogenic trauma of healthy cortical tissue, subcortical white matter tracts, cortical and subependymal veins. A sulcal approach minimises length of the trajectory through healthy brain tissue but still involves substantial destruction of grey and white matter structures. The conventional corticotomy involves coagulation or suctioning of considerable volume of tissue until the lesion is reached. To minimise damage to the normal brain tissue during ventricular access, the authors describe a technique using Dandy cannula and a finger of an ordinary surgical rubber glove to access ventricle and to obtain the much-desired radial exposure through a tubular corridor. In addition, the Dandy cannula can be linked to frameless neuronavigation to facilitate accurate and shortest trajectory to the lesion.

Single Cortical Microinfarcts Lead to Widespread Microglia/Macrophage Migration Along the White Matter

Loss of cognitive function with aging is a complex and poorly understood process. Recently, clinical research has linked the occurrence of cortical microinfarcts to cognitive decline. Cortical microinfarcts form following the occlusion of penetrating vessels and are considered to be restricted to the proximity of the occluded vessel. Whether and how such local events propagate and affect remote brain regions remain unknown. To this end, we combined histological analysis and longitudinal diffusion tensor imaging (DTI), following the targeted-photothrombotic occlusion of single cortical penetrating vessels. Occlusions resulted in distant tissue reorganization across the mouse brain. This remodeling co-occurred with the formation of a microglia/macrophage migratory path along subcortical white matter tracts, reaching the contralateral hemisphere through the corpus callosum and leaving a microstructural signature detected by DTI-tractography. CX3CR1-deficient mice exhibited shorter trail lengths, differential remodeling, and only ipsilateral white matter tract changes. We concluded that microinfarcts lead to brain-wide remodeling in a microglial CX3CR1-dependent manner.

Optimizing the onco-functional balance in supratentorial brain tumour surgery: A single institution’s initial experience with intraoperative cortico-subcortical mapping and monitoring in Singapore

Intraoperative cortical mapping provides functional information that permits the safe and maximal resection of supratentorial lesions infiltrating the so-called eloquent cortex or subcortical white matter tracts. Primary and secondary brain tumours located in eloquent cortex can render surgical treatment ineffective if it results in new or worsening neurology. A cohort of forty-six consecutive patients with supratentorial tumours of variable pathology involving eloquent cortical regions and aided with intraoperative neurophysiology were included for retrospective analysis at a single-centre tertiary institution. Intraoperative neurophysiological data has been related to immediate post-operative neurologic status as well as 3-month follow-up in patients that underwent awake or asleep surgical resection. Patients that experienced new or worsening neurologic symptoms post-operatively demonstrated a high incidence of recovery at 3-months. Those without new neurologic symptoms post-operatively demonstrated little to no worsening at 3-months. Our study explored the extent to which cortical mapping permitted safe surgical resection whilst preserving neurologic function. To the authors’ knowledge this is the first documented case series in Singapore that has incorporated a systematic and individually tailored multimodal workflow to cortico-subcortical mapping and monitoring for the safe resection of infiltrative lesions of the supratentorial region.

Anatomy and white matter connections of the lateral occipital cortex.

White matter tracts link different regions of the brain, and the known functions of those interconnected regions may offer clues about the roles that white matter tracts play in information relay. The authors of this report discuss the structure and function of the lateral occipital lobe and how the lateral occipital lobe communicates with other regions via white matter tracts. The authors used generalized q-sampling imaging and cadaveric brain dissections to uncover the subcortical white matter connections of the lateral occipital lobe. The authors created GQI of ten healthy controls and dissected ten cadaveric brains. The middle longitudinal fasciculus, vertical occipital fasciculus, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiations, and a diverse array of U-shaped fibers connect the lateral occipital lobe to itself, parts of the temporal, parietal, and medial occipital cortices. The complex functional processes attributed to the lateral occipital lobe, including object recognition, facial recognition, and motion perception are likely related to the subcortical white matter tracts described within this study. There was good concordance between the white matter tracts generated using GQI and the white matter tracts that were found after dissection of the cadaveric brains. This article presents the anatomic connections of the lateral occipital lobe and discusses the associated functions.

Benefits of MR Diffusion Tensor Imaging and Fiber Tractography Over Conventional MRI in Preoperative Evaluation of Pediatric Brain Tumors

AbstractBackground: Diffusion tensor imaging (DTI) is a nonin-vasive magnetic resonance imaging (MRI) modality which accurately shows the location and orientation of subcortical white matter (WM) tracts. The surgeon benefits from DTI as it depicts the relationship of the intra-axial tumor to local WM tracts in multiple planes.Aim of Study: The purpose of this study is to evaluate the role of MR diffusion tensor imaging and fiber tractography and its benefits over conventional MRI in accurate preoperative localization of important eloquent areas in pediatric brain tissue and their relation to the brain tumor. The aim of the study is to help the surgeon in planning his surgical corridor which causes the least damage and minimizes the postoperative neurological deficits.Patients and Methods: A total of fifty patients with brain tumors were included in this study using pre-operative contrast-enhanced magnetic resonance imaging and DTI fiber tractog-raphy for preoperative localization of important white matter tracts. Diffusion tensor imaging, by improving the recognition and characterization of white matter tracts, offers a glimpse into the brain microstructure at a scale that is not easily accessible with other modalities.Results: The extent of white matter pathway involvement was clearly identified in all patients by using color-coded DT imaging maps and MR Tractography.The study revealed that the most common tract involve-ment pattern detected was pattern (displacement). It was seen in 36 cases representing 72% of all cases. Pattern I (not affected) was detected in 6 cases representing 12%. Pattern III (edematous) was detected in 11 cases representing 22%. Pattern IV (partially disrupted) was detected in 13 cases representing 26%. Pattern V (destroyed) was detected in 3 cases representing 6%. Combined pattern of affection has been detected in most of the cases.Conclusion: The effect of cerebral neoplasms on white matter pathways is not precisely understood with the aid of standard diagnostic modalities. Diffusion-tensor imaging allowed for the preoperative identification of white matter pathways involved by tumor but the preoperative planning should be optimally complemented by various intraoperative procedures in order to insure a good neurological outcome of the surgery and valid functional prognosis.

Time course images of cellular injury and recovery in murine brain with high-resolution GRIN lens system

Time course, in vivo imaging of brain cells is crucial to fully understand the progression of secondary cellular damage and recovery in murine models of injury. We have combined high-resolution gradient index lens technology with a model of diffuse axonal injury in rodents to enable repeated visualization of fine features of individual cells in three-dimensional space over several weeks. For example, we recorded changes in morphology in the same axons in the external capsule numerous times over 30 to 60 days, before and after induced traumatic brain injury. We observed the expansion of secondary injury and limited recovery of individual axons in this subcortical white matter tract over time. In another application, changes in microglial activation state were visualized in the penumbra region of mice before and after ischemia induced by middle carotid artery occlusion. The ability to collect a series of high-resolution images of cellular features of the same cells pre- and post-injury enables a unique opportunity to study the progression of damage, spontaneous healing, and effects of therapeutics in mouse models of neurodegenerative disease and brain injury.

The Effect of Antenatal Betamethasone on White Matter Inflammation and Injury in Fetal Sheep and Ventilated Preterm Lambs

Antenatal administration of betamethasone (BM) is a common antecedent of preterm birth, but there is limited information about its impact on the acute evolution of preterm neonatal brain injury. We aimed to compare the effects of maternal BM in combination with mechanical ventilation on the white matter (WM) of late preterm sheep. At 0.85 of gestation, pregnant ewes were randomly assigned to receive intra-muscular (i.m.) saline (n = 9) or i.m. BM (n = 13). Lambs were delivered and unventilated controls (UVC_Sal, n = 4; UVC_BM, n = 6) were humanely killed without intervention; ventilated lambs (Vent_Sal, n = 5; Vent_BM, n = 7) were injuriously ventilated for 15 min, followed by conventional ventilation for 75 min. Cardiovascular and cerebral haemodynamics and oxygenation were measured continuously. The cerebral WM underwent assessment of inflammation and injury, and oxidative stress was measured in the cerebrospinal fluid (CSF). In the periventricular and subcortical WM tracts, the proportion of amoeboid (activated) microglia, the density of astrocytes, and the number of blood vessels with protein extravasation were higher in UVC_BM than in UVC_Sal (p < 0.05 for all). During ventilation, tidal volume, mean arterial pressure, carotid blood flow, and oxygen delivery were higher in ­Vent_BM lambs (p < 0.05 vs. Vent_Sal). In the subcortical WM, microglial infiltration was increased in the Vent_Sal group compared to UVC_Sal. The proportion of activated microglia and protein extravasation was higher in the Vent_BM group compared to Vent_Sal within the periventricular and subcortical WM tracts (p < 0.05). CSF oxidative stress was increased in the Vent_BM group compared to UVC_Sal, UVC_BM, and Vent_Sal groups (p < 0.05). Antenatal BM was associated with inflammation and vascular permeability in the WM of late preterm fetal sheep. During the immediate neonatal period, the increased carotid perfusion and oxygen delivery in BM-treated lambs was associated with increased oxidative stress, microglial activation and microvascular injury.

Using 3D spatial correlations to improve the noise robustness of multi component analysis of 3D multi echo quantitative T2 relaxometry data

PurposeWe present a computationally feasible and iterative multi-voxel spatially regularized algorithm for myelin water fraction (MWF) reconstruction. This method utilizes 3D spatial correlations present in anatomical/pathological tissues and underlying B1+-inhomogeneity or flip angle inhomogeneity to enhance the noise robustness of the reconstruction while intrinsically accounting for stimulated echo contributions using T2-distribution data alone. MethodsSimulated data and in vivo data acquired using 3D non-selective multi-echo spin echo (3DNS-MESE) were used to compare the reconstruction quality of the proposed approach against those of the popular algorithm (the method by Prasloski et al.) and our previously proposed 2D multi-slice spatial regularization spatial regularization approach. We also investigated whether the inter-sequence correlations and agreements improved as a result of the proposed approach. MWF-quantifications from two sequences, 3DNS-MESE vs 3DNS-gradient and spin echo (3DNS-GRASE), were compared for both reconstruction approaches to assess correlations and agreements between inter-sequence MWF-value pairs. MWF values from whole-brain data of six volunteers and two multiple sclerosis patients are being reported as well. ResultsIn comparison with competing approaches such as Prasloski's method or our previously proposed 2D multi-slice spatial regularization method, the proposed method showed better agreements with simulated truths using regression analyses and Bland-Altman analyses. For 3DNS-MESE data, MWF-maps reconstructed using the proposed algorithm provided better depictions of white matter structures in subcortical areas adjoining gray matter which agreed more closely with corresponding contrasts on T2-weighted images than MWF-maps reconstructed with the method by Prasloski et al. We also achieved a higher level of correlations and agreements between inter-sequence (3DNS-MESE vs 3DNS-GRASE) MWF-value pairs. ConclusionThe proposed algorithm provides more noise-robust fits to T2-decay data and improves MWF-quantifications in white matter structures especially in the sub-cortical white matter and major white matter tract regions.