We would like to thank the whole Service of Neuroradiology. We would like to thank Lis Prussen for her work in the library.

NOTA: Este protocolo segue as orientações do Centre Hospitalier de Luxembourg no Luxemburgo. 1 Preparação de Diffusion Tensor Imaging para a via visual para Neurocirurgia e Acompanhamento <ol style="margin-left: 40px;"><li> Realizar uma ressonância magnética-scan pelo menos um dia antes da cirurgia estritamente axial usando 32 direções de gradiente e um b0-imagem. Tenha em estreito contato com a unidade de neurorradiologia a qualquer momento. NOTA: Adicione claro para o neurorradiologista que as imagens após a cirurgia são as mesmas que aquelas antes da operação. </li><li> Usando um de 3 Tesla MRI, faça uma 3DT1 ponderadas e DTI-seqüência scans. Realizar uma seqüência 3DT1 ponderada após a cirurgia também. </li></ol> 2 usando a estação de Planejamento <ol><li> Transfira os dados de varredura em T2, 3DT1 ponderada e DTI-seqüência de imagem digital e comunicações em medicina (DICOM). Este procedimento leva até 7 min. NOTA: Don `t parar o procedimento before ter transferido todas as seqüências. É possível parar e continuar mais tarde, dependendo da data da cirurgia. </li><li> Abra o programa de sistema de navegação cirúrgica. Clique em Arquivo e depois em Importar DICOM. Repetir este procedimento três vezes para todas as sequências acima mencionadas. <ol><li> Clique em Adicionar para exibir. Adicionar cada seqüência separadamente. Don `t tentar prosseguir com Vista. </li></ol></li><li> Clique em Ferramentas. Abrir preparação DTI Tensor. Observar uma nova janela no meio do ecrã. </li><li> Conclua as seguintes quatro etapas. <ol><li> Realizar Atribuição Gradiente como o primeiro passo. <ol><li> Altere o valor de b de 1.000 para 800 s / mm ² na parte inferior direita da janela. </li><li> Ajustar o limite no canto superior direito da janela. Fazê-lo manualmente, basta escrever um número ou mover um cursor. 20 pode ser um valor aceitável. É uma experiência pessoal e não é obrigatório. </li></ol></li><li> Realizar o registro de Gradient como a segunda etapa. <ol> &lt;li&gt; Clique no botão All Auto. Este procedimento leva até 5 min. </li><li> Clique em Verificar todos os registros. Sem verificar os registos de que não é possível continuar. </li></ol></li><li> Co-registro executar como o terceiro passo. <ol><li> Coregister MR1 e imagens MR2 B0 manualmente. No final, verificar todas as inscrições. NOTA: É possível executar este passo automaticamente. No entanto, os resultados podem não ser sempre satisfatório no final. </li></ol></li><li> Realize Tensor computação como a quarta e última etapa, <ol><li> Certifique-se de FA / DEC / ADC estão ligados. Se não clicar. </li><li> Clique em Calcular. Este procedimento levará apenas alguns segundos. </li></ol></li></ol></li><li> Salve todos os dados e continuar com fibertracking. Não pare sem salvar tudo. </li></ol> 3. Fibertracking NOTA: Anatomic conhecimento da via visual é muito importante para o sucesso da técnica. <ol stYLE = &quot;margin-left: 40px;&quot;&gt; <li> Prepare-se para encontrar os três pontos importantes onde as fibras têm que passar. </li><li> Determine o quiasma usando conhecimento anatômico. <ol><li> Use um ROI como ponto de partida e deixar que as fibras passam. ROIs são definidos pelo médico. </li><li> Alternativamente, o segmento na região suspeita. Clique Segmentação no canto inferior esquerdo e outra janela aparecerá. Áreas segmentadas são áreas anatomicamente definido. <ol><li> Pinte a região manualmente. Vá para cima e para baixo para incluir todo o quiasma. Salve o procedimento e voltar. </li></ol></li><li> Rastrear as fibras quer a partir da região de interesse ou para a área segmentada ou ambos. </li><li> As fibras de atingir o núcleo geniculado esquerda (LGN), que é o segundo ponto importante da via visual. O ângulo máximo era de 50 O risco de falsos tractos surgirá se o ângulo é demasiado elevada. <ol><li> Existe a possibilidade de segmentar o LGN como mostrado com o quiasmae acompanhar as fibras. Depois de ter segmentado quiasma óptico, fibras pista que correm do LGN e de chegada no quiasma ou vice-versa. </li></ol></li><li> Segmento do córtex visual. Proceder como no caso do quiasma. Isso pode levar algum tempo como imagem 3DT1 ponderada contém 160 fatias. </li><li> Rastrear as fibras do córtex visual do LGN. É possível controlá-los a partir do LGN para o córtex visual bem. </li><li> Se o córtex visual é invadido por tumor ou edema, em seguida, usar uma região de interesse no local de uma zona segmentada e, em seguida, deixar as fibras correm na direcção do LGN. NOTA: Se o edema é segmentado por vezes, pode invadir o córtex visual, em seguida, em seguida, o córtex visual pode não ser capaz de segmentado totalmente porque o computador não posso distinguir entre eles. Isso é porque é necessário colocar um ROI. </li><li> Repita tudo para o outro hemisfério. </li><li> Comece com o hemisfério saudável em primeiro lugar. Nota:É possível começar com o outro também, mas talvez seja mais fácil para acompanhar as fibras do hemisfério saudável primeiro a tornar-se uma primeira ideia sobre a situação. Não é obrigatório, é apenas um conselho. </li></ol></li><li> Segmento da lesão cerebral e do edema. Proceder como mencionado acima, no ponto 3.2.2. <ol><li> Atribua uma cor para cada área segmentada ou lesão, a fim de distinguir melhor. </li></ol></li><li> Salve o procedimento após cada etapa, no caso de acontecimentos imprevistos ou em caso de uma emergência. </li><li> Exportar todos os dados localmente. É possível exportá-la para a sala de operações diretamente, mas ele isn `t recomendado. <ol><li> Pressione Arquivo e depois exportar objetos 3D. Certifique-se de exportar apenas o exame de navegação. </li><li> Don `t exportar o Exame Hybrid. </li></ol></li><li> Digite craniana. Escolha o paciente certo, em seguida, pressione Stealthmerge. Escolha imagens 3DT1 ponderadas como exame de referência. </li><li> Criar um modelo 3D e inserir tudo. </li><li> Importe o i dadosn sala de operação. </li></ol>

<ol>
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The authors declare that they have no competing financial interests.

DTI é uma técnica que permite o neurocirurgião visualizar tratos de substância branca in vivo 8. O caminho visual é um desses intervalos. Embora este método fornece aos médicos novas possibilidades em relação ao tratamento de pacientes com lesões relativas às regiões eloquentes do cérebro que temos a dizer que algumas limitações desta técnica ainda existem. A primeira e mais óbvia desafio é mudança cérebro, que continua sendo um problema sob investigação 4. Após a ab...

Imagiologia tensor de difusão (DTI) é usado para representar WMT de forma não invasiva no cérebro humano 1. Tem sido usado na última década para reduzir o risco de prejudicar eloquentes áreas do cérebro durante uma cirurgia. DTI foi realizada em cinqüenta pacientes entre Março de 2012 e Janeiro de 2014 e retratam a via visual. DTI pode melhorar a preservação de áreas eloqüentes do cérebro durante a cirurgia, fornecendo informações importantes sobre a localização anatômica de tratos de substância branca. Foi incorporada ao planejamento estratégico para ressecção de lesões cerebrais complexos 1. No entanto, o retrato da via visual continua a ser um desafio, porque não existe um padrão para os parâmetros de DTI, a colocação dos volumes e interpretação dos resultados de 12 sementes. Diferentes algoritmos foram implementados até agora 19-21. Algumas abordagens concentrado em métodos determinísticos 19, 22-25. Outros estavam usando métodos probabilísticos, 26,27,29. Mais recentemente, técnicas usando campos tensores Q-bola, da difusão espectral e alta resolução angular de difusão de imagens (Hardi) estão sendo usados ​​para descrever tratos de substância branca, entre outros a via visual 1,13-15,18. No entanto, o tempo necessário para HARDI é significativamente maior com 45 min, o software não está disponível comercialmente e enfatiza as aplicações científicas 18. O período de ensino para Hardi parece ser maior do que para o DTI 18. O protocolo apresentado é fácil viável e pode ser utilizado para a rotina diária em operações neurocirúrgicas, a fim de evitar a morbidade e melhorar o resultado de pós-operatório. O tempo adicional para este protocolo é inferior a 9 min que é significativamente mais rápido do que outros protocolos 1,9,12,16. Reconhecendo o fato de que muitos algoritmos sofisticados foram desenvolvidos recentemente, os restringe de papelprópria para o uso de um software comercialmente disponível e aprovado pela FDA. No entanto, é obrigatório ter em conta as limitações desta técnica que são mencionados acima.

<table><tbody><tr><td>3-Tesla-MRI</td><td>General Electric</td><td>Signa LX version 9.1</td><td></td></tr><tr><td>Surgical Navigation System Program</td><td>Medtronic</td><td>9734478</td><td></td></tr><tr><td>Surgical Navigation System Program</td><td>Medtronic</td><td>4500810331&amp;nbsp; 20016318</td><td></td></tr></tbody></table>

dti of the visual pathway - white matter tracts and cerebral lesions

<html> DTI é uma técnica que identifica tratos de substância branca (WMT) não-invasiva em pacientes saudáveis ​​e não-saudáveis, utilizando medidas de difusão. Semelhante a vias visuais (VP), WMT não são visíveis com MRI clássica ou intra-operatório com microscópio. DIT vai ajudar neurocirurgiões para evitar a destruição da VP ao remover lesões adjacentes a este WMT. Efetuamos DTI em cinqüenta pacientes, antes e após a cirurgia, entre março de 2012 a janeiro de 2014 Para navegar usamos uma seqüência 3DT1 ponderado. Além disso, foi realizado um T2 e DTI-sequências. Os parâmetros utilizados foram, FOV: 200 x 200 mm, espessura de fatia de 2 mm, e matriz de aquisição: 96 x 96 originando voxels quase isotrópica de 2 x 2 x 2 mm. Axial MRI foi realizada utilizando um gradiente de direcção 32 e um b0-imagem. Usamos Echo-Planar-Imaging (EPI) e ASSET imagens paralelas com um fator de aceleração de 2 e b-valor de 800 s / mm ². O tempo de varredura foi inferior a 9 min. ent &quot;&gt; Os DTI-dados obtidos foram processados ​​utilizando um FDA aprovou o programa de sistema de navegação cirúrgica que utiliza uma abordagem de fibra de rastreamento simples conhecido como atribuição fibra de rastreamento contínuo (FACT). Isto é baseado na propagação de linhas entre as regiões de interesse ( ROI), que é definida por um médico. um ângulo máximo de 50, FA valor de 0,10 e valor parada ADC de 0,20 mm ² / s começar foram os parâmetros utilizados para tractography. Existem algumas limitações para esta técnica. A aquisição prazo limitado impõe trade-offs na qualidade da imagem. Outro ponto importante que não deve ser negligenciado é a mudança do cérebro durante a cirurgia. Quanto a esta última ressonância magnética intra-operatória pode ser útil. Além disso, o risco de falsos positivos, ou negativos extensões falsas precisa ser levado em conta o que pode comprometer os resultados finais.

<html> Este protocolo permite que o médico para retratar adequadamente as principais partes do VP. Ele pode ser usado com uma pequena quantidade de tempo, a fim de evitar danos em doentes com lesões cerebrais próximos de zonas eloquentes. Controlos pós-operatórios mostram também bons resultados. VP é retratado na Figura 7 após o paciente foi operado de um glioblastoma. Figura 2 mostra o vice-presidente após o retorno de um glioblastoma. Os autores reconhecem o fato de as dificul...

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DTI of the Visual Pathway - White Matter Tracts and Cerebral Lesions

Imagem por tensores de difusão (DTI) foi realizada para tentar descrever as principais partes do sistema visual. O objectivo era utilizar um FDA aprovou estação comercial padrão que pode ser usado para a rotina diária, a fim de tentar reduzir os danos de pós-operatório da via visual nos pacientes.

DTI do Caminho Visual - substância branca panfletos e Cerebral Lesões

DTI is a technique that identifies white matter tracts (WMT) non-invasively in healthy and non-healthy patients using diffusion measurements. Similar to ...

dti-of-the-visual-pathway-white-matter-tracts-and-cerebral-lesions

Research

JoVE Journal

Medicine

13.9K visualizações.  Centre Hospitalier de Luxembourg.  Imagem por tensores de difusão (DTI) foi realizada para tentar descrever as principais partes do sistema visual. O objectivo era utilizar um FDA aprovou estação comercial padrão que pode ser usado para a rotina diária, a fim de tentar reduzir os danos de pós-operatório da via visual nos pacientes. 

Vídeo: DTI of the Visual Pathway - White Matter Tracts and Cerebral Lesions

Dissection of Human Vitreous Body Elements for Proteomic Analysis

The vitreous is an optically clear, collagenous extracellular matrix that fills the inside of the eye and overlies the retina. 1,2 Abnormal interactions between vitreous substructures and the retina underlie several vitreoretinal diseases, including retinal tear and detachment, macular pucker, macular hole, age-related macular degeneration, vitreomacular traction, proliferative vitreoretinopathy, proliferative diabetic retinopathy, and inherited vitreoretinopathies. 1,2 The molecular composition of the vitreous substructures is not known. Since the vitreous body is transparent with limited surgical access, it has been difficult to study its substructures at the molecular level. We developed a method to separate and preserve these tissues for proteomic and biochemical analysis. The dissection technique in this experimental video shows how to isolate vitreous base, anterior hyaloid, vitreous core, and vitreous cortex from postmortem human eyes. One-dimensional SDS-PAGE analyses of each vitreous component showed that our dissection technique resulted in four unique protein profiles corresponding to each substructure of the human vitreous body. Identification of differentially compartmentalized proteins will reveal candidate molecules underlying various vitreoretinal diseases.

This video shows an effective technique for differentiating and dissecting the various semi-transparent structures of the human vitreous body in post mortem eyes.

Dissecção da Human Elements Corpo Vítreo para Análise Proteômica

The vitreous is an optically clear, collagenous extracellular matrix that fills the inside of the eye and overlies the retina. 1,2 Abnormal interactions ...

Medicina

Probing the Brain in Autism Using fMRI and Diffusion Tensor Imaging

Newly emerging theories suggest that the brain does not function as a cohesive unit in autism, and this discordance is reflected in the behavioral symptoms displayed by individuals with autism. While structural neuroimaging findings have provided some insights into brain abnormalities in autism, the consistency of such findings is questionable. Functional neuroimaging, on the other hand, has been more fruitful in this regard because autism is a disorder of dynamic processing and allows examination of communication between cortical networks, which appears to be where the underlying problem occurs in autism. Functional connectivity is defined as the temporal correlation of spatially separate neurological events1. Findings from a number of recent fMRI studies have supported the idea that there is weaker coordination between different parts of the brain that should be working together to accomplish complex social or language problems2,3,4,5,6. One of the mysteries of autism is the coexistence of deficits in several domains along with relatively intact, sometimes enhanced, abilities. Such complex manifestation of autism calls for a global and comprehensive examination of the disorder at the neural level. A compelling recent account of the brain functioning in autism, the cortical underconnectivity theory,2,7 provides an integrating framework for the neurobiological bases of autism. The cortical underconnectivity theory of autism suggests that any language, social, or psychological function that is dependent on the integration of multiple brain regions is susceptible to disruption as the processing demand increases. In autism, the underfunctioning of integrative circuitry in the brain may cause widespread underconnectivity. In other words, people with autism may interpret information in a piecemeal fashion at the expense of the whole. Since cortical underconnectivity among brain regions, especially the frontal cortex and more posterior areas 3,6, has now been relatively well established, we can begin to further understand brain connectivity as a critical component of autism symptomatology.
A logical next step in this direction is to examine the anatomical connections that may mediate the functional connections mentioned above. Diffusion Tensor Imaging (DTI) is a relatively novel neuroimaging technique that helps probe the diffusion of water in the brain to infer the integrity of white matter fibers. In this technique, water diffusion in the brain is examined in several directions using diffusion gradients. While functional connectivity provides information about the synchronization of brain activation across different brain areas during a task or during rest, DTI helps in understanding the underlying axonal organization which may facilitate the cross-talk among brain areas. This paper will describe these techniques as valuable tools in understanding the brain in autism and the challenges involved in this line of research.

Neuroimaging techniques, such as functional MRI and Diffusion Tensor Imaging have become increasingly useful in characterizing the cognitive and neural deficits in autism. An examination of brain connectivity in autism at a network level along with adaptations for scanning children with developmental disabilities is presented.

Sondando o cérebro no autismo utilizando fMRI e Difusão Tensor Imagem

Newly emerging theories suggest that the brain does not function as a cohesive unit in autism, and this discordance is reflected in the behavioral ...

Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when studying the brain, as the functional role that a brain area fulfills may be largely defined by its connections to other brain areas. In this report, we describe a novel, non-invasive approach for relating brain structure and function using magnetic resonance imaging (MRI). This approach, a combination of structural imaging of long-range fiber connections and functional imaging data, is illustrated in two distinct cognitive domains, visual attention and face perception. Structural imaging is performed with diffusion-weighted imaging (DWI) and fiber tractography, which track the diffusion of water molecules along white-matter fiber tracts in the brain (Figure 1). By visualizing these fiber tracts, we are able to investigate the long-range connective architecture of the brain. The results compare favorably with one of the most widely-used techniques in DWI, diffusion tensor imaging (DTI). DTI is unable to resolve complex configurations of fiber tracts, limiting its utility for constructing detailed, anatomically-informed models of brain function. In contrast, our analyses reproduce known neuroanatomy with precision and accuracy. This advantage is partly due to data acquisition procedures: while many DTI protocols measure diffusion in a small number of directions (e.g., 6 or 12), we employ a diffusion spectrum imaging (DSI)1, 2 protocol which assesses diffusion in 257 directions and at a range of magnetic gradient strengths. Moreover, DSI data allow us to use more sophisticated methods for reconstructing acquired data. In two experiments (visual attention and face perception), tractography reveals that co-active areas of the human brain are anatomically connected, supporting extant hypotheses that they form functional networks. DWI allows us to create a "circuit diagram" and reproduce it on an individual-subject basis, for the purpose of monitoring task-relevant brain activity in networks of interest.

We describe a novel approach for simultaneous analysis of brain function and structure using magnetic resonance imaging (MRI). We assess brain structure with high-resolution diffusion-weighted imaging and white-matter fiber tractography. Unlike standard structural MRI, these techniques allow us to directly relate anatomical connectivity to functional properties of brain networks.

Co-análise de estrutura e função cerebral usando ressonância magnética funcional e imagem ponderada em difusão

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when ...

Neurociência

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.

Diffusion tensor imaging (DTI) basically serves as an MRI-based tool to identify in vivo the microstructure of the brain and pathological processes due to neurological disorders within the cerebral white matter. DTI-based analyses allow for application to brain diseases both at the group level and in single subject data.

Diffusion Tensor Imagem por Ressonância Magnética na Análise de Doenças Neurodegenerativas

Diffusion tensor imaging (DTI) techniques provide information on the microstructural processes of the cerebral white matter (WM) in vivo. The present ...

Measuring Connectivity in the Primary Visual Pathway in Human Albinism Using Diffusion Tensor Imaging and Tractography

In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed as candidate sites for misrouting. Since a correlation between the number of lateral geniculate nucleus (LGN) relay neurons and LGN size has been shown, and based on previously reported reductions in LGN volumes in human albinism, we suggest that fiber projections from LGN to the primary visual cortex (V1) are also reduced. Studying structural differences in the visual system of albinism can improve the understanding of the mechanism of misrouting and subsequent clinical applications. Diffusion data and tractography are useful for mapping the OR (optic radiation). This manuscript describes two algorithms for OR reconstruction in order to compare brain connectivity in albinism and controls.An MRI scanner with a 32-channel head coil was used to acquire structural scans. A T1-weighted 3D-MPRAGE sequence with 1 mm3 isotropic voxel size was used to generate high-resolution images for V1 segmentation. Multiple proton density (PD) weighted images were acquired coronally for right and left LGN localization. Diffusion tensor imaging (DTI) scans were acquired with 64 diffusion directions. Both deterministic and probabilistic tracking methods were run and compared, with LGN as the seed mask and V1 as the target mask. Though DTI provides relatively poor spatial resolution, and accurate delineation of OR may be challenging due to its low fiber density, tractography has been shown to be advantageous both in research and clinically. Tract based spatial statistics (TBSS) revealed areas of significantly reduced white matter integrity within the OR in patients with albinism compared to controls. Pairwise comparisons revealed a significant reduction in LGN to V1 connectivity in albinism compared to controls. Comparing both tracking algorithms revealed common findings, strengthening the reliability of the technique.

This manuscript describes deterministic and probabilistic algorithms for white matter (WM) reconstruction, used to examine differences in optic radiation (OR) connectivity between albinism and controls. Although probabilistic tractography follows the true course of nerve fibers more closely, deterministic tractography was run to compare the reliability and reproducibility of both techniques.

Medição Conectividade no Visual principal via de albinismo humano utilizando tensor de difusão e tractography

In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed ...

Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation

The purpose of this study is to show the methodology for the examination of the white matter connections of the supplementary motor area (SMA) complex (pre-SMA and SMA proper) using a combination of fiber dissection techniques on cadaveric specimens and magnetic resonance (MR) tractography. The protocol will also describe the procedure for a white matter dissection of a human brain, diffusion tensor tractography imaging, and three-dimensional documentation. The fiber dissections on human brains and the 3D documentation were performed at the University of Minnesota, Microsurgery and Neuroanatomy Laboratory, Department of Neurosurgery. Five postmortem human brain specimens and two whole heads were prepared in accordance with Klingler's method. Brain hemispheres were dissected step by step from lateral to medial and medial to lateral under an operating microscope, and 3D images were captured at every stage. All dissection results were supported by diffusion tensor imaging. Investigations on the connections in line with Meynert's fiber tract classification, including association fibers (short, superior longitudinal fasciculus I and frontal aslant tracts), projection fibers (corticospinal, claustrocortical, cingulum, and frontostriatal tracts), and commissural fibers (callosal fibers) were also conducted.

The purpose of this study is to show each step of the fiber dissection technique on human cadaveric brains, the 3D documentation of these dissections, and the diffusion tensor imaging of the anatomically dissected fiber pathways.

Conexões de Fibra da Área Suplementar de Motor Revisitada: Metodologia de Dissecção de Fibras, DTI e Documentação Tridimensional

The purpose of this study is to show the methodology for the examination of the white matter connections of the supplementary motor area (SMA) complex ...

Diffusion Tensor Magnetic Resonance Imaging in Chronic Spinal Cord Compression

Chronic spinal cord compression is the most common cause of spinal cord impairment in patients with nontraumatic spinal cord damage. Conventional magnetic resonance imaging (MRI) plays an important role in both confirming the diagnosis and evaluating the degree of compression. However, the anatomical detail provided by conventional MRI is not sufficient to accurately estimate neuronal damage and/or assess the possibility of neuronal recovery in chronic spinal cord compression patients. In contrast, diffusion tensor imaging (DTI) can provide quantitative results according to the detection of water molecule diffusion in tissues. In the present study, we develop a methodological framework to illustrate the application of DTI in chronic spinal cord compression disease. DTI fractional anisotropy (FA), apparent diffusion coefficients (ADCs), and eigenvector values are useful for visualizing microstructural pathological changes in the spinal cord. Decreased FA and increases in ADCs and eigenvector values were observed in chronic spinal cord compression patients compared to healthy controls. DTI could help surgeons understand spinal cord injury severity and provide important information regarding prognosis and neural functional recovery. In conclusion, this protocol provides a sensitive, detailed, and noninvasive tool to evaluate spinal cord compression.

Here, we present a protocol for the application of diffusion tensor imaging parameters to evaluate spinal cord compression.

Imagem latente de ressonância magnética do tensor da difusão na compressão crônica da medula espinal

Chronic spinal cord compression is the most common cause of spinal cord impairment in patients with nontraumatic spinal cord damage. Conventional magnetic ...

Advanced Diffusion Imaging in The Hippocampus of Rats with Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is the most common type of acquired brain injury. Since patients with traumatic brain injury show a tremendous variability and heterogeneity (age, gender, type of trauma, other possible pathologies, etc.), animal models play a key role in unraveling factors that are limitations in clinical research. They provide a standardized and controlled setting to investigate the biological mechanisms of injury and repair following TBI. However, not all animal models mimic the diffuse and subtle nature of mTBI effectively. For example, the commonly used controlled cortical impact (CCI) and lateral fluid percussion injury (LFPI) models make use of a craniotomy to expose the brain and induce widespread focal trauma, which are not commonly seen in mTBI. Therefore, these experimental models are not valid to mimic mTBI. Thus, an appropriate model should be used to investigate mTBI. The Marmarou weight drop model for rats induces similar microstructural alterations and cognitive impairments as seen in patients who sustain mild trauma; therefore, this model was selected for this protocol. Conventional computed tomography and magnetic resonance imaging (MRI) scans commonly show no damage following a mild injury, because mTBI induces often only subtle and diffuse injuries. With diffusion weighted MRI, it is possible to investigate microstructural properties of brain tissue, which can provide more insight into the microscopic alterations following mild trauma. Therefore, the goal of this study is to obtain quantitative information of a selected region-of-interest (i.e., hippocampus) to follow up disease progression after obtaining a mild and diffuse brain injury.

The overall goal of this procedure is to obtain quantitative microstructural information of the hippocampus in a rat with mild traumatic brain injury. This is done using an advanced diffusion-weighted magnetic resonance imaging protocol and region-of-interest based analysis of parametric diffusion maps.

Imagem latente avançada da difusão no Hippocampus dos ratos com ferimento de cérebro traumático suave

Mild traumatic brain injury (mTBI) is the most common type of acquired brain injury. Since patients with traumatic brain injury show a tremendous ...

Role of Diffusion MRI Tractography in Endoscopic Endonasal Skull Base Surgery

Endoscopic endonasal surgery has gained a prominent role in the management of complex skull base tumors. It allows the resection of a large group of benign and malignant lesions through a natural anatomical extra-cranial pathway, represented by the nasal cavities, avoiding brain retraction and neurovascular manipulation. This is reflected by the patients' prompt clinical recovery and the low risk of permanent neurological sequelae, representing the main caveat of conventional skull base surgery. This surgery must be tailored to each specific case, considering its features and relationship with surrounding neural structures, mostly based on preoperative neuroimaging. Advanced MRI techniques, such as tractography, have been rarely adopted in skull base surgery due to technical issues: lengthy and complicated processes to generate reliable reconstructions for inclusion in the neuronavigation system. 
This paper aims to present the protocol implemented in the institution and highlights the synergistic collaboration and teamwork between neurosurgeons and the neuroimaging team (neurologists, neuroradiologists, neuropsychologists, physicists, and bioengineers) with the final goal of selecting the optimal treatment for each patient, improving the surgical results and pursuing the advancement of personalized medicine in this field.

We present a protocol to integrate diffusion MRI tractography in patient work-up to endoscopic endonasal surgery for a skull base tumor. The methods for adopting these neuroimaging studies in the pre- and intra-operative phases are described.

Papel da Ramografia de Ressonância Magnética em Cirurgia de Base do Crânio Endonasal Endoscópica

Endoscopic endonasal surgery has gained a prominent role in the management of complex skull base tumors. It allows the resection of a large group of ...

Using Diffusion Tensor Imaging in Traumatic Brain Injury

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
Traditional brain imaging techniques using MRI are very good at visualizing the gross structures of the brain. A structural brain image made with MRI provides high contrast of the borders between gray and white matter, and information about the size and shape of brain structures. However, these images do not detail the underlying structure and integrity of white matter networks in the brain, which consist of axon bundles that interconnect local and distant brain regions.
Diffusion MRI uses pulse sequences that are sensitive to the diffusion of water molecules. By measuring the direction of diffusion, it is possible to make inferences about the structure of white matter networks in the brain. Water molecules within an axon are constrained in their movements by the cell membrane; instead of randomly moving in every direction with equal probability (isotropic movement), they are more likely to move in certain directions, in parallel with the axon (anisotropic movement; Figure 1). Therefore, measures of diffusion anisotropy are thought to reflect properties of the white matter such as fiber density, axon thickness, and degree of myelination. One common measure is fractional anisotropy (FA). FA values range from 0, which represents completely isotropic movement, to 1, reflecting maximum anisotropy.
<img alt="Figure 1" src="/files/ftp_upload/10276/10276fig1.jpg" /> 
Figure 1: Diffusion anisotropy. When the direction of diffusion is unconstrained and random, movement is measured in all directions equally. This is isotropic diffusion (A). When water molecules are contained within the axon of a neuron, diffusion is anisotropic, tending to occur more frequently along the direction of the axon (B). <a href="http://www.jove.com/files/ftp_upload/10276/10276fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In this experiment we will use diffusion tensor imaging (DTI) to measure white matter integrity in traumatic brain injury (TBI). TBI occurs when an external force injures the brain, such as a blow to the head or a sudden movement like the kind that might occur in a car accident. This type of brain injury from mechanical forces is associated with diffuse axonal injury-damage to white matter throughout the brain. Because it is an injury affecting white matter integrity, standard neuroimaging techniques may not reveal the damage. However, measures of diffusion are especially sensitive to these anatomical changes. Following a study by Kraus et al.1, we compare a group of healthy controls to a group of people with TBI and use diffusion imaging to measure the effect of TBI on cerebral white matter. Furthermore, we will test the relationship between white matter integrity and cognitive function using an attention task.2 This study uses a region of interest (ROI) approach focusing on three white matter tracts: the splenium of the corpus callosum, the anterior corona radiata, and the superior longitudinal fasciculus (Figure 2).
<img alt="Figure 2" src="/files/ftp_upload/10276/10276fig2.jpg" /> 
Figure 2: Regions of interest. The three ROIs, defined from the ICBM DTI-81 atlas, are shown here in horizontal slices through the brain. In green is the splenium of the corpus callosum. The splenium is the most posterior part of the corpus callosum. In blue is the anterior corona radiata. The superior longitudinal fasciculus is shown in red. <a href="http://www.jove.com/files/ftp_upload/10276/10276fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Diffusion Tensor Imaging in Traumatic Brain Injury

Usando difusão tensor imagem em lesão cerebral traumática

Source: Laboratories of Jonas T. Kaplan and Sarah I. Gimbel&#8212;University of Southern California
Traditional brain imaging techniques using MRI are ...