Name: phase contrast magnetic resonance imaging in the rat common carotid artery
Uploaded: 2018-09-05T15:30:00.000+00:00
Duration: 7 min 2 s
Description: Watch this Scientific Journal Video about Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery at JoVE.com

Este trabalho foi apoiado por concessões do Ministério da ciência e tecnologia, Taiwan, sob número de concessão de MOST-105-2314-B-039-044-MY2.

O cuidado institucional e comissões de utilização (IACUC) da universidade médica de China aprovaram todos os procedimentos.
1. animal preparação e acompanhamento
<ol><li>Deixe todos os objetos magneticamente sensíveis tais como carteiras, chaves, cartão de crédito, etc. fora da sala de scanner antes de iniciar a preparação de animais para fazer a varredura de MRI.</li>
	<li>Inicialmente anestesia o rato (rato de Sprague-Dawley (SD) macho 2 meses, 280 – 350 g) em uma caixa de indução usando uma mistura de 5% de isoflurano (ISO) e oxigênio (2 L/min) por 3-5 min, conforme necessário.</li>
	<li>Quando o animal está reclinado e exibe sem resposta com uma pitada de cauda ou dedo do pé, interrompa a administração de ISO e transferir o animal para a sala de digitalização.</li>
	<li>Coloque o rato na cama em posição cabeça MRI e entregar 2-3% ISO através de um dispositivo de cone de nariz para manter a anestesia.</li>
	<li>Monitor de respiração, colocando um sensor respiratória travesseiro sob o tronco do animal.</li>
	<li>Conecte o sensor com um sistema respiratório e verificar se há taxa de respiração entre 40-50 batimentos por minuto (bpm).</li>
	<li>Para aquisição de PC-MRI cine-condomínio fechado, coloque um eléctrodo em cada sobre a pata dianteira direita e o hind esquerdo pata, respectivamente (Figura 1a).</li>
	<li>Torce os cabos do eletrocardiograma (ECG) juntos.</li>
	<li>Use um suporte de cabeça com orelha bares e um bar de mordida para proteger o animal para restringir o movimento da cabeça.</li>
	<li>Use um sistema ou gaze almofadas de aquecimento de ar quente para manter a temperatura corporal enquanto no imã.</li>
	<li>Certifique-se de que a onda R é clara sobre o monitor de ECG (Figura 1b) e colocar o animal no scanner. Não há nenhuma necessidade de colocar a bobina de superfície no topo do pescoço do animal como imagens são adquiridas pela bobina volume.</li>
</ol>2. MRI aquisição
<ol><li>Uso 2 – 3% ISO para manter a anestesia durante todo o procedimento da imagem latente. Controlar continuamente as respostas fisiológicas e manter tão constante quanto possível.</li>
	<li>Começa as ressonâncias, uma vez que o animal é colocado dentro do scanner e continua a ser fisiologicamente estável. Neste estudo, usar um animal pequeno 7 T sistema MRI com uma força de gradiente de 630 mT/m, mas outras forças de campo de sistemas de MRI animais pequenos podem ser usadas.</li>
	<li>Selecione a sequência de "Localizador" no monitor do console do scanner MRI e adquirir imagens sagitais e scout imagens ao longo de todas as três orientações usando qualquer sequência de aquisição de imagem rápida, por exemplo, o eco de spin rápida, criar coronal, axial, . A finalidade destes scout imagens é determinar os aviões da imagem latente.</li>
	<li>Certifique-se de que o centro da cabeça e do pescoço do animal está no centro do ímã. Se necessário, ajuste a posição do animal até atingir a posição correta. Se o animal é reposicionado, repita a digitalização para obter imagens de escoteiro.</li>
	<li>Selecione a sequência de "tempo-de-voo (TOF) angiografia" no monitor do console do scanner MRI e adquirir um angiograma TOF 2D primeiro para determinar a exata localização anatômica do CCA. Use os seguintes parâmetros de digitalização: repetição tempo (TR) / eco tempo (TE) = 22/4,87 ms, aleta ângulo = 90°, campo de visão (FOV) = 40 × 40 mm2, tamanho de matriz = 256 × 256, espessura da fatia 0,6 mm, com o número de excitação (NEX) = 1. Nota: O nome da sequência de TOF poderia ser vendedor-específicas. O usuário pode inserir esses parâmetros no monitor do console.</li>
	<li>Certifique-se que a banda de saturação é "na" e é colocada na parte superior para evitar interferência de sinais venosas. Nota: Para a banda de saturação, geralmente vem com a sequência TOF. Se a banda de saturação não mostra no monitor, por favor avise a pessoa do serviço.</li>
	<li>Depois de localizar o CCA usando o angiograma TOF, o plano de imagem de PC-ressonância para o centro de CCA-alvo e orientar tais que a fatia é perpendicular à direção do fluxo de sangue (Figura 2a).</li>
	<li>Certifique-se que tanto a respiração e o gating ECG são conectados ao sistema de MRI, mostrando o sinal claro sobre o monitor de computador (Figura 1b) e definir o módulo de gatilho para ser "em" no "modo de gatilho" no monitor do console do scanner MRI.</li>
	<li>Confirme que respostas fisiológicas do animal são estáveis antes de iniciar a varredura de MRI-PC a partir do computador de monitoramento (Figura 1b). Verifique se as seleções associadas são "na" em ambos o monitor de computador e o monitor de console do varredor de MRI. Nota: A fisiologia monitoramento sistema utilizado neste estudo é fornecida pela vender. Para scanners mais animais, os sistemas de monitoramento de Fisiologia semelhantes são fornecido e vender específicos.</li>
	<li>Selecione a sequência de sequência de PC-MRI do monitor console do scanner MRI e executar gated PC-ressonâncias usando os seguintes parâmetros: TR/TE=15.55/4.51 ms (mínimo TR e TE), flip ângulo = 30°, FOV = 40 × 40 mm2, tamanho de matriz = 192 × 192, fatia espessura = 2 mm, velocidade de codificação (VENC) = 120 cm/s, com NEX = 8. VENC unidirecional é adquirido na direção através de avião. Nota: O tempo de verificação é aproximadamente 8,5 min, mas o tempo de verificação real pode ser ligeiramente diferente entre os animais devido à variação em ciclos cardíacos.</li>
	<li>Repita as etapas de 2,6 – 2,9 de aquisição de imagem se a região de interesse (ROI) deve ser alterado para outro local no CCA, tais como à bifurcação 4.</li>
	<li>Retire o animal do scanner e devolvê-lo para sua gaiola de recuperação quando a verificação for concluída.</li>
	<li>Aquecer o animal com uma lâmpada de aquecimento para manter a temperatura corporal. Manter a lâmpada pelo menos 15 cm do animal para evitar o superaquecimento.</li>
	<li>Quando o animal começa a se mover e exibe uma resposta a uma pitada de cauda ou dedo do pé, desliga a lâmpada de aquecimento.</li>
</ol>3. processamento de dados
<ol><li>Salve dados de MRI na Digital Imaging and Communications em formato de medicina (DICOM) ou qualquer outro formato de vender de específicos. Gerar cine série com dois tipos de imagens: uma imagem de grandeza (imagem de Anatomia) e uma fase (Figura 2b). Nota: Em alguns scanners, o terceiro tipo de imagem, que pode ser a imagem de fase magnitude imagem x ou o complexo-diferença (subtração complexa entre as duas aquisições com diferentes gradientes de velocidade-codificação), é gerado. A terceira imagem depende do fornecedor.</li>
	<li>Pré-processa os dados de imagem. Secreta a fase da imagem para o mapa de velocidade e corrigir o erro de deslocamento de fase 5. Nota: A imagem da fase tem uma unidade senhor arbitrária de intensidade de sinal em vez de valores de velocidade verdadeira, mas a intensidade de sinal do senhor é linearmente proporcional à velocidade. O máximo sinal de MRI da imagem de fase é tipicamente atribuído como o valor do VENC... e o mínimo sinal é atribuído o valor oposto de VENC. Consulte o arquivo de código suplementar 1 para obter um exemplo do script Matlab e pressione o botão de "executar".</li>
	<li>Delinear o ROI com cuidado ao traçar a fronteira do CCA. Como a artéria pode dilatar-se e construir durante as várias fases cardíacas, delinear ROIs para cada período de tempo. Calcule o fluxo de sangue através da integração sobre a artéria, ROI, ou seja, velocidade × área. O fluxo de sangue resultou de cada artéria foi nas unidades de mL/s. Consulte o arquivo de código complementar 2 para obter um exemplo do script Matlab e pressione o botão de "executar".</li>
</ol>

<ol>
	<li>Zakszewski, E., Schmit, B., Kurpad, S., Budde, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diffusion+imaging+in+the+rat+cervical+spinal+cord.">Diffusion imaging in the rat cervical spinal cord.</a> J Vis Exp. (98), (2015).</li><li>Wise, R. G., Al-Shafei, A. I., Carpenter, T. A., Hall, L. D., Huang, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+measurement+of+blood+and+myocardial+velocity+in+the+rat+heart+by+phase+contrast+MRI+using+sparse+q-space+sampling.">Simultaneous measurement of blood and myocardial velocity in the rat heart by phase contrast MRI using sparse q-space sampling.</a> J Magn Reson Imaging. 22 (5), 614-627 (2005).</li><li>Skardal, K., Espe, E. K., Zhang, L., Aronsen, J. M., Sjaastad, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-Directional+Evaluation+of+Mitral+Flow+in+the+Rat+Heart+by+Phase-Contrast+Cardiovascular+Magnetic+Resonance.">Three-Directional Evaluation of Mitral Flow in the Rat Heart by Phase-Contrast Cardiovascular Magnetic Resonance.</a> PLoS One. 11 (3), e0150536 (2016).</li><li>Peng, S. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase-contrast+magnetic+resonance+imaging+for+the+evaluation+of+wall+shear+stress+in+the+common+carotid+artery+of+a+spontaneously+hypertensive+rat+model+at+7T:+Location-specific+change,+regional+distribution+along+the+vascular+circumference,+and+reproducibility+analysis.">Phase-contrast magnetic resonance imaging for the evaluation of wall shear stress in the common carotid artery of a spontaneously hypertensive rat model at 7T: Location-specific change, regional distribution along the vascular circumference, and reproducibility analysis.</a> Magn Reson Imaging. 34 (5), 624-631 (2016).</li><li>Yu, H. Y., Peng, H. H., Wang, J. L., Wen, C. Y., Tseng, W. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+the+pulse+wave+velocity+of+the+descending+aorta+using+axial+velocity+profiles+from+phase-contrast+magnetic+resonance+imaging.">Quantification of the pulse wave velocity of the descending aorta using axial velocity profiles from phase-contrast magnetic resonance imaging.</a> Magn Reson Med. 56 (4), 876-883 (2006).</li><li>Peng, S. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+phase-contrast+MRI+for+the+quantification+of+whole-brain+cerebral+blood+flow.">Optimization of phase-contrast MRI for the quantification of whole-brain cerebral blood flow.</a> J Magn Reson Imaging. 42 (4), 1126-1133 (2015).</li><li>Peng, S. L., Shih, C. T., Huang, C. W., Chiu, S. C., Shen, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+analysis+of+blood+flow+and+wall+shear+stress+in+the+common+carotid+artery+of+rat+model+by+phase-contrast+MRI.">Optimized analysis of blood flow and wall shear stress in the common carotid artery of rat model by phase-contrast MRI.</a> Sci Rep. 7 (1), 5253 (2017).</li><li>Bozgeyik, Z., Berilgen, S., Ozdemir, H., Tekatas, A., Ogur, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+effects+of+sildenafil+citrate+(viagra)+on+vertebral+artery+blood+flow+in+patients+with+vertebro-basilar+insufficiency.">Evaluation of the effects of sildenafil citrate (viagra) on vertebral artery blood flow in patients with vertebro-basilar insufficiency.</a> Korean J Radiol. 9 (6), 477-480 (2008).</li><li>Swampillai, J., Rakebrandt, F., Morris, K., Jones, C. J., Fraser, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+effects+of+caffeine+and+tobacco+on+arterial+function+and+wave+travel.">Acute effects of caffeine and tobacco on arterial function and wave travel.</a> Eur J Clin Invest. 36 (12), 844-849 (2006).</li><li>Neff, K. W., Horn, P., Schmiedek, P., Duber, C., Dinter, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2D+cine+phase-contrast+MRI+for+volume+flow+evaluation+of+the+brain-supplying+circulation+in+moyamoya+disease.">2D cine phase-contrast MRI for volume flow evaluation of the brain-supplying circulation in moyamoya disease.</a> AJR Am J Roentgenol. 187 (1), W107-W115 (2006).</li><li>Stalder, A. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+2D+and+3D+phase+contrast+MRI:+optimized+analysis+of+blood+flow+and+vessel+wall+parameters.">Quantitative 2D and 3D phase contrast MRI: optimized analysis of blood flow and vessel wall parameters.</a> Magn Reson Med. 60 (5), 1218-1231 (2008).</li><li>Dall'Armellina, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+method+for+quantification+of+regional+cardiac+function+in+mice+using+phase-contrast+MRI.">Improved method for quantification of regional cardiac function in mice using phase-contrast MRI.</a> Magn Reson Med. 67 (2), 541-551 (2012).</li><li>Peng, S. L., Ravi, H., Sheng, M., Thomas, B. P., Lu, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Searching+for+a+truly+&amp;#34;iso-metabolic&amp;#34;+gas+challenge+in+physiological+MRI.">Searching for a truly &amp;#34;iso-metabolic&amp;#34; gas challenge in physiological MRI.</a> J Cereb Blood Flow Metab. 37 (2), 715-725 (2017).</li><li>Liu, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+assessment+of+global+cerebral+metabolic+rate+of+oxygen+(CMRO2)+in+neonates+using+MRI.">Quantitative assessment of global cerebral metabolic rate of oxygen (CMRO2) in neonates using MRI.</a> NMR Biomed. 27 (3), 332-340 (2014).</li><li>Xu, F., Ge, Y., Lu, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+quantification+of+whole-brain+cerebral+metabolic+rate+of+oxygen+(CMRO2)+by+MRI.">Noninvasive quantification of whole-brain cerebral metabolic rate of oxygen (CMRO2) by MRI.</a> Magn Reson Med. 62 (1), 141-148 (2009).</li><li>Lotz, J., Meier, C., Leppert, A., Galanski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+flow+measurement+with+phase-contrast+MR+imaging:+basic+facts+and+implementation.">Cardiovascular flow measurement with phase-contrast MR imaging: basic facts and implementation.</a> Radiographics. 22 (3), 651-671 (2002).</li><li>Pelc, N. J., Herfkens, R. J., Shimakawa, A., Enzmann, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+contrast+cine+magnetic+resonance+imaging.">Phase contrast cine magnetic resonance imaging.</a> Magn Reson Q. 7 (4), 229-254 (1991).</li><li>Kim, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accelerated+phase-contrast+cine+MRI+using+k-t+SPARSE-SENSE.">Accelerated phase-contrast cine MRI using k-t SPARSE-SENSE.</a> Magn Reson Med. 67 (4), 1054-1064 (2012).</li><li>Valvano, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accelerating+4D+flow+MRI+by+exploiting+low-rank+matrix+structure+and+hadamard+sparsity.">Accelerating 4D flow MRI by exploiting low-rank matrix structure and hadamard sparsity.</a> Magn Reson Med. 78 (4), 1330-1341 (2017).</li></ol>

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PC-ressonância magnética é uma abordagem abrangente para avaliação não invasiva e longitudinal do fluxo de sangue. Apresentamos um protocolo para a realização de PC-MRI do rato CCA. Este procedimento é fácil de executar em qualquer animal varredor de MRI e demonstra boa reprodutibilidade.
A técnica de PC-MRI ganhou crescente popularidade em humano 10,11 , bem como estudos em animais 4,<sup ...

Ressonância magnética (RM) é uma abordagem versátil que fornece informações detalhadas sobre fisiologia e estruturas internas do corpo e cada vez mais está sendo usada para o diagnóstico clínico e em estudos pré-clínicos em animais. Modelos animais são vitais para uma melhor compreensão de considerável implicação clínica 1. Como modelos animais diferem consideravelmente dos humanos em relação a requisitos de anestesia e parâmetros fisiológicos, otimização dos processos de MRI de tais animais assume importância.
MRI de contraste de fase (PC-MRI) é um tipo especializado de ressonância magnética que usa a velocidade das rotações fluindo para quantificar os parâmetros de fluxo-relacionados tais como o fluxo de sangue. Com PC-MRI, padrões de fluxo nas artérias principais usando modelos animais de mapeamento pode ajudar a lançar luz sobre patologias cardiovasculares 2. Além disso, o PC-MRI não invasiva pode monitorar as alternâncias inerentes na circulação sanguínea em condições fisiopatológicas 3. Estas observações sugerem que o PC-MRI é uma abordagem valiosa que pode ser usada em modelos animais de doenças cardiovasculares.
Neste relatório, nós descrevemos um método para a quantificação do fluxo sanguíneo na artéria carótida comum (CCA) de ratos. Os dois CCAs fornecem a cabeça e o pescoço com sangue oxigenado, e a doença de artéria carótida é das principais causas de acidente vascular cerebral. Portanto, detectar a patologia precoce em CCA é crucial. Este procedimento tem uma duração de cerca de 15 min e pode ser potencialmente aplicado às condições com alterações hemodinâmicas, tais aterosclerose ou acidente vascular cerebral.

<table><tbody><tr><td>7T small animal MRI system</td><td>Bruker</td><td></td><td></td></tr><tr><td>Isoflurane&amp;nbsp;</td><td>Baxter</td><td>1001936040</td><td>anesthetic</td></tr><tr><td>ECG lead&amp;nbsp;</td><td>3M</td><td>2269T</td><td></td></tr><tr><td>Matlab</td><td>MathWorks</td><td></td><td>sofeware for image processing</td></tr><tr><td>Monitoring and gating system</td><td>SA instruments, Inc</td><td>Model 1030</td><td></td></tr></tbody></table>

phase contrast magnetic resonance imaging in the rat common carotid artery

Contraste fase ressonância magnética (MRI-PC) é uma abordagem não-invasiva que pode quantificar os parâmetros de fluxo-relacionados tais como o fluxo de sangue. Estudos anteriores mostraram que o fluxo sanguíneo anormal pode estar associado com risco vascular sistêmico. Assim, o PC-MRI pode facilitar a tradução dos dados obtidos a partir de modelos animais de doenças cardiovasculares para investigações clínicas pertinentes. Neste relatório, descrevemos o procedimento para medir o fluxo sanguíneo na artéria carótida comum (CCA) de ratos utilizando PC cine-condomínio fechado-MRI e discutir os métodos de análise pertinente. Este procedimento pode ser executado em um animal vivo, anestesiado e não requer eutanásia após o procedimento. Os parâmetros de digitalização propostos produzem medições reproduzíveis para o fluxo de sangue, indicando excelente reprodutibilidade dos resultados. O procedimento de PC-MRI descrito neste artigo pode ser usado para testes farmacológicos, fisiopatológico avaliação e avaliação hemodinâmica cerebral.

Geometria de fatia correta é crucial para garantir o sucesso do experimento PC-MRI. O posicionamento de avião exata imagem produz uma forma de "round" artéria (Figura 3a), e como angulação aumenta, ou seja, quando é menos perpendicular à artéria, a geometria resultante da artéria torna-se ovoide, levando a maior volume parcial efeitos (Figura 3b). Efeitos de volume parcial severa provocaria a superestimação de...

Watch this Scientific Journal Video about Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery at JoVE.com

Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery

O objectivo geral deste procedimento é para medir o fluxo sanguíneo na artéria carótida comum de rato usando contraste fase não invasiva imagiologia por ressonância magnética.

Imagens de ressonância magnética fase contraste na artéria carótida comum de rato

Phase contrast magnetic resonance imaging (PC-MRI) is a noninvasive approach that can quantify flow-related parameters such as blood flow. Previous ...

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Research

JoVE Journal

Medicine

9.4K visualizações.  Chang Gung Memorial Hospital. O objectivo geral deste procedimento é para medir o fluxo sanguíneo na artéria carótida comum de rato usando contraste fase não invasiva imagiologia por ressonância magnética.

Vídeo: Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery

Focal Cerebral Ischemia Model by Endovascular Suture Occlusion of the Middle Cerebral Artery in the Rat

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable clinical state; in the development of animal models of focal ischemia, however, achieving reproducibility of experimentally induced infarct volume is essential. The rat is a widely used animal model for stroke due to its relatively low animal husbandry costs and to the similarity of its cranial circulation to that of humans2,3. In humans, the middle cerebral artery (MCA) is most commonly affected in stroke syndromes and multiple methods of MCA occlusion (MCAO) have been described to mimic this clinical syndrome in animal models. Because recanalization commonly occurs following an acute stroke in the human, reperfusion after a period of occlusion has been included in many of these models. In this video, we demonstrate the transient endovascular suture MCAO model in the spontaneously hypertensive rat (SHR). A filament with a silicon tip coating is placed intraluminally at the MCA origin for 60 minutes, followed by reperfusion. Note that the optimal occlusion period may vary in other rat strains, such as Wistar or Sprague-Dawley. Several behavioral indicators of stroke in the rat are shown. Focal ischemia is confirmed using T2-weighted magnetic resonance images and by staining brain sections with 2,3,5-triphenyltetrazolium chloride (TTC) 24 hours after MCAO.

Surgical induction of ischemic brain damage in the rat is a widely used model for stroke research. Here we demonstrate the induction of focal cerebral ischemia by occlusion of the middle cerebral artery. Visualization of the resulting infarct by histological staining and magnetic resonance imaging is also shown.

Modelo de isquemia focal cerebral por oclusão Suture Endovascular da artéria cerebral média no Rat

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable ...

Neurociência

Optimized System for Cerebral Perfusion Monitoring in the Rat Stroke Model of Intraluminal Middle Cerebral Artery Occlusion

The translational potential of pre-clinical stroke research depends on the accuracy of experimental modeling. Cerebral perfusion monitoring in animal models of acute ischemic stroke allows to confirm successful arterial occlusion and exclude subarachnoid hemorrhage. Cerebral perfusion monitoring can also be used to study intracranial collateral circulation, which is emerging as a powerful determinant of stroke outcome and a possible therapeutic target. Despite a recognized role of Laser Doppler perfusion monitoring as part of the current guidelines for experimental cerebral ischemia, a number of technical difficulties exist that limit its widespread use. One of the major issues is obtaining a secure and prolonged attachment of a deep-penetration Laser Doppler probe to the animal skull. In this video, we show our optimized system for cerebral perfusion monitoring during transient middle cerebral artery occlusion by intraluminal filament in the rat. We developed in-house a simple method to obtain a custom made holder for twin-fibre (deep-penetration) Laser Doppler probes, which allow multi-site monitoring if needed. A continuous and prolonged monitoring of cerebral perfusion could easily be obtained over the intact skull.

Cerebral perfusion monitoring has been demonstrated to improve accuracy in ischemic stroke models. Technical difficulties often limit the use of this essential tool for cerebrovascular research. In this video, an optimized system is shown to obtain a single or multi-site hemodynamic monitoring during intraluminal middle cerebral artery occlusion in rats.

Sistema otimizado para Monitorização de perfusão cerebral no modelo do rato do curso de oclusão da artéria cerebral média intraluminal

The translational potential of pre-clinical stroke research depends on the accuracy of experimental modeling. Cerebral perfusion monitoring in animal ...

Medicina

Diffusion Imaging in the Rat Cervical Spinal Cord

Magnetic resonance imaging (MRI) is the state of the art approach for assessing the status of the spinal cord noninvasively, and can be used as a diagnostic and prognostic tool in cases of disease or injury. Diffusion weighted imaging (DWI), is sensitive to the thermal motion of water molecules and allows for inferences of tissue microstructure. This report describes a protocol to acquire and analyze DWI of the rat cervical spinal cord on a small-bore animal system. It demonstrates an imaging setup for the live anesthetized animal and recommends a DWI acquisition protocol for high-quality imaging, which includes stabilization of the cord and control of respiratory motion. Measurements with diffusion weighting along different directions and magnitudes (b-values) are used. Finally, several mathematical models of the resulting signal are used to derive maps of the diffusion processes within the spinal cord tissue that provide insight into the normal cord and can be used to monitor injury or disease processes noninvasively.

The goal of this protocol is to obtain high-quality diffusion weighted magnetic resonance imaging (DWI) of the rat spinal cord for noninvasive characterization of tissue microstructure. This protocol describes optimizations of the MRI sequence, radiofrequency coil, and analysis methods to enable DWI images free from artifacts.

A seqüência de difusão na Medula Espinhal Rat Cervical

Magnetic resonance imaging (MRI) is the state of the art approach for assessing the status of the spinal cord noninvasively, and can be used as a ...

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics disturbance in affected cells. Diffusion weighted magnetic resonance imaging (MRI) identifies regions that are damaged, potentially irreversibly, by hypoxia-ischemia. Alterations in glucose utilization in the affected tissue may be detectable by positron emission tomography (PET) imaging of 2-deoxy-2-(18F)fluoro-&#7429;-glucose ([18F]FDG) uptake. Due to the rapid and variable nature of injury in this animal model, acquisition of both modes of data must be performed simultaneously in order to meaningfully correlate PET and MRI data. In addition, inter-animal variability in the hypoxic-ischemic injury due to vascular differences limits the ability to analyze multi-modal data and observe changes to a group-wise approach if data is not acquired simultaneously in individual subjects. The method presented here allows one to acquire both diffusion-weighted MRI and [18F]FDG uptake data in the same animal before, during, and after the hypoxic challenge in order to interrogate immediate physiological changes.

The method presented here uses simultaneous positron emission tomography and magnetic resonance imaging. In the cerebral hypoxia-ischemia model, dynamic changes in diffusion and glucose metabolism occur during and after injury. The evolving and irreproducible damage in this model necessitates simultaneous acquisition if meaningful multi-modal imaging data are to be acquired.

Simultânea de imagem PET / MRI Durante Rato isquemia-hipoxia cerebral

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics ...

A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat model of ischemic stroke, differences in quantitative T1 and T2 MRI relaxation times (qT1 and qT2) between the ischemic lesion (delineated by low diffusion) and the contralateral non-ischemic hemisphere increase with time from stroke onset. The time dependency of MRI relaxation time differences is heuristically described by a linear function and thus provides a simple estimate of stroke onset time. Additionally, the volumes of abnormal qT1 and qT2 within the ischemic lesion increase linearly with time providing a complementary method for stroke timing. A (semi)automated computer routine based on the quantified diffusion coefficient is presented to delineate acute ischemic stroke tissue in rat ischemia. This routine also determines hemispheric differences in qT1 and qT2 relaxation times and the location and volume of abnormal qT1 and qT2 voxels within the lesion. Uncertainties associated with onset time estimates of qT1 and qT2 MRI data vary from &plusmn; 25 min to &plusmn; 47 min for the first 5 hours of stroke. The most accurate onset time estimates can be obtained by quantifying the volume of overlapping abnormal qT1 and qT2 lesion volumes, termed 'Voverlap' (&plusmn; 25 min) or by quantifying hemispheric differences in qT2 relaxation times only (&plusmn; 28 min). Overall, qT2 derived parameters outperform those from qT1. The current MRI protocol is tested in the hyperacute phase of a permanent focal ischemia model, which may not be applicable to transient focal brain ischemia.

A protocol for stroke onset time estimation in a rat model of stroke exploiting quantitative magnetic resonance imaging (qMRI) parameters is described. The procedure exploits diffusion MRI for delineation of the acute stroke lesion and quantitative T1 and T2 (qT1 and qT2) relaxation times for timing of stroke.

Um protocolo de ressonância magnética para estimativa de tempo de início curso em situações de isquemia Cerebral permanente

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat ...

Quantitative MRI of Endothelial Permeability and (Dys)function in Atherosclerosis

Cardiovascular diseases are the leading causes of death worldwide. A permeable/leaky and dysfunctional endothelium is considered the earliest marker of vascular damage and thought to drive atherosclerosis. A method to identify these changes in vivo would be desirable in the clinic. Magnetic resonance imaging (MRI)-based tools and other technologies have enabled a profound understanding of the role of the endothelium in cardiovascular diseases and risk in vivo. There is, however, a need for reproducible and simple approaches for extracting quantifiable data reflective of endothelial damage from a single imaging study. A non-invasive, easy-to-implement, and quantitative MRI workflow was developed to acquire and analyze images that allow the quantification of two imaging biomarkers of arterial endothelial damage (leakiness/permeability and dysfunction). Here, the protocol describes the application of this method in the brachiocephalic artery of atherosclerotic ApoE-/- mice using a clinical MRI scanner. First, late gadolinium enhancement (LGE) and Modified Look-Locker Inversion Recovery (MOLLI) T1 mapping protocols to quantify endothelial leakage using an albumin-binding probe are described. Second, anatomic, and quantitative blood flow sequences to measure endothelial dysfunction, in response to acetylcholine are described. Importantly, the method outlined here allows the acquisition of high-spatial-resolution 3D images with large volumetric coverage enabling accurate segmentation of vessel wall structures to improve inter- and intra-observer variability and to increase reliability and reproducibility. Additionally, it provides quantitative data without the need for high-temporal resolution for complex kinetic modeling, making it model-independent and even allowing for imaging of highly mobile vessels (coronary arteries). Therefore, the approach simplifies and expedites data analysis. Finally, this method can be implemented on different scanners, can be extended to image different arterial beds, and is clinically applicable for use in humans. This method could be used to diagnose and treat patients with atherosclerosis by adopting a precision-medicine approach.

Quantitative MRI of Endothelial Permeability and Dysfunction in Atherosclerosis

We have developed an accurate, non-invasive, and easy-to-use method to quantify endothelial permeability and dysfunction in the arteries using Magnetic Resonance Imaging (MRI), named qMETRIC. This technique enables assessing vascular damage and cardiovascular risk associated with atherosclerosis in preclinical models and humans.

Cardiovascular diseases are the leading causes of death worldwide. A permeable/leaky and dysfunctional endothelium is considered the earliest marker of ...

Bioengenharia

Ferric Chloride-induced Canine Carotid Artery Thrombosis: A Large Animal Model of Vascular Injury

Occlusive arterial thrombosis leading to cerebral ischemic stroke and myocardial infarction contributes to ~13 million deaths every year globally. Here, we have translated a vascular injury model from a small animal into a large animal (canine), with slight modifications that can be used for pre-clinical screening of prophylactic and thrombolytic agents. In addition to the surgical methods, the modified protocol describes the step-by-step methods to assess carotid artery canalization by angiography, detailed instructions to process both the brain and carotid artery for histological analysis to verify carotid canalization and cerebral hemorrhage, and specific parameters to complete an assessment of downstream thromboembolic events by utilizing magnetic resonance imaging (MRI). In addition, specific procedural changes from the previously well-established small animal model necessary to translate into a large animal (canine) vascular injury are discussed.

Here, we present the modifications necessary to a well characterized and commonly used small animal ferric chloride-induced (FeCl3) carotid artery injury model for use in a large animal vascular injury model. The resulting model can be utilized for pre-clinical trial assessment of both prophylactic and thrombolytic pharmacological and mechanical interventions.

Trombose da artéria carótida canino induzida por cloreto férrico: Um modelo Animal grande de lesão Vascular

Occlusive arterial thrombosis leading to cerebral ischemic stroke and myocardial infarction contributes to ~13 million deaths every year globally. Here, ...

Middle Cerebral Artery Occlusion Allowing Reperfusion via Common Carotid Artery Repair in Mice

The ischemic stroke is a major cause of adult long-term disability and death worldwide. The current treatments available are limited, with only tissue plasminogen activator (tPA) as an approved drug treatment to target ischemic strokes. Current research in the field of ischemic stroke focuses on better understanding the pathophysiology of stroke, to develop and investigate novel pharmaceutical targets. Reliable experimental stroke models are crucial for the progression of potential treatments. The middle cerebral artery occlusion (MCAO) model is clinically relevant and the most frequently used surgical model of ischemic stroke in rodents. However, the outcomes of this model, such as lesion volume, are associated with high levels of variability, particularly in mice. The alternative MCAO model described here allows the reperfusion of the common carotid artery (CCA) and the increased perfusion of the middle cerebral artery (MCA) territory, using a tissue pad with fibrinogen-based sealant to repair the vessel, and the improved welfare of the mice by avoiding external carotid artery (ECA) ligation. This reduces the reliance on the Circle of Willis, which is known to be highly anatomically variable in mice. Representative data show that using this alternative surgical approach decreases the variability in lesion volumes between the traditional MCAO approach and the alternative approach described here.

Intraluminal filament occlusion of the middle cerebral artery is the most frequently used in vivo model of experimental stroke in rodents. An alternative surgical approach to allow common carotid artery repair is performed here, which allows the reperfusion of the common carotid artery and a full reperfusion to the middle cerebral artery territory.

Oclusão de artéria Cerebral média, permitindo a reperfusão através de reparação de artéria carótida comum em ratos

The ischemic stroke is a major cause of adult long-term disability and death worldwide. The current treatments available are limited, with only tissue ...

Cardiac Magnetic Resonance Imaging

Source: Frederick W. Damen and <a href="https://www.jove.com/author/Craig+J._Goergen">Craig J. Goergen</a>, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
In this video, high field, small-bore magnetic resonance imaging (MRI) with physiological monitoring is demonstrated to acquire gated cine loops of the murine cardiovascular system. This procedure provides a basis for assessing left-ventricular function, visualizing vascular networks, and quantifying motion of organs due to respiration. Comparable small animal cardiovascular imaging modalities include high-frequency ultrasound and micro-computed tomography (CT); however, each modality is associated with trade-offs that should be considered. While ultrasound does provide high spatial and temporal resolution, imaging artifacts are common. For example, dense tissue (i.e., the sternum and ribs) can limit imaging penetration depth, and hyperechoic signal at the interface between gas and liquid (i.e., pleura surrounding the lungs) can blur contrast in nearby tissue. Micro-CT in contrast does not suffer from as many in-plane artifacts, but does have lower temporal resolution and limited soft-tissue contrast. Furthermore, micro-CT uses X-ray radiation and often requires the use of contrast agents to visualize vasculature, both of which are known to cause side effects at high doses including radiation damage&#160; and renal injury. Cardiovascular MRI provides a nice compromise between these techniques by negating the need for ionizing radiation and providing the user with the ability to image without contrast agents (although contrast agents are often used for MRI).
This data was acquired with a triggering Fast Low Angle SHot (FLASH) MRI sequence that was gated off of the R-peaks in the cardiac cycle and expiratory plateaus in respiration. These physiological events were monitored through subcutaneous electrodes and a pressure-sensitive pillow that was secured against the abdomen. To ensure the mouse was properly warmed, a rectal temperature probe was inserted and used to control the output of a MRI-safe heating fan. Once the animal was inserted into the bore of the MRI scanner and navigation sequences were run to confirm positioning, the gated FLASH imaging planes were prescribed and data acquired. Overall, high field MRI is a powerful research tool that can provide soft tissue contrast for the study of small animal disease models.

Cardiac MRI: Principle and Imaging

Ressonância Magnética Cardíaca

Source: Frederick W. Damen and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
In this video, high ...

Education

JoVE Science Education

Engenharia

Engenharia Biomédica

 Phase Contrast Magnetic Resonance Imaging to Assess Blood Flow in the Arteries of a Rat

<a href='https://app.jove.com/v/57304/phase-contrast-magnetic-resonance-imaging-rat-common-carotid'>Source: Chiu, S., et al. Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery. J. Vis. Exp. (2018).</a>This video demonstrates phase contrast magnetic resonance imaging (PC-MRI) to measure blood flow in the common carotid artery of a rat. After securing an anesthetized rat on the MRI bed and ensuring stable physiological parameters, the common carotid artery is scanned to capture images at defined intervals. Blood flow is then computed from these images to evaluate changes throughout the cardiac cycle.

Source: Chiu, S., et al. Phase Contrast Magnetic Resonance Imaging in the Rat Common Carotid Artery. J. Vis. Exp. (2018).This video demonstrates phase ...