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>

Não há nada para divulgar.

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 border="0" cellpadding="0" cellspacing="0" width="875">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">7T small animal MRI system</td>
			<td style="width:123px;">Bruker</td>
			<td style="width:344px;"></td>
			<td style="width:193px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Isoflurane&#160;</td>
			<td>Baxter</td>
			<td>1001936040</td>
			<td>anesthetic</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">ECG lead&#160;</td>
			<td>3M</td>
			<td>2269T</td>
			<td style="width:193px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Matlab</td>
			<td>MathWorks</td>
			<td></td>
			<td>sofeware for image processing</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Monitoring and gating system</td>
			<td>SA instruments, Inc</td>
			<td>Model 1030</td>
			<td style="width:193px;"></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 ...

phase-contrast-magnetic-resonance-imaging-rat-common-carotid

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

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.
Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.
Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.
Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.

An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF.

Avaliação Strain Ressonância Magnética Derivado do Miocárdio Usando o controle de recursos

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that ...

Medicina

Training a Sophisticated Microsurgical Technique: Interposition of External Jugular Vein Graft in the Common Carotid Artery in Rats

Neointimal hyperplasia is one the primary causes of stenosis in arterialized veins that are of great importance in arterial coronary bypass surgery, in peripheral arterial bypass surgery as well as in arteriovenous fistulas.1-5 The experimental procedure of vein graft interposition in the common carotid artery by using the cuff-technique has been applied in several research projects to examine the aetiology of neointimal hyperplasia and therapeutic options to address it. 6-8 The cuff prevents vessel anastomotic remodeling and induces turbulence within the graft and thereby the development of neointimal hyperplasia.
Using the superior caval vein graft is an established small-animal model for venous arterialization experiment.9-11 This current protocol refers to an established jugular vein graft interposition technique first described by Zou et al., 9 as well as others.12-14 Nevertheless, these cited small animal protocols are complicated.
To simplify the procedure and to minimize the number of experimental animals needed, a detailed operation protocol by video training is presented. This video should help the novice surgeon to learn both the cuff-technique and the vein graft interposition. Hereby, the right external jugular vein was grafted in cuff-technique in the common carotid artery of 21 female Sprague Dawley rats categorized in three equal groups that were sacrificed on day 21, 42 and 84, respectively. Notably, no donor animals were needed, because auto-transplantations were performed. The survival rate was 100 % at the time point of sacrifice. In addition, the graft patency rate was 60 % for the first 10 operated animals and 82 % for the remaining 11 animals. The blood flow at the time of sacrifice was 8&plusmn;3 ml/min. In conclusion, this surgical protocol considerably simplifies, optimizes and standardizes this complicated procedure. It gives novice surgeons easy, step-by-step instruction, explaining possible pitfalls, thereby helping them to gain expertise fast and avoid useless sacrifice of experimental animals.

Neointimal hyperplasia is the primary cause of stenosis in arterialized veins. We propose a new protocol whereby the right external jugular vein is grafted using the cuff technique in the common carotid artery of Sprague Dawley rats. The survival rate was 100 % at the time point of sacrifice.

Treinar um técnica microcirúrgica sofisticado: Interposição de enxerto de veia jugular externa na artéria carótida comum em ratos

Neointimal hyperplasia is one the primary causes of stenosis in arterialized veins that are of great importance in arterial coronary bypass surgery, in ...

Multi-modal Imaging of Angiogenesis in a Nude Rat Model of Breast Cancer Bone Metastasis Using Magnetic Resonance Imaging, Volumetric Computed Tomography and Ultrasound

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell proliferation in the bone marrow cavity as well as for interaction of tumor and bone cells resulting in local bone destruction. Our aim was to develop a model of experimental bone metastasis that allows in vivo assessment of angiogenesis in skeletal lesions using non-invasive imaging techniques.
For this purpose, we injected 105 MDA-MB-231 human breast cancer cells into the superficial epigastric artery, which precludes the growth of metastases in body areas other than the respective hind leg1. Following 25-30 days after tumor cell inoculation, site-specific bone metastases develop, restricted to the distal femur, proximal tibia and proximal fibula1. Morphological and functional aspects of angiogenesis can be investigated longitudinally in bone metastases using magnetic resonance imaging (MRI), volumetric computed tomography (VCT) and ultrasound (US).
MRI displays morphologic information on the soft tissue part of bone metastases that is initially confined to the bone marrow cavity and subsequently exceeds cortical bone while progressing. Using dynamic contrast-enhanced MRI (DCE-MRI) functional data including regional blood volume, perfusion and vessel permeability can be obtained and quantified2-4. Bone destruction is captured in high resolution using morphological VCT imaging. Complementary to MRI findings, osteolytic lesions can be located adjacent to sites of intramedullary tumor growth. After contrast agent application, VCT angiography reveals the macrovessel architecture in bone metastases in high resolution, and DCE-VCT enables insight in the microcirculation of these lesions5,6. US is applicable to assess morphological and functional features from skeletal lesions due to local osteolysis of cortical bone. Using B-mode and Doppler techniques, structure and perfusion of the soft tissue metastases can be evaluated, respectively. DCE-US allows for real-time imaging of vascularization in bone metastases after injection of microbubbles7.
In conclusion, in a model of site-specific breast cancer bone metastases multi-modal imaging techniques including MRI, VCT and US offer complementary information on morphology and functional parameters of angiogenesis in these skeletal lesions.

In the pathogenesis of bone metastasis, angiogenesis is a crucial process and therefore represents a target for imaging and therapy. Here, we present a rat model of site-specific breast cancer bone metastasis and describe strategies to non-invasively image angiogenesis in vivo using magnetic resonance imaging, volumetric computed tomography and ultrasound.

Multi-modal de imagem de angiogênese em um modelo de rato nu de Câncer de mama utilizando a ressonância magnética, tomografia computadorizada volumétrica e ultra-som

Angiogenesis is an essential feature of cancer growth and metastasis formation. In bone metastasis, angiogenic factors are pivotal for tumor cell ...

A Murine Model of Stent Implantation in the Carotid Artery for the Study of Restenosis

Despite the considerable progress made in the stent development in the last decades, cardiovascular diseases remain the main cause of death in western countries. Beside the benefits offered by the development of different drug-eluting stents, the coronary revascularization bears also the life-threatening risks of in-stent thrombosis and restenosis. Research on new therapeutic strategies is impaired by the lack of appropriate methods to study stent implantation and restenosis processes. Here, we describe a rapid and accessible procedure of stent implantation in mouse carotid artery, which offers the possibility to study in a convenient way the molecular mechanisms of vessel remodeling and the effects of different drug coatings.

A model of stent implantation in mouse carotid artery is described. Compared to other similar methods, this procedure is very rapid, simple and accessible, offering the possibility to study in a convenient way the vascular wall reaction to different drug-eluting stents and the molecular mechanisms of restenosis.

Um modelo murino de implante de stent na artéria carótida para o Estudo da reestenose

Despite  the considerable progress made in the stent development in the last decades,  cardiovascular diseases remain the main cause of death in western ...

Adult Mouse Venous Hypertension Model: Common Carotid Artery to External Jugular Vein Anastomosis.

The understanding of the pathophysiology of brain arteriovenous malformations and arteriovenous fistulas has improved thanks to animal models. A rat model creating an artificial fistula between the common carotid artery (CCA) and the external jugular vein (EJV) has been widely described and proved technically feasible. This construct provokes a consistent cerebral venous hypertension (CVH), and therefore has helped studying the contribution of venous hypertension to formation, clinical symptoms, and prognosis of brain AVMs and dural AVFs. Equivalent mice models have been only scarcely described and have shown trouble with stenosis of the fistula. An established murine model would allow the study of not only pathophysiology but also potential genetic therapies for these cerebrovascular diseases.
We present a model of arteriovenous fistula that produces a durable intracranial venous hypertension in the mouse. Microsurgical anastomosis of the murine CCA and EJV can be difficult due to diminutive anatomy and frequently result in a non-patent fistula. In this step-by-step protocol we address all the important challenges encountered during this procedure. Avoiding excessive retraction of the vein during the exposure, using 11-0 sutures instead of 10-0, and making a carefully planned end-to-side anastomosis are some of the critical steps. Although this method requires advanced microsurgical skills and a longer learning curve that the equivalent in the rat, it can be consistently developed.
This novel model has been designed to integrate transgenic mouse techniques with a previously well-established experimental system that has proved useful to study brain AVMs and dural AVFs. By opening the possibility of using transgenic mice, a broader spectrum of valid models can be achieved and genetic treatments can also be tested. The experimental construct could also be further adapted to the study of other cerebrovascular diseases related with venous hypertension such as migraine, transient global amnesia, transient monocular blindness, etc.

We describe a method for creating a reliable model of cerebral venous hypertension in the adult mouse. This model has been widely described and tested in the rat. This new counterpart in the mice opens the possibility of using genetic modified animals and thereby broadens the applications of the model.

Adulto Rato venoso Hipertensão Modelo: artéria carótida comum para External Jugular Vein anastomose.

The understanding of the pathophysiology of brain arteriovenous malformations and arteriovenous fistulas has improved thanks to animal models. A rat model ...

Vascular Balloon Injury and Intraluminal Administration in Rat Carotid Artery

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and cellular mechanisms involved in vascular smooth muscle dedifferentiation, neointima formation and vascular remodeling. Male Sprague-Dawley rats are the most frequently employed animals for this model. Female rats are not preferred as female hormones are protective against vascular diseases and thus introduce a variation into this procedure. The left carotid is typically injured with the right carotid serving as a negative control. Left carotid injury is caused by the inflated balloon that denudes the endothelium and distends the vessel wall. Following injury, potential therapeutic strategies such as the use of pharmacological compounds and either gene or shRNA transfer can be evaluated. Typically for gene or shRNA transfer, the injured section of the vessel lumen is locally transduced for 30 min with viral particles encoding either a protein or shRNA for delivery and expression in the injured vessel wall. Neointimal thickening representing proliferative vascular smooth muscle cells usually peaks at 2 weeks after injury. Vessels are mostly harvested at this time point for cellular and molecular analysis of cell signaling pathways as well as gene and protein expression. Vessels can also be harvested at earlier time points to determine the onset of expression and/or activation of a specific protein or pathway, depending on the experimental aims intended. Vessels can be characterized and evaluated using histological staining, immunohistochemistry, protein/mRNA assays, and activity assays. The intact right carotid artery from the same animal is an ideal internal control. Injury-induced changes in molecular and cellular parameters can be evaluated by comparing the injured artery to the internal right control artery. Likewise, therapeutic modalities can be evaluated by comparing the injured and treated artery to the control injured only artery.

This protocol uses a balloon catheter to cause an intraluminal injury on the rat carotid artery and henceforth elicit neointimal hyperplasia. This is a well-established model for studying the mechanisms of vascular remodeling in response to injury. It is also widely used to determine the validity of potential therapeutic approaches.

Lesão Balloon Vascular e Administração Intraluminal em Rat Carótida

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and ...

Dynamic Contrast Enhanced Magnetic Resonance Imaging of an Orthotopic Pancreatic Cancer Mouse Model

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) has been limitedly used for orthotopic pancreatic tumor xenografts due to severe respiratory motion artifact in the abdominal area. Orthotopic tumor models offer advantages over subcutaneous ones, because those can reflect the primary tumor microenvironment affecting blood supply, neovascularization, and tumor cell invasion. We have recently established a protocol of DCE-MRI of orthotopic pancreatic tumor xenografts in mouse models by securing tumors with an orthogonally bent plastic board to prevent motion transfer from the chest region during imaging. The pressure by this board was localized on the abdominal area, and has not resulted in respiratory difficulty of the animals. This article demonstrates the detailed procedure of orthotopic pancreatic tumor modeling using small animals and DCE-MRI of the tumor xenografts. Quantification method of pharmacokinetic parameters in DCE-MRI is also introduced. The procedure described in this article will assist investigators to apply DCE-MRI for orthotopic gastrointestinal cancer mouse models.

The goal of this protocol is to apply dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for orthotopic pancreatic tumor xenografts in mice. DCE-MRI is a non-invasive method to analyze microvasculature in a target tissue, and useful to assess vascular response in a tumor following a novel therapy.

Contraste Dinâmico aprimorada Ressonância Magnética de um Modelo de câncer de pâncreas Orthotopic Rato

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) has been limitedly used for orthotopic pancreatic tumor xenografts due to severe ...

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 ...

Cardiac Magnetic Resonance Imaging at 7 Tesla

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher magnetic field strengths and potentially provides improved signal contrast and spatial resolution. While promising results have been achieved, ultra-high field CMR is challenging due to energy deposition constraints and physical phenomena such as transmission field non-uniformities and magnetic field inhomogeneities. In addition, the magneto-hydrodynamic effect renders the synchronization of the data acquisition with the cardiac motion difficult. The challenges are currently addressed by explorations into novel magnetic resonance technology. If all impediments can be overcome, ultra-high field CMR may generate new opportunities for functional CMR, myocardial tissue characterization, microstructure imaging or metabolic imaging. Recognizing this potential, we show that multi-channel radio frequency (RF) coil technology tailored for CMR at 7 Tesla together with higher order B0 shimming and a backup signal for cardiac triggering facilitates high fidelity functional CMR. With the proposed setup, cardiac chamber quantification can be accomplished in examination times similar to those achieved at lower field strengths. To share this experience and to support the dissemination of this expertise, this work describes our setup and protocol tailored for functional CMR at 7 Tesla.

The sensitivity gain inherent to ultrahigh field magnetic resonance holds promise for high spatial resolution imaging of the heart. Here, we describe a protocol customized for functional cardiovascular magnetic resonance (CMR) at 7 Tesla using an advanced multi-channel radio-frequency coil, magnetic field shimming and a triggering concept.

Ressonância magnética cardíaca na Tesla 7

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher ...

In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium

The goal of this method is to introduce a transgene into the endothelium of isolated segments of both rabbit common carotid arteries. The method achieves focal endothelial-selective transgenesis, thereby allowing an investigator to determine the biological roles of endothelial-expressed transgenes and to quantify the in vivo transcriptional activity of DNA sequences in large artery endothelial cells. The method uses surgical isolation of rabbit common carotid arteries and an arteriotomy to deliver a transgene-expressing viral vector into the arterial lumen. A short incubation period of the vector in the lumen, with subsequent aspiration of the lumen contents, is sufficient to achieve efficient and durable expression of the transgene in the endothelium, with no detectable transduction or expression outside of the isolated arterial segment. The method allows assessment of the biological activities of transgene products both in normal arteries and in models of human vascular disease, while avoiding systemic effects that could be caused either by targeting gene delivery to other sites (e.g. the liver) or by the alternative approach of delivering genetic constructs to the endothelium by germ line transgenesis. Application of the method is limited by the need for a skilled surgeon and anesthetist, a well-equipped operating room, the costs of purchasing and housing rabbits, and the need for expertise in gene-transfer vector construction and use. Results obtained with this method include: transgene-related alterations in arterial structure, cellularity, extracellular matrix, or vasomotor function; increases or reductions in arterial inflammation; alterations in vascular cell apoptosis; and progression, retardation, or regression of diseases such as intimal hyperplasia or atherosclerosis. The method also allows measurement of the ability of native and synthetic DNA regulatory sequences to alter transgene expression in endothelial cells, providing results that include: levels of transgene mRNA, levels of transgene protein, and levels of transgene enzymatic activity.

In Vivo Gene Transfer to the Rabbit Common Carotid Artery Endothelium

This method is to introduce a transgene into the endothelium of rabbit carotid arteries. Introduction of the transgene allows the assessment of the biological role of the transgene product either in normal arteries or disease models. The method is also useful for measuring activity of DNA regulatory sequences.

Na Vivo Transferência de genes para o endotélio da artéria carótida comum de coelho

The goal of this method is to introduce a transgene into the endothelium of isolated segments of both rabbit common carotid arteries. The method achieves ...