Este trabajo fue financiado por becas del Ministerio de ciencia y tecnología de Taiwán, bajo el número de MOST-105-2314-B-039-044-MY2.

El cuidado institucional y comités del uso (IACUC) de la Universidad de Medicina China aprobó todos los procedimientos.
1. animal, preparación y seguimiento
<ol><li>Dejar todos los objetos magnéticamente sensibles tales como carteras, llaves, tarjeta de crédito, etc. fuera de la sala de escáner antes de comenzar la preparación de animales para la exploración de MRI.</li>
	<li>Inicialmente anestesiar la rata (rata de Sprague-Dawley (SD) macho de 2 meses, 280 – 350 g) en una caja de inducción utilizando una mezcla de 5% isoflurano (ISO) y oxígeno (2 L/min) por 3-5 min, según sea necesario.</li>
	<li>Cuando el animal está recostado y no exhibe respuesta a una pizca de cola o dedo del pie, deje de administración ISO y traslado del animal a la sala de exploración.</li>
	<li>Colocar la rata en la cama de MRI en una posición propensa cefálico y el ISO 2-3% a través de un dispositivo de cono nariz para el mantenimiento de la anestesia.</li>
	<li>Monitor de respiración mediante la colocación de un sensor de almohadilla respiratoria bajo el torso del animal.</li>
	<li>Conecte el sensor a un cheque para la tarifa de respiración entre 40-50 latidos por minuto (bpm) y las vías respiratorias.</li>
	<li>Para adquisición de PC-MRI cine cerrado, colocar un electrodo en la forepaw derecha y pata trasera izquierda, respectivamente (Figura 1a).</li>
	<li>Tuerza los cables de electrocardiografía (ECG).</li>
	<li>Utilice un soporte con barras de oreja y una barra de bocado para fijar el animal para restringir el movimiento de la cabeza.</li>
	<li>Utilice un aire caliente calefacción almohadillas de sistema o una gasa para mantener la temperatura corporal mientras que en el imán.</li>
	<li>Asegúrese de que la onda R es evidente en el monitor de ECG (Figura 1b) y coloque el animal en el escáner. No hay necesidad para colocar la bobina de superficie en la parte superior de cuello del animal como imágenes son adquiridas por la bobina de volumen.</li>
</ol>2. resonancia magnética adquisición
<ol><li>ISO de 2 – 3% de uso para mantener la anestesia durante el procedimiento entero de la proyección de imagen. Monitorear respuestas fisiológicas y mantener lo más constante posible.</li>
	<li>Iniciar las exploraciones de MRI una vez que el animal se coloca en el escáner y sigue siendo fisiológicamente estable. En este estudio, utilizar un animal pequeño de T 7 sistema de MRI con una fuerza del gradiente de 630 mT/m, pero pueden utilizarse otras fuerzas del campo de sistemas de MRI de animales pequeños.</li>
	<li>Seleccione la secuencia de "Localizador" del monitor de la consola del explorador de MRI y adquirir imágenes de scout a lo largo de los tres orientaciones con cualquier secuencia de adquisición de imagen rápido, por ejemplo, el eco de la vuelta rápida, para crear coronal, axial y sagital . El propósito de estas imágenes del explorador es determinar los planos de proyección de imagen.</li>
	<li>Asegúrese de que el centro de la cabeza y el cuello del animal está en el centro del imán. Si es necesario, ajuste la posición del animal hasta alcanzar la posición correcta. Si el animal es colocado de nuevo, repetir la exploración para obtener imágenes de scout.</li>
	<li>Seleccione la secuencia de "tiempo de vuelo (TOF) angiograma" del monitor de la consola del explorador de MRI y adquirir un angiograma TOF 2D para determinar la localización anatómica exacta del CCA. Utilice los siguientes parámetros de análisis: repetición tiempo (TR) / eco tiempo (TE) = 22/4.87 ms, flip ángulo = 90°, campo de visión (FOV) = 40 × 40 mm2, tamaño de matriz = 256 × 256, rebanada de espesor 0,6 mm, con la cantidad de excitación (NEX) = 1. Nota: El nombre de la secuencia TOF podría ser vendedor-específicas. El usuario puede insertar estos parámetros en el monitor de la consola.</li>
	<li>Asegúrese de que la banda de saturación es "on" y se coloca en la parte superior para evitar interferencias de señales venosas. Nota: Para la banda de saturación, normalmente viene con la secuencia TOF. Si la banda de saturación no aparece en el monitor, por favor notifique a la persona de servicio.</li>
	<li>Después de localizar la CCA con el angiograma de la TOF, orientar el plano de la imagen de la PC-resonancia magnética para el centro de la CCA y orientar tales que el segmento es perpendicular a la dirección del flujo de sangre (Figura 2a).</li>
	<li>Asegúrese de que tanto la respiración como gating ECG son conectados al sistema de MRI, mostrando la clara señal en el monitor del ordenador (Figura 1b) y configurar el módulo de disparo que "on" en el "modo de disparo" del monitor de la consola del explorador de MRI.</li>
	<li>Confirman que las respuestas fisiológicas del animal son estables antes de iniciar la exploración de MRI de PC desde el equipo de monitoreo (Figura 1b). Comprobar que bloquea las selecciones "a" en el monitor del ordenador y el monitor de la consola del explorador de MRI. Nota: La fisiología sistema utilizado en este estudio es proporcionada por el vendedor. Escáneres más animales, los sistemas de vigilancia similar fisiología son proporcionados y vendedor-específicas.</li>
	<li>Seleccione la secuencia de secuencia de MRI de la PC desde el monitor de la consola del explorador de MRI y realizar análisis de PC-RM cerradas usando los siguientes parámetros: TR/TE=15.55/4.51 ms mínimo TR y TE, tapa ángulo = 30°, FOV = 40 × 40 mm2, tamaño de matriz = 192 × 192, rebanada espesor = 2 mm, velocidad de codificación (VENC) = 120 cm/s, con NEX = 8. VENC unidireccional es adquirida en la dirección a través de avión. Nota: El tiempo de exploración es de aproximadamente 8,5 min, pero el tiempo real de exploración pueden variar entre animales debido a la variación en los ciclos cardiacos.</li>
	<li>Repita los pasos 2,6 – 2,9 de adquisición de la imagen si la región de interés (ROI) es cambiarse a otra ubicación en el CCA, como a las 4de la bifurcación.</li>
	<li>Quitar el animal del explorador y volver a su jaula de recuperación cuando la exploración haya terminado.</li>
	<li>Caliente al animal con una lámpara de calefacción para mantener la temperatura corporal. Mantenga la lámpara al menos 15 cm del animal para evitar el sobrecalentamiento.</li>
	<li>Cuando el animal empieza a moverse y exhibe una respuesta a una pizca de cola o dedo del pie, apague la lámpara de calefacción.</li>
</ol>3. procesamiento de datos
<ol><li>Guardar datos de MRI en imagen Digital y comunicaciones en medicina (DICOM) formato o cualquier otro formato de vendedor-específicas. Generar series de cine con dos tipos de imágenes: una imagen de magnitud (imagen de la anatomía) y una imagen de fase (figura 2b). Nota: En algunos exploradores, el tercer tipo de imagen, que podría ser la magnitud x fase de la imagen o el complejo-diferencia (la resta compleja entre las dos adquisiciones con diferentes gradientes de codificación de velocidad), se genera. La tercera imagen es dependiente del proveedor.</li>
	<li>Procesamiento previo de los datos de imagen. Encubierta la fase de la imagen en el mapa de la velocidad y corregir el error de offset de la fase 5. Nota: La imagen de fase tiene una unidad arbitraria de Señor de intensidad de la señal en lugar de valores de velocidad verdadera, pero la intensidad de la señal del Señor es linealmente proporcional a la velocidad. La máxima señal de MRI de la imagen de fase normalmente se asigna como el valor del VENC, y la mínima señal se le asigna el valor opuesto de VENC. Ver archivo de código adicional 1 para un ejemplo de la secuencia de comandos de Matlab y presione el botón de "Ejecutar".</li>
	<li>Delinear el ROI cuidadosamente trazando el límite de la CCA. La arteria puede dilatar y construir durante las distintas fases cardiacas, delinear ROIs para cada plazo. Calcular el flujo de sangre mediante la integración sobre el retorno de la inversión, es decir, velocidad x área de la arteria. El flujo de la sangre resultante de cada arteria fue en las unidades de mL/seg. Ver archivo de código suplementario 2 un ejemplo de la secuencia de comandos de Matlab y presione el botón de "Ejecutar".</li>
</ol>

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No hay nada que revelar.

PC-MRI es un enfoque integral para la evaluación no invasiva y longitudinal del flujo de sangre. Presentamos un protocolo para realizar PC-MRI de la rata CCA. Este procedimiento es fácil de realizar en cualquier animal explorador de MRI y demuestra buena reproducibilidad.
La técnica de PC-RM ha ganado creciente popularidad en humano 10,11 , así como los estudios en animales de 4,...

La proyección de imagen de resonancia magnética (MRI) es un método versátil que proporciona información detallada sobre fisiología y estructuras internas del cuerpo y cada vez más se está utilizando para el diagnóstico clínico y en los estudios preclínicos en animales. Los modelos animales son vitales para una mejor comprensión de la importante implicación clínica 1. Como modelos animales difieren considerablemente de los seres humanos con respecto a los requisitos de la anestesia y parámetros fisiológicos, optimización de procedimientos de MRI para estos animales adquiere importancia.
MRI de contraste de fase (PC-MRI) es un tipo especializado de resonancia magnética que utiliza la velocidad de flujos tiradas para cuantificar parámetros relacionados con el flujo como flujo de sangre. Con PC-MRI, el mapeo de patrones de flujo en las arterias principales usando los modelos animales puede ayudar a arrojar luz sobre patologías cardiovasculares 2. Además, PC-MRI no invasiva puede monitorizar las alteraciones inherentes en el flujo sanguíneo en condiciones patofisiológicas 3. Estas observaciones sugieren que PC-RM es un método valioso que puede utilizarse en modelos animales de enfermedades cardiovasculares.
En este informe, describimos un método para la cuantificación del flujo sanguíneo en la arteria carótida común (CCA) de las ratas. Los dos sistemas de la fuente la cabeza y el cuello con sangre oxigenada, y la enfermedad de la arteria carótida es una causa importante de accidente cerebrovascular. Por lo tanto, es fundamental detectar la patología temprana en el CCA. Este procedimiento tiene una duración de unos 15 min y puede ser potencialmente aplicado a condiciones con alteraciones de la hemodinámica, tal arterioesclerosis o un accidente cerebrovascular.

<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

Fase contraste RMN (PC-) es un método no invasivo que puede cuantificar parámetros relacionados con el flujo como flujo de sangre. Estudios previos han demostrado que el flujo anormal de sangre puede estar asociado con riesgo vascular sistémico. Así, PC-MRI puede facilitar la traducción de los datos obtenidos de modelos animales de enfermedades cardiovasculares para las investigaciones clínicas pertinentes. En este informe, describir el procedimiento para medir el flujo sanguíneo en la arteria carótida común (CCA) de ratas usando MRI de PC cine cerrado y discutir los métodos de análisis pertinentes. Este procedimiento se puede realizar en un animal vivo, anestesiado y no requiere la eutanasia después del procedimiento. Los parámetros de análisis propuestos producen mediciones repetibles para el flujo de sangre, que indica la excelente reproducibilidad de los resultados. El procedimiento PC-MRI que se describe en este artículo puede utilizarse para la prueba farmacológica evaluación fisiopatológica y evaluación de la hemodinámica cerebral.

Geometría de corte correcta es fundamental para asegurar el éxito del experimento PC-MRI. El posicionamiento del plano de imagen precisa da una forma "redonda" de la arteria (figura 3a), y forma angular aumenta, es decir, cuando es menos perpendicular a la arteria, la geometría resultante de la arteria se convierte en ovoide, llevando a mayor volumen parcial efectos (figura 3b). Efectos de volumen parcial severa darí...

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

El objetivo general de este procedimiento es medir el flujo sanguíneo en la arteria carótida común de rata mediante el uso de resonancia magnética nuclear contraste fase no invasiva.

Fase contraste resonancia magnética en la arteria carótida común de rata

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 vistas.  Chang Gung Memorial Hospital. El objetivo general de este procedimiento es medir el flujo sanguíneo en la arteria carótida común de rata mediante el uso de resonancia magnética nuclear contraste fase no invasiva.

Video: 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.

Evaluación de Resonancia Magnética Derivado deformación miocárdica mediante función de seguimiento

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 ...

Investigación

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.

La formación de una sofisticada técnica de microcirugía: La interposición de injerto de la vena yugular externa en la arteria carótida común en ratas

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.

Multimodal de imágenes de la angiogénesis en un modelo de rata desnuda de las metástasis óseas del cáncer de pecho utilizando imágenes de resonancia magnética, tomografía computarizada y la ecografía volumétrica

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.

Un modelo murino de la implantación de un stent en la arteria carótida para el Estudio de la reestenosis

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.

Adultos Mouse hipertensión venosa: Modelo: arteria carótida común a la vena yugular externa anastomosis.

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.

Lesión Vascular Globo y Administración intraluminal en rata arteria 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.

Dynamic Contrast mejorada de imagen de resonancia magnética de un modelo ortotópico de cáncer pancreático del ratón

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.

Simultánea de imágenes PET / RM Durante cerebral del ratón hipoxia-isquemia

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.

Resonancia magnética cardiaca en 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 ...

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.

En Vivo Transferencia génica en el endotelio de la arteria carótida común conejo

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 ...