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 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><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

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

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 cerebral focal por oclusión endovascular de sutura de la arteria cerebral media en la rata

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 ...

Investigación

Neurociencias

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 optimizado para la monitorización de la perfusión cerebral en el modelo de rata de Carrera intraluminal oclusión arteria cerebral media

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

Medicina

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to return to normal in a large majority of patients2, which is mainly due to current lack of clinical treatment for acute stroke. This necessitates understanding the physiological effects of cerebral ischemia on brain tissue over time and is a major area of active research. Towards this end, experimental progress has been made using rats as a preclinical model for stroke, particularly, using non-invasive methods such as 18F-fluorodeoxyglucose (FDG) coupled with Positron Emission Tomography (PET) imaging3,10,17. Here we present a strategy for inducing cerebral ischemia in rats by middle cerebral artery occlusion (MCAO) that mimics focal cerebral ischemia in humans, and imaging its effects over 24 hr using FDG-PET coupled with X-ray computed tomography (CT) with an Albira PET-CT instrument. A VOI template atlas was subsequently fused to the cerebral rat data to enable a unbiased analysis of the brain and its sub-regions4. In addition, a method for 3D visualization of the FDG-PET-CT time course is presented. In summary, we present a detailed protocol for initiating, quantifying, and visualizing an induced ischemic stroke event in a living Sprague-Dawley rat in three dimensions using FDG-PET.

Non-invasive Imaging and Analysis of Cerebral Ischemia in Living Rats Using Positron Emission Tomography with 18F-FDG

Brain damage resulting from cerebral ischemia may be non-invasively imaged and studied in rats using pre-clinical positron emission tomography coupled with the injectable radioactive probe, 18F-fluorodeoxyglucose. Further, the use of modern software tools that include volume of interest (VOI) brain templates dramatically increase the quantitative information gleaned from these studies.

De imagen no invasivas y Análisis de la isquemia cerebral en ratas vivas utilizando Tomografía por emisión de positrones con<sup&gt; 18</sup&gt; F-FDG

Stroke is the third leading cause of death among Americans 65 years of age or older1. The quality of life for patients who suffer from a stroke fails to ...

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.

Imágenes de difusión en la médula espinal de rata 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.

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 ...

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.

Un protocolo de imagen de resonancia magnética para la estimación de tiempo de inicio de movimiento en 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.

<meta charset="utf8"></head><body>Resonancia magnética cuantitativa de la permeabilidad y disfunción endotelial en la aterosclerosis

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.

Resonancia magnética cuantitativa de la permeabilidad endotelial y la (dis)función en la aterosclerosis

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

Bioingeniería

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.

Trombosis de la arteria carótida canina cloruro férrico-inducida: Un modelo Animal grande de lesión Vascular

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

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

Resonancia Magnética Cardíaca

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

Fase contraste resonancia magnética en la arteria carótida común de rata

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