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

Diese Arbeit wurde durch Zuschüsse vom Ministerium für Wissenschaft und Technologie, Taiwan, unter Grant-Nummer von MOST-105-2314-B-039-044-MY2 unterstützt.

Die institutionelle Pflege und Nutzung Ausschüsse (IACUC) von der China Medical University genehmigt alle Verfahren.
(1) tierische Vorbereitung und Begleitung
<ol><li>Lassen Sie alle magnetisch empfindlilch Objekte wie Geldbörsen, Schlüssel, Kreditkarte usw. außerhalb des Scanners Zimmers vor Beginn der tierischen Vorbereitung auf MRI Scan.</li>
	<li>Zunächst die Ratte (2 Monate alten männlichen Sprague-Dawley (SD) Ratte, 280-350 g) in eine Induktion-Box mit einer Mischung aus 5 % Isofluran (ISO) und Sauerstoff (2 L/min) für 3 – 5 min, nach Bedarf zu betäuben.</li>
	<li>Wenn das Tier Liegerad und keine Reaktion auf eine Rute oder Zehe Prise zeigt, ISO Verwaltung unterbrechen und das Tier in den Scan Raum zu übertragen.</li>
	<li>Legen Sie die Ratte in die MRI-Bett in Bauchlage Kopf voran, und liefern Sie ca. 2-3 % ISO durch eine Nase Kegel-Gerät für die Aufrechterhaltung der Narkose.</li>
	<li>Atmung zu überwachen, indem man einen Sensor Atemwege Kissen unter das Tier Torso.</li>
	<li>Schließen Sie den Sensor an ein Atmungssystem und suchen Sie nach Atemfrequenz zwischen 40-50 Schlägen pro Minute (Bpm).</li>
	<li>Cine-gated PC-MRI Akquisition, legen Sie eine Elektrode auf der rechten Vorderpfote und der linken hinteren Pfote bzw. (Abbildung 1a).</li>
	<li>Verdrillen Sie die Elektrokardiographie (EKG) Kabel.</li>
	<li>Verwenden Sie einen Kopf Halter mit Ohr-Bars und eine Snack-Bar, um das Tier um Kopfbewegungen einzuschränken zu sichern.</li>
	<li>Verwenden Sie eine Warmluftheizung System oder Gaze-Pads, um Körpertemperatur während im Magneten.</li>
	<li>Sicherzustellen Sie, dass der R-Zacke klar auf dem ECG Monitor (Abbildung 1 b ist), und legen Sie das Tier in den Scanner. Es gibt keine Notwendigkeit, die Oberfläche Spule oben auf den Hals des Tieres zu platzieren, wie Bilder von der Lautstärke-Spule erworben werden.</li>
</ol>(2) MRI-Übernahme
<ol><li>Verwenden Sie 2 – 3 % ISO um Anästhesie während des gesamten bildgebenden Verfahrens beizubehalten. Ständige Überwachung physiologischen Reaktionen und möglichst konstant zu halten.</li>
	<li>Die MRI-Scans zu starten, sobald das Tier im Inneren des Scanners platziert und weiterhin physiologisch stabil sein. In dieser Studie verwenden ein 7 T kleines Tier MRT-System mit einer Steigung Stärke von 630 m/m, aber andere Feldstärken von kleinen Tieren MRT-Systeme eingesetzt werden.</li>
	<li>Wählen Sie die Sequenz "Localizer" aus der Konsole Monitor von der MRI-Scanner und erwerben Scout entlang aller drei Ausrichtungen mit schnelle Bildfolge Erwerb, z.B., die schnelle Spin-Echo, koronale, axial, erstellen und sagittale Bilder zu . Der Zweck dieser scout Bilder besteht darin, die bildgebende Flugzeuge zu bestimmen.</li>
	<li>Stellen Sie sicher, dass das Zentrum von Kopf und Hals des Tieres in der Mitte des Magneten. Passen Sie ggf. das Tier Position, bis die richtige Position erreicht ist. Wenn das Tier neu positioniert ist, wiederholen Sie Scannen um Scout Bilder zu erhalten.</li>
	<li>Wählen Sie die "Time-of-Flight (TOF) Angiogramm" Sequenz aus der Konsole Monitor von der MRI-Scanner und erwerben ein 2D TOF Angiogramm zunächst zu prüfen, die genaue anatomische Lage des CCA. Verwenden Sie die folgenden Scan-Parameter: Wiederholung Zeit (TR) / echo der Zeit (TE) = 22/4,87 ms, flipwinkel = 90°, Sichtfeld (FOV) = 40 × 40 mm2, Matrixgröße = 256 × 256, Scheibendicke 0,6 mm, mit der Anzahl der Erregung (NEX) = 1. Hinweis: Der Name der TOF-Sequenz könnte Vender-spezifisch sein. Die Benutzer kann diese Parameter in der Konsole Monitor einfügen.</li>
	<li>Stellen Sie sicher, dass die Sättigung Band ist "on" und sich auf der Oberseite zur Vermeidung von Interferenzen von venösen Signale befindet. Hinweis: Für die Sättigung Band kommt es in der Regel mit der TOF-Sequenz. Wenn die Sättigung Band nicht auf dem Monitor angezeigt wird, wenden Sie der Person.</li>
	<li>Nach dem Auffinden der CCA mit TOF-Angiogramm, Ziel der Bildebene des PC-MRT in die Mitte des CCA und orientieren, so dass die Scheibe senkrecht zur Richtung des Blutflusses (Abbildung 2a).</li>
	<li>Sicherzustellen Sie, dass Atmung und ECG Anspritzung angeschlossenen MRI, zeigen das klare Signal auf dem Monitor Computer (Abbildung 1 b), und Sie das Trigger-Modul legen "auf" in den "Trigger-Modus" aus der Konsole Monitor des Mr-Gerätes sein.</li>
	<li>Bestätigen Sie, dass das Tier physiologischen Reaktionen stabil sind, vor Einleitung eines PC-MRT-Untersuchung von den Überwachungscomputer (Abbildung 1 b). Überprüfen Sie, ob gating Auswahlen "auf" in den Monitor-Computer und Konsole Monitor des MRT sind. Hinweis: Die Physiologie, die in dieser Studie verwendeten Überwachungssystem wird von dem Verkäufer bereitgestellt. Für die meisten tierischen Scanner sind die ähnlichen Physiologie-monitoring-Systeme und Vender-spezifische.</li>
	<li>Wählen Sie die Reihenfolge der PC-MRT-Sequenz aus der Konsole Monitor von der MRI-Scanner und geschlossenen PC-MRI-Scans mit den folgenden Parametern ausführen: TR/TE=15.55/4.51 ms (minimale TR und TE), flip Winkel = 30°, FOV = 40 × 40 mm2, Matrixgröße = 192 × 192, Scheibe Dicke = 2 mm, Geschwindigkeit Codierung (VENC) = 120 cm/s, mit NEX = 8. Unidirektionale VENC wird in der Richtung durch die Ebene erworben. Hinweis: Die Scan-Zeit ist etwa 8,5 min, aber die eigentliche Scan-Zeit möglicherweise geringfügig unter den Tieren durch die Variation der herzzyklen.</li>
	<li>Wiederholen Sie die Schritte 2,6 – 2,9 der Bildaufnahme, wenn die Region of Interest (ROI) ist an einen anderen Speicherort in der CCA, wie z. B. an der Bifurkation 4geändert werden.</li>
	<li>Das Tier aus dem Scanner zu entfernen und zu ihrer Erholung Käfig zurück, wenn der Scan abgeschlossen ist.</li>
	<li>Wärmen Sie das Tier mit einer Wärmelampe auf Körpertemperatur zu halten. Halten Sie die Lampe mindestens 15 cm entfernt von dem Tier um eine Überhitzung zu verhindern.</li>
	<li>Wenn das Tier beginnt sich zu bewegen und eine Antwort auf eine Rute oder Zehe Prise stellt, schalten Sie die Heizung-Lampe.</li>
</ol>(3) die Verarbeitung der Daten
<ol><li>Speichern Sie MRT-Daten in Digital Imaging and Communications in Medicine (DICOM) oder jede andere Vender-spezifische Format. Cine-Serie mit zwei Arten von Bildern zu generieren: eine Größenordnung Bild (Anatomie) und ein Phase-Bild (Abb. 2 b). Hinweis: Bei einigen Scannern die dritte Art von Bild, das die Größe Bild × Phase Bild oder den Komplex-Unterschied (die komplexe Subtraktion zwischen den beiden Akquisitionen mit unterschiedlicher Geschwindigkeit Codierung Gradienten) sein könnte, wird erzeugt. Das dritte Bild ist Hersteller-abhängig.</li>
	<li>Vorverarbeitung der Bilddaten. Verdeckte die Phase in der Geschwindigkeit-Karte Bild und korrigieren Phasenversatz Fehler 5. Hinweis: Die Phase-Bild hat eine willkürliche Herr Einheit der Signalintensität anstelle von true Velocity-Werte, aber der Herr Signalintensität ist linear proportional zur Strömungsgeschwindigkeit. Die maximale MRT-Signal aus dem Phase-Bild ist in der Regel als Wert der VENC zugewiesen, und das minimale Signal erhält den entgegengesetzten Wert VENC. Finden Sie ein Beispiel für die Matlab-Skript-zusätzlicher Codedatei 1 und drücken Sie die TasteAusführen".</li>
	<li>Skizzieren Sie den ROI sorgfältig Nachzeichnen der Begrenzung des CCA. Da die Arterie kann erweitern und in den verschiedenen Lebensabschnitten kardiale konstruieren, abzugrenzen ROIs für jeden Zeitrahmen. Berechnen Sie den Blutfluss durch die Integration über der Arterie ROI, d. h., Geschwindigkeit × Bereich. Die entstandenen Durchblutung jeder Arterie war in den Einheiten der mL/s. Sehen Sie zusätzlicher Codedatei 2 ein Beispiel für das Matlab-Skript zu, und drücken Sie die TasteAusführen".</li>
</ol>

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PC-MRI ist ein umfassender Ansatz für non-invasive und longitudinale Auswertung des Blutflusses. Wir präsentieren Ihnen ein Protokoll für die Durchführung von PC-MRI der Ratte CCA. Dieses Verfahren ist einfach, in jedem Tier MRT durchzuführen und zeigt gute Reproduzierbarkeit.
Die PC-MRI-Technik hat zunehmende Popularität in menschlichen 10,11 , sowie Tierstudien 4,12. Un...

Magnetresonanztomographie (MRT) ist ein vielseitiger Ansatz, der liefert detaillierte Informationen über interne Körperstrukturen und Physiologie, und wird zunehmend für die klinische Diagnose und in präklinischen tierexperimentellen Studien genutzt. Tiermodelle sind entscheidend für ein besseres Verständnis der erhebliche klinische Implikation 1. Da Tiermodelle deutlich von Menschen im Hinblick auf die Anästhesie Anforderungen und physiologischen Parametern unterscheiden, nimmt Optimierung der MRI-Verfahren für solche Tiere Bedeutung.
Phase Kontrast MRI (PC-MRT) ist eine spezielle Art von MRI, die die Geschwindigkeit des fließenden Spins verwendet, um Fluss-relevante Parameter wie Blutfluss zu quantifizieren. Mit PC-MRI können mapping Strömungsmuster in den großen Arterien mit Tiermodellen Aufschluss über Herz-Kreislauf-Krankheiten 2. Darüber hinaus kann PC-MRI nicht-invasiv die inhärente Wechsel des Blutflusses im pathophysiologischen Bedingungen 3überwachen. Diese Beobachtungen legen nahe, dass PC-MRI ist ein wertvoller Ansatz in Tiermodellen der menschlichen Herz-Kreislauf-Krankheiten verwendet werden kann.
In diesem Bericht beschreiben wir eine Methode zur Quantifizierung des Blutflusses in die gemeinsame Halsschlagader (CCA) von Ratten. Zwei CCAs Kopf und Hals mit sauerstoffreichem Blut zu versorgen, und die Halsschlagader-Krankheit ist eine der Hauptursachen für Schlaganfall. Nachweis der frühen Pathologie in der CCA ist daher entscheidend. Dieses Verfahren hat eine Laufzeit von ca. 15 min und kann potenziell auf Bedingungen mit Veränderungen der Hämodynamik, solche Arteriosklerose oder Schlaganfall angewendet werden.

<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

Phase Kontrast Magnetresonanz-Bildgebung (PC-MRI) ist eine nicht-invasive Ansatz, der Fluss-relevante Parameter wie Blutfluss quantifizieren kann. Frühere Studien haben gezeigt, dass abnormale Blutfluss mit systemischen vaskulären Risiko verbunden sein kann. So kann PC-MRI die Übersetzung der Daten aus Tiermodellen der Herz-Kreislauf-Krankheiten, relevante klinische Untersuchungen erleichtern. In diesem Bericht wir beschreiben das Verfahren für die Messung von Blutfluss in die gemeinsame Halsschlagader (CCA) von Ratten mit Cine-gated PC-MRI und entsprechenden Analysemethoden zu diskutieren. Dieses Verfahren kann in einem Leben, narkotisierten Tier durchgeführt werden und erfordert keine Euthanasie nach dem Eingriff. Die vorgeschlagenen Scanparameter liefern wiederholbare Messungen für Blutfluss, zeigt hervorragende Reproduzierbarkeit der Ergebnisse. Die PC-MRT-Verfahren in diesem Artikel beschriebenen kann für pharmakologische Tests, pathophysiologische Bewertung und zerebrale Hämodynamik Bewertung verwendet werden.

Richtige Scheibe Geometrie ist von zentraler Bedeutung für den Erfolg des PC-MRI-Experiments. Das genaue Bild Flugzeug Positionierung ergibt sich eine "Runde" Arterie Form (Abbildung 3a), und mit zunehmender Winkelungen, d. h., wenn es weniger senkrecht auf die Arterie ist die resultierende Geometrie der Arterie wird eiförmig, führt zu größeren Teilvolumen Effekte (Abb. 3 b). Schwere Teilvolumen Wirkung führt zu di...

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

Das übergeordnete Ziel dieses Verfahrens ist es, den Blutfluss in der Ratte gemeinsame Halsschlagader Messen mithilfe nicht-invasive Phase Kontrast Magnetresonanz-Bildgebung.

Phase Kontrast Magnetresonanz-Bildgebung in der Ratte gemeinsame Halsschlagader

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

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Medicine

9.4K Aufrufe.  Chang Gung Memorial Hospital. Das übergeordnete Ziel dieses Verfahrens ist es, den Blutfluss in der Ratte gemeinsame Halsschlagader Messen mithilfe nicht-invasive Phase Kontrast Magnetresonanz-Bildgebung.

Serie: 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.

Fokaler zerebraler Ischämie-Modell von Endovascular Suture Verschluss der mittleren Hirnarterie im 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 ...

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Neurowissenschaften

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.

Optimierte System for Cerebral Perfusion Überwachung im Rat Stroke Modell 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 ...

Medizin

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.

Diffusionsbildgebung in der Ratte Halsmark

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.

Gleichzeitige PET / MRT-Bildgebung während Maus zerebrale Hypoxie-Ischämie

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.

Ein Magnet-Resonanz-Tomographie-Protokoll für Schlaganfall auftreten Zeit Schätzung in ständigen zerebraler Ischämie

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

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

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

Quantitative MRI of Endothelial Permeability and Dysfunction in Atherosclerosis

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

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

Biotechnik

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.

Eisenchlorid-induzierte eckzahn Halsschlagader Thrombosen: Eine große Tiermodell der Gefäßverletzung

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

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

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

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

Mittlere zerebrale Arterie Okklusion so dass Reperfusion über gemeinsame Halsschlagader Reparatur bei Mäusen

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

Cardiac Magnetic Resonance Imaging

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

Cardiac MRI: Principle and Imaging

Kardiale Magnetresonanztomographie

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

Lehre

JoVE Science Education

Ingenieurwesen

Biomedizinische Technik

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

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

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