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

Questo lavoro è stato sostenuto da sovvenzioni dal Ministero della scienza e della tecnologia, Taiwan, sotto il numero di concessione di MOST-105-2314-B-039-044-MY2.

La cura istituzionale e uso comitati (IACUC) di China Medical University ha approvato tutte le procedure.
1. animale preparazione e monitoraggio
<ol><li>Lasciare tutti gli oggetti magneticamente suscettibili quali portafogli, chiavi, carta di credito, ecc. all'esterno della camera dello scanner prima di iniziare la preparazione degli animali per l'esame di MRI.</li>
	<li>Inizialmente anestetizzare il rat (ratto Sprague-Dawley (deviazione standard) maschio di 2 mesi, 280 – 350 g) in una scatola di induzione utilizzando una miscela di 5% isoflurane (ISO) e ossigeno (2 L/min) per 3 – 5 min, se necessario.</li>
	<li>Quando l'animale è recumbent e non mostre nessuna risposta a un pizzico di punta o coda, interrompere la somministrazione di ISO e trasferire l'animale nella stanza di scansione.</li>
	<li>Posizionare il ratto nel letto MRI in posizione prona a capofitto e consegnare 2-3% ISO attraverso un dispositivo di cono di naso per mantenere l'anestesia.</li>
	<li>Respirazione di monitor posizionando un sensore respiratoria cuscino sotto il busto dell'animale.</li>
	<li>Collegare il sensore a un sistema respiratorio e verificare per tasso respiratorio tra 40-50 battiti al minuto (bpm).</li>
	<li>Per l'acquisizione di PC-MRI cine-gated, posizionare un elettrodo ogni sulla zampa anteriore destra e la sinistra posteriore della zampa, rispettivamente (Figura 1a).</li>
	<li>Attorcigliare i cavi di elettrocardiografia (ECG).</li>
	<li>Utilizzare un supporto per testine con orecchio bar e un morso per proteggere l'animale per limitare il movimento della testa.</li>
	<li>Utilizzare un sistema o una garza pastiglie di riscaldamento ad aria per mantenere la temperatura corporea mentre nel magnete.</li>
	<li>Assicurarsi che l'onda R è chiaro sul monitor ECG (Figura 1b) e inserire l'animale nello scanner. Non c'è nessun bisogno di posizionare la bobina di superficie nella parte superiore il collo dell'animale come immagini vengono acquisite dalla bobina di volume.</li>
</ol>2. MRI acquisizione
<ol><li>Utilizzare 2 – 3% ISO per mantenere l'anestesia durante l'intera procedura di imaging. Monitorare continuamente le risposte fisiologiche e mantenere quanto più possibile costante.</li>
	<li>Avviare le scansioni MRI, una volta che l'animale è posto all'interno dello scanner e continua ad essere fisiologicamente stabile. In questo studio, utilizzare un animale di piccola T 7 sistema MRI con una resistenza di pendenza di 630 metri, ma possono essere utilizzati altri punti di forza di campo di sistemi MRI per piccoli animali.</li>
	<li>Selezionare la sequenza di "Localizzatore" dal monitor console dello scanner MRI e acquisire immagini scout lungo tutti e tre gli orientamenti utilizzando qualsiasi sequenza di acquisizione rapida delle immagini, ad esempio, l'eco di rotazione veloce, per creare coronale, assiale e immagini sagittali . Lo scopo di questi scout immagini consiste nel determinare i piani di formazione immagini.</li>
	<li>Assicurarsi che il centro della testa e del collo dell'animale è al centro del magnete. Se necessario, regolare la posizione dell'animale fino a quando non viene raggiunta la posizione corretta. Se l'animale viene riposizionata, ripetere la scansione per ottenere immagini scout.</li>
	<li>Selezionare la sequenza di "tempo di volo (TOF) angiogramma" dal monitor console dello scanner MRI e acquisire un angiogramma 2D TOF in primo luogo per accertare l'esatta posizione anatomica del CCA. Utilizzare i seguenti parametri di scansione: ripetizione tempo (TR) / echo tempo (TE) = 22/4,87 ms, flip angolo = 90°, campo visivo (FOV) = 40 × 40 mm2, dimensione della matrice = 256 × 256, spessore 0,6 mm, con il numero di eccitazione (NEX) = 1. Nota: Il nome della sequenza TOF potrebbe essere vender-specifici. L'utente può inserire questi parametri nel monitor console.</li>
	<li>Assicurarsi che la band di saturazione è "on" ed è posizionata sulla parte superiore per evitare le interferenze da segnali di venosi. Nota: Per la band di saturazione, viene solitamente con la sequenza TOF. Se la banda di saturazione non viene visualizzato sul monitor, si prega di avvisare la persona di servizio.</li>
	<li>Dopo aver individuato il CCA utilizzando l'angiogramma TOF, il piano dell'immagine del PC-MRI al centro del CCA di destinazione e orientare tale che la fetta è perpendicolare alla direzione di flusso sanguigno (Figura 2a).</li>
	<li>Assicurarsi che la respirazione sia ECG gating sono collegati al sistema MRI, mostrando il chiaro segnale del computer monitor (Figura 1b) e impostare il modulo trigger di essere "on" in "modalità operativa" dal monitor console dello scanner MRI.</li>
	<li>Confermare che le risposte fisiologiche dell'animale sono stabili prima di iniziare la scansione del PC-MRI dal monitoraggio computer (Figura 1b). Verificare che le selezioni Gate sono "on" nel monitor computer e il monitor console di scanner MRI. Nota: La fisiologia monitoraggio sistema utilizzato in questo studio è fornita dal vender. Per gli scanner più animali, i sistemi di monitoraggio di fisiologia simili sono forniti e vender-specifici.</li>
	<li>Selezionare la sequenza di sequenza di PC-MRI dal monitor console dello scanner MRI ed eseguire scansioni del PC-MRI gated utilizzando i seguenti parametri: TR/TE=15.55/4.51 ms (minimo TR e TE), flip angle = 30°, FOV = 40 × 40 mm2, dimensione della matrice = 192 × 192, fetta spessore = 2 mm, velocità di codifica (VENC) = 120 cm/s, con NEX = 8. VENC unidirezionale viene acquisito nella direzione del attraverso-piano. Nota: Il tempo di scansione è di circa 8,5 min, ma il tempo di scansione effettiva può essere leggermente diverso tra gli animali a causa della variazione nei cicli cardiaci.</li>
	<li>Ripetere i passaggi da 2.6 – 2,9 di acquisizione dell'immagine se la regione di interesse (ROI) è di essere cambiato in un'altra posizione del CCA, come ad esempio presso la biforcazione 4.</li>
	<li>Rimuovere l'animale dallo scanner e restituirlo alla sua gabbia di recupero quando la scansione è completata.</li>
	<li>Caldo l'animale con una lampada riscaldante per mantenere la temperatura corporea. Tenere la lampada almeno 15 cm dall'animale per evitare il surriscaldamento.</li>
	<li>Quando l'animale comincia a muoversi ed esibisce una risposta ad un pizzico di punta o coda, spegnere la lampada di riscaldamento.</li>
</ol>3. elaborazione dei dati
<ol><li>Salvare i dati di MRI in Digital Imaging and Communications in formato medicina (DICOM) o qualsiasi altro formato di vender-specifici. Generare la serie cine con due tipi di immagini: una grandezza immagine (anatomia) e un'immagine di fase (Figura 2b). Nota: In alcuni scanner, il terzo tipo di immagine, che potrebbe essere l'immagine di grandezza immagine × fase o il complesso-differenza (sottrazione complessa tra le due acquisizioni con diversi gradienti di velocità di codifica), viene generato. La terza immagine è dipendente dal fornitore.</li>
	<li>Pre-elaborare i dati di immagine. Segreta la fase immagine nella mappa delle velocità e correggere l'errore di offset di fase 5. Nota: L'immagine di fase ha un'unità di MR arbitraria dell'intensità del segnale invece di valori della velocità vera, ma l'intensità di segnale del signor è linearmente proporzionale alla velocità. Il massimo segnale di MRI dall'immagine fase in genere viene assegnato come valore di VENC e il minimo segnale viene assegnato il valore opposto di VENC. Vedere file di codice supplementare 1 per un esempio dello script Matlab e premere il pulsante di "eseguire".</li>
	<li>Delineare il ROI attentamente tracciando il contorno del CCA. Come l'arteria può dilatare e costruire durante le varie fasi cardiache, delineare ROIs per ogni intervallo di tempo. Calcolare il flusso di sangue integrando sopra l'arteria ROI, cioè, velocità × area. Il flusso di sangue è derivato di ogni arteria era nelle unità di mL/s. Vedere file di codice supplementare 2 per un esempio dello script Matlab e premere il pulsante di "eseguire".</li>
</ol>

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Non c'è niente di divulgare.

PC-MRI è un approccio globale per la valutazione non invasiva e longitudinale del flusso sanguigno. Vi presentiamo un protocollo per l'esecuzione di PC-MRI del ratto CCA. Questa procedura è facile da eseguire in qualsiasi animale scanner MRI e dimostra buona riproducibilità.
La tecnica di PC-MRI ha guadagnato la popolarità aumentante in umano 10,11 , nonché gli studi sugli animali 4,<sup class="x...

La formazione immagine a risonanza magnetica (MRI) è un approccio versatile che fornisce informazioni dettagliate sulla fisiologia e strutture interne del corpo e sempre più sta usanda per la diagnosi clinica e negli studi sugli animali preclinici. Modelli animali sono vitali per una migliore comprensione di notevole implicazione clinica 1. Come modelli animali differiscono notevolmente da esseri umani per quanto riguarda l'anestesia requisiti e parametri fisiologici, ottimizzazione delle procedure di MRI per tali animali assume importanza.
MRI di contrasto di fase (PC-MRI) è un tipo specializzato di MRI che utilizza la velocità dei giri che scorre per quantificare il flusso relativi parametri quali il flusso di sangue. Con PC-MRI, mappatura schemi di flusso nelle arterie principali utilizzando modelli animali può aiutare a fare luce su patologie cardiovascolari 2. Inoltre, PC-MRI non invadente può monitorare le alternanze insite nel flusso sanguigno in condizioni fisiopatologiche 3. Queste osservazioni suggeriscono che PC-MRI è un valido approccio che può essere utilizzato nei modelli animali di malattie cardiovascolari.
In questo rapporto, descriviamo un metodo per la quantificazione del flusso sanguigno nell'arteria carotica comune (CCA) dei ratti. I due CCAs fornire la testa ed il collo con sangue ossigenato, e la malattia dell'arteria carotica è delle principali cause di ictus. Pertanto, rilevando la patologia iniziale in CCA è fondamentale. Questa procedura ha una durata di circa 15 min e potenzialmente applicabile a condizioni con alterazioni di emodinamica, tale aterosclerosi o ictus.

<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 di contrasto risonanza magnetica (PC-MRI) è un approccio non invasivo che può quantificare il flusso relativi parametri quali il flusso di sangue. Gli studi precedenti hanno indicato che il flusso sanguigno anormale può essere associato con il rischio vascolare sistemico. Quindi, PC-MRI può facilitare la traduzione dei dati ottenuti da modelli animali di malattie cardiovascolari a indagini cliniche pertinenti. In questo rapporto, descriviamo la procedura per la misurazione del flusso sanguigno nell'arteria carotica comune (CCA) di ratti utilizzando cine-gated PC-MRI e discutere i metodi di analisi pertinenti. Questa procedura può essere eseguita in un animale vivo, anestetizzato e non richiede l'eutanasia dopo la procedura. I parametri di scansione proposti resa misurazioni ripetibili per il flusso di sangue, che indica eccellente riproducibilità dei risultati. La procedura di PC-MRI descritta in questo articolo può essere utilizzata per test farmacologici, valutazione patofisiologica e valutazione emodinamica cerebrale.

Corretta fetta della geometria è fondamentale per garantire il successo dell'esperimento PC-MRI. Il posizionamento di un'immagine precisa aereo produce una forma di "turno" dell'arteria (Figura 3a), e come l'angolazione aumenta, vale a dire, quando è meno perpendicolare all'arteria, la geometria risultante dell'arteria diventa Ovo, portando a maggiore volume parziale effetti (Figura 3b). Effetti di volume parziale seve...

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

L'obiettivo generale di questa procedura è quello di misurare il flusso sanguigno nell'arteria carotica comune ratto utilizzando la risonanza magnetica di contrasto di fase non invadente.

Fase di contrasto risonanza magnetica nell'arteria carotica comune ratto

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

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Research

JoVE Journal

Medicine

9.4K Views.  Chang Gung Memorial Hospital. L'obiettivo generale di questa procedura è quello di misurare il flusso sanguigno nell'arteria carotica comune ratto utilizzando la risonanza magnetica di contrasto di fase non invadente.

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.

Modello di ischemia cerebrale focale da occlusione endovascolare Sutura della arteria cerebrale media nel ratto

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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Neuroscienze

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 ottimizzato per il monitoraggio perfusione cerebrale nel modello Rat Stroke of intraluminale occlusione dell&#39;arteria cerebrale media

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

Medicina

Diffusion Imaging in the Rat Cervical Spinal Cord

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

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

Diffusion Imaging nel midollo spinale cervicale Rat

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.

Simultanea Imaging PET / MRI Durante mouse cerebrale ipossia-ischemia

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 protocollo di risonanza magnetica per la stima del tempo di corsa inizio nell'Ischemia cerebrale permanente

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

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

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

Quantitative MRI of Endothelial Permeability and Dysfunction in Atherosclerosis

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

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

Bioingegneria

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.

Trombosi dell'arteria carotica canini cloruro ferrico-indotta: Un grande modello animale di danno vascolare

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.

Occlusione dell'arteria cerebrale centrale consentendo di riperfusione tramite riparazione dell'arteria carotica comune nei topi

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

Imaging a risonanza magnetica cardiaca

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

Didattica

JoVE Science Education

Ingegneria

Ingegneria biomedica

 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 ...