Technical Aspects of in vivo Small Animal CMR Imaging

Li, Hao; Abaei, Alireza; Metze, Patrick; Just, Steffen; Lu, Kun; Rasche, Volker

doi:10.3389/fphy.2020.00183

Cited by 8 publications

(9 citation statements)

References 216 publications

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“…Most conventional ways to investigate the cardiovascular system lack the integrated assessment. For instance, cardiac function is extensively assessed in vivo through various imaging modalities, e.g., echocardiography and magnetic resonance imaging ( Ram et al, 2011 ; Botnar and Makowski, 2012 ; Li et al, 2020 ). Albeit this provides great knowledge on cardiac function in vivo , the results from these studies are often seen in isolation and not in conjunction to any physiological changes in peripheral vascular resistance and blood pressure.…”

Section: Introductionmentioning

confidence: 99%

Phenylephrine-Induced Cardiovascular Changes in the Anesthetized Mouse: An Integrated Assessment of in vivo Hemodynamics Under Conditions of Controlled Heart Rate

et al. 2022

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ObjectiveInvestigating the cardiovascular system is challenging due to its complex regulation by humoral and neuronal factors. Despite this complexity, many existing research methods are limited to the assessment of a few parameters leading to an incomplete characterization of cardiovascular function. Thus, we aim to establish a murine in vivo model for integrated assessment of the cardiovascular system under conditions of controlled heart rate. Utilizing this model, we assessed blood pressure, cardiac output, stroke volume, total peripheral resistance, and electrocardiogram (ECG).HypothesisWe hypothesize that (i) our in vivo model can be utilized to investigate cardiac and vascular responses to pharmacological intervention with the α1-agonist phenylephrine, and (ii) we can study cardiovascular function during artificial pacing of the heart, modulating cardiac function without a direct vascular effect.MethodsWe included 12 mice that were randomly assigned to either vehicle or phenylephrine intervention through intraperitoneal administration. Mice were anesthetized with isoflurane and intubated endotracheally for mechanical ventilation. We measured blood pressure via a solid-state catheter in the aortic arch, blood flow via a probe on the ascending aorta, and ECG from needle electrodes on the extremities. Right atrium was electrically paced at a frequency ranging from 10 to 11.3 Hz before and after either vehicle or phenylephrine administration.ResultsPhenylephrine significantly increased blood pressure, stroke volume, and total peripheral resistance compared to the vehicle group. Moreover, heart rate was significantly decreased following phenylephrine administration. Pacing significantly decreased stroke volume and cardiac output both prior to and after drug administration. However, phenylephrine-induced changes in blood pressure and total peripheral resistance were maintained with increasing pacing frequencies compared to the vehicle group. Total peripheral resistance was not significantly altered with increasing pacing frequencies suggesting that the effect of phenylephrine is primarily of vascular origin.ConclusionIn conclusion, this in vivo murine model is capable of distinguishing between changes in peripheral vascular and cardiac functions. This study underlines the primary effect of phenylephrine on vascular function with secondary changes to cardiac function. Hence, this in vivo model is useful for the integrated assessment of the cardiovascular system.

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Section: Introductionmentioning

confidence: 99%

Phenylephrine-Induced Cardiovascular Changes in the Anesthetized Mouse: An Integrated Assessment of in vivo Hemodynamics Under Conditions of Controlled Heart Rate

et al. 2022

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“…According to the different directions in which the myocardium deforms, imaging modalities calculate myocardial strain in three principal directions (radial, circumferential, and longitudinal). Over the years, cardiovascular magnetic resonance (CMR) imaging has proven to be an accurate and versatile imaging modality to quantify myocardial deformation due to its feasibility to provide high-quality images of the heart with high temporal and spatial resolution, permitting accurate myocardial border delineation and cardiac assessment [ 7 – 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…With the introduction of the myocardial tagging technique by Zerhouni et al and Axel and Dougherty [ 11 , 12 ], the measurement of myocardial strain using CMR imaging became possible. In tagging MRI, a pulse train combined with a gradient pulse is applied to create saturated stripes and spatially modulate the longitudinal magnetization prior to the conventional image acquisition [ 10 ]. The measurement of myocardial strain is based on the utilization of tag deformation over the cardiac cycle [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…The CMR-FT algorithm is mainly based on optical flow technology and was commercially available. After defining regions of endocardial and epicardial borders at end-diastole, CMR-FT tracks the respective features over the cardiac cycle by correlation of similar regions in the subsequent frames [ 10 , 14 ]. As CMR-FT is a promising novel method for the quantification of myocardial strain from routinely acquired cine CMR images without specific strain image acquisition sequence, and the analysis can be performed in a retrospective manner without time-consuming postprocessing, it has the potential for a fast assessment of myocardial deformation.…”

Section: Introductionmentioning

confidence: 99%

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Quantification of Biventricular Myocardial Strain Using CMR Feature Tracking: Reproducibility in Small Animals

Metze

et al. 2021

BioMed Research International

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Myocardial strain is a well-validated parameter for evaluating myocardial contraction. Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a novel method for the quantitative measurements of myocardial strain from routine cine acquisitions. In this study, we investigated the influence of temporal resolution on tracking accuracy of CMR-FT and the intraobserver, interobserver, and interstudy reproducibilities for biventricular strain analysis in mice from self-gated CMR at 11.7 T. 12 constitutive nexilin knockout (Nexn-KO) mice, heterozygous (Het, N = 6 ) and wild-type (WT, N = 6 ), were measured with a well-established self-gating sequence twice within two weeks. CMR-FT measures of biventricular global and segmental strain parameters were derived. Interstudy, intraobserver, and interobserver reproducibilities were investigated. For the assessment of the impact of the temporal resolution for the outcome in CMR-FT, highly oversampled semi-4 chamber and midventricular short-axis data were acquired and reconstructed with 10 to 80 phases per cardiac cycle. A generally reduced biventricular myocardial strain was observed in Nexn-KO Het mice. Excellent intraobserver and interobserver reproducibility was achieved in all global strains (ICC range from 0.76 to 0.99), where global right ventricle circumferential strain (RCSSAX) showed an only good interobserver reproducibility (ICC 0.65, 0.11-0.89). For interstudy reproducibility, left ventricle longitudinal strain (LLSLAX) was the most reproducible measure of strain (ICC 0.90, 0.71-0.97). The left ventricle radial strain (LRSSAX) (ICC 0.50, 0.10-0.83) showed fair reproducibility and RCSSAX (ICC 0.36, 0.14-0.74) showed only poor reproducibility. In general, compared with global strains, the segmental strains showed relatively lower reproducibility. A minimal temporal resolution of 20 phases per cardiac cycle appeared sufficient for CMR-FT strain analysis. The analysis of myocardial strain from high-resolution self-gated cine images by CMR-FT provides a highly reproducible method for assessing myocardial contraction in small rodent animals. Especially, global LV longitudinal and circumferential strain revealed excellent reproducibility of intra- and interobserver and interstudy measurements.

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“…Further, contrast agents such as late gadolinium enhancement (LGE) can be utilized as a contrast agent to assess myocardial viability and fibrosis during cardiac MRI. − In comparison to healthy myocardium, the gadolinium diffuses more quickly in and out of pathological myocardium, with increased extracellular space . Analysis of this dynamic allows identification of the healthy, injured and border regions of the myocardium after ischemic injury.…”

Section: Current Progress Of Pcl In Cardiac Tissue Engineeringmentioning

confidence: 99%

Current Applications of Polycaprolactone as a Scaffold Material for Heart Regeneration

Schmitt

Dwyer

Coulombe

2022

ACS Appl. Bio Mater.

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Despite numerous advances in treatments for cardiovascular disease, heart failure (HF) remains the leading cause of death worldwide. A significant factor contributing to the progression of cardiovascular diseases into HF is the loss of functioning cardiomyocytes. The recent growth in the field of cardiac tissue engineering has the potential to not only reduce the downstream effects of injured tissues on heart function and longevity but also re-engineer cardiac function through regeneration of contractile tissue. One leading strategy to accomplish this is via a cellularized patch that can be surgically implanted onto a diseased heart. A key area of this field is the use of tissue scaffolds to recapitulate the mechanical and structural environment of the native heart and thus promote engineered myocardium contractility and function. While the strong mechanical properties and anisotropic structural organization of the native heart can be largely attributed to a robust extracellular matrix, similar strength and organization has proven to be difficult to achieve in cultured tissues. Polycaprolactone (PCL) is an emerging contender to fill these gaps in fabricating scaffolds that mimic the mechanics and structure of the native heart. In the field of cardiovascular engineering, PCL has recently begun to be studied as a scaffold for regenerating the myocardium due to its facile fabrication, desirable mechanical, chemical, and biocompatible properties, and perhaps most importantly, biodegradability, which make it suitable for regenerating and re-engineering function to the heart after disease or injury. This review focuses on the application of PCL as a scaffold specifically in myocardium repair and regeneration and outlines current fabrication approaches, properties, and possibilities of PCL incorporation into engineered myocardium, as well as provides suggestions for future directions and a roadmap toward clinical translation of this technology.

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Technical Aspects of in vivo Small Animal CMR Imaging

Cited by 8 publications

References 216 publications

Phenylephrine-Induced Cardiovascular Changes in the Anesthetized Mouse: An Integrated Assessment of in vivo Hemodynamics Under Conditions of Controlled Heart Rate

Phenylephrine-Induced Cardiovascular Changes in the Anesthetized Mouse: An Integrated Assessment of in vivo Hemodynamics Under Conditions of Controlled Heart Rate

Quantification of Biventricular Myocardial Strain Using CMR Feature Tracking: Reproducibility in Small Animals

Current Applications of Polycaprolactone as a Scaffold Material for Heart Regeneration

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