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1.
Am J Physiol Heart Circ Physiol ; 321(4): H650-H662, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34448639

RESUMO

The role of the Na+/K+-ATPase (NKA) in heart failure associated with myocardial infarction (MI) is poorly understood. The elucidation of its precise function is hampered by the existence of two catalytic NKA isoforms (NKA-α1 and NKA-α2). Our aim was to analyze the effects of an increased NKA-α2 expression on functional deterioration and remodeling during long-term MI treatment in mice and its impact on Ca2+ handling and inotropy of the failing heart. Wild-type (WT) and NKA-α2 transgenic (TG) mice (TG-α2) with a cardiac-specific overexpression of NKA-α2 were subjected to MI injury for 8 wk. As examined by echocardiography, gravimetry, and histology, TG-α2 mice were protected from functional deterioration and adverse cardiac remodeling. Contractility and Ca2+ transients (Fura 2-AM) in cardiomyocytes from MI-treated TG-α2 animals showed reduced Ca2+ amplitudes during pacing or after caffeine application. Ca2+ efflux in cardiomyocytes from TG-α2 mice was accelerated and diastolic Ca2+ levels were decreased. Based on these alterations, sarcomeres exhibited an enhanced sensitization and thus increased contractility. After the acute stimulation with the ß-adrenergic agonist isoproterenol (ISO), cardiomyocytes from MI-treated TG-α2 mice responded with increased sarcomere shortenings and Ca2+ peak amplitudes. This positive inotropic response was absent in cardiomyocytes from WT-MI animals. Cardiomyocytes with NKA-α2 as predominant isoform minimize Ca2+ cycling but respond to ß-adrenergic stimulation more efficiently during chronic cardiac stress. These mechanisms might improve the ß-adrenergic reserve and contribute to functional preservation in heart failure.NEW & NOTEWORTHY Reduced systolic and diastolic calcium levels in cardiomyocytes from NKA-α2 transgenic mice minimize the desensitization of the ß-adrenergic signaling system. These effects result in an improved ß-adrenergic reserve and prevent functional deterioration and cardiac remodeling.


Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Insuficiência Cardíaca/enzimologia , Contração Miocárdica , Infarto do Miocárdio/enzimologia , Traumatismo por Reperfusão Miocárdica/enzimologia , Miócitos Cardíacos/enzimologia , Receptores Adrenérgicos beta/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Remodelação Ventricular , Agonistas Adrenérgicos beta/farmacologia , Animais , Sinalização do Cálcio/efeitos dos fármacos , Modelos Animais de Doenças , Feminino , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/fisiopatologia , Masculino , Camundongos Transgênicos , Contração Miocárdica/efeitos dos fármacos , Infarto do Miocárdio/genética , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Traumatismo por Reperfusão Miocárdica/genética , Traumatismo por Reperfusão Miocárdica/patologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/patologia , Receptores Adrenérgicos beta/efeitos dos fármacos , ATPase Trocadora de Sódio-Potássio/genética , Remodelação Ventricular/efeitos dos fármacos
2.
Eur J Nucl Med Mol Imaging ; 46(7): 1407-1416, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30798427

RESUMO

PURPOSE: Cardiac amyloidosis (CA) is a rare cause of heart failure with frequently delayed diagnosis, because specific early signs or symptoms are missing. Recently, direct amyloid imaging using positron emission tomography/computed tomography (PET/CT) has emerged. The aim of this study was to examine the performance of 18F-florbetaben-PET/CT in detection of CA, and compare it to echocardiography (echo), cardiac MRI (CMR) and scintigraphy. Additionally, the use of 18F-florbetaben-PET/CT for quantification of amyloid burden and monitoring of treatment response was assessed. METHODS: Twenty-two patients with proven (n = 5) or clinical suspicion (n = 17) of CA underwent 18F-florbetaben-PET/CT for diagnostic work-up. Qualitative and quantitative assessment including calculation of myocardial tracer retention (MTR) was performed, and compared to echo (n = 20), CMR (n = 16), scintigraphy (n = 16) and serologic biomarkers (NT-proBNP, cTnT, free light chains). In four patients, follow-up PET/CT was available (after treatment initiation, n = 3; surveillance, n = 1). RESULTS: PET demonstrated myocardial 18F-florbetaben retention consistent with CA in 14/22 patients. Suspicion of CA was subsequently dropped in all eight PET-negative patients. Amyloid subtypes showed characteristic retention patterns (AL > AA > ATTR; all p < 0.005). MTR correlated with morphologic and functional parameters, as measured by CMR and echo (all r| > 0.47|, all p < 0.05), but not with cardiac biomarkers. Changes in MTR from baseline to follow-up corresponded well to treatment response, as assessed by cardiac biomarkers and performance status. CONCLUSIONS: Imaging of cardiac amyloidosis (CA) with 18F-florbetaben-PET/CT is feasible and might be useful in differentiating CA subtypes.


Assuntos
Amiloidose/diagnóstico por imagem , Ecocardiografia , Coração/diagnóstico por imagem , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Cintilografia , Adulto , Idoso , Amiloidose/sangue , Compostos de Anilina , Biomarcadores/sangue , Feminino , Insuficiência Cardíaca/sangue , Insuficiência Cardíaca/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Estilbenos , Resultado do Tratamento , Adulto Jovem
4.
Magn Reson Med ; 76(6): 1887-1894, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-26743137

RESUMO

PURPOSE: An algorithm is presented to enable cardiac and respiratory self-gating in combination with Inversion Recovery Look-Locker read-outs. METHODS: A radial inversion recovery snapshot FLASH sequence was adapted for retrospective cardiac T1 measurements in mice. Cardiac and respiratory data were extracted from the k-space center of radial projections and an adapted method for retrospective cardiac synchronization is introduced. Electrocardiogram (ECG) data was acquired concurrently for validation of the proposed self-gating technique. T1 maps generated by the proposed technique were compared with maps reconstructed with the ECG reference. RESULTS: Respiratory gating and cardiac trigger points could be obtained for the whole time course of the relaxation dynamic and correlate very well to the ECG signal. T1 maps reconstructed with the self-gating technique are in very good agreement with maps reconstructed with the external reference. CONCLUSION: The proposed method extends "wireless" cardiac MRI to non-steady-state inversion recovery measurements. T1 maps were generated with a quality comparable to ECG based reconstructions. As the method does not rely on an ECG trigger signal it provides easier animal handling. Magn Reson Med 76:1887-1894, 2016. © 2016 International Society for Magnetic Resonance in Medicine.


Assuntos
Artefatos , Técnicas de Imagem de Sincronização Cardíaca/métodos , Aumento da Imagem/métodos , Imagem Cinética por Ressonância Magnética/métodos , Infarto do Miocárdio/diagnóstico por imagem , Técnicas de Imagem de Sincronização Respiratória/métodos , Algoritmos , Animais , Feminino , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Processamento de Sinais Assistido por Computador
5.
Radiology ; 274(3): 879-87, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25393945

RESUMO

PURPOSE: To develop and validate a fast cardiac magnetic resonance imaging T1 mapping technique with high spatial resolution based on a radial inversion-recovery (IR) spoiled gradient-echo acquisition. MATERIALS AND METHODS: Approval for the study was granted by the local institutional review board, and all subjects gave written informed consent. An electrocardiographically triggered radial single-shot IR (TRASSI) sequence was developed in conjunction with a custom-written fitting algorithm. The proposed imaging technique was validated in phantom measurements and then used for cardiac T1 mapping in 62 subjects with or without cardiac disease. The study population included 51 healthy subjects, three patients with arrhythmia, and eight patients with myocardial infarction. The potential heart rate dependency of the TRASSI method was tested by using linear regression analysis. Statistically significant differences between the sexes and various section orientations were analyzed with a Student t test for independent groups and a repeated-measures analysis of variance for dependent groups. RESULTS: High-spatial-resolution T1 maps (1.17 × 1.17 mm) without motion artifacts and without heart rate dependency (slope = -0.0303, R(2) = 0.0000887, P = .899) were acquired with an acquisition time of less than 6 seconds in all subjects. The mean T1 of healthy left ventricular myocardium across all examined subjects was 1031 msec ± 33 (standard deviation). Testing for reproducibility in three individuals with 34 repetitive measurements revealed a mean standard deviation of 4.1 msec (0.412%). Subacute and chronic myocardial infarction could be detected in all eight patients. T1 disturbances due to arrhythmia proved to be minimal in three patients (standard deviation, <1.2%). CONCLUSION: Fast and accurate cardiac T1 mapping is feasible within a single-shot IR experiment.


Assuntos
Arritmias Cardíacas/diagnóstico , Técnicas de Imagem Cardíaca/métodos , Eletrocardiografia , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética/métodos , Infarto do Miocárdio/diagnóstico , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
6.
Magn Reson Med ; 74(6): 1705-15, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25446550

RESUMO

PURPOSE: A method for the quantification of perfusion in murine myocardium is demonstrated. The method allows for the reconstruction of perfusion maps on arbitrary time points in the heart cycle while addressing problems that arise due to the irregular heart beat of mice. METHODS: A flow-sensitive alternating inversion recovery arterial spin labeling method using an untriggered FLASH-read out with random sampling is used. Look-Locker conditions are strictly maintained. No dummy pulses or mechanism to reduce deviation from Look-Locker conditions are needed. Electrocardiogram and respiratory data are recorded for retrospective gating and triggering. A model-based technique is used to reconstruct missing k-space data to cope with the undersampling inherent in retrospectively gated methods. Acquisition and reconstruction were validated numerically and in phantom measurements before in vivo experimentation. RESULTS: Quantitative perfusion maps were acquired within a single slice measurement time of 11 min. Perfusion values are in good accordance to literature values. Myocardial infarction could be clearly visualized and results were confirmed with histological results. CONCLUSION: The proposed method is capable of producing quantitative perfusion maps on arbitrary positions in the heart cycle within a short measurement time. The method is robust against irregular breathing patterns and heart rate changes and can be implemented on all scanners.


Assuntos
Técnicas de Imagem de Sincronização Cardíaca/métodos , Angiografia por Ressonância Magnética/métodos , Modelos Cardiovasculares , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Imagem de Perfusão do Miocárdio/métodos , Animais , Velocidade do Fluxo Sanguíneo , Simulação por Computador , Feminino , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Camundongos , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade
8.
Circulation ; 128(17): 1878-88, 2013 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-24025595

RESUMO

BACKGROUND: Monocytes and macrophages are indispensable in the healing process after myocardial infarction (MI); however, the spatiotemporal distribution of monocyte infiltration and its correlation to prognostic indicators of reperfused MI have not been well described. METHODS AND RESULTS: With combined fluorine 19/proton ((1)H) magnetic resonance imaging, we noninvasively visualized the spatiotemporal recruitment of monocytes in vivo in a rat model of reperfused MI. Blood monocytes were labeled by intravenous injection of (19)F-perfluorocarbon emulsion 1 day after MI. The distribution patterns of monocyte infiltration were correlated to the presence of microvascular obstruction (MVO) and intramyocardial hemorrhage. In vivo, (19)F/(1)H magnetic resonance imaging performed in series revealed that monocyte infiltration was spatially inhomogeneous in reperfused MI areas. In the absence of MVO, monocyte infiltration was more intense in MI regions with serious ischemia-reperfusion injuries, indicated by severe intramyocardial hemorrhage; however, monocyte recruitment was significantly impaired in MVO areas accompanied by severe intramyocardial hemorrhage. Compared with MI with isolated intramyocardial hemorrhage, MI with MVO resulted in significantly worse pump function of the left ventricle 28 days after MI. CONCLUSIONS: Monocyte recruitment was inhomogeneous in reperfused MI tissue. It was highly reduced in MVO areas defined by magnetic resonance imaging. The impaired monocyte infiltration in MVO regions could be related to delayed healing and worse functional outcomes in the long term. Therefore, monocyte recruitment in MI with MVO could be a potential diagnostic and therapeutic target that could be monitored noninvasively and longitudinally by (19)F/(1)H magnetic resonance imaging in vivo.


Assuntos
Movimento Celular/fisiologia , Circulação Coronária/fisiologia , Hemorragia/fisiopatologia , Imageamento por Ressonância Magnética/métodos , Monócitos/citologia , Infarto do Miocárdio/fisiopatologia , Reperfusão Miocárdica , Animais , Modelos Animais de Doenças , Feminino , Radioisótopos de Flúor , Hemorragia/diagnóstico por imagem , Macrófagos/citologia , Macrófagos/fisiologia , Microcirculação/fisiologia , Monócitos/fisiologia , Infarto do Miocárdio/diagnóstico por imagem , Prótons , Cintilografia , Ratos , Ratos Wistar , Cicatrização/fisiologia
9.
Magn Reson Med ; 71(5): 1784-97, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-23836533

RESUMO

PURPOSE: The quantification of myocardial perfusion using a Look-Locker flow-sensitive alternating inversion recovery- arterial spin labeling experiment is considered. Due to the anatomy of the heart, a substantial but unintended partial inversion of the inflowing blood occurs during the slice-selective inversion. Both, the partial inversion as well as the Look-Locker pulse train, influence the myocardial perfusion quantification and are addressed in this work. METHODS: The mean relaxation time approximation is used to calculate the monoexponential relaxation time of the signal in perfused tissue under Look-Locker readout. The left ventricular blood serves as an approximation of the inflowing blood in the description of FAIR-ASL measurements with global and slice-selective inversion to correctly quantify the myocardial perfusion. RESULTS: The analysis shows that the myocardial perfusion can be overestimated if the T1 -based quantification method is not adapted respecting the Look-Locker pulse train explicitly. Additionally, it turns out that without correction for the partial inversion of the blood pool during the slice-selective inversion the myocardial perfusion is underestimated. CONCLUSION: It is shown that the Look-Locker readout as well as the nonideal slice-selective inversion experiment have a considerable influence and have to be included properly to correctly quantify myocardial perfusion.


Assuntos
Artefatos , Circulação Coronária/fisiologia , Coração/anatomia & histologia , Interpretação de Imagem Assistida por Computador/métodos , Angiografia por Ressonância Magnética/métodos , Imagem de Perfusão do Miocárdio/métodos , Circulação Pulmonar/fisiologia , Algoritmos , Animais , Humanos , Aumento da Imagem/métodos , Camundongos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
10.
Sci Rep ; 14(1): 11130, 2024 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-38750100

RESUMO

CMR at 3.0T in the presence of active cardiac implants remains a challenge due to susceptibility artifacts. Beyond a signal void that cancels image information, magnetic field inhomogeneities may cause distorted appearances of anatomical structures. Understanding influencing factors and the extent of distortion are a first step towards optimizing the image quality of CMR with active implants at 3.0T. All measurements were obtained at a clinical 3.0T scanner. An in-house designed phantom with a 3D cartesian grid of water filled spheres was used to analyze the distortion caused by four representative active cardiac devices (cardiac loop recorder, pacemaker, 2 ICDs). For imaging a gradient echo (3D-TFE) sequence and a turbo spin echo (2D-TSE) sequence were used. The work defines metrics to quantify the different features of distortion such as changes in size, location and signal intensity. It introduces a specialized segmentation technique based on a reaction-diffusion-equation. The distortion features are dependent on the amount of magnetic material in the active implants and showed a significant increase when measured with the 3D TFE compared to the 2D TSE. This work presents a quantitative approach for the evaluation of image distortion at 3.0T caused by active cardiac implants and serves as foundation for both further optimization of sequences and devices but also for planning of imaging procedures.


Assuntos
Imageamento Tridimensional , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Humanos , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Artefatos , Marca-Passo Artificial
11.
Sci Rep ; 14(1): 2426, 2024 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-38287086

RESUMO

Cardiac myocyte sodium (Na+) homoeostasis is pivotal in cardiac diseases and heart failure. Intracellular Na+ ([Na+]i) is an important regulator of excitation-contraction coupling and mitochondrial energetics. In addition, extracellular Na+ ([Na+]e) and its water-free storage trigger collagen cross-linking, myocardial stiffening and impaired cardiac function. Therefore, understanding the allocation of tissue Na+ to intra- and extracellular compartments is crucial in comprehending the pathophysiological processes in cardiac diseases. We extrapolated [Na+]e using a three-compartment model, with tissue Na+ concentration (TSC) measured by in vivo 23Na-MRI, extracellular volume (ECV) data calculated from T1 maps, and [Na+]i measured by in vitro fluorescence microscopy using Na+ binding benzofuran isophthalate (SBFI). To investigate dynamic changes in Na+ compartments, we induced pressure overload (TAC) or myocardial infarction (MI) via LAD ligation in mice. Compared to SHAM mice, TSC was similar after TAC but increased after MI. Both TAC and MI showed significantly higher [Na+]i compared to SHAM (around 130% compared to SHAM). Calculated [Na+]e increased after MI, but not after TAC. Increased TSC after TAC was primarily driven by increased [Na+]i, but the increase after MI by elevations in both [Na+]i and [Na+]e.


Assuntos
Experimentação Animal , Insuficiência Cardíaca , Infarto do Miocárdio , Camundongos , Animais , Sódio/metabolismo , Insuficiência Cardíaca/metabolismo , Miócitos Cardíacos/metabolismo , Infarto do Miocárdio/metabolismo , Imageamento por Ressonância Magnética/métodos
12.
Sci Rep ; 14(1): 11009, 2024 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-38744988

RESUMO

Cardiac magnetic resonance (CMR) imaging allows precise non-invasive quantification of cardiac function. It requires reliable image segmentation for myocardial tissue. Clinically used software usually offers automatic approaches for this step. These are, however, designed for segmentation of human images obtained at clinical field strengths. They reach their limits when applied to preclinical data and ultrahigh field strength (such as CMR of pigs at 7 T). In our study, eleven animals (seven with myocardial infarction) underwent four CMR scans each. Short-axis cine stacks were acquired and used for functional cardiac analysis. End-systolic and end-diastolic images were labelled manually by two observers and inter- and intra-observer variability were assessed. Aiming to make the functional analysis faster and more reproducible, an established deep learning (DL) model for myocardial segmentation in humans was re-trained using our preclinical 7 T data (n = 772 images and labels). We then tested the model on n = 288 images. Excellent agreement in parameters of cardiac function was found between manual and DL segmentation: For ejection fraction (EF) we achieved a Pearson's r of 0.95, an Intraclass correlation coefficient (ICC) of 0.97, and a Coefficient of variability (CoV) of 6.6%. Dice scores were 0.88 for the left ventricle and 0.84 for the myocardium.


Assuntos
Aprendizado Profundo , Modelos Animais de Doenças , Infarto do Miocárdio , Animais , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/fisiopatologia , Suínos , Reprodutibilidade dos Testes , Processamento de Imagem Assistida por Computador/métodos , Imagem Cinética por Ressonância Magnética/métodos , Humanos , Coração/diagnóstico por imagem , Coração/fisiopatologia , Volume Sistólico , Imageamento por Ressonância Magnética/métodos
13.
Arterioscler Thromb Vasc Biol ; 32(10): 2350-7, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22879583

RESUMO

OBJECTIVE: Noninvasive imaging of atherosclerosis remains challenging in clinical applications. Here, we applied noninvasive molecular imaging to detect vascular cell adhesion molecule-1 in early and advanced atherosclerotic lesions of apolipoprotein E-deficient mice. METHODS AND RESULTS: Ultrasmall superparamagnetic iron oxide particles functionalized with (P03011) or without (P3007) vascular cell adhesion molecule-1-binding peptide were visualized by ultra high-field (17.6 T) magnetic resonance. Injection of P03011 resulted in a marked signal loss in the aortic root of apolipoprotein E-deficient mice fed a Western diet for 8 and 26 weeks in vivo and ex vivo, compared with preinjection measurements, P3007-injected mice, and P03011- or P3007-injected age-matched C57BL/6 controls. Histological analyses revealed iron accumulations in the intima, in colocalization with vascular cell adhesion molecule-1-expressing macrophages and endothelial cells. Coherent anti-Stokes Raman scattering microscopy demonstrated iron signals in the intima and media of the aortic root in the P03011-injected but not untreated apolipoprotein E-deficient mice, localized to macrophages, luminal endothelial-like cells, and medial regions containing smooth muscle cells. Electron microscopy confirmed iron particles enclosed in endothelial cells and in the vicinity of smooth muscle cells. CONCLUSIONS: Using a combination of innovative imaging modalities, in this study, we demonstrate the feasibility of applying P03011 as a contrast agent for imaging of atherosclerosis.


Assuntos
Aterosclerose/metabolismo , Aterosclerose/patologia , Compostos Férricos/metabolismo , Nanopartículas , Molécula 1 de Adesão de Célula Vascular/metabolismo , Vasculite/metabolismo , Vasculite/patologia , Animais , Apolipoproteínas E/deficiência , Apolipoproteínas E/genética , Aterosclerose/genética , Modelos Animais de Doenças , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Macrófagos/metabolismo , Macrófagos/patologia , Imageamento por Ressonância Magnética/métodos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Análise Espectral Raman , Túnica Íntima/metabolismo , Túnica Íntima/patologia
14.
J Cardiovasc Magn Reson ; 15: 88, 2013 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-24083810

RESUMO

BACKGROUND: The aortic pulse-wave velocity (PWV) is an important indicator of cardiovascular risk. In recent studies MRI methods have been developed to measure this parameter noninvasively in mice. Present techniques require additional hardware for cardiac and respiratory gating. In this work a robust self-gated measurement of the local PWV in mice without the need of triggering probes is proposed. METHODS: The local PWV of 6-months-old wild-type C57BL/6J mice (n=6) was measured in the abdominal aorta with a retrospectively triggered radial Phase Contrast (PC) MR sequence using the flow-area (QA) method. A navigator signal was extracted from the CMR data of highly asymmetric radial projections with short repetition time (TR=3 ms) and post-processed with high-pass and low-pass filters for retrospective cardiac and respiratory gating. The self-gating signal was used for a reconstruction of high-resolution Cine frames of the aortic motion. To assess the local PWV the volume flow Q and the cross-sectional area A of the aorta were determined. The results were compared with the values measured with a triggered Cartesian and an undersampled triggered radial PC-Cine sequence. RESULTS: In all examined animals a self-gating signal could be extracted and used for retrospective breath-gating and PC-Cine reconstruction. With the non-triggered measurement PWV values of 2.3±0.2 m/s were determined. These values are in agreement with those measured with the triggered Cartesian (2.4±0.2 m/s) and the triggered radial (2.3±0.2 m/s) measurement. Due to the strong robustness of the radial trajectory against undersampling an acceleration of more than two relative to the prospectively triggered Cartesian sampling could be achieved with the retrospective method. CONCLUSION: With the radial flow-encoding sequence the extraction of a self-gating signal is feasible. The retrospective method enables a robust and fast measurement of the local PWV without the need of additional trigger hardware.


Assuntos
Aorta Abdominal/fisiologia , Imagem Cinética por Ressonância Magnética , Microscopia , Análise de Onda de Pulso/métodos , Rigidez Vascular , Algoritmos , Animais , Meios de Contraste , Estudos de Viabilidade , Frequência Cardíaca , Interpretação de Imagem Assistida por Computador , Camundongos Endogâmicos C57BL , Modelos Animais , Valor Preditivo dos Testes , Taxa Respiratória , Processamento de Sinais Assistido por Computador , Fatores de Tempo
15.
Circ Cardiovasc Imaging ; 16(9): e014742, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37725674

RESUMO

Fluorine-19 (19F) magnetic resonance imaging is a unique quantitative molecular imaging modality that makes use of an injectable fluorine-containing tracer that generates the only visible 19F signal in the body. This hot spot imaging technique has recently been used to characterize a wide array of cardiovascular diseases and seen a broad range of technical improvements. Concurrently, its potential to be translated to the clinical setting is being explored. This review provides an overview of this emerging field and demonstrates its diagnostic potential, which shows promise for clinical translation. We will describe 19F magnetic resonance imaging hardware, pulse sequences, and tracers, followed by an overview of cardiovascular applications. Finally, the challenges on the road to clinical translation are discussed.


Assuntos
Doenças Cardiovasculares , Sistema Cardiovascular , Humanos , Flúor , Sistema Cardiovascular/diagnóstico por imagem , Doenças Cardiovasculares/diagnóstico por imagem , Imagem Molecular
16.
Magn Reson Med ; 68(6): 1963-72, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22383393

RESUMO

There are serious concerns regarding safety when performing magnetic resonance imaging in patients with implanted conductive medical devices, such as cardiac pacemakers, and associated leads, as severe incidents have occurred in the past. In this study, several approaches for altering an implant's lead design were systematically developed and evaluated to enhance the safety of implanted medical devices in a magnetic resonance imaging environment. The individual impact of each design change on radiofrequency heating was then systematically investigated in functional lead prototypes at 1.5 T. Radiofrequency-induced heating could be successfully reduced by three basic changes in conventional pacemaker lead design: (1) increasing the lead tip area, (2) increasing the lead conductor resistance, and (3) increasing outer lead insulation conductivity. The findings show that radiofrequency energy pickup in magnetic resonance imaging can be reduced and, therefore, patient safety can be improved with dedicated construction changes according to a "safe by design" strategy. Incorporation of the described alterations into implantable medical devices such as pacemaker leads can be used to help achieve favorable risk-benefit-ratios when performing magnetic resonance imaging in the respective patient group.


Assuntos
Eletrodos , Imageamento por Ressonância Magnética/instrumentação , Marca-Passo Artificial , Desenho de Equipamento , Análise de Falha de Equipamento , Temperatura Alta
17.
J Cardiovasc Magn Reson ; 14: 12, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22296883

RESUMO

BACKGROUND: One of the safety concerns when performing electrophysiological (EP) procedures under magnetic resonance (MR) guidance is the risk of passive tissue heating due to the EP catheter being exposed to the radiofrequency (RF) field of the RF transmitting body coil. Ablation procedures that use catheters with irrigated tips are well established therapeutic options for the treatment of cardiac arrhythmias and when used in a modified mode might offer an additional system for suppressing passive catheter heating. METHODS: A two-step approach was chosen. Firstly, tests on passive catheter heating were performed in a 1.5 T Avanto system (Siemens Healthcare Sector, Erlangen, Germany) using a ASTM Phantom in order to determine a possible maximum temperature rise. Secondly, a phantom was designed for simulation of the interface between blood and the vascular wall. The MR-RF induced temperature rise was simulated by catheter tip heating via a standard ablation generator. Power levels from 1 to 6 W were selected. Ablation duration was 120 s with no tip irrigation during the first 60 s and irrigation at rates from 2 ml/min to 35 ml/min for the remaining 60 s (Biotronik Qiona Pump, Berlin, Germany). The temperature was measured with fluoroscopic sensors (Luxtron, Santa Barbara, CA, USA) at a distance of 0 mm, 2 mm, 4 mm, and 6 mm from the catheter tip. RESULTS: A maximum temperature rise of 22.4°C at the catheter tip was documented in the MR scanner. This temperature rise is equivalent to the heating effect of an ablator's power output of 6 W at a contact force of the weight of 90 g (0.883 N). The catheter tip irrigation was able to limit the temperature rise to less than 2°C for the majority of examined power levels, and for all examined power levels the residual temperature rise was less than 8°C. CONCLUSION: Up to a maximum of 22.4°C, the temperature rise at the tissue surface can be entirely suppressed by using the catheter's own irrigation system. The irrigated tip system can be used to increase MR safety of EP catheters by suppressing the effects of unwanted passive catheter heating due to RF exposure from the MR scanner.


Assuntos
Ablação por Cateter/instrumentação , Catéteres , Imagem por Ressonância Magnética Intervencionista/instrumentação , Temperatura , Ablação por Cateter/efeitos adversos , Desenho de Equipamento , Falha de Equipamento , Segurança de Equipamentos , Imagem por Ressonância Magnética Intervencionista/efeitos adversos , Teste de Materiais , Imagens de Fantasmas , Irrigação Terapêutica
18.
Europace ; 14(2): 230-7, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21933802

RESUMO

AIMS: Uncertainty exists over the importance of device-detected short-duration atrial arrhythmias. Continuous atrial diagnostics, through home monitoring (HM) technology (BIOTRONIK, Berlin, Germany), provides a unique opportunity to assess frequency and quantity of atrial fibrillation (AF) episodes defined as atrial high-rate events (AHRE). METHODS AND RESULTS: Prospective data from 560 heart failure (HF) patients (age 67 ± 10 years, median ejection fraction 27%) patients with a cardiac resynchronization therapy (CRT) device capable of HM from two multi-centre studies were analysed. Atrial high-rate events burden was defined as the duration of mode switch in a 24-h period with atrial rates of >180 beats for at least 1% or total of 14 min per day. The primary endpoint was incidence of a thromboembolic (TE) event. Secondary endpoints were cardiovascular death, hospitalization because of AF, or worsening HF. Over a median 370-day follow-up AHRE occurred in 40% of patients with 11 (2%) patients developing TE complications and mortality rate of 4.3% (24 deaths, 16 with cardiovascular aetiology). Compared with patients without detected AHRE, patients with detected AHRE>3.8 h over a day were nine times more likely to develop TE complications (P= 0.006). The majority of patients (73%) did not show a temporal association with the detected atrial episode and their adverse event, with a mean interval of 46.7 ± 71.9 days (range 0-194) before the TE complication. CONCLUSION: In a high-risk cohort of HF patients, device-detected atrial arrhythmias are associated with an increased incidence of TE events. A cut-off point of 3.8 h over 24 h was associated with significant increase in the event rate. Routine assessment of AHRE should be considered with other data when assessing stroke risk and considering anti-coagulation initiation and should also prompt the optimization of cardioprotective HF therapy in CRT patients.


Assuntos
Fibrilação Atrial/dietoterapia , Fibrilação Atrial/mortalidade , Eletrocardiografia Ambulatorial/estatística & dados numéricos , Insuficiência Cardíaca/mortalidade , Insuficiência Cardíaca/prevenção & controle , Serviços de Assistência Domiciliar/estatística & dados numéricos , Idoso , Fibrilação Atrial/prevenção & controle , Terapia de Ressincronização Cardíaca , Estudos de Coortes , Feminino , Insuficiência Cardíaca/diagnóstico , Humanos , Internacionalidade , Masculino , Prevalência , Reprodutibilidade dos Testes , Medição de Risco , Fatores de Risco , Sensibilidade e Especificidade , Análise de Sobrevida , Taxa de Sobrevida
19.
Sci Rep ; 12(1): 6285, 2022 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-35428775

RESUMO

Recent technical advancements allow cardiac MRI (CMR) examinations in the presence of so-called MRI conditional active cardiac implants at 3.0 T. However, the artifact burden caused by susceptibility effects remain an obstacle. All measurements were obtained at a clinical 3.0 T scanner using an in-house designed cubic phantom and optimized sequences for artifact evaluation (3D gradient echo sequence, multi-slice 2D turbo spin echo sequence). Reference sequences according to the American Society for Testing and Materials (ASTM) were additionally applied. Four representative active cardiac devices and a generic setup were analyzed regarding volume and shape of the signal void. For analysis, a threshold operation was applied to the grey value profile of each data set. The presented approach allows the evaluation of the signal void and shape even for larger implants such as ICDs. The void shape is influenced by the orientation of the B0-field and by the chosen sequence type. The distribution of ferromagnetic material within the implants also matters. The void volume depends both on the device itself, and on the sequence type. Disturbances in the B0 and B1 fields exceed the visual signal void. This work presents a reproducible and highly defined approach to characterize both signal void artifacts at 3.0 T and their influencing factors.


Assuntos
Artefatos , Próteses e Implantes , Imageamento por Ressonância Magnética , Imãs , Imagens de Fantasmas
20.
Clin Case Rep ; 10(11): e6568, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36397843

RESUMO

Intracavitary thrombi are an important differential diagnosis of cardiac masses. Cardiac magnetic resonance imaging (CMR) allows their non-invasive characterization. This case highlights extensive cardiac thrombi detected by CMR as solitary presentation of antiphospholipid syndrome.

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