MRI of left ventricular function

Cardiac magnetic resonance imaging (CMR) is widely recognized as the most accurate noninvasive imaging modality for the assessment of left ventricular (LV) function. By use of state-of-the-art magnetic resonance imaging (MRI) scanners, electrocardiography (ECG)-gated cine images depicting LV function with high contrast and excellent spatial and temporal resolution are readily acquired in breath-holds of 5 to 10 heartbeats. For patients in whom breath-holding and ECG gating are difficult, real-time cine imaging without ECG gating and breath-holding can be performed. LV function can be qualitatively assessed from cine images, or alternatively, parameters such as LV volumes, ejection fraction, and mass may be quantified via computer-based analysis software. In addition, techniques such as myocardial tagging and newer variants can be used to qualitatively or quantitatively assess regional intramyocardial strain, twist, and torsion. Many of the CMR methods have undergone clinical evaluation in the settings of high-dose dobutamine stress testing and determination of myocardial viability. These methods are also very accurate for prognosis in coronary heart disease patients and may be quite useful for the detection of contractile dyssynchrony. When used together with other CMR techniques such as first-pass perfusion imaging or late gadolinium enhancement, CMR of LV function provides a wealth of information in a single imaging study.     

Advances in Myocardial Perfusion MR Imaging: Physiological Implications,the Importance of Quantitative Analysis,and Impact on Patient Care in Coronary Artery Disease

Stress myocardial perfusion imaging (MPI) is the preferred test in patients with intermediate-to-high clinical likelihood of coronary artery disease (CAD) and can be used as a gatekeeper to avoid unnecessary revascularization. Cardiac magnetic resonance (CMR) has a number of favorable characteristics, including: (1) high spatial resolution that can delineate subendocardial ischemia; (2) comprehensive assessment of morphology, global and regional cardiac functions, tissue characterization, and coronary artery stenosis; and (3) no radiation exposure to patients. According to meta-analysis studies, the diagnostic accuracy of perfusion CMR is comparable to positron emission tomography (PET) and perfusion CT, and is better than single-photon emission CT (SPECT) when fractional flow reserve (FFR) is used as a reference standard. In addition, stress CMR has an excellent prognostic value. One meta-analysis study demonstrated the annual event rate of cardiovascular death or non-fatal myocardial infarction was 4.9% and 0.8%, respectively, in patients with positive and negative stress CMR. Quantitative assessment of perfusion CMR not only allows the objective evaluation of regional ischemia but also provides insights into the pathophysiology of microvascular disease and diffuse subclinical atherosclerosis. For accurate quantification of myocardial perfusion, saturation correction of arterial input function is important. There are two major approaches for saturation correction, one is a dual-bolus method and the other is a dual-sequence method. Absolute quantitative mapping with myocardial perfusion CMR has good accuracy in detecting coronary microvascular dysfunction. Flow measurement in the coronary sinus (CS) with phase contrast cine CMR is an alternative approach to quantify global coronary flow reserve (CFR). The measurement of global CFR by quantitative analysis of perfusion CMR or flow measurement in the CS permits assessment of microvascular disease and diffuse subclinical atherosclerosis, which may provide improved prediction of future event risk in patients with suspected or known CAD. Multi-institutional studies to validate the diagnostic and prognostic values of quantitative perfusion CMR approaches are required.     

Kardiale Magnetresonanztomographie

Cardiac magnetic resonance imaging (CMR) has evolved over the past 20 years from a research-based imaging modality to an indispensable routine procedure in cardiac diagnostics. In addition to the morphological representation of cardiac anatomy, whereby only noninvasive multidetector computed tomography (MDCT) is superior, another strength of CMR is the assessment of cardiac function and tissue differentiation. This requires that the radiologist performing the examination and analyzing the results has good knowledge of cardiac and thoracic anatomy and a detailed knowledge of the various cardiovascular diseases, hemodynamics, and pathophysiology. CMR reliably allows determination of a range of easy to determine quantitative parameters such as ventricular ejection fraction and also the valvular regurgitation fraction, which allows objective assessment of cardiac function. Especially the possibility to differentiate inflamed, viable, and ischemic tissue using adenosine stress MRI in the last 10 years has led to routine use of CMR. Even compared to competing nuclear medicine procedures, CMR is important for treatment decision-making and for prognosis estimation, thus, making it an indispensable component of cardiovascular diagnostics.     

新型冠状病毒肺炎心血管并发症的影像学研究进展

新型冠状病毒肺炎（COVID-19）可累及心血管系统引起心肌炎或其他心血管并发症,导致病人死亡率显著增加。超声心动图、心脏MR（CMR）、CT等多种无创性影像技术在COVID-19心血管并发症的诊断、治疗指导和预后评估中发挥了重要作用,特别是CMR不仅能评估心脏形态、结构方面的变化,还能判断COVID-19病人的心肌组织学异常,为预后提供新的影像学指标。就COVID-19心血管并发症的影像学研究进展予以综述。     

The role of stress cardiac magnetic resonance in women

Coronary artery disease (CAD) is the leading cause of death in women. Nevertheless, extensive evidence demonstrates under-diagnosis and under-treatment of women for suspected or known ischemic heart disease (IHD). Stress cardiac magnetic resonance (CMR) is becoming readily available and offers significant advantages over other stress imaging modalities. The high spatial and temporal resolution of CMR provides the unique ability to identify subendocardial ischemia, viability, and the presence of microvascular disease. Furthermore, CMR is free from ionizing radiation, and image quality is not compromised by attenuation artifacts or patient size. Over the past two decades, evidence-based data have demonstrated the high diagnostic and prognostic performance of stress CMR in the context of IHD, often superior to other stress imaging techniques. Importantly, ad hoc studies confirmed these results in women with known or suspected IHD. Stress CMR warrants consideration as the modality of choice for women requiring an imaging test for ischemia given its strong evidence base, superior test characteristics, comprehensive nature, and unique ability to characterize both epicardial and microvascular disease.     

Dobutamine stress magnetic resonance imaging

Cardiovascular magnetic resonance imaging (CMR) provides superior imaging of cardiac structure and function that makes it a useful tool in the diagnosis of cardiovascular disease. The heart's response to stress has long been used as a diagnostic aid for identifying a cardiovascular etiology for patient symptoms or for cardiovascular risk stratification. Historically, this has been done with stress nuclear scintigraphy or echocardiography techniques. A distinct advantage of CMR over these modalities is greater image quality resulting in better test characteristics; this review summarizes the techniques and principles involved in dobutamine stress MRI. Electronic Publication     

CMR在心房结构和功能评估中的应用进展

心房的结构和功能的改变对心血管疾病的诊断和预后具有重要意义。心脏磁共振（CMR）是定量评估心腔大小和功能的金标准,可以早期发现心力衰竭、房颤、缺血性心脏病以及先天性心脏病等疾病所致的心房结构和功能的异常。就CMR对心房结构和功能评估的临床应用及其研究进展进行综述。     

3-Tesla-Magnetresonanztomographie zur Untersuchung von Kindern und Erwachsenen mit angeborenen Herzfehlern

Cardiovascular magnetic resonance imaging (CMR) has become a routinely used imaging modality for congenital heart disease. A CMR examination allows the assessment of thoracic anatomy, global and regional cardiac function, blood flow in the great vessels and myocardial viability and perfusion. In the clinical routine cardiovascular MRI is mostly performed at field strengths of 1.5 Tesla (T). Recently, magnetic resonance systems operating at a field strengths of 3 T became clinically available and can also be used for cardiovascular MRI. The main advantage of CMR at 3 T is the gain in the signal-to-noise ratio resulting in improved image quality and/or allowing higher acquisition speed. Several further differences compared to MRI systems with lower field strengths have to be considered for practical applications. This article describes the impact of CMR at 3 T in patients with congenital heart disease by meanings of methodical considerations and case studies.     

Functional MRI in ischemic heart disease based on detection of contraction abnormalities.

Even though several non-invasive techniques are available for the assessment of coronary artery disease and the detection of myocardial ischemia, many coronary angiograms yield negative results, thus, warranting higher accuracy for non-invasive tests. The detection of obstructive coronary artery disease is only possible during physical or pharmacological stress. Currently, the assessment of wall motion abnormalities by echocardiography is clinically the most widely used method. However, a significant number of patients yield suboptimal or non-diagnostic images despite improvements with harmonic imaging. Cardiovascular magnetic resonance (CMR) imaging allows a non-invasive visualization of the heart with high spatial and temporal resolution. Gradient echo CMR images permit an exact and reproducible determination of global and regional left ventricular function, wall thickness and wall thickening and identical pharmacological stress protocols, as currently used for dobutamine stress echocardiography, can be implemented for CMR imaging. A review of the literature on dobutamine stress CMR for the detection of stress induced wall motion abnormalities is presented and the safety of CMR stress examinations is discussed. The results show, that especially in those patients with suboptimal echocardiographic image quality dobutamine stress CMR is superior in comparison with dobutamine stress echocardiography and may replace echocardiography in these patients. Further possibilities by the use of myocardial tagging or intravascular contrast agents are outlined.     

Evaluation of the microcirculation: Advances in cardiac magnetic resonance perfusion imaging

Conclusion  In this review we have examined the role of perfusion CMR for evaluating the integrity and function of the microcirculation. We have discussed the techniques for fully quantifying myocardial blood flow and the impact of different imaging parameters on quantification. Perfusion CMR not only identifies the presence of microvascular obstruction after a myocardial infarction but also relates it to patient prognosis. The ability to absolutely quantify myocardial blood flow improves the detection and evaluation of epicardial coronary disease and its risk factors. CMR perfusion imaging has proved to be an invaluable tool for understanding the integral role of the microcirculation in a variety of other cardiac disorders. Another advantage of perfusion CMR is the ability to measure differences in subendocardial and subepicardial blood flow. Newer techniques such as ASL and BOLD imaging promise to further improve the ability of CMR to assess the microcirculation without the use of exogenous contrast agents.     

糖尿病心肌病的CMR诊断及研究进展

心脏磁共振（CMR）成像技术具有多参数、多成像序列的特点,可以对糖尿病心肌病（DbCM）进行早期诊断,评价DbCM存在的心脏结构重塑、心脏整体和局部的收缩和舒张功能障碍、心肌灌注受损、心脏局部及弥漫性纤维化及心脏能量代谢和脂质异常,为病人的早期治疗及预后评估提供重要信息。就CMR对DbCM的心脏组织特征、风险评估和远期预后方面的诊断予以综述。     

Differential Diagnosis of Thick Myocardium according to Histologic Features Revealed by Multiparametric Cardiac Magnetic Resonance Imaging

Left ventricular (LV) wall thickening, or LV hypertrophy (LVH), is common and occurs in diverse conditions including hypertrophic cardiomyopathy (HCM), hypertensive heart disease, aortic valve stenosis, lysosomal storage disorders, cardiac amyloidosis, mitochondrial cardiomyopathy, sarcoidosis and athlete’s heart. Cardiac magnetic resonance (CMR) imaging provides various tissue contrasts and characteristics that reflect histological changes in the myocardium, such as cellular hypertrophy, cardiomyocyte disarray, interstitial fibrosis, extracellular accumulation of insoluble proteins, intracellular accumulation of fat, and intracellular vacuolar changes. Therefore, CMR imaging may be beneficial in establishing a differential diagnosis of LVH. Although various diseases share LV wall thickening as a common feature, the histologic changes that underscore each disease are distinct. This review focuses on CMR multiparametric myocardial analysis, which may provide clues for the differentiation of thickened myocardium based on the histologic features of HCM and its phenocopies.     

Cardiovascular magnetic resonance imaging of coronary atherothrombosis

Summary  Atherothrombosis, defined as atherosclerotic lesion disruption with superimposed thrombus formation, is the major cause of acute coronary syndromes and cardiovascular death. CMR imaging of coronary atherothrombosis is challenging because of the small caliber of the vessels combined with respiratory and cardiac motion. Freebreathing 3D CMR coronary vessel wall imaging has enabled in vivo quantification of coronary plaque burden and remodeling as a marker of subclinical CAD. Molecular imaging via novel target-specific contrast agents such as fibrin-binding agents to detect arterial thrombus shows great promise as the new frontier in noninvasive imaging. Advances in molecular imaging and CMR techniques offer the potential for direct imaging of coronary thrombosis and in-stent thrombosis by use of novel fibrin-binding molecular MR contrast agents. Although the current role of noninvasive CMR imaging of atherothrombosis remains investigational, these techniques should enhance our understanding of the natural history of acute coronary syndromes and thereby facilitate strategies to prevent acute coronary syndromes and cardiovascular death in vulnerable patients.     

心血管MR成像在缺血性心脏病中的应用

缺血性心脏病（IHD）不同阶段的病理组织学改变与病人预后和生活质量密切相关。心血管MR（CMR）成像技术具有多参数、多成像序列,能对IHD进行早期诊断,评价微血管阻塞、心肌内出血、瘢痕心肌和舒张末期心室壁厚度,通过对急慢性心肌梗死进行早期诊断和远期风险评估,为病人的早期治疗及降低预后风险提供信息。就CMR在急慢性IHD心肌组织特征、风险评估和病人远期预后方面的应用予以综述。     

负荷心肌灌注显像与超声心动图对CAD患者的诊断和风险分级

负荷心肌灌注显像和负荷超声心动图是两种非侵入性诊断技术,对冠心病的诊断和风险分级具有重要价值,但两种技术均存在优势与不足。对冠心病的诊断,负荷心肌灌注显像比负荷超声心动图敏感性更高,但后者的特异性略高。在冠心病患者的风险分级方面,负荷心肌灌注显像比负荷超声心动图更有价值,如果负荷心肌灌注显像结果为阴性,即使冠脉造影证实为冠心病的患者,也提示为一个风险非常低的冠心病患者。     

The role of positron emission tomography in the evaluation of myocardial ischemia in women

Cardiovascular disease continues to be the number one cause of death in women, yet most women are unaware of their risk. Over the last decade, radionuclide myocardial perfusion imaging with positron emission tomography (PET) has become a powerful tool for the diagnosis and risk stratification of patients with known or suspected coronary artery disease (CAD). This editorial viewpoint will review the maturing role of PET imaging in women, particularly as applied to the evaluation of ischemic heart disease. Specifically, we focus on distinct advantages offered by PET imaging in the evaluation of myocardial ischemia in women: (1) improved diagnostic accuracy, including in the presence of breast or adipose tissue and small left ventricular cavity size, (2) decreased radiation exposure through the use of short-lived radiopharmaceuticals, and (3) the ability to quantify myocardial blood flow and coronary flow reserve to diagnose ischemia, even in the absence of obstructive CAD. As such, cardiac PET perfusion imaging stands to play a unique role in defining the diagnosis and prognosis of women with ischemic heart disease, while also guiding new treatment strategies for their more prevalent cardiovascular disease phenotypes.     

Cardiovascular MRI for the assessment of heart failure: focus on clinical management and prognosis

Cardiovascular MR (CMR) has an emerging role in the noninvasive diagnostic assessment of heart failure (HF). Different imaging sequences allow for a detailed assessment of cardiac morphology, function, myocardial perfusion, tissue characterization, and blood flow measurement. This article reviews the key applications of CMR in HF, with special focus on how CMR may influence the diagnostic and therapeutic approach of HF patients.     

Diagnosis of coronary artery disease with dobutamine-stress MRI

Dobutamine-stress cardiovascular magnetic resonance (CMR) is a new diagnostic tool for the non-invasive detection of coronary artery disease. Technological advances in CMR have evolved this technique to an adequate alternative to the standard cardiac stress tests. Its high reproducibility and excellent image quality of the anatomical features of the left ventricle and left ventricular function at rest and during stress make it an ideal technique for the comprehensive evaluation of patients with suspected coronary artery disease. Besides its ability to detect myocardial ischemia, CMR has proved to be diagnostic for myocardial viability as well. A recent technical refinement in CMR using myocardial tagging has improved the diagnostic accuracy for myocardial ischemia even further. Dobutamine-stress CMR is used to identify wall motion abnormalities of the left ventricle in patients with proven or suspected coronary artery disease [1-4]. Dobutamine-stress CMR has emerged as a highly accurate and safe diagnostic modality [1-4]. Recently, the use of high-dose dobutamine CMR in combination with the myocardial tagging technique has been reported, with excellent diagnostic results. The use of this new technique and the clinical applications are discussed.     

负荷心肌灌注显像中心率和血压变化预测女性心血管事件的研究进展

女性相比男性具有不同的冠状动脉（冠脉）解剖生理基础及神经激素水平,这导致其更多表现为非阻塞性冠脉微循环功能障碍。核素心肌灌注显像（MPI）血流绝对定量技术是一种无创性诊断冠心病（CAD）并对其进行风险评估的功能性检查方法。负荷试验中的心率和血压变化作为自主神经功能的替代指标,对女性血流灌注参数乃至不良心血管事件有一定的预测作用。笔者就负荷MPI中心率和血压变化对CAD诊断及风险评估的增益价值进行综述,为推进负荷MPI的临床应用及制定用以改善女性自主神经功能为靶点的诊疗方案提供依据。     

The cardiac magnetic resonance (CMR) approach to assessing myocardial viability

Cardiac magnetic resonance (CMR) is a noninvasive imaging method that can determine myocardial anatomy, function, perfusion, and viability in a relative short examination. In terms of viability assessment, CMR can determine viability in a non-contrast enhanced scan using dobutamine stress following protocols comparable to those developed for dobutamine echocardiography. CMR can also determine viability with late gadolinium enhancement (LGE) methods. The gadolinium-based contrast agents used for LGE differentiate viable myocardium from scar on the basis of differences in cell membrane integrity for acute myocardial infarction. In chronic myocardial infarction, the scarred tissue enhances much more than normal myocardium due to increases in extracellular volume. LGE is well validated in pre-clinical and clinical studies that now span from almost a cellular level in animals to human validations in a large international multicenter clinical trial. Beyond infarct size or infarct detection, LGE is a strong predictor of mortality and adverse cardiac events. CMR can also image microvascular obstruction and intracardiac thrombus. When combined with a measure of area at risk like T2-weighted images, CMR can determine infarct size, area at risk, and thus estimate myocardial salvage 1-7 days after acute myocardial infarction. Thus, CMR is a well validated technique that can assess viability by gadolinium-free dobutamine stress testing or late gadolinium enhancement.