Cardiac magnetic resonance imaging: A teaching atlas with emphasizing current clinical indications

Cardiovascular magnetic resonance (CMR) is an amazing technology that continues to provide new innovative approaches for evaluating the heart and blood vessels. It can assess cardiac morphology, function, perfusion, viability, coronary and peripheral arteries, and metabolism and tissue characterization. The basic pulse sequences of CMR include; Spin Echo, Gradient echo, and Steady stet free precision. Current clinical indications of CMR are multiple and continuously evolving. CMR often works in complementary fashions to other cardiac imaging techniques or to resolve residual diagnostic dilemma. The purpose of this illustrative review is to review current clinical applications of CMR and to provide physicians and technologists with simple, and regular CMR cases form daily practice. Each case discusses briefly the related clinical history, followed by CMR imaging findings, and simple discussion to highlight the role of CMR in a particular cardiovascular disorder.     

Cardiac and pericardial tumors: A potential application of positron emission tomography-magnetic resonance imaging

Cardiac and pericardial masses may be neoplastic, benign and malignant, non-neoplastic such as thrombus or simple pericardial cysts, or normal variants cardiac structure can also be a diagnostic challenge. Currently, there are several imaging modalities for diagnosis of cardiac masses; each technique has its inherent advantages and disadvantages. Echocardiography, is typically the initial test utilizes in such cases, Echocardiography is considered the test of choice for evaluation and detection of cardiac mass, it is widely available, portable, with no ionizing radiation and provides comprehensive evaluation of cardiac function and valves, however, echocardiography is not very helpful in many cases such as evaluation of extracardiac extension of mass, poor tissue characterization, and it is non diagnostic in some cases. Cross sectional imaging with cardiac computed tomography provides a three dimensional data set with excellent spatial resolution but utilizes ionizing radiation, intravenous iodinated contrast and relatively limited functional evaluation of the heart. Cardiac magnetic resonance imaging(CMR) has excellent contrast resolution that allows superior soft tissue characterization. CMR offers comprehensive evaluation of morphology, function, tissue characterization. The great benefits of CMR make CMR a highly useful tool in the assessment of cardiac masses.(Fluorine 18) fluorodeoxygluocse(FDG) positron emission tomography(PET) has become a corner stone in several oncological application such as tumor staging, restaging, treatment efficiency, FDG is a very useful imaging modality in evaluation of cardiac masses. A recent advance in the imaging technology has been the development of integrated PET-MRI system that utilizes the advantages of PET and MRI in a single examination. FDG PET-MRI provides complementary information on evaluation of cardiac masses. The purpose of this review is to provide several clinical scenarios on the incremental value of PET and MRI in the evaluation of cardiac masses.     

Cardiovascular Magnetic Resonance Imaging For Assessment Of Cardiac Thrombus

Cardiac thrombus provides a substrate for embolic events and an indication for anticoagulant therapy. Cardiac magnetic resonance (CMR) imaging enables thrombus to be detected based on intrinsic tissue characteristics related to avascular tissue composition. Delayed enhancement CMR tissue characterization has been well validated for thrombus assessment using references of both pathology and clinical thromboembolic outcomes. Comparative studies have demonstrated CMR to yield improved thrombus detection compared to echocardiography, which typically detects thrombus based on anatomic appearance. Experimental studies have demonstrated the feasibility of targeted CMR contrast agents for assessing thrombus composition and chronicity. This review examines established and emerging literature on use of CMR for assessing cardiac thrombus.     

Current clinical applications of stress wall motion analysis with cardiac magnetic resonance imaging.

Over the last years the indications for cardiac magnetic resonance (CMR) imaging have rapidly broadened, in particular those dealing with the non-invasive detection of myocardial ischemia. This review describes the imaging technique, methodology and safety aspects of stress cine magnetic resonance imaging and summarizes the current knowledge with regard to its applicability in clinical routine.     

Calcified mass in the right atrium extending into the inferior vena cava with pulmonary artery embolization. Typical or atypical myxoma?

Cardiac masses are divided into neoplastic and non-neoplastic. They usually represent a diagnostic challenge given their relative rarity, their infrequent symptoms, and the overall difficulty with dynamic imaging of the heart. While echocardiography is useful in the initial evaluation of a suspected mass, cardiac magnetic resonance (CMR) imaging is the best imaging modality to characterize cardiac tumors due to its superior tissue characterization and its higher contrast resolution. For neoplastic, primary cardiac tumors are rare (0.05%). Atrial myxoma is the most common cardiac (50%) mass. About 75%-80% of myxoma are seen in the left atrium. Atypical myxoma is a term describing myxoma arising in other nonleft atrial locations. 20%-25% myxomas arise from the right atrium and 5% or less from the ventricles. We present a case of a 59-year-old female patient presenting with severe dyspnea. Her chest noncontrast CT showed a calcified mass lesion in the right atrium extending into the inferior vena cava. She underwent cardiac MRI for better tissue characterization. The cardiac MRI revealed a very irregular, highly spiculated, heavily calcified, heterogeneous, and nonenhancing lesion within the right atrium extending into the inferior vena cava. Via dynamic imaging, no evidence of mobile components was present. Via T1, T2 along with pre- and postcontrast imaging, the mass was confirmed to be calcified without a fibrotic component or evidence of thrombus. The above findings raised the possibility of atypical myxoma.     

Accuracy of Cardiac Magnetic Resonance Imaging in Diagnosing Pediatric Cardiac Masses: A Multicenter Study

BackgroundAfter diagnosis of a cardiac mass, clinicians must weigh the benefits and risks of ascertaining a tissue diagnosis. Limited data are available on the accuracy of previously developed noninvasive pediatric cardiac magnetic resonance (CMR)-based diagnostic criteria.ObjectivesThe goals of this study were to: 1) evaluate the CMR characteristics of pediatric cardiac masses from a large international cohort; 2) test the accuracy of previously developed CMR-based diagnostic criteria; and 3) expand diagnostic criteria using new information.MethodsCMR studies (children 0-18 years of age) with confirmatory histological and/or genetic diagnosis were analyzed by 2 reviewers, without knowledge of prior diagnosis. Diagnostic accuracy was graded as: 1) single correct diagnosis; 2) correct diagnosis among a differential; or 3) incorrect diagnosis.ResultsOf 213 cases, 174 (82%) had diagnoses that were represented in the previously published diagnostic criteria. In 70% of 174 cases, both reviewers achieved a single correct diagnosis (94% of fibromas, 71% of rhabdomyomas, and 50% of myxomas). When ≤2 differential diagnoses were included, both reviewers reached a correct diagnosis in 86% of cases. Of 29 malignant tumors, both reviewers indicated malignancy as a single diagnosis in 52% of cases. Including ≤2 differential diagnoses, both reviewers indicated malignancy in 83% of cases. Of 6 CMR sequences examined, acquisition of first-pass perfusion and late gadolinium enhancement were independently associated with a higher likelihood of a single correct diagnosis.ConclusionsCMR of cardiac masses in children leads to an accurate diagnosis in most cases. A comprehensive imaging protocol is associated with higher diagnostic accuracy.     

Evaluating cardiac sources of embolic stroke with MRI

The evaluation of patients with stroke includes identifying its etiology in order to appropriately tailor therapy. Currently, the diagnostic work-up includes imaging of the brain, the arteries of the head and neck, the aorta, and the heart. Traditional methods of imaging include magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), duplex ultrasound, and transthoracic echocardiography (TTE) and/or transesophageal echocardiography (TEE). While echocardiography remains a cornerstone in the field of cardiac imaging, MRI is increasingly able to assess for the most common causes of cardioembolic stroke such as left atrial/left atrial appendage thrombus, left ventricular thrombus, aortic atheroma, cardiac masses and patent foramen ovale. This review will focus on the advantages and limitations of echocardiography and cardiac magnetic resonance (CMR) imaging in diagnosing patients suspected of having an embolic stroke and the role these modalities play in clinical practice today.     

Important Advances in Technology and Unique Applications Related to Cardiac Magnetic Resonance Imaging

Cardiac magnetic resonance has become a well-established imaging modality and is considered the gold standard for myocardial tissue viability assessment and ventricular volumes quantification. Recent technological hardware and software advancements in magnetic resonance imaging technology have allowed the development of new methods that can improve clinical cardiovascular diagnosis and prognosis. The advent of a new generation of higher magnetic field scanners can be beneficial to various clinical applications. Also, the development of faster acquisition techniques have allowed mapping of the magnetic relaxation properties T1, T2, and T2* in the myocardium that can be used to quantify myocardial diffuse fibrosis, determine the presence of edema or inflammation, and measure iron within the myocardium, respectively. Another recent major advancement in CMR has been the introduction of three-dimension (3D) phase contrast imaging, also known as 4D flow. The following review discusses key advances in cardiac magnetic resonance technology and their potential to improve clinical cardiovascular diagnosis and outcomes.     

Clinical Applications for Cardiovascular Magnetic Resonance Imaging at 3 Tesla

Cardiovascular magnetic resonance (CMR) imaging has evolved rapidly and is now accepted as a powerful diagnostic tool with significant clinical and research applications. Clinical 3 Tesla (3 T) scanners are increasingly available and offer improved diagnostic capabilities compared to 1.5 T scanners for perfusion, viability, and coronary imaging. Although technical challenges remain for cardiac imaging at higher field strengths such as balanced steady state free precession (bSSFP) cine imaging, the majority of cardiac applications are feasible at 3 T with comparable or superior image quality to that of 1.5 T. This review will focus on the benefits and limitations of 3 T CMR for common clinical applications and examine areas in development for potential clinical use.     

Can cardiovascular MRI be used to more definitively characterize cardiac masses initially identified using echocardiography?

In diagnosing cardiac and paracardiac masses, cardiac MRI (CMR) has gained acceptance as the gold standard. CMR has been observed to be superior to echocardiography in characterizing soft‐tissue structures and, specifically, in classifying cardiac masses. The aim of our study was to evaluate the association between mortality and cardiac or paracardiac masses initially identified by echocardiography (ECHO) and confirmed by CMR. Between January 2002 and August 2007, a total of 158 patients underwent both ECHO and CMR for the evaluation of cardiac masses that were equivocal or undefined by ECHO. The primary study endpoints were 5‐year all‐cause mortality and 5‐year cardiac mortality. Causes of death as of April 1, 2015 were obtained from medical records or the National Death Index. Patients were analyzed according to mass type determined by CMR using the Kruskal–Wallis test, Kaplan–Meier curves, and the log‐rank test. Over a mean duration of follow‐up of 10.4 ± 2.9 years (range: 0.01–12 years) post‐CMR, the overall all‐cause mortality rate was 25.9% (41/158). Median age at death was 76 years and there were 21 females (51.2%). Mortality rates in the different classifications of cardiac masses by CMR were as follows: 20% (1/5) in patients with a Nondiagnostic CMR; 20% (1/5) in Other Diagnoses; 17.9% (7/39) in No Masses (includes Normal Anatomical Variants); 16.7% (3/18) in Benign Masses; 23.8% (15/63) in Fat; 50% (5/10) in Thrombus; and 61.5% (8/13) in Malignant Mass. The mean survival time in patients with No Mass (n = 39) was not significantly longer than patients with any type of cardiac mass (n = 114) (P = .16). No significant difference was found in age at death between patients when grouped by CMR classification (P = .40). However, among CMR‐confirmed masses, there were some significant differences by mass classification type (P = .006). During the follow‐up period, 26% (41/158) of patients died and 22% (9/41) of the deaths were cardiovascular related; there was no significant difference in mean survival times with respect to cause of mortality (P = .23). In patients with cardiac masses, dually confirmed by ECHO and CMR, significant differences in survival time were observed based upon CMR classified type of mass while CMR was instrumental in obviating invasive biopsy.     

The role of cardiovascular magnetic resonance in heart failure

Cardiovascular Magnetic Resonance (CMR) is an accepted gold standard for non-invasive, accurate, and reproducible assessment of cardiac mass and function. The interest in its use for viability, myocardial perfusion and coronary artery imaging is also widespread and growing rapidly as the hardware and expertise becomes available in more centres, and the scans themselves become more cost effective. In patients with heart failure, accurate and reproducible serial assessment of remodelling is of prognostic importance and the lack of exposure to ionizing radiation is helpful. The concept of an integrated approach to heart failure and its complications using CMR is fast becoming a reality, and this will be tested widely in the coming few years, with the new generation of dedicated CMR scanners.     

Cardiac MRI For Myocardial Ischemia

Proper assessment of the physiologic impact of coronary artery stenosis on the LV myocardium can affect patient prognosis and treatment decisions. Cardiac magnetic resonance imaging (CMR) assesses myocardial perfusion by imaging the myocardium during a first-pass transit of an intravenous gadolinium bolus, with spatial and temporal resolution substantially higher than nuclear myocardial perfusion imaging. Coupled with late gadolinium enhancement (LGE) imaging for infarction during the same imaging session, CMR with vasodilating stress perfusion imaging can qualitatively and quantitatively assess the myocardial extent of hypoperfusion from coronary stenosis independent of infarcted myocardium. This approach has been validated experimentally, and multiple clinical trials have established its diagnostic robustness when compared to stress single-photon emission computed tomography. In specialized centers, dobutamine stress CMR has been shown to have incremental diagnostic value above stress echocardiography due to its high imaging quality and ability to image the heart with no restriction of imaging window. This paper reviews the technical aspects, diagnostic utility, prognostic values, challenges to clinical adaptation, and future developments of stress CMR imaging.     

Diagnosis and management of ischemic cardiomyopathy: Role of cardiovascular magnetic resonance imaging

Coronary artery disease (CAD) represents an important cause of mortality. Cardiovascular magnetic resonance (CMR) imaging evolved as an imaging modality that allows the assessment of myocardial function, perfusion, contractile reserve and extent of fibrosis in a single comprehensive exam. This review highlights the role of CMR in the differential diagnosis of acute chest pain by detecting the location of obstructive CAD or necrosis and identifying other conditions like stress cardiomyopathy or myocarditis that can present with acute chest pain. Besides, it underlines the prognostic implication of perfusion abnormalities in the setting of acute chest pain. Furthermore, the review addresses the role of CMR to detect significant CAD in patients with stable CAD. It elucidates the accuracy and clinical utility of CMR with respect to other imaging modalities like single-photon emission computed tomography and positron emission tomography. Besides, the prognostic value of CMR stress testing is discussed. Additionally, it summarizes the available CMR techniques to assess myocardial viability and describes algorithm to identify those patient who might profit from revascularization those who should be treated medically. Finally, future promising imaging techniques that will provide further insights into the fundamental disease processes in ischemic cardiomyopathy are discussed.     

Diagnosis and follow‐up of idiopathic dilatation of inferior vena cava

In the absence of cardiac pathology, the presence of a dilated inferior vena cava (IVC) is considered idiopathic. To date, this phenomenon has only been described in athletic individuals as an adaptation to chronically augmented venous return. This is the largest prospective cohort study, following ten individuals with idiopathic dilated IVC against an age‐matched control group with annual echocardiograms and cardiac magnetic resonance (CMR) imaging for a median of 55 months. No significant difference was found between echocardiography and CMR measurements in IVC diameter assessment both at baseline and at follow‐up. Over the study period, there was no significant progression of the IVC in diameter as measured either by echocardiography or CMR. None of the patients suffered any cardiovascular events, and there were no hospitalizations. Our findings indicate the benign nature of this condition and provide reassurance with regard to future clinical implications.     

Principles, current status and clinical implications of ischaemic heart disease assessment by cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging (CMR) has matured into a robust, accurate and highly reproducible imaging modality for the assessment of cardiac function and ischaemic heart disease. The unique physical properties of CMR permit depiction of pathology-specific tissue contrast based on differences in tissue composition, such as myocardial oedema, necrosis and fibrosis. This can be imaged at high spatial resolution allowing characterisation of the acuity of an ischaemic event, the presence and extent of myocardial ischaemia, necrosis and viability. Prognostically important information obtained from CMR evaluation of ischaemic heart disease, such as left ventricular ejection fraction, infarct size and transmurality, infarct location and the presence of intraventricular mechanical dyssynchrony may be used to guide coronary revascularisation, device and medical therapies.     

Usefulness of cardiac magnetic resonance imaging for detecting acute myocardial infarction in patients with no significant electrocardiogram changes

A 73-year-old man presented with suspected acute myocardial infarction at the outpatient clinic. However, the clinical symptoms and the laboratory findings were not diagnostic. Only emergency cardiac magnetic resonance imaging (MRI) was helpful in making a definitive diagnosis of acute myocardial infarction. Cardiac MRI is a useful diagnostic tool for suspected acute coronary syndrome in emergency room settings when conventional modalities do not provide a definitive diagnosis.     

Comparison of the angiographic myocardial blush grade with delayed‐enhanced cardiac magnetic resonance for the assessment of microvascular obstruction in acute myocardial infarctions

Background: Both myocardial blush grade (MBG) and cardiac magnetic resonance (CMR) are imaging tools that can assess myocardial reperfusion after primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI). Objectives: We studied the relation between MBG and gadolinium‐enhanced CMR for the assessment of microvascular obstruction (MVO) in patients with acute ST‐elevated myocardial infarction (STEMI) treated by primary PCI. Material and Methods: MBG was assessed in 39 patients with initial TIMI 0 STEMI successfully treated by PCI, resulting in TIMI 3 flow grade and complete ST‐segment resolution. These MBG values were related to MVO determined by CMR, performed between 2 and 7 days after PCI. Left ventricular (LV) volumes were determined at baseline and at 6‐month follow‐up. Results: No statistical relation was found between MBG and MVO extent at CMR (P = 0.63). Regarding MBG 0 and 1 as a sign of MVO, the sensitivity and specificity of these scores were 53.8 and 75%, respectively. In this study, CMR determined MVO was the only significant LV remodeling predicting factor (β = 31.8; P = 0.002), whatever the MBG status was. Conclusion: MBG underestimates MVO after an optimal revascularization in AMI compared with CMR. This study suggests the superior accuracy of delayed‐enhanced magnetic resonance over MBG for the assessment of myocardial reperfusion injury that is needed in clinical trials, where the principal endpoint is the reduction of infarct size and MVO. © 2009 Wiley‐Liss, Inc.     

Assessment of myocardial viability: comparison of echocardiography versus cardiac magnetic resonance imaging in the current era

Detecting viable myocardium, whether hibernating or stunned, is of clinical significance in patients with coronary artery disease and left ventricular dysfunction. Echocardiographic assessments of myocardial thickening and endocardial excursion during dobutamine infusion provide a highly specific marker for myocardial viability, but with relatively less sensitivity. The additional modalities of myocardial contrast echocardiography and tissue Doppler have recently been proposed to provide further, quantitative measures of myocardial viability assessment. Cardiac magnetic resonance (CMR) has become popular for the assessment of myocardial viability as it can assess cardiac function, volumes, myocardial scar, and perfusion with high-spatial resolution. Both 'delayed enhancement' CMR and dobutamine stress CMR have important roles in the assessment of patients with ischaemic cardiomyopathy. This article reviews the recent advances in both echocardiography and CMR for the clinical assessment of myocardial viability. It attempts to provide a pragmatic approach toward the patient-specific assessment of this important clinical problem.     

心脏核磁共振在心肌淀粉样变中的诊断价值

目的 研究心内膜心肌活检(EMB)确诊心肌淀粉样变性(CA)患者的临床和心脏核磁共振(CMR)特点,明确CMR在CA中的诊断价值.方法 回顾性分析2006年9月至2010年12月期间EMB确诊CA并行CMR检查患者的临床表现、心电图、心脏超声及CMR结果.结果 共18例患者通过EMB确诊为CA,其中5例进行了CMR检查.5例患者均有心力衰竭的临床表现以及心电图改变,心脏超声示左心室向心性肥厚,心肌回声增强、颗粒样回声,左心房扩大,限制性舒张功能不全.CMR主要表现为左心室壁增厚,室间隔增厚明显,双房均增大,心室收缩功能正常或减低,舒张功能均不同程度受限,部分伴有心包及胸腔积液,延迟钆显像(LGE)呈不同程度的延迟强化,位于左心室心内膜下或心肌弥漫性延迟强化,部分患者强化可为线样、颗粒样或斑片状.随病程延长,心肌LGE程度及范围有更严重的趋势,与心电图改变一致.结论 CMR有助于CA诊断及病情判断,为CA重要的无创检查方法之一.临床怀疑CA患者可早期进行CMR检查,特别是在没有开展EMB检查的医院.