Delayed enhancement cardiovascular magnetic resonance assessment of non-ischaemic cardiomyopathies.

Non-ischaemic cardiomyopathies (NICMs) are chronic, progressive myocardial diseases with distinct patterns of morphological, functional, and electrophysiological changes. In the setting of cardiomyopathy (CM), determining the exact aetiology is important because the aetiology is directly related to treatment and patient survival. Determining the exact aetiology, however, can be difficult using currently available imaging techniques, such as echocardiography, radionuclide imaging or X-ray coronary angiography, since overlap of features between CMs may be encountered. Cardiovascular magnetic resonance (CMR) imaging has recently emerged as a new non-invasive imaging modality capable of providing high-resolution images of the heart in any desired plane. Delayed contrast enhanced CMR (DE-CMR) can be used for non-invasive tissue characterization and may hold promise in differentiating ischaemic from NICMs, as the typical pattern of hyperenhancement can be classified as 'ischaemic-type' or 'non-ischaemic type' on the basis of pathophysiology of ischaemia. This article reviews the potential of DE-CMR to distinguish between ischaemic and NICM as well as to differentiate non-ischaemic aetiologies. Rather than simply describing various hyperenhancement patterns that may occur in different disease states, our goal will be (i) to provide an overall imaging approach for the diagnosis of CM and (ii) to demonstrate how this approach is based on the underlying relationships between contrast enhancement and myocardial pathophysiology.     

Role of magnetic resonance contrast agents in cardiac imaging

Improvements in magnetic resonance imaging (MRI) technology allow adequate spatial and temporal resolution to capture cardiac anatomy and contractile function in exceptional detail and with little risk. However, tissue characterization of the pathophysiologic state of the myocardium may require special indicators or MR contrast agents. These must be tailored for detection by the MRI process, but available agents are effective at low dose and provide a wide range of indicator properties (e.g., myocardial extracellular space, blood pool, capillary permeability and membrane transport). Each agent has a dynamic washin and washout time-intensity curve that may reflect myocardial perfusion or consequences of ischemia. The combined use of MRI and MR contrast agents may provide a single diagnostic examination that fully and quantitatively assesses all indexes of cardiac performance. Such information would be both global and regional, and would be well tolerated by patients. The cost, value and cost-effectiveness of such studies remain speculative.     

Danon disease: characteristic late gadolinium enhancement pattern on cardiac magnetic resonance imaging

Danon disease is a rare entity associated with the clinical triad of mental retardation, skeletal myopathy, and severe hypertrophic cardiomyopathy. We report two cases of Danon disease and describe the results of the cardiac magnetic resonance imaging studies that were conducted to assess the pattern of cardiac hypertrophy.     

Delayed enhancement magnetic resonance imaging predicts response to cardiac resynchronization therapy in patients with intraventricular dyssynchrony.

OBJECTIVES: We evaluated the ability of delayed enhancement magnetic resonance imaging (DE-MRI) to predict clinical response to cardiac resynchronization therapy (CRT). BACKGROUND: Cardiac resynchronization therapy reduces morbidity and mortality in selected heart failure patients. However, up to 30% of patients do not have a response. We hypothesized that scar burden on DE-MRI predicts response to CRT. METHODS: The DE-MRI was performed on 28 heart failure patients undergoing CRT. Patients with QRS > or =120 ms, left ventricular ejection fraction < or =35%, New York Heart Association functional class II to IV, and dyssynchrony > or =60 ms were studied. Baseline and 3-month clinical follow-up, wall motion, 6-min walk, and quality of life assessment were performed. The DE-MRI was performed 10 min after 0.20 mmol/kg intravenous gadolinium. Scar measured by planimetry was correlated with response criteria. RESULTS: Twenty-three patients completed the protocol (mean age 64.9 +/- 11.7 years), with 12 (52%) having a history of myocardial infarction. Thirteen (57%) patients met response criteria. Percent total scar was significantly higher in the nonresponse versus response group (median and interquartile range of 24.7% [18.1 to 48.7] vs. 1.0% [0.0 to 8.7], p = 0.0022) and predicted nonresponse by receiver-operating characteristic analysis (area = 0.94). At a cutoff value of 15%, percent total scar provided a sensitivity and specificity of 85% and 90%, respectively, for clinical response to CRT. Similarly, septal scar < or =40% provided a 100% sensitivity and specificity for response. Regression analysis showed linear correlations between percent total scar and change in each of the individual response criteria. CONCLUSIONS: The DE-MRI accurately predicted clinical response to CRT. This technique offers unique information in the assessment of patients referred for CRT.     

Usefulness of cardiac magnetic resonance imaging for coronary artery disease detection

Cardiac magnetic resonance imaging (cMRI) is a promising non-invasive technique to assess the presence of coronary artery disease (CAD), which is free of ionizing radiation and iodine contrast. cMRI can detect CAD by angiographic methods or indirectly by perfusion stress techniques. While coronary angiography by cMRI remains limited to research protocols, stress perfusion cMRI is currently being applied worldwide in the clinical setting. Studies have shown good correlation between adenosine-induced stress myocardial perfusion cMRI and single-photon-emission computed tomography or positron emission tomography to detect CAD. Quantitative methods to analyze cMRI perfusion data have been developed in an attempt to provide a more objective imaging interpretation. Standardization of such quantitative methods, with minimal operator dependency, would be useful for clinical and research applications. Myocardial perfusion reserve (MPR), calculated using Fermi deconvolution technique, has been compared with well established anatomical and physiological CAD detection techniques. MPR appears to be the most accurate quantitative index to detect anatomical and hemodynamically significant CAD. Beyond physiological assessment of CAD, cMRI provides information regarding regional and global left ventricular function and morphology, myocardial infarction size, transmurality and viability. Such comprehensive information would require the performance of multiple tests if other modalities were used. This article describes current applications of cMRI for evaluation of patients with CAD.     

Functional assessment of myoblast transplantation for cardiac repair with magnetic resonance imaging

BACKGROUND: Contraction of transplanted myoblasts and their effects on function and remodeling after myocardial infarction remain controversial. AIM: We used magnetic resonance imaging (MRI) to study wall thickening and left ventricular (LV) function and geometry after myoblast transplantation. METHODS AND RESULTS: Three weeks after cryo-infarction rabbits were randomized to receive an injection of approximately 2 x 10(8) myoblasts (n=8) or medium (n=9) into the scar. Cine MRI and contrast enhanced (ce) MRI images were acquired before injection (baseline) and 4 weeks later (endpoint). Regional wall thickening was measured at the site of transmural hyperenhancement. In the control group, regional wall thickening decreased to -15.3+/-8.6% at baseline, which further decreased to -18.3+/-5.7% at endpoint. Further, end-diastolic volume increased from 3.96+/-0.27 to 5.00+/-0.46 ml and end-systolic volume from 2.23+/-0.19 to 2.96+/-0.30 ml (both P<0.05 vs. baseline), which was accompanied by increased LV wall volumes (P<0.05 vs. baseline). In contrast, myoblast transplantation increased regional wall thickening from -11.9+/-15.9% at baseline to 26.9+/-17.0% (P<0.05 vs. control), which resulted in significantly improved two-dimensional ejection fractions at the infarct level and prevented the increase in end-diastolic and end-systolic volumes and wall volume. CONCLUSION: Intracardiac myoblast transplantation after myocardial infarction improves regional wall thickening and prevents progressive left ventricular remodeling.     

Lyme carditis: persistent local delayed enhancement by cardiac magnetic resonance imaging

Lyme borreliosis (LB) is the most common tick-born disease in the Northern Hemisphere. During early disseminated Lyme disease cardiac manifestation can occur. We report a case of isolated Lyme myocarditis with transitory total atrioventricular (AV)-block and myocardial necrosis indicated by a rise in Troponin-T (TNT). Antibiotic treatment resulted in complete resolution of the AV-block, but a local epimyocardial contrast enhancement persisted as shown by cardiac magnetic resonance imaging (MRI).     

Three-dimensional cardiac magnetic resonance imaging

Evaluation of time-varying cardiac structure and function is challenging because of the three-dimensional (3-D) anatomy and time-varying (4-D) behavior of the heart. Historically, contrast angiography has served as the cornerstone of cardiac diagnosis because of its excellent spatial and temporal resolution. However, magnetic resonance (MR) imaging is now increasingly applied because of the wide variety of available MR imaging and data acquisition techniques, including spin-echo, gradient-echo, wall motion techniques, 1H 31P spectroscopy, and, most recently, echo-planar imaging. Planar 2-D MR imaging is used to characterize many aspects of cardiac structure and function, including anatomic relationships, valvular heart disease, ischemic heart disease, and congenital abnormalities, among others. The development of imaging display and data postprocessing analysis techniques have paralleled the growth of these image and data acquisition schemes and, increasingly, an emphasis has been placed on defining structure and function in 3-D, or even 4-D. Three-dimensional reconstructions of the heart have commonly relied on conventional planar MR image acquisition techniques; a 3-D volume of data is then created from stacked 2-D images. Surface reconstruction and graphical rendering techniques are used to generate representations of the heart that depict 3-D and 4-D cardiac structure and function. These techniques have been used both clinically and experimentally in a variety of settings, including ischemic heart disease, MR coronary angiography, and congenital heart disease.     

Usefulness of magnetic resonance imaging in the assessment of endomyocardial disease

Endomyocardial disease is a restrictive cardiomyopathy that includes L?ffler endocarditis, which is characterized by hypereosinophilia, and endomyocardial fibrosis, which is not. Echocardiography enables cardiac function and anatomy to be assessed and the differential diagnosis of other causes of restrictive disease, but magnetic resonance imaging provides information about the tissue itself. Furthermore, paramagnetic contrast agents are useful in detecting myocardial abnormalities. We report three cases of endomyocardial disease and the typical findings of magnetic resonance imaging.     

Role of cardiac magnetic resonance imaging in ischaemic heart disease

Cardiac magnetic resonance imaging is a new imaging method that has much to offer clinicians caring for patients with ischaemic heart disease. This article describes briefly the basic principles and practical aspects of cardiac magnetic resonance imaging, and summarizes the pathophysiology of ischaemic heart disease. Then it discusses in detail the use of cardiac magnetic resonance imaging for detection of coronary artery disease, and for assessment of acute and stable coronary syndromes.     

Right ventricular thrombus detection and multimodality imaging using contrast echocardiography and cardiac magnetic resonance imaging

We present the case of right ventricular thrombus formation associated with a right ventricular infarct secondary to a proximal right coronary artery thrombus, which was not evident on transthoracic echocardiography but detected on both delayed gadolinium enhanced magnetic resonance imaging and microsphere contrast echocardiography. The diagnosis of right ventricular thrombosis altered the decision to place an implantable cardiac defibrillator in this patient. Anticoagulation with warfarin resulted in resolution of the thrombus. This case highlights the utility of multimodality imaging in the detection and follow-up of right ventricular thrombus in the setting of right ventricular myocardial infarction, and the effectiveness of anticoagulation therapy.