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Wagner, Anja; Bruder, Oliver; Mahrholdt, Heiko
doi: 10.1007/s12410-010-9015-ypmid: N/A
Myocarditis is most commonly caused by a viral infection. Most cases are subclinical or only mildly symptomatic; however, patients can also present with heart failure, sudden cardiac death, or chest pain. Traditional noninvasive diagnostic tests are limited by a low sensitivity and specificity. The role of endomyocardial biopsy has been recently redefined but remains unclear for most patients. Cardiovascular magnetic resonance (CMR) imaging is an emerging technique that holds promise to diagnose patients with suspected myocarditis noninvasively. However, currently CMR is not able to assess the severity of inflammation, nor to definitely detect the underlying pathogen. Hence, whether it is necessary to obtain detailed histopathological information using biopsies in addition to a preceding CMR study has to be decided in consideration of the individual circumstances.
Ishida, Masaki; Morton, Geraint; Schuster, Andreas; Nagel, Eike; Chiribiri, Amedeo
doi: 10.1007/s12410-010-9013-0pmid: N/A
Myocardial perfusion MRI is acquired with a T1-weighted dynamic MRI sequence. Fully quantitative analysis of myocardial perfusion MRI allows the absolute quantification of myocardial blood flow (MBF) through the use of complex mathematical modeling. There are essentially two main methods for quantification of absolute MBF: the linear time-invariant model and the compartment model. Maximized contrast-to-noise ratio and the reasonable linearity of signal intensity in blood and myocardium are crucial for the accuracy of absolute MBF quantification by MRI. Quantitative assessment of MBF permits an accurate and objective assessment of myocardial perfusion and perfusion reserve in patients. This is of particular significance in patients with coronary artery disease but will also provide a means for investigating globally altered MBF in patients with microvascular disease of the heart. Furthermore, quantification of MBF with magnetic resonance can provides us with an important tool for monitoring disease progression and measuring the response to therapeutic interventions.
doi: 10.1007/s12410-010-9008-xpmid: N/A
Cardiovascular magnetic resonance (CMR) has important contributions to make to the assessment of heart valve disease. These can be complementary to routine echocardiographic assessment, for example in the quantification of valve regurgitation and clarification of the nature and level(s) of right or left ventricular outflow tract obstruction. In ischemic mitral regurgitation, CMR allows the assessment of myocardial scarring and viability as well as the nature of valve dysfunction. CMR provides a noninvasive alternative to echocardiography in patients with inconsistent findings or limited acoustic access. For studies of multidirectional flow, CMR can measure all three directional components of velocity in voxels distributed in three dimensions and through the phases of the cycle. More clinically applicable, however, are volumetric flow measurements, forward or regurgitant, through planes transecting one or both great arteries. These derived measurements are prone to errors caused by slight background phase offsets, which may require appropriate correction.
Kellman, Peter; Hernando, Diego; Arai, Andrew
doi: 10.1007/s12410-010-9012-1pmid: 20401158
The presence of intramyocardial fat may form a substrate for arrhythmias, and fibrofatty infiltration of the myocardium has been shown to be associated with sudden death. Therefore, noninvasive detection could have high prognostic value. Fat-water–separated imaging in the heart by MRI is a sensitive means of detecting intramyocardial fat and characterizing fibrofatty infiltration. It is also useful in characterizing fatty tumors and delineating epicardial and/or pericardial fat. Multi-echo methods for fat and water separation provide a sensitive means of detecting small concentrations of fat with positive contrast and have a number of advantages over conventional chemical-shift fat suppression. Furthermore, fat and water–separated imaging is useful in resolving artifacts that may arise due to the presence of fat. Examples of fat-water–separated imaging of the heart are presented for patients with ischemic and nonischemic cardiomyopathies, as well as general tissue classification.
Subramanian, Sharath; Tawakol, Ahmed
doi: 10.1007/s12410-010-9014-zpmid: N/A
The molecular and biological processes that take place in atherosclerotic plaque play an important role in determining the pathologic progression of the plaque. Current imaging techniques primarily inform about plaque structure and thus fail to assess the functional aspects of atherosclerosis. Accordingly, imaging of plaque biology might provide important incremental information about the underlying disease process. An emerging body of work shows that molecular imaging with fluorodeoxyglucose—positron emission tomography (PET) can provide information about plaque biology. This review provides an overview of the development of vascular PET imaging, with an evaluation of current and potential future uses of this imaging modality.
Christen, Thomas; Shimizu, Koichi; Libby, Peter
doi: 10.1007/s12410-010-9011-2pmid: N/A
Endomyocardial biopsy with its inherent invasiveness and morbidity calls for the development of noninvasive imaging methods to evaluate heart transplant recipients. While conventional imaging technologies report on anatomical and metabolic changes in heart grafts, macrophage-targeted imaging could allow disease detection before gross anatomical and functional changes have occurred. One important approach in magnetic resonance–based molecular imaging exploits an increased T2/T2* relaxation effect, occurring when phagocytic cells localized in the heart graft take up iron-oxide nanoparticles. This methodology of nanoparticle reporting on immune cell accumulation in the graft combined with precise functional and morphological information of cardiac MRI has potential to supplant endomyocardial biopsy. The use of multifunctional nanoparticles fit for multiple imaging modalities (magnetic, optical, and nuclear) will help improve methods of ex vivo and in vitro imaging of allograft rejection and also further our knowledge of allograft rejection by providing a tool for nondestructive serial in vivo assessment.
doi: 10.1007/s12410-009-9001-4pmid: 20396619
Stem cell therapy has been heralded as a novel therapeutic option for cardiovascular disease. In vivo molecular imaging has emerged as an indispensible tool in investigating stem cell biology post-transplantation into the myocardium and in evaluating the therapeutic efficacy. This review highlights the features of each molecular imaging modality and discusses how these modalities have been applied to evaluate stem cell therapy.
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