Current Cardiovascular Imaging Reports

Potters, Wouter; Marquering, Henk; VanBavel, Ed; Nederveen, Aart

doi: 10.1007/s12410-014-9257-1pmid: N/A

This study reviews the application of velocity-encoded magnetic resonance imaging (MRI) for the calculation of wall shear stress (WSS). The basics of velocity-encoded MRI and WSS are reviewed and calculation methods for estimation of the WSS from 2D or 3D (cine) velocity-encoded MRI data are presented. In recent years, there has been a trend towards 3D WSS quantification methods. Current clinical applications of WSS are discussed, including an overview of estimated WSS magnitudes in different patient groups at multiple anatomical locations (aorta, carotid arteries, and intracranial aneurysms). A large variation was found between different WSS calculation methods. The future of MRI-based WSS calculations depends on its prognostic and diagnostic value, both of which need to be further explored in clinical studies. In this context, both further improvement of the quality of velocity-encoded MRI data and scan time reduction are pivotal.

Guensch, Dominik; Friedrich, Matthias

doi: 10.1007/s12410-014-9261-5pmid: N/A

This article reviews technical aspects and the current status of novel cardiovascular magnetic resonance (CMR) approaches to assessing myocardial perfusion, specifically oxygenation-sensitive magnetic resonance imaging, comparing their diagnostic targets and clinical role with those of other imaging approaches. The paper includes discussions of relevant pathophysiological aspects of myocardial ischemia and the clinical context of revascularization in patients with suspected or known coronary artery disease. Research using oxygenation-sensitive CMR may play an important role for a better understanding of the interplay of coronary artery stenosis, blood flow reduction, and their impact on actual myocardial ischemia.

Ali, Muhammad; Pulli, Benjamin; Chen, John

doi: 10.1007/s12410-014-9258-0pmid: 24729833

Molecular imaging is highly advantageous as various insidious inflammatory events can be imaged in a serial and quantitative fashion. Combined with the conventional imaging modalities like computed tomography (CT), magnetic resonance (MR), and nuclear imaging, it helps us resolve the extent of ongoing pathology, quantify inflammation, and predict outcome. Macrophages are increasingly gaining importance as an imaging biomarker in inflammatory cardiovascular diseases. Macrophages, recruited to the site of injury, internalize necrotic or foreign material. Along with phagocytosis, activated macrophages release proteolytic enzymes like matrix metalloproteinases (MMPs) and cathepsins into the extracellular environment. Proinflammatory monocytes and macrophages also induce tissue oxidative damage through the inflammatory enzyme myeloperoxidase (MPO). In this review we will highlight recent advances in molecular macrophage imaging. Particular stress will be given to macrophage functional and enzymatic activity imaging, which targets phagocytosis, proteolysis, and myeloperoxidase activity imaging.

Graaf, Wolter; Vandoorne, Katrien; Arslan, Fatih; Nicolay, Klaas; Strijkers, Gustav

doi: 10.1007/s12410-014-9260-6pmid: N/A

Fibrosis is a common feature of heart disease and is associated with adverse cardiac remodeling and poor clinical outcome. Because of the lack of routine noninvasive patient-specific tissue characterization tools, the development of new treatment strategies for cardiovascular disease specifically targeting undesired fibrosis in the myocardial wall is slow. Cardiovascular magnetic resonance imaging has developed into the gold-standard tool to assess various aspects of myocardial anatomy and function. In recent years, magnetic resonance imaging has also emerged as a promising technique to fulfill the need for a noninvasive assessment of myocardial fibrosis through the use of Gd-based contrast agents and the quantification of the longitudinal relaxation time T1. This paper reviews the current use of T1 mapping for the assessment of myocardial fibrosis, with particular focus on imaging techniques and their validation.

Dall’Armellina, Erica; Ferreira, Vanessa; Neubauer, Stefan

doi: 10.1007/s12410-014-9262-4pmid: N/A

The major advantage of T1 mapping techniques lies in the quantitative assessment of the tissue composition on a voxel by voxel basis. Both native and postcontrast T1 mapping, including extracellular volume (ECV) mapping, are promising cardiovascular magnetic resonance (CMR) imaging techniques, which may provide more insight into the clinical meaning of myocardial injury in acute coronary syndromes, and into the relationship between extracellular volume and long term LV remodeling. Native T1 mapping has been shown to allow depiction of edema and myocardial area at risk with greater sensitivity than any other standard imaging technique such as T2 weighted imaging. ECV mapping is very promising for the assessment of extracellular volume as validated with histologic sample of collagen fraction. However, only few studies have been published so far. These methods may become a cornerstone for the clinical applications of quantitative mapping techniques for myocardial tissue characterization, with on-going efforts toward further validation and standardization.

Fernández-Jiménez, Rodrigo; Fernández-Friera, Leticia; Sánchez-González, Javier; Ibáñez, Borja

doi: 10.1007/s12410-014-9259-zpmid: N/A

Myocardial in vivo tissue characterization is of great importance because it can provide meaningful information to understand pathophysiological processes underlying different cardiac diseases. Ex vivo histologic analyses of tissue samples have been classically considered the gold standard in the study of tissue properties and its composition. However, over the past decade, there has been a growing interest in the in vivo myocardial characterization with different imaging techniques, which can potentially be translated into the clinics in order to make an early diagnosis and evaluate serial changes, opening the possibility of dynamic evaluation. Animal models have become an essential tool to achieve this goal. This article aims at concisely reviewing recent and significant developments in the field of imaging techniques—mostly cardiac magnetic resonance—in relevant animal models of tissue characterization of area at risk, edema, and fibrosis.