Quantitative T2 mapping of the mouse heart by segmented MLEV phase-cycled T2 preparation.

Purpose: A high-quality, reproducible, multi-slice T2-mapping protocol for the mouse heart is presented.

Methods: A T2-prepared sequence with composite 90° and 180° radiofrequency pulses in a segmented MLEV phase cycling scheme was developed. The T2-mapping protocol was optimized using simulations and evaluated with phantoms.

Paramagnetic liposomes for molecular MRI and MRI-guided drug delivery.

Liposomes are a versatile class of nanoparticles with tunable properties, and multiple liposomal drug formulations have been clinically approved for cancer treatment. In recent years, an extensive library of gadolinium (Gd)-containing liposomal MRI contrast agents has been developed for molecular and cellular imaging of disease-specific markers and for image-guided drug delivery. This review discusses the advances in the development and novel applications of paramagnetic liposomes in molecular and cellular imaging, and in image-guided drug delivery.

Embryonic cardiomyocyte, but not autologous stem cell transplantation, restricts infarct expansion, enhances ventricular function, and improves long-term survival.

Aims: Controversy exists in regard to the beneficial effects of transplanting cardiac or somatic progenitor cells upon myocardial injury. We have therefore investigated the functional short- and long-term consequences after intramyocardial transplantation of these cell types in a murine lesion model.

Methods And Results: Myocardial infarction (MI) was induced in mice (n = 75), followed by the intramyocardial injection of 1-2×10(5) luciferase- and GFP-expressing embryonic cardiomyocytes (eCMs), skeletal myoblasts (SMs), mesenchymal stem cells (MSCs) or medium into the infarct.

Passive targeting of lipid-based nanoparticles to mouse cardiac ischemia-reperfusion injury.

Reperfusion therapy is commonly applied after a myocardial infarction. Reperfusion, however, causes secondary damage. An emerging approach for treatment of ischemia-reperfusion (IR) injury involves the delivery of therapeutic nanoparticles to the myocardium to promote cell survival and constructively influence scar formation and myocardial remodeling.

Internalization of paramagnetic phosphatidylserine-containing liposomes by macrophages.

Background: Inflammation plays an important role in many pathologies, including cardiovascular diseases, neurological conditions and oncology, and is considered an important predictor for disease progression and outcome. In vivo imaging of inflammatory cells will improve diagnosis and provide a read-out for therapy efficacy. Paramagnetic phosphatidylserine (PS)-containing liposomes were developed for magnetic resonance imaging (MRI) and confocal microscopy imaging of macrophages.

Distribution of lipid-based nanoparticles to infarcted myocardium with potential application for MRI-monitored drug delivery.

Adverse cardiac remodeling after myocardial infarction ultimately causes heart failure. To stimulate reparative processes in the infarct, efficient delivery and retention of therapeutic agents is desired. This might be achieved by encapsulation of drugs in nanoparticles.

Targeting of ICAM-1 on vascular endothelium under static and shear stress conditions using a liposomal Gd-based MRI contrast agent.

Background: The upregulation of intercellular adhesion molecule-1 (ICAM-1) on the endothelium of blood vessels in response to pro-inflammatory stimuli is of major importance for the regulation of local inflammation in cardiovascular diseases such as atherosclerosis, myocardial infarction and stroke. In vivo molecular imaging of ICAM-1 will improve diagnosis and follow-up of patients by non-invasive monitoring of the progression of inflammation.

Results: A paramagnetic liposomal contrast agent functionalized with anti-ICAM-1 antibodies for multimodal magnetic resonance imaging (MRI) and fluorescence imaging of endothelial ICAM-1 expression is presented.

Contrast-enhanced MRI of murine myocardial infarction - part II.

Mouse models are increasingly used to study the pathophysiology of myocardial infarction in vivo. In this area, MRI has become the gold standard imaging modality, because it combines high spatial and temporal resolution functional imaging with a large variety of methods to generate soft tissue contrast. In addition, (target-specific) MRI contrast agents can be employed to visualize different processes in the cascade of events following myocardial infarction.

Contrast-enhanced MRI of murine myocardial infarction - part I.

The use of contrast agents has added considerable value to the existing cardiac MRI toolbox that can be used to study murine myocardial infarction, as it enables detailed in vivo visualization of the molecular and cellular processes that occur in the infarcted and remote tissue. A variety of non-targeted and targeted contrast agents to study myocardial infarction are available and under development. Manganese, which acts as a calcium analogue, can be used to assess cell viability.

Regional contrast agent quantification in a mouse model of myocardial infarction using 3D cardiac T1 mapping.

Background: Quantitative relaxation time measurements by cardiovascular magnetic resonance (CMR) are of paramount importance in contrast-enhanced studies of experimental myocardial infarction. First, compared to qualitative measurements based on signal intensity changes, they are less sensitive to specific parameter choices, thereby allowing for better comparison between different studies or during longitudinal studies. Secondly, T1 measurements may allow for quantification of local contrast agent concentrations.

Three-dimensional T1 mapping of the mouse heart using variable flip angle steady-state MR imaging.

Cardiac MR T(1) mapping is a promising quantitative imaging tool for the diagnosis and evaluation of cardiomyopathy. Here, we present a new preclinical cardiac MRI method enabling three-dimensional T(1) mapping of the mouse heart. The method is based on a variable flip angle analysis of steady-state MR imaging data.

Mouse myocardial first-pass perfusion MR imaging.

A first-pass myocardial perfusion sequence for mouse cardiac MRI is presented. A segmented ECG-triggered acquisition combined with parallel imaging acceleration was used to capture the first pass of a Gd-DTPA bolus through the mouse heart with a temporal resolution of 300-400 msec. The method was applied in healthy mice (N = 5) and in mice with permanent occlusion of the left coronary artery (N = 6).

Current applications of nanotechnology for magnetic resonance imaging of apoptosis.

Apoptosis, or programmed cell death, is a morphologically and biochemically distinct form of cell death, which together with proliferation plays an important role in tissue development and homeostasis. Insufficient apoptosis is important in the pathology of various disorders such as cancer and autoimmune diseases, whereas a high apoptotic activity is associated with myocardial infarction, neurodegenerative diseases, and advanced atherosclerotic lesions. Consequently, apoptosis is recognized as an important therapeutic target, which should be either suppressed, e.

Internalization of annexin A5-functionalized iron oxide particles by apoptotic Jurkat cells.

Apoptosis plays an important role in the etiology of various diseases. Several studies have reported on the use of annexin A5-functionalized iron oxide particles for the detection of apoptosis with MRI, both in vitro and in vivo. The protein annexin A5 binds with high affinity to the phospholipid phosphatidylserine, which is exposed in the outer leaflet of the apoptotic cell membrane.