Noninvasive assessment of cardiac abnormalities in experimental autoimmune myocarditis by magnetic resonance microscopy imaging in the mouse.

Myocarditis is an inflammation of the myocardium, but only -10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-α 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-α 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies

Noninvasive Assessment of Cardiac Abnormalities in Experimental Autoimmune Myocarditis by Magnetic Resonance Microscopy Imaging in the Mouse

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-α 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-α 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies

Epitope Mapping of SERCA2a Identifies an Antigenic Determinant That Induces Mainly Atrial Myocarditis in A/J Mice

Sarcoplasmic/endoplasmic reticulum Ca2+ adenosine triphosphatase (SERCA)2a, a critical regulator of calcium homeostasis, is known to be decreased in heart failure. Patients with myocarditis or dilated cardiomyopathy develop autoantibodies to SERCA2a suggesting that they may have pathogenetic significance. In this report, we describe epitope mapping analysis of SERCA2a in A/J mice that leads us to make five observations: 1) SERCA2a contains multiple T cell epitopes that induce varying degrees of myocarditis. One epitope, SERCA2a 971–990, induces widespread atrial inflammation without affecting noncardiac tissues; the cardiac abnormalities could be noninvasively captured by echocardiography, electrocardiography, and magnetic resonance microscopy imaging. 2) SERCA2a 971–990-induced disease was associated with the induction of CD4 T cell responses and the epitope preferentially binds MHC class II/IAk rather than IEk. By creating IAk/and IEk/SERCA2a 971–990 dextramers, the T cell responses were determined by flow cytometry to be Ag specific. 3) SERCA2a 971–990-sensitized T cells produce both Th1 and Th17 cytokines. 4) Animals immunized with SERCA2a 971–990 showed Ag-specific Abs with enhanced production of IgG2a and IgG2b isotypes, suggesting that SERCA2a 971–990 can potentially act as a common epitope for both T cells and B cells. 5) Finally, SERCA2a 971–990-sensitized T cells were able to transfer disease to naive recipients. Together, these data indicate that SERCA2a is a critical autoantigen in the mediation of atrial inflammation in mice and that our model may be helpful to study the inflammatory events that underlie the development of conditions such as atrial fibrillation in humans

Applications of novel MRI technologies in tissue engineering and disease diagnosis

Magnetic resonance imaging (MRI) and magnetic resonance elastography (MRE) are increasingly under investigation to explore their potential role in establishing effective evaluation methods for the procedure of tissue regeneration carried out in vitro, in vivo, and in disease diagnosis. To this end, there is a continuous pursuit of novel tools both in vitro and in vivo. For instance, there is a great need for the development and evaluation of an MR-compatible incubation system that enables simultaneous monitoring and culturing of cell and tissue constructs using MRI techniques. Such an imaging-compatible incubation system eliminates exposing the culture to the risks of temperature shock, sample contamination, and handling/stress during evaluation tests. Samples, therefore, are not wasted, and can be implanted in animal models for following in vivo experiments. While in vitro tissue engineering studies allow for extraction of useful information, the experimental conditions cannot be truly replicated in the in vivo environment. Animal models, therefore, are critical to assess and characterize the regeneration of the engineered tissues. Furthermore, continuous observation of regenerating tissues using imaging modalities can lead to a decreased number of animals, where each animal acts as its own control. In an effort to develop a device to promote the role of MRI in tissue engineering, including extraction of leading biomarkers for in vitro studies, the e-incubator system was developed, which is an autonomous MRI-compatible incubation system. MRI was also applied in vivo on mouse models to show the potential of different MRI contrast mechanisms in characterizing tissue-engineered bone and cartilage. The engineered constructs were also imaged in vivo using MRE to characterize their stiffness changes. Furthermore, the role of MRE in diagnosis of nonalcoholic fatty liver disease (NAFLD) was investigated by monitoring the variations of liver stiffness followed by the analysis of changes in gene expression of fibrosis-specific genes in a mouse model. Altogether, this dissertation work showed the potential of MRI technologies in promoting tissue engineering and disease diagnosis through introducing the e-incubator system, providing noninvasive in vivo imaging markers for bone and cartilage regeneration, and describing MRE as an effective noninvasive method for early detection of NAFLD

Design and Fabrication of an MRI-Compatible, Autonomous Incubation System

Tissue engineers have long sought access to an autonomous, imaging-compatible tissue incubation system that, with minimum operator handling, can provide real-time visualization and quantification of cells, tissue constructs, and organs. This type of screening system, capable of operating noninvasively to validate tissue, can overcome current limitations like temperature shock, unsustainable cellular environments, sample contamination, and handling/stress. However, this type of system has been a major challenge, until now. Here, we describe the design, fabrication, and characterization of an innovative, autonomous incubation system that is compatible with a 9.4 T magnetic resonance imaging (MRI) scanner. Termed the e-incubator (patent pending; application number: 13/953,984), this microcontroller-based system is integrated into an MRI scanner and noninvasively screens cells and tissue cultures in an environment where temperature, pH, and media/gas handling are regulated. The 4-week study discussed herein details the continuous operation of the e-incubator for a tissue-engineered osteogenic construct, validated by LIVE/DEAD® cell assays and histology. The evolving MR quantitative parameters of the osteogenic construct were used as biomarkers for bone tissue engineering and to further validate the quality of the product noninvasively before harvesting. Importantly, the e-incubator reliably facilitates culturing cells and tissue constructs to create engineered tissues and/or investigate disease therapies

MRI-Compatible Bioreactors and Methods of Using

This disclosure describes a MRI-compatible bioreactor that allows a biological sample to be imaged in culture without disrupting or compromising the culture

Motion and temporal B0 shift corrections for quantitative susceptibility mapping (QSM) and R2* mapping using dual-echo spiral navigators and conjugate-phase reconstruction

Purpose: To develop an efficient navigator-based motion and temporal B0 shift correction technique for 3D multi-echo gradient-echo (ME-GRE) MRI for quantitative susceptibility mapping (QSM) and R2* mapping. Theory and Methods: A dual-echo 3D spiral navigator was designed to interleave with the Cartesian ME-GRE acquisitions, allowing the acquisition of both low- and high-echo time signals. We additionally designed a novel conjugate-phase based reconstruction method for the joint correction of motion and temporal B0 shifts. We performed both numerical simulation and in vivo human scans to assess the performance of the methods. Results: Numerical simulation and human brain scans demonstrated that the proposed technique successfully corrected artifacts induced by both head motions and temporal B0 changes. Efficient B0-change correction with conjugate-phase reconstruction can be performed on less than 10 clustered k-space segments. In vivo scans showed that combining temporal B0 correction with motion correction further reduced artifacts and improved image quality in both R2* and QSM images. Conclusion: Our proposed approach of using 3D spiral navigators and a novel conjugate-phase reconstruction method can improve susceptibility-related measurements using MR.Comment: 7 figure

The e-incubator: a magnetic resonance imaging-compatible mini incubator.

The tissue engineering community has been vocal regarding the need for noninvasive instruments to assess the development of tissue-engineered constructs. Medical imaging has helped fulfill this role. However, specimens allocated to a test tube for imaging cannot be tested for a prolonged period or returned to the incubator. Therefore, samples are essentially wasted due to potential contamination and transfer in a less than optimal growth environment. In turn, we present a standalone, miniature, magnetic resonance imaging-compatible incubator, termed the e-incubator. This incubator uses a microcontroller unit to automatically sense and regulate physiological conditions for tissue culture, thus allowing for concurrent tissue culture and evaluation. The e-incubator also offers an innovative scheme to study underlying mechanisms related to the structural and functional evolution of tissues. Importantly, it offers a key step toward enabling real-time testing of engineered tissues before human transplantation. For validation purposes, we cultured tissue-engineered bone constructs for 4 weeks to test the e-incubator. Importantly, this technology allows for visualizing the evolution of temporal and spatial morphogenesis. In turn, the e-incubator can filter deficient constructs, thereby increasing the success rate of implantation of tissue-engineered constructs, especially as construct design grows in levels of complexity to match the geometry and function of patients\u27 unique needs

Detection of Cardiac Artery Disease by Using the DCAD (b) Module

Introduction: In patients with cardiac artery disease, a myocardial perfusion scan, which is a non-invasive method, is utilized. This study is conducted to develop an advantageous software applicable to quantitative myocardial SPECT perfusion. Material and Methods: Each cross-section of the left ventricle was segmented by applying a fuzzy clustering method. After obtaining the myocardial skeleton of the left ventricle from its short axis cross sections, we made use of fuzzy logic to decide whether the pixel belongs to the myocardial muscle and any perfusion perturbation or not. The reconstructed image was divided into 18 equivolume sectors. The features were extracted in each sector and, finally, were compared with a normal data bank. Results: Abnormal critical conditions in rest and stress studies and coronary artery disease diagnosis were investigated in a set of about 317 images. Measurement and allocation of different myocardial sectors to specific coronary arteries were accomplished by utilizing collected information about the patients (75 men and 62 women), and the validity of the artery obstruction diagnosis has been proven in 40 patients undergoing coronary angiography. Conclusion: Our developed software DCAD (b) has demonstrated a considerably good performance in the diagnosis of coronary artery occlusion and can be a promising method aiding nuclear medicine specialists in their diagnosis

Magnetic resonance elastography methodology for the evaluation of tissue engineered construct growth.

Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use of destructive assessment is not acceptable. A proposed alternative is the use of an imaging process called magnetic resonance elastography. Elastography is a nondestructive method for determining the engineered outcome by measuring local mechanical property values (i.e., complex shear modulus), which are essential markers for identifying the structure and functionality of a tissue. As a noninvasive means for evaluation, the monitoring of engineered constructs with imaging modalities such as magnetic resonance imaging (MRI) has seen increasing interest in the past decade. For example, the magnetic resonance (MR) techniques of diffusion and relaxometry have been able to characterize the changes in chemical and physical properties during engineered tissue development. The method proposed in the following protocol uses microscopic magnetic resonance elastography (μMRE) as a noninvasive MR based technique for measuring the mechanical properties of small soft tissues. MRE is achieved by coupling a sonic mechanical actuator with the tissue of interest and recording the shear wave propagation with an MR scanner. Recently, μMRE has been applied in tissue engineering to acquire essential growth information that is traditionally measured using destructive mechanical macroscopic techniques. In the following procedure, elastography is achieved through the imaging of engineered constructs with a modified Hahn spin-echo sequence coupled with a mechanical actuator. As shown in Figure 1, the modified sequence synchronizes image acquisition with the transmission of external shear waves; subsequently, the motion is sensitized through the use of oscillating bipolar pairs. Following collection of images with positive and negative motion sensitization, complex division of the data produce a shear wave image. Then, the image is assessed using an inversion algorithm to generate a shear stiffness map. The resulting measurements at each voxel have been shown to strongly correlate (R(2)\u3e0.9914) with data collected using dynamic mechanical analysis. In this study, elastography is integrated into the tissue development process for monitoring human mesenchymal stem cell (hMSC) differentiation into adipogenic and osteogenic constructs as shown in Figure 2