Name: cardiac magnetic resonance for the evaluation of suspected cardiac thrombus: conventional and emerging techniques
Uploaded: 2019-06-11T12:30:00
Description: Watch this Scientific Journal Video about Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques at JoVE.com

The authors acknowledge support from the Department of Diagnostic Imaging at the H. Lee Moffitt Cancer Center and Research Institute.

The following protocol follows the departmental clinical guidelines and is adherent to the institution&#8217;s human research ethics guidelines.
1. Prepare for MRI Data Acquisition
<ol>
	<li>Conduct a safety screening.
	<ol>
		<li>Evaluate for renal impairment8.
		<ol>
			<li>Avoid gadolinium contrast in patients with stage 4 or 5 chronic kidney disease (estimated glomerular filtration rate &#60;30 mL/min/1.71 m2) not on chronic dialysis, p...

<ol>
	<li>Lichtenberger, J. P., Dulberger, A. R., Gonzales, P. E., Bueno, J., Carter, B. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MR+imaging+of+cardiac+masses.">MR imaging of cardiac masses.</a> Topics in Magnetic Resonance Imaging. 27 (2), 103-111 (2018).</li><li>Motwani, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MR+imaging+of+cardiac+tumors+and+masses:+a+review+of+methods+and+clinical+applications.">MR imaging of cardiac tumors and masses: a review of methods and clinical applications.</a> Radiology. 268 (1), 26-43 (2013).</li><li>Jeong, D., Patel, A., Francois, C. J., Gage, K. L., Fradley, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+magnetic+resonance+imaging+in+oncology.">Cardiac magnetic resonance imaging in oncology.</a> Cancer Control. 24 (2), 147-160 (2017).</li><li>Goyal, P., Weinsaft, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+magnetic+resonance+imaging+for+assessment+of+cardiac+thrombus.">Cardiovascular magnetic resonance imaging for assessment of cardiac thrombus.</a> Methodist DeBakey Cardiovascular Journal. 9 (3), 132 (2013).</li><li>Jeong, D., Gage, K. L., Berman, C. G., Montilla-Soler, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+magnetic+resonance+for+evaluating+catheter+related+FDG+avidity.">Cardiac magnetic resonance for evaluating catheter related FDG avidity.</a> Case Reports in Radiology. , 1-4 (2016).</li><li>Caspar, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+resonance+evaluation+of+cardiac+thrombi+and+masses+by+T1+and+T2+mapping:+an+observational+study.">Magnetic resonance evaluation of cardiac thrombi and masses by T1 and T2 mapping: an observational study.</a> International Journal of Cardiovascular Imaging. 33 (4), 551-559 (2017).</li><li>Ferreira, V. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-contrast+T1-mapping+detects+acute+myocardial+edema+with+high+diagnostic+accuracy:+a+comparison+to+T2-weighted+cardiovascular+magnetic+resonance.">Non-contrast T1-mapping detects acute myocardial edema with high diagnostic accuracy: a comparison to T2-weighted cardiovascular magnetic resonance.</a> Journal of Cardiovascular Magnetic Resonance. 14 (42), (2012).</li><li>Srichai, M. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical,+imaging,+and+pathological+characteristics+of+left+ventricular+thrombus:+a+comparison+of+contrast-enhanced+magnetic+resonance+imaging,+transthoracic+echocardiography,+and+transesophageal+echocardiography+with+surgical+or+pathological+validation.">Clinical, imaging, and pathological characteristics of left ventricular thrombus: a comparison of contrast-enhanced magnetic resonance imaging, transthoracic echocardiography, and transesophageal echocardiography with surgical or pathological validation.</a> American Heart Journal. 152 (1), 75-84 (2006).</li><li>. ACR committee on drugs and contrast media. Version 10.3 Available from: <a target="_blank" href="https://www.acr.org/-/media/ACR/Files/Clinical-Resources/Contrast_Media.pdf">https://www.acr.org/-/media/ACR/Files/Clinical-Resources/Contrast_Media.pdf</a> (2018)</li><li>. ACR-NASCI-SPR practice parameter for the performance and interpretation of cardiac magnetic resonance imaging (MRI). (Resolution 5) Available from: <a target="_blank" href="https://www.acr.org/-/media/ACR/Files/Practice-Parameters/MR-Cardiac.pdf">https://www.acr.org/-/media/ACR/Files/Practice-Parameters/MR-Cardiac.pdf</a> (2016)</li><li>Bogaert, J., Dymarkowski, S., Taylor, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Clinical cardiac MRI. , (2005).</li><li>Kramer, C. M., Barkhausen, J., Flamm, S. D., Kim, R. J., Nagel, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardized+cardiovascular+magnetic+resonance+(CMR)+protocols+2013+update.">Standardized cardiovascular magnetic resonance (CMR) protocols 2013 update.</a> Journal of Cardiovascular Magnetic Resonance. 15 (91), 1-10 (2013).</li><li>Fratz, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+and+protocols+for+cardiovascular+magnetic+resonance+in+children+and+adults+with+congenital+heart+disease:+SCMR+expert+consensus+group+on+congenital+heart+disease.">Guidelines and protocols for cardiovascular magnetic resonance in children and adults with congenital heart disease: SCMR expert consensus group on congenital heart disease.</a> Journal of Cardiovascular Magnetic Resonance. 15 (51), 1-26 (2013).</li><li>Al-Wakeel-Marquard, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+T1+mapping+in+congenital+heart+disease:+bolus+vs.+infusion+protocols+for+measurements+of+myocardial+extracellular+volume+fraction.">Cardiac T1 mapping in congenital heart disease: bolus vs. infusion protocols for measurements of myocardial extracellular volume fraction.</a> International Journal of Cardiovascular Imaging. 33 (12), 1961-1968 (2017).</li><li>Messroghli, D. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modified+Look-Locker+inversion+recovery+(MOLLI)+for+high+resolution+T1+mapping+of+the+heart.">Modified Look-Locker inversion recovery (MOLLI) for high resolution T1 mapping of the heart.</a> Magnetic Resonance Medicine. 52 (1), 141-146 (2004).</li><li>Messroghli, D. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+recommendations+for+cardiovascular+magnetic+resonance+mapping+of+T1,+T2,+T2*+and+extracellular+volume:+A+consensus+statement+by+the+Society+for+Cardiovascular+Magnetic+Resonance+(SCMR)+endorsed+by+the+European+Association+for+Cardiovascular+Imaging+(EACVI).">Clinical recommendations for cardiovascular magnetic resonance mapping of T1, T2, T2* and extracellular volume: A consensus statement by the Society for Cardiovascular Magnetic Resonance (SCMR) endorsed by the European Association for Cardiovascular Imaging (EACVI).</a> Journal of Cardovascular Magnetic Resonance. 19 (1), 75 (2017).</li><li>Foltz, W. D., Al-Kwifi, O., Sussman, M. S., Stainsby, J. A., Wright, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+spiral+imaging+for+measurement+of+myocardial+T2+relaxation.">Optimized spiral imaging for measurement of myocardial T2 relaxation.</a> Magnetic Resonance Medicine. 49 (6), 1089-1097 (2003).</li><li>Kvernby, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+three-dimensional+myocardial+T1+and+T2+mapping+in+one+breath+hold+with+3D-QALAS.">Simultaneous three-dimensional myocardial T1 and T2 mapping in one breath hold with 3D-QALAS.</a> Journal of Cardiovascular Magnetic Resonance. 20 (16), 102 (2014).</li><li>Kvernby, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+feasibility+of+3D-QALAS+&#8211;+single+breath-hold.">Clinical feasibility of 3D-QALAS &#8211; single breath-hold.</a> 3D myocardial T1 and T2-mapping. Magnetic Resonance Imaging. 38, 13-20 (2017).</li><li>Schulz-Menger, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardized+image+interpretation+and+post+processing+in+cardiovascular+magnetic+resonance:+Society+for+cardiovascular+magnetic+resonance+(SCMR)+Board+of+Trustees+task+force+on+standardized+post+processing.">Standardized image interpretation and post processing in cardiovascular magnetic resonance: Society for cardiovascular magnetic resonance (SCMR) Board of Trustees task force on standardized post processing.</a> Journal of Cardiovascular Magnetic Resonance. 15 (35), 1-19 (2013).</li><li>Hundley, W. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Society+for+cardiovascular+magnetic+resonance+guidelines+for+reporting+cardiovascular+magnetic+resonance+examinations.">Society for cardiovascular magnetic resonance guidelines for reporting cardiovascular magnetic resonance examinations.</a> Journal of Cardiovascular Magnetic Resonance. 11 (5), 1-11 (2009).</li><li>Pazos-Lopez, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Value+of+CMR+for+the+differential+diagnosis+of+cardiac+masses.">Value of CMR for the differential diagnosis of cardiac masses.</a> Journal of the American College of Cardiology: Cardiovascular Imaging. 7 (9), 896-905 (2014).</li><li>Kubler, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T1+and+T2+mapping+for+tissue+characterization+of+cardiac+myxoma.">T1 and T2 mapping for tissue characterization of cardiac myxoma.</a> International Journal of Cardiology. 169 (1), e17-e20 (2013).</li></ol>

With the increasing quality and frequency of diagnostic imaging, it is not uncommon to discover incidental cardiac masses when performing imaging for unrelated indications. Patients with cardiac masses are often asymptomatic, and if present, symptoms are typically nonspecific.
The diagnosis of cardiac thrombus is important not only for differentiating thrombus from benign or malignant cardiac tumors, but also for determining the need for anticoagulation and prevention of embolic events<sup cla...

Cardiac magnetic resonance (CMR) imaging is an important diagnostic modality for the evaluation of cardiovascular function and pathology. Technological advances allow for reduced acquisition time, improved spatial and temporal resolution, as well as higher quality tissue characterization. These advances are particularly useful in the evaluation of cardiac masses.
Echocardiography remains the first line imaging modality for the initial evaluation of cardiac masses, specifically with respect to mass location, morphology, and physiologic impact. However, echocardiography is limited by poor tissue characterization, a restricted field of view, and operator dependent image quality. Cardiac computed tomography (CT) is often utilized as a second-line imaging modality for assessing cardiac masses. Advantages of cardiac CT over other modalities include excellent spatial resolution and a superior ability in detecting calcifications. The main disadvantage of cardiac CT is patient exposure to ionizing radiation. Additional limitations include decreased temporal resolution and soft tissue contrast resolution. CMR is emerging as a valuable tool in the characterization of cardiac masses detected on echocardiography or CT. Compared to CT, CMR does not expose patients to ionizing radiation. In addition, CMR can be useful in treatment and surgical planning1,2.
A thrombus is the most common cardiac mass. The most common locations for cardiac thrombi are the left atrium and left atrial appendage, especially in the setting of atrial fibrillation or a dysfunctional left ventricle1,3. The diagnosis of thrombus is important for the prevention of embolic events as well as establishing the need for anticoagulation. CMR can aide in determining the acuity of a thrombus. Acute thrombus typically demonstrates intermediate T1- and T2-weighted signal intensity relative to the myocardium due to high amounts of oxygenated hemoglobin. Increased methemoglobin content in the subacute thrombus results in lower T1-weighted signal intensity and intermediate or increased T2-weighted signal intensity. With a chronic thrombus, methemoglobin and water are replaced with fibrous tissue leading to decreased T1- and T2-weighted signal intensity1,2,3.
The avascular composition gives a cardiac thrombus intrinsic tissue characteristics that can be exploited by contrast enhanced CMR, to aide in the differentiation of a thrombus from other cardiac tumors4. An organized thrombus does not enhance while true cardiac lesions enhance on post contrast imaging due to the presence of intratumoral vascularity3. Arterial perfusion imaging allows real time assessment of vascularity within a mass and is critical to differentiate a thrombus from a tumor. Perfusion within a mass can also be useful in the delineation of a bland thrombus from a tumor thrombus. Cine imaging provides advantages over other modalities that can be subject to motion artifact, and the temporal resolution provided by real time gated perfusion imaging increases sensitivity in detecting enhancement5.
T1 mapping is a MR technique that allows pre-contrast native T1 relaxation times and post-contrast extracellular volume calculation to detect pathologic alterations in tissue. By adding a quantitative dimension to CMR, T1 mapping can help differentiate various disease processes from the normal myocardium. An emerging application is the characterization of cardiac masses and delineation of masses from cardiac thrombi. Previous studies performed on a 1.5 T Aera XQ scanner have reported native T1 relaxation times of a recent thrombus (911 &#177; 177 ms) and a chronic thrombus (1,169 &#177; 107 ms)6. Other pertinent native T1 relaxation times include lipoma (278 &#177; 29 ms), calcifications (621 &#177; 218 ms), melanoma (736 ms), and normal myocardium (950 &#177; 21 ms). This data suggests that T1 mapping can add quantitative information to a non-contrast exam which in the setting of contraindication to IV gadolinium could be extremely useful6,7.
Contrast-enhanced CMR has been well validated for the detection of a left ventricular thrombus. It has been shown to provide the highest sensitivity and specificity (88% and 99%, respectively) for detection of a left ventricular thrombus compared to transthoracic (23% and 96%, respectively) and transesophageal (40% and 96%, respectively) echocardiography8. Currently, there are no large-scale studies validating the utility of CMR for assessing a thrombus in other chambers of the heart3.
Despite the many advantages of CMR over other imaging modalities for evaluating cardiac masses, there are also limitations. CMR, like cardiac CT, relies on electrocardiographic gating. This can cause artifact and image degradation in patients with significant arrhythmias. Image quality can also be degraded when scanning patients who have difficulty complying with breath hold requirements. However, faster acquisition times and respiratory gating techniques allow for quality images during free breathing. The presence of certain implanted devices is a contraindication for CMR and poses as a major disadvantage, although the number of MR compatible implantable devices is increasing1,2.
In summary, specific CMR sequences can be utilized to develop a dedicated MR imaging protocol for the evaluation of a suspected cardiac thrombus. The method presented here will provide instructions for the acquisition of CMR data for evaluation of a suspected thrombus. Pre-procedure screening, sequence selection, troubleshooting, post-processing, volumetric analysis, and report generation will be discussed.

<table border="0" cellpadding="0" cellspacing="0" style="width:1335px;" width="1334">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">MRI Scanner</td>
			<td style="width:272px;">Siemens Healthcare 
			Erlangen, Germany</td>
			<td style="width:344px;">Magnetom Aera 1.5 Tesla&#160;</td>
			<td style="width:503px;">MRI scanner that will be used for the demonstration</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Post processing software&#160;</td>
			<td>Medis 
			The Netherlands</td>
			<td>Qmass software</td>
			<td>post processing software for ventricular volumetric and T1 mapping analysis</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Scanner processing software</td>
			<td>Siemens Healthcare 
			Erlangen, Germany</td>
			<td>Myomaps&#160;</td>
			<td>Scanner sequence package and post processing software</td>
		</tr>
	</tbody>
</table>

cardiac magnetic resonance for the evaluation of suspected cardiac thrombus: conventional and emerging techniques

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The appearance of a mass on certain magnetic resonance (MR) sequences can help differentiate a thrombus from competing diagnoses such as a tumor. T1 and T2 signal characteristics of a thrombus are related to the evolution of hemoglobin properties. A thrombus typically does not enhance following contrast administration, which also helps differentiation from a tumor. We also highlight the emerging role of T1 mapping in the evaluation of a thrombus, which can add another level of support in diagnosis. Prior to any CMR exam, patient screening and interviews are critical to ensure safety and to optimize patient comfort. Effective communication during the exam between the technologist and the patient promotes proper breath holding technique and higher quality images. Volumetric post processing and structured reporting are helpful to ensure that the radiologist answers the ordering services&#39; question and communicates these results effectively. Optimal pre-MR safety evaluation, CMR exam execution, and post exam processing and reporting allow for delivery of high quality radiological service in the evaluation of a suspected cardiac thrombus.

The CMR protocol designed for the evaluation and diagnosis of cardiac thrombus encompasses patient screening and preparation, data acquisition utilizing specific sequences, data post-processing, and report generation. Specific signal characteristics on given sequences can infer with high accuracy the diagnosis of a cardiac thrombus and differentiate these from the competing diagnosis of a cardiac tumor. Table 1 highlights the conventional and emerging CMR sequences that a...

Watch this Scientific Journal Video about Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques at JoVE.com

Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

The goal of this article is to describe how cardiac magnetic resonance can be used for the evaluation and diagnosis of a suspected cardiac thrombus. The method presented will describe data acquisition as well as the pre-procedure and post-procedure protocol.

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The ...

Cardiac Magnetic Resonance or CMR is important in the evaluation for potential thrombus because CMR can provide a definitive diagnosis of the etiology of a cardiac mass. CMR has advantages over other modalities such as echocardiography as CMR can provide multi-sequenced detailed characterization of soft tissue masses where echo offers primarily visualization and size measurements. Prior to the MRI, the patients are screened for metal or implanted devices that may be contraindicated.If gadolinium is to be given, they are screened for allergies and renal function to ensure adequate safety. Cardiac MRI imaging faces several challenges. For optimal imaging, patients need to hold their breath.Sometimes patients with shortness of breath have difficulty accomplishing this task. The EKG is also used for imaging and patients with cardiac arrhythmias may disrupt the gating. Parameters need to be adjusted to accomplish this goal.Demonstrating the cardiac MRI exam with me will be Deb Brannon, our lead MRI technologist, and Chad Woodhouse, a cardiac MRI technologist. Before beginning the acquisition, provide the patient with headphones connected to the technologist's microphone so that commands can be efficiently communicated and place electrocardiogram leads in the optimal positions on the left chest. After confirming adequate EKG signal, the patient's position is confirmed on the scan table and an appropriately sized surface coil for maximizing signal-to-noise ratio is placed over the heart.Inform the patient to breathe when instructed during the imaging by holding breath at the end of expiration. Imaging reproducibility is higher with this type of breath hold compared to inspiratory breath holds. When the patient is ready, obtain the scout images, the bright blood balanced cine steady-state free precision axial stack with full heart coverage.Then obtain approximate two and four chamber sequences which will help with further scan prescriptions. For tissue characterization, obtain the black blood triple inversion recovery sequence. Obtain native T1 mapping scans.To perform the first pass arterial perfusion module, deliver 0.05 to 0.1 millimoles per kilograms of contrast agent at a three to four milliliter per second administration rate. Then obtain dynamic first pass perfusion images along the axial plane or plane that best highlights the mass in question until the contrast passes through the left ventricle myocardium imaged during contrast injection. 10 minutes after the gadolinium injection, run the T1 scout sequence which will help define the scan time to inversion which will be approximately 200 to 450 milliseconds at 1.5 Tesla and 300 to 500 milliseconds at 3 Tesla.Then obtain six to eight millimeter phase sensitive inversion recovery slices with the inversion time set. It is important to note that the proper inversion time setting will increase with each minute beyond the contrast injection. It is also recommended to acquire a high TI image around 600 milliseconds as thrombus should have an old black appearance at this setting while myocardium and tumors may have intermediate signal.Evaluate the mass on cine bSSFP images. Axial plane is often helpful in imaging cardiac masses. For cardiac thrombus evaluation, the thrombus can demonstrate increased T2 weighted signal intensity in the subacute time period as this lateral right atrial mass demonstrates or low T2 weighted signal intensity in the chronic time period as shown in this right atrial mass in a different patient.In cardiac thrombus evaluation, the mass in question is carefully analyzed for any internal perfusion that would suggest against thrombus and signify the presence of a vascular tumor. Evaluate for late gadolinium enhancement imaging within the suspected mass. No solid regions of internal late gadolinium enhancement are expected within a thrombus.Here convention and emerging CMR sequences that are commonly used to evaluate for cardiac thrombus are shown. Cardiac thrombus is presented on the important CMR sequences. Highlighted by arrows, there is a mass in the right ventricle.This mass has low signal on bSSFP and T2 weighted images and lacks internal arterial perfusion. A corresponding CT image shows hypodensity within the mass. Delayed post contrast imaging shows no internal late gadolinium enhancement.The native T1 map shows mildly elevated T1 relaxation time. These findings are consistent with cardiac thrombus. In contrast to cardiac thrombus, a patient with hepatocellular carcinoma metastatic to the right atrium is also presented.The mass at the right cavoatrial junction has low signal on bSSFP and intermediate signal on T2 weighted images. There is decreased native T1 relaxation time within the mass and mild internal enhancement is visible on the MRA image. These findings are consistent with intracardiac metastasis.It's important to acquire high quality images, to repeat images if there is degradation due to patient motion, and to adjust scan parameters to make breath hold times manageable. Cardiac MR often gives a definitive diagnosis of cardiac thrombus adding to echo results by providing excellent soft tissue characterization with a perfusion and enhancement evaluation.

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Medicine

Remote Magnetic Navigation for Accurate, Real-time Catheter Positioning and Ablation in Cardiac Electrophysiology Procedures

New remote navigation systems have been developed to improve current limitations of conventional manually guided catheter ablation in complex cardiac substrates such as left atrial flutter. This protocol describes all the clinical and invasive interventional steps performed during a human electrophysiological study and ablation to assess the accuracy, safety and real-time navigation of the Catheter Guidance, Control and Imaging (CGCI) system. Patients who underwent ablation of a right or left atrium flutter substrate were included. Specifically, data from three left atrial flutter and two counterclockwise right atrial flutter procedures are shown in this report. One representative left atrial flutter procedure is shown in the movie. This system is based on eight coil-core electromagnets, which generate a dynamic magnetic field focused on the heart. Remote navigation by rapid changes (msec) in the magnetic field magnitude and a very flexible magnetized catheter allow real-time closed-loop integration and accurate, stable positioning and ablation of the arrhythmogenic substrate.

This report provides a detailed description of a new remote navigation system based on magnetic driven forces, which has been recently introduced as a new robotic tool for human cardiac electrophysiology procedures.

New remote navigation systems have been developed to improve current limitations of conventional manually guided catheter ablation in complex cardiac ...

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)-&#945; 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-&#945; 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.

This study demonstrates the successful establishment of magnetic resonance microscopy imaging as a non-invasive tool to assess the cardiac abnormalities in mice affected with autoimmune myocarditis. The data indicate that the technique can be used to monitor the disease-progression in live animals.

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events ...

Visualization of Streptococcus pneumoniae within Cardiac Microlesions and Subsequent Cardiac Remodeling

During bacteremia Streptococcus pneumoniae can translocate across the vascular endothelium into the myocardium and form discrete bacteria-filled microscopic lesions (microlesions) that are remarkable due to the absence of infiltrating immune cells. Due to their release of cardiotoxic products, S. pneumoniae within microlesions are thought to contribute to the heart failure that is frequently observed during fulminate invasive pneumococcal disease in adults. Herein is demonstrated a protocol for experimental mouse infection that leads to reproducible cardiac microlesion formation within 30 hr. Instruction is provided on microlesion identification in hematoxylin &#38; eosin stained heart sections and the morphological distinctions between early and late microlesions are highlighted. Instruction is provided on a protocol for verification of S. pneumoniae within microlesions using antibodies against pneumococcal capsular polysaccharide and immunofluorescent microscopy. Last, a protocol for antibiotic intervention that rescues infected mice and for the detection and assessment of scar formation in the hearts of convalescent mice is provided. Together, these protocols will facilitate the investigation of the molecular mechanisms underlying pneumococcal cardiac invasion, cardiomyocyte death, cardiac remodeling as a result of exposure to S. pneumoniae, and the immune response to the pneumococci in the heart.

Visualization of Streptococcus pneumoniae within Cardiac Microlesions and Subsequent Cardiac Remodeling

Streptococcus pneumoniae forms discrete non-purulent microscopic lesions in the heart. Outlined is the protocol for a murine model of cardiac microlesion formation. Instruction is provided on microlesion visualization using microscopy, discrimination between early and late microlesions, and methods to detect cardiac remodeling in hearts of convalescent animals.

During bacteremia Streptococcus pneumoniae can translocate across the vascular endothelium into the myocardium and form discrete bacteria-filled ...

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene and cell therapies are highly promising alternative approaches for CVD treatment. However, the broad clinical application of gene therapy is greatly limited by the lack of suitable gene delivery systems. The development of appropriate gene delivery vectors can provide a solution to current challenges in cell therapy. In particular, existing drawbacks, such as limited efficiency and low cell retention in the injured organ, could be overcome by appropriate cell engineering (i.e., genetic) prior to transplantation. The presented protocol describes the efficient and safe transient modification of endothelial cells using a polyethyleneimine superparamagnetic magnetic nanoparticle (PEI/MNP)-based delivery vector. Also, the algorithm and methods for cell characterization are defined. The successful intracellular delivery of microRNA (miR) into human umbilical vein endothelial cells (HUVECs) has been achieved without affecting cell viability, functionality, or intercellular communication. Moreover, this approach was proven to cause a strong functional effect in introduced exogenous miR. Importantly, the application of this MNP-based vector ensures cell magnetization, with accompanying possibilities of magnetic targeting and non-invasive MRI tracing. This may provide a basis for magnetically guided, genetically engineered cell therapeutics that can be monitored non-invasively with MRI.

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

This manuscript describes the efficient, non-viral delivery of miR to endothelial cells by a PEI/MNP vector and their magnetization. Thus, in addition to genetic modification, this approach allows for magnetic cell guidance and MRI detectability. The technique can be used to improve the characteristics of therapeutic cell products.

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene ...

Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed in mice is high. Phenotypic characterization of these mouse models also requires the examination of cardiac function and morphology. Echocardiography and magnetic resonance imaging (MRI) are commonly used approaches to characterize cardiac function and morphology in mice. Echocardiographic and MRI equipment specialized for use in small rodents is&#160;expensive and requires a dedicated space. This protocol describes cardiac measurements in mice using a clinical echocardiographic system with a 15 MHz human vascular probe. Measurements are performed on anesthetized adult mice. At least three image sequences are recorded and analyzed for each animal in M-mode in the parasternal short-axis view. Afterwards, cardiac histological examination is performed, and cardiomyocyte diameters are determined on hematoxylin-eosin- or wheat germ agglutinin (WGA)-stained paraffin sections. Vessel density is determined morphometrically after Pecam-1 immunostaining. The protocol has been applied successfully to pharmacological studies and different genetic animal models under baseline conditions, as well as after experimental myocardial infarction by the permanent ligation of the left anterior descending coronary artery (LAD). In our experience, echocardiographic investigation is limited to anesthetized animals and is feasible in adult mice weighing at least 25 g.

Echocardiographic examination is frequently used in mice. Expensive high-resolution ultrasound devices have been developed for this purpose. This protocol describes an affordable echocardiographic procedure combined with histological morphometric analyses to determine cardiac morphology.

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed ...

Cardiac Magnetic Resonance Imaging at 7 Tesla

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher magnetic field strengths and potentially provides improved signal contrast and spatial resolution. While promising results have been achieved, ultra-high field CMR is challenging due to energy deposition constraints and physical phenomena such as transmission field non-uniformities and magnetic field inhomogeneities. In addition, the magneto-hydrodynamic effect renders the synchronization of the data acquisition with the cardiac motion difficult. The challenges are currently addressed by explorations into novel magnetic resonance technology. If all impediments can be overcome, ultra-high field CMR may generate new opportunities for functional CMR, myocardial tissue characterization, microstructure imaging or metabolic imaging. Recognizing this potential, we show that multi-channel radio frequency (RF) coil technology tailored for CMR at 7 Tesla together with higher order B0 shimming and a backup signal for cardiac triggering facilitates high fidelity functional CMR. With the proposed setup, cardiac chamber quantification can be accomplished in examination times similar to those achieved at lower field strengths. To share this experience and to support the dissemination of this expertise, this work describes our setup and protocol tailored for functional CMR at 7 Tesla.

The sensitivity gain inherent to ultrahigh field magnetic resonance holds promise for high spatial resolution imaging of the heart. Here, we describe a protocol customized for functional cardiovascular magnetic resonance (CMR) at 7 Tesla using an advanced multi-channel radio-frequency coil, magnetic field shimming and a triggering concept.

CMR at an ultra-high field (magnetic field strength B0&#160;&#8805; 7 Tesla) benefits from the signal-to-noise ratio (SNR) advantage inherent at higher ...

Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the recognized standard-of-care for blood flow quantification based on phase contrast MRI. While such measurement of blood flow has been possible in adults for decades, methods to extend this capability to fetal blood flow have only recently been developed.
Fetal blood flow quantification in major vessels is important for monitoring fetal pathologies such as congenital heart disease (CHD) and fetal growth restriction (FGR). CHD causes alterations in the cardiac structure and vasculature that change the course of blood in the fetus. In FGR, the path of blood flow is altered through the dilation of shunts such that the oxygenated blood supply to the brain is increased. Blood flow quantification enables assessment of the severity of the fetal pathology, which in turn allows for suitable&#160;in utero&#160;patient management and planning for postnatal care.
The primary challenges of applying phase contrast MRI to the human fetus include small blood vessel size, high fetal heart rate, potential MRI data corruption due to maternal respiration, unpredictable fetal movements, and lack of conventional cardiac gating methods to synchronize data acquisition. Here, we describe recent technical developments from our lab that have enabled the quantification of fetal blood flow using phase contrast MRI, including advances in accelerated imaging, motion compensation, and cardiac gating.

Here we present a protocol for measuring fetal blood flow rapidly with MRI and retrospectively performing motion correction and cardiac gating.

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the ...

Development and Evaluation of 3D-Printed Cardiovascular Phantoms for Interventional Planning and Training

Catheter-based interventions are standard treatment options for cardiovascular pathologies. Therefore, patient-specific models could help training physicians&#39; wire-skills as well as improving planning of interventional procedures. The aim of this study was to develop a manufacturing process of patient-specific 3D-printed models for cardiovascular interventions.
To create a 3D-printed elastic phantom, different 3D-printing materials were compared to porcine biological tissues (i.e., aortic tissue) in terms of mechanical characteristics. A fitting material was selected based on comparative tensile tests and specific material thicknesses were defined. Anonymized contrast-enhanced CT-datasets were collected retrospectively. Patient-specific volumetric models were extracted from these datasets and subsequently 3D-printed. A pulsatile flow loop was constructed to simulate the intraluminal blood flow during interventions. Models&#39; suitability for clinical imaging was assessed by x-ray imaging, CT, 4D-MRI and (Doppler) ultrasonography. Contrast medium was used to enhance visibility in x-ray-based imaging. Different catheterization techniques were applied to evaluate the 3D-printed phantoms in physicians&#39; training as well as for pre-interventional therapy planning.
Printed models showed a high printing resolution (~30 &#181;m) and mechanical properties of the chosen material were comparable to physiological biomechanics. Physical and digital models showed high anatomical accuracy when compared to the underlying radiological dataset. Printed models were suitable for ultrasonic imaging as well as standard x-rays. Doppler ultrasonography and 4D-MRI displayed flow patterns and landmark characteristics (i.e., turbulence, wall shear stress) matching native data. In a catheter-based laboratory setting, patient-specific phantoms were easy to catheterize. Therapy planning and training of interventional procedures on challenging anatomies (e.g., congenital heart disease (CHD)) was possible.
Flexible patient-specific cardiovascular phantoms were 3D-printed, and the application of common clinical imaging techniques was possible. This new process is ideal as a training tool for catheter-based (electrophysiological) interventions and can be used in patient-specific therapy planning.

Here we present development of a mock circulation setup for multimodal therapy evaluation, pre-interventional planning, and physician-training on cardiovascular anatomies. With the application of patient-specific tomographic scans, this setup is ideal for therapeutic approaches, training, and education in individualized medicine.

Catheter-based interventions are standard treatment options for cardiovascular pathologies. Therefore, patient-specific models could help training ...

Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla

The overall goal of this article is to demonstrate a state-of-the-art ultrahigh field (UHF) magnetic resonance (MR) protocol of the brain at 7.0 Tesla in multiple sclerosis (MS) patients. MS is a chronic inflammatory, demyelinating, neurodegenerative disease that is characterized by white and gray matter lesions. Detection of spatially and temporally disseminated T2-hyperintense lesions by the use of MRI at 1.5 T and 3 T represents a crucial diagnostic tool in clinical practice to establish accurate diagnosis of MS based on the current version of the 2017 McDonald criteria. However, the differentiation of MS lesions from brain white matter lesions of other origins can sometimes be challenging due to their resembling morphology at lower magnetic field strengths (typically 3 T). Ultrahigh field MR (UHF-MR) benefits from increased signal-to-noise ratio and enhanced spatial resolution, both key to superior imaging for more accurate and definitive diagnoses of subtle lesions. Hence, MRI at 7.0 T has shown encouraging results to overcome the challenges of MS differential diagnosis by providing MS-specific neuroimaging markers (e.g., central vein sign, hypointense rim structures and differentiation of MS grey matter lesions). These markers and others can be identified by other MR contrasts other than T1 and T2 (T2*, phase, diffusion) and substantially improve the differentiation of MS lesions from those occurring in other neuroinflammatory conditions such as neuromyelitis optica and Susac syndrome. In this article, we describe our current technical approach to study cerebral white and grey matter lesions in MS patients at 7.0 T using different MR acquisition methods. The up-to-date protocol includes the preparation of the MR setup including the radio-frequency coils customized for UHF-MR, standardized screening, safety and interview procedures with MS patients, patient positioning in the MR scanner and acquisition of dedicated brain scans tailored for examining MS.

Here, we present a protocol to acquire magnetic resonance (MR) images of multiple sclerosis (MS) patient brains at 7.0 Tesla. The protocol includes preparation of the setup including the radio-frequency coils, standardized interview procedures with MS patients, subject positioning in the MR scanner and MR data acquisition.

The overall goal of this article is to demonstrate a state-of-the-art ultrahigh field (UHF) magnetic resonance (MR) protocol of the brain at 7.0 Tesla in ...

In vitro Assessment of Cardiac Reprogramming by Measuring Cardiac Specific Calcium Flux with a GCaMP3 Reporter

Cardiac reprogramming has become a potentially promising therapy to repair a damaged heart. By introducing multiple transcription factors, including Mef2c, Gata4, Tbx5 (MGT), fibroblasts can be reprogrammed into induced cardiomyocytes (iCMs). These iCMs, when generated in situ in an infarcted heart, integrate electrically and mechanically with the surrounding myocardium, leading to a reduction in scar size and an improvement in heart function. Because of the relatively low reprogramming efficiency, purity, and quality of the iCMs, characterization of iCMs remains a challenge. The currently used methods in this field, including flow cytometry, immunocytochemistry, and qPCR, mainly focus on cardiac-specific gene and protein expression but not on the functional maturation of iCMs. Triggered by action potentials, the opening of voltage-gated calcium channels in cardiomyocytes leads to a rapid influx of calcium into the cell. Therefore, quantifying the rate of calcium influx is a promising method to evaluate cardiomyocyte function. Here, the protocol introduces a method to evaluate iCM function by calcium (Ca2+) flux. An &#945;MHC-Cre/Rosa26A-Flox-Stop-Flox-GCaMP3 mouse strain was established by crossing Tg(Myh6-cre)1Jmk/J (referred to as Myh6-Cre below) with Gt(ROSA)26Sortm38(CAG-GCaMP3)Hze/J (referred to as Rosa26A-Flox-Stop-Flox-GCaMP3 below) mice. Neonatal cardiac fibroblasts (NCFs) from P0-P2 neonatal mice were isolated and cultured in vitro, and a polycistronic construction of MGT was introduced to NCFs, which led to their reprogramming to iCMs. Because only successfully reprogrammed iCMs will express GCaMP3 reporter, the functional maturation of iCMs can be visually assessed by Ca2+ flux with fluorescence microscopy. Compared with un-reprogrammed NCFs, NCF-iCMs showed significant calcium transient flux and spontaneous contraction, similar to CMs. This protocol describes in detail the mouse strain establishment, isolation and selection of neonatal mice hearts, NCF isolation, production of retrovirus for cardiac reprogramming, iCM induction, the evaluation of iCM Ca2+ flux using our reporter line, and related statistical analysis and data presentation. It is expected that the methods described here will provide a valuable platform to assess the functional maturation of iCMs for cardiac reprogramming studies.

We describe here, the establishment and application of an Tg(Myh6-cre)1Jmk/J /Gt(ROSA)26Sortm38(CAG-GCaMP3)Hze/J (referred to as &#945;MHC-Cre/Rosa26A-Flox-Stop-Flox-GCaMP3 below) mouse reporter line for cardiac reprogramming assessment. Neonatal cardiac fibroblasts (NCFs) isolated from the mouse strain are converted into induced cardiomyocytes (iCMs), allowing for convenient and efficient evaluation of reprogramming efficiency and functional maturation of iCMs via calcium (Ca2+) flux.

Cardiac reprogramming has become a potentially promising therapy to repair a damaged heart. By introducing multiple transcription factors, including ...