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
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	<li>Conduct a safety screening.
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		<li>Evaluate for renal impairment8.
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			<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>
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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. 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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 ...

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