Cardiovascular MRI in Practice: A Teaching File Approach

Cardiovascular MR imaging has become a robust, clinically useful mod- ity, and the rapid pace of innovation and important information it conveys have attracted.
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In this situation, imaging can be timed to when cardiac motion is minimal i. The use of MR angiography has been well validated in a variety of vascular regions, most notably for evaluation of renal artery stenosis where it compares favorably with digital subtraction angiography.

The examination can be performed in 30 minutes. No arterial puncture is required. Parallel Imaging Acquisition Techniques Although the different scanner manufacturers have their own proprietary implementations, all support parallel imaging techniques. These allow a reduction in image acquisition time, or improvement in spatial resolution with the same imaging time, but at a cost of mildly reduced signal-to-noise.

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Overview Summary Cardiac MR imaging has made tremendous progress in the past decade. Multiple different sequences are available and provide the ability to interrogate cardiac structure, function, and viability with unparalleled precision. These sequences individually and in combination provide a diverse palette from which to choose.

Injuries can result from the static magnetic field projectile impact injuries , very rapid gradient-field switching induction of electric currents leading to peripheral nerve stimulation , RF-energy deposition heating of the imaged portion of the body , and acoustic noise. The institution of policies that strictly limit access to the magnet room minimizes the risks of projectile injuries from the static magnetic field.

For instance, patients are extensively screened prior to imaging, and all facility personnel undergo dedicated training in MR safety. The use of MR-safe or compatible equipment stethoscopes, wheelchairs, gurneys, oxygen tanks, infusion pumps, monitors, etc. All scanners monitor the slew rate and calculate the SAR to help prevent nerve stimulation and heating. Acoustic noise of dB or more are generated from the vibration or motion of the gradient coils during image acquisition. The use of protective hearing devices, such as headphones or earplugs, reduces noise to levels that do not result in hearing impairment or patient discomfort.

In practice, continuous communication with the patient throughout the examination is important for patent comfort and safety. Patients with medical devices or implants can face additional potential hazards, including device References heating, movement, or malfunction. For example, ferromagnetic aneurysm clips or electronic medical devices e. However, there is a specific subset of patients with a metallic implants or devices that can safely undergo MRI.

A comprehensive list of devices and implants that are compatible with undergoing MRI scanning can be found elsewhere. At most institutions, MRI scans are not performed in patients with implanted pacemakers or defibrillators because of the potential risk of device malfunction, excessive device or lead heating, or induction of currents within the leads. Recently, however, a few preliminary reports have emerged, suggesting that MRI can be possible in patients with modern pacemakers and defibrillators in whom the benefits are deemed greater than the risks.

Recently, in several small case series, it has been reported that a small subset of patients with end-stage renal disease, receiving gadolinium contrast, may be at risk for developing nephrogenic systemic fibrosis NSF NSF is characterized by an increased tissue deposition of collagen, often resulting in thickening and tightening of the skin and predominantly involving the distal extremities. Additionally, fibrosis may affect other organs, including skeletal muscles, lungs, pulmonary vasculature, heart, and diaphragm. Although a definitive causal link with gadolinium contrast agents has yet to be established, gadolinium contrasts agents should be utilized cautiously and alternative tests considered in patients with severe renal disease, particularly those undergoing peritoneal dialysis or hemodialysis, or with acute renal failure.

A policy statement regarding the use of gadolinium contrast agents in the setting of renal disease has been published by the American College of Radiology. Fuster V, Kim RJ. Frontiers in cardiovascular magnetic resonance. Contrast-enhanced MR imaging of the heart: Cardiovascular magnetic resonance imaging: J Am Coll Cardiol. Late gadolinium cardiovascular magnetic resonance in the assessment of myocardial viability. Delayed enhancement cardiovascular magnetic resonance assessment of non-ischaemic cardiomyopathies. The evolving role of cardiovascular magnetic resonance imaging in nonischemic cardiomyopathy.

Niendorf T, Sodickson DK. Parallel imaging in cardiovascular MRI: Comparison of left ventricular ejection fraction and volumes in heart failure by echocardiography, radionuclide ventriculography and cardiovascular magnetic resonance; are they interchangeable? Quantification of right and left ventricular function by cardiovascular magnetic resonance.


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MR imaging of myocardial perfusion and viability. Contrastenhanced MRI and routine single photon emission computed tomography SPECT perfusion imaging for detection of subendocardial myocardial infarcts: Magnetic resonance imaging in the evaluation of the pericardium. Magnetic resonance imaging of pericardial disease and cardiac masses. MR imaging in ischemic heart disease.

Radiol Clin North Am. The role of cardiovascular magnetic resonance in heart failure. Eur J Heart Fail. Signal-tonoise ratio behavior of steady-state free precession. TrueFISP—technical considerations and cardiovascular applications. Usefulness of segmented trueFISP cardiac pulse sequence in evaluation of congenital and acquired adult cardiac abnormalities.

Myocardial perfusion imaging by magnetic resonance imaging. Myocardial perfusion imaging by cardiac magnetic resonance. First-pass myocardial perfusion MR imaging with interleaved notched saturation: Magnetic resonance versus radionuclide pharmacological stress perfusion imaging for flow-limiting stenoses of varying severity. Improved detection of coronary artery disease by stress perfusion cardiovascular magnetic resonance with the use of delayed enhancement infarction imaging. Diagnostic performance of stress perfusion and delayedenhancement MR imaging in patients with coronary artery disease.

Relationship of MRI delayed contrast enhancement to irreversible injury, infarct age, and contractile function. Myocardial magnetic resonance imaging contrast agent concentrations after reversible and irreversible ischemic injury. Contrast-enhanced magnetic resonance imaging of myocardium at risk: An improved MR imaging technique for the visualization of myocardial infarction.

Rapid detection of myocardial infarction by subsecond, free-breathing delayed contrast-enhancement cardiovascular magnetic resonance. Cardiovascular magnetic resonance assessment of human myocarditis: New non-invasive approaches for the diagnosis of cardiomyopathy: Ernst Schering Res Found Workshop.

Evaluation of cardiac valvular disease with MR imaging: Cardiovascular flow measurement with phase-contrast MR imaging: Buonocore MH, Bogren H. Factors influencing the accuracy and precision of velocity-encoded phase imaging.

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High-resolution magnetic resonance angiography of the renal arteries using parallel imaging acquisition techniques at 3. Zhang H, Prince MR. Breath-hold, contrast-enhanced, three-dimensional MR angiography. MR angiography in the abdomen. Optimization of contrast timing for breath-hold three-dimensional MR angiography.

J Magn Reson Imaging. Three-dimensional contrast-enhanced magnetic resonance angiography of the abdominal arterial system. Aorta and runoff vessels: Pelvic and lower extremity arterial imaging: Diabetes and peripheral arterial occlusive disease: Single breath-hold real-time cine MR imaging: Shellock FG, Kanal E. Bioeffects, Safety, and Patient Management. Biomedical Research Publishing Group; Cardiac magnetic resonance imaging in a patient with implantable cardioverter-defibrillator. Clinical utility and safety of a protocol for noncardiac and cardiac magnetic resonance imaging of patients with permanent pacemakers and implantable-cardioverter defibrillators at 1.

Each of these sequences can provide complementary information, often of incremental value. The desire for the most comprehensive imaging possible, however, must be counterbalanced with the recognition of the limited time available for scanning based on patient tolerance and scanner availability.

The judicious use of resources mandates that the essential information be acquired in the least amount of time possible. At a minimum, a standard cardiac MR examination should provide a comprehensive evaluation of the structure and function of the heart. Additionally, in the vast majority of patients, myocardial tissue characterization—with an assessment of infarction, scarring, and viability—provides substantial clinical value at minimal time cost.

In light of the above, our standard cardiac examination includes the following: To localize the heart within the chest and determine the appropriate cardiac imaging planes. Cine images in the short-axis plane from above the mitral valve through the cardiac apex, as well as in the standard orthogonal long axis views—2-chamber, 4-chamber, and 3-chamber or left ventricular outflow tract views. For the analysis of global cardiac structure and function, regional wall motion, and the calculation of volumes and mass. Delayed-enhancement images spatially matched to the cine images.

For the evaluation of myocardial infarction and viability, and tissue characterization. At some centers, stress perfusion imaging using adenosine has become so commonplace as to become a part of the standard examination. The standard examination would begin as usual and proceed through the acquisition of Cine images. At this point, the patient is moved partially out of the magnet to improve visibility during the administration 17 18 2.

Timeline for adenosine stress perfusion MR of adenosine. Contrast is then administered dose, 0. On the console, the perfusion images are observed as they are acquired, with breath-holding starting from the appearance of contrast in the right ventricular cavity. If the scanner software does not provide real-time image display, breath-holding should be started no more than 5—6 seconds after beginning gadolinium injection. Breath-holding is performed to ensure the best possible image quality i. Once the contrast bolus has transited the LV myocardium, adenosine is stopped and imaging is completed 5—10 seconds later.

Typically, the total imaging time is 40—50 seconds, and the total time of adenosine infusion is 3 to 3. During vasodilation, direct access to the patient is limited only during imaging of the first pass. Prior to the rest perfusion scan, a waiting period of about 15 minutes is required for contrast to sufficiently clear from the blood pool. Subsequently, the perfusion sequence with contrast is repeated without adenosine. Approximately 5 minutes after rest perfusion, delayed enhancement imaging can be performed.

The total scan time for a comprehensive cardiac MR stress test, including cine imaging, stress and rest perfusion, and delayed enhancement is usually well under 45 minutes. The timeline is displayed in Figure 2. Obviously, different clinical circumstances will result in appropriate modification of the basic cardiac MR examination, with additional modules added as needed.

For example, in patients with angina referred for stress perfusion imaging from the emergency department, if this is their first evaluation, we typically add tomographic imaging of the entire chest. In the setting of congenital heart disease, MR angiographic images are frequently added to the standard morphologic images, and velocity-encoded flow studies are also usually necessary in this setting. Proposed standard protocols for a variety of cardiac disorders are included in the appendix. Interpretation and Reporting For general clinical reporting, we use the 17segment model recommended by the American Heart Association.

Visual interpretation of cine and delayed enhancement images using the segment model ventricular systolic function is graded visually using a 5-point scale ranging from normal wall motion to dyskinesis. LV ejection fraction is also provided, and estimated from visual inspection of all the short- and long-axis views. Occasionally, LVEF is quantitatively measured by planimetry, such as in patients undergoing chemotherapy with potentially cardiotoxic agents.

The delayed enhancement images are also interpreted using a 5-point scale. Examples of myocardial segments with various transmural extents of hyperenhancement are shown in Figure 2. It is important that the delayed enhancement images are interpreted with the cine images immediately Figure 2. Typical images showing myocardial segments dashed white lines with various transmural extents of hyperenhancement.

The cine images can provide a reference of the diastolic wall thickness of each region. This will be helpful if delayed enhancement imaging is performed before there is significant contrast washout from the LV cavity, and there is difficulty in differentiating the bright signal from the LV cavity from hyperenhanced myocardium Figure 2. Stress and rest perfusion images are scored for perfusion defects in 16 segments segment 17 at the apex usually is not visualized. Then, a systematic stepwise approach is used to determine the presence or absence of coronary artery disease.

Cardiovascular Mri In Practice A Teaching File Approach 2008

Importantly, we use an interpretation algorithm that includes data from delayed enhancement imaging to improve the accuracy of detecting coronary artery disease over that of perfusion imaging alone Figure 2. In the latter, matched defects are regarded as artifacts and not suggestive of CAD. When both DE-MRI and stress perfusion MRI are abnormal, the test is scored positive for ischemia if the perfusion defect is larger than the area of infarction. The interpretation algorithm is based on two simple principles.

Thus, one method could be used to confirm the results of the other. Short-axis view of a patient with an anterior wall myocardial infarction. Diastolic still-frame taken from the cine images before gadolinium administration is compared to the delayed enhancement image taken both early and late following gadolinium injection.

Note that it is difficult to differentiate the bright LV cavity from the subendocardial infarction in the early 2 mins delayed enhancement image. The cine frame, by showing the diastolic wall thickness in the anterior wall, provides evidence that there is subendocardial hyperenhancement in the anterior wall on the early delayed enhancement image. The late 17 mins delayed enhancement image provides confirmation that there is subendocardial hyperenhancement in the anterior wall. From, J Cardiovasc Magn Reson ;5: Interpretation algorithm for incorporating delayed enhancement imaging DE-MRI with stress and rest perfusion MRI for the detection of coronary disease.

A Schema of the interpretation algorithm. Hyperenhanced myocardium consistent with a prior myocardial infarction MI is detected. Does not include isolated midwall or epicardial hyperenhancement which can occur in nonischemic disorders. No evidence of prior MI or inducible perfusion defects. No evidence of prior MI but perfusion defects are present with adenosine that are absent or reduced at rest. The interpretation algorithm step 1 classified this patient as positive for CAD. Coronary angiography verified disease in a circumflex marginal artery.

Cine MRI demonstrated normal contractility. The interpretation algorithm step 3 classified this patient as positive for CAD. The interpretation algorithm step 4 classified the perfusion defects as artifactual. Coronary angiography demonstrated normal coronary arteries. Modified from Klem et al, Circulation ; This is because infarcted regions will accumulate the 22 2.

In comparison with the competing modality of echocardiography, it has been shown to have significantly less interobserver and intraobserver variability, and superior reproducibility. Typical measurements are performed using the stack of short axis images, with tracing of the endocardial contour performed at end-diastole and endsystole. The areas are summed over the volume of tissue imaged, and the difference between the volumes at systole and diastole therefore represent the stroke volume. Simultaneous tracing of the epicardial contours allows assessment of myocardial mass, as well as wall thickening.

Various computer Table 2. Accuracy and reproducibility of MRI for cardiac volumes and mass. Willerson et al, eds. Cardiovascular Medicine 3rd ed. A clinical cardiovascular magnetic resonance service: Detection of myocardial ischemia by stress perfusion cardiovascular magnetic resonance. The Standard Cardiac Exam 4. Standardized myocardial segmentation and nomenclature for tomographic imaging of the heart: How we perform delayed enhancement imaging.

J Cardiovasc Magn Reson. Reduction in sample size for studies of remodeling in heart failure by the use of cardiovascular magnetic resonance. Multiple experimental studies have demonstrated an excellent spatial correlation between the extent of hyperenhancement on delayed-enhancement imaging, and areas of myocardial necrosis acute MI or scarring chronic MI at histopathology Figure 3. For instance, myocardial regions that demonstrate little or no evidence of hyperenhancement i.

Comparison of ex-vivo, high resolution delayed enhancement MR images with acute myocardial necrosis defined histologically by triphenyltetrazolium chloride TTC staining. Note that the size and shape of the infarcted region yellowish-white region defined histologically by TTC staining is nearly exactly matched by the size and shape of the hyperenhanced bright region on the delayed enhancement image.

Modified from Circulation ; However, in this situation, it is important to remember that both myocardial viability and functional improvement are a continuum, and not simply a binary—yes or no—function. These regions are recognized as dark central areas surrounded by hyperenhanced necrotic myocardium Figure 3. This finding indicates the presence of damaged microvasculature in the core of an area of infarction.

The likelihood of recovery of wall motion following revascularization is inversely related to the transmural extent of infarction hyperenhancement on delayed-enhancement imaging, even in severely hypokinetic, akinetic, or dyskinetic segments. From N Engl J Med ; Labels refer to time after administration of gadolinium contrast. From Kim RJ, et al. Assessment of myocardial viability by contrast enhancement. Higgins CB, de Roos A, eds. T2-weighted imaging may also be helpful as acute infarctions are often hyperintense whereas chronic infarctions are not Figure 3.

It is far more common then the competing modality of dobutamine cine MR, and the patient is directly accessible outside the scanner bore for all but approximately 30 seconds of the adenosine infusion. For a full discussion of the technical aspects of perfusion imaging, see Chapters 1 and 2. Its diagnostic performance has been evaluated in number of patient studies. Overall, these studies have shown good correlations with radionuclide imaging and x-ray coronary angiography, although there have been some variable results. Unfortunately, many of the studies used a quantitative approach i.

Although a quantitative approach has the advantage, potentially, of allowing absolute blood flow to be measured or parametric maps of perfusion to be generated, the approach is laborious and requires extensive interactive post-processing. At present, a quantitative approach is not feasible for everyday clinical use. In contrast, image interpretation by simple visual assessment would be a realistic approach for a clinical CMR practice. Unfortunately, the results in the literature regarding visual assessment of perfusion MRI are mixed, generally demonstrating adequate sensitivity but relatively poor specificity for the detection of CAD.

In large part, image artifacts are responsible for reduced specificity. However, there is no reason to interpret the stress perfusion images in isolation. In this context, it is noteworthy that recently an interpretation algorithm Figure 2. The protocol and interpretation of stress perfusion imaging is reviewed in detail in Chapter 2.

However, coronary MRA is technically demanding for several reasons. The coronary arteries are small 3—5 mm and tortuous compared with other vascular beds that are imaged by MRA, and there is nearly constant motion during both the respiratory and cardiac cycles. Thus, precise assessment of stenosis severity and visualization of distal segments are difficult, leading to intermediate sensitivity and specificity values for the detection of CAD in validation studies.

Stress perfusion MRI studies in humans with coronary angiography comparison. From Kim et al: Magnetic Resonance Imaging of the Heart. Total Average Author Year Table 3. Ischemic Heart Disease and Non-Ischemic Cardiomyopathies Evaluation of Patients with Dilated Cardiomyopathy More recently, SSFP sequences that offer superior signal-to-noise ratio in combination with wholeheart approaches24, 25 analogous to multi-detector CT and parallel imaging to reduce scan times have improved the reliability of coronary MRA.

These sequences typically can be run with submillimeter in-plane spatial resolution 0. Additionally, with the use of modifications that compensate for respiratory drift,26 imaging can usually be completed in under 10 minutes. Parallel imaging with undersampling in two rather than only one dimension will reduce scanning time further. This acquisition took 8 minutes.

Perhaps more importantly, in patients with dilated cardiomyopathy, delayed-enhancement imaging may be useful in distinguishing between ischemic and nonischemic etiology in the great majority of cases. It has been speculated that these patients may have had prior episodes of coronary occlusion with recanalization. Patients with dilated cardiomyopathy are subject to the development of ventricular thrombi Case Compared with transthoracic echocardiography, cardiac MR may have more than a two-fold increase in sensitivity for the detection of LV thrombus.

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In addition, delayed-enhancement imaging can be helpful in localizing regions where thrombi are prone to develop, as studies have demonstrated their frequent adherence to sites of prior infarction. Given the advantages of a wide field of view, tomographic imaging with 3D coverage, and uniform image resolution, cine MR is capable of detecting regions of localized hypertrophy that are missed by echocardiography. DE-CMR in a patient with hypertrophic cardiomyopathy. Note the characteristic hyperenhancement of the septum at the RV insertion site Anderson-Fabry Disease This is an X-linked enzyme deficiency alphagalactosidase resulting in the accumulation of abnormal metabolites in various tissues throughout the body.

Typically, involvement of the kidneys or heart results in significant morbidity and mortality. As expected from the X-linked inheritance, males are predominantly affected, but female carriers may sometimes be involved as well. As opposed to HCM, which demonstrates patchy enhancement predominantly affecting the regions of hypertrophy and the RV-septal insertion sites, hyperenhancement in Fabry disease has a predilection for the inferolateral wall at the basal level Figure 3.

The reason for this finding is uncertain. Reports indicate that this finding is likely due to profound expansion of the extracellular volume of the myocardium, as well as more rapid Cardiac involvement is the most common cause of death in systemic amyloidosis, and cardiac amyloidosis is the most common identifiable cause of restrictive cardiomyopathy.

Additionally, thickening of the interatrial septum and of the atrial walls are findings strongly suggestive of the diagnosis. Although often subendocardial, the pattern is clearly distinct from the usual CAD pattern in that the hyperenhancement does not follow a coronary artery distribution. From an imaging point-of-view, the presence of diffuse myocardial involvement may make setting the parameters for delayed-enhancement imaging problematic.

Additionally, unlike the situation in normal patients, in whom the LV Figure 3. Diffuse subendocardial enhancement is noted on this delayed-enhancement short-axis image from a patient with amyloidosis been shown to correlate with the severity of cardiac involvement. In addition, given the availability of enzyme replacement,43 follow-up studies to assess the effect of therapeutic intervention may be best performed with CMR. Ischemic Heart Disease and Non-Ischemic Cardiomyopathies clearance of gadolinium contrast from the blood pool.

Historically, CMR examinations employed spin-echo pulse sequences in an attempt to visualize fatty infiltration of the RV myocardium as well as RV free-wall thinning. However, interpretation of these images was often difficult because of motion artifact, and volume averaging with adjacent epicardial and pericardial fat. As a result, relying on the presence or absence of fat on these images is a frequent cause of misdiagnosis,51 and the presence or absence of fat and RV wall thinning by CMR are not included among the Task Force criteria for diagnosis. A 4-chamber delayed-enhancement image showing hyperenhancement of the RV free wall and the apical half of the interventricular septum in a patient with confirmed ARVD Case No normal patient demonstrated abnormal hyperenhancement of the right ventricle.

This likely reflects the relative insensitivity of the most frequently used diagnostic tools. Typically, patchy hyperenhancement is typically found along the epicardium or mid-myocardium in a non-CAD pattern Figure 3. Basal and septal involvement is frequent. Non-Ischemic Cardiomyopathies 35 Figure 3. A 2-chamber A and short-axis B delayed-enhancement images of a patient with sarcoid.

Note the inferior wall epicardial enhancement in a non-CAD pattern Myocarditis Several different CMR pulse sequences have been used to evaluate patients with suspected acute myocarditis. T2-weighted A and delayed-enhancement B 2-chamber views images in a patient with myocarditis. Note the high signal in the anterior and inferior walls in the apical region in a non-CAD pattern on both images 36 3. Ischemic Heart Disease and Non-Ischemic Cardiomyopathies observed during the acute setting often decrease in size significantly during follow up.

This process likely represents myocardial healing as regions of myocardial necrosis are replaced with collagenous scar tissue. Herpes simplex 6 had a predilection for septal involvement, and seemed to correlate with the development of progressive disease. Most patients survive the initial phase of illness, and remain asymptomatic for years. Scarring occurred most commonly in the LV apex and inferolateral wall. Both non-CAD type isolated epicardial or mid-wall involvement and CAD type indistinguishable from prior myocardial infarction scar patterns were observed.

The presence and pattern of scarring on delayed-enhancement imaging is often quite distinct, and a pattern recognition approach based on the visualization of abnormal enhancement will often provide useful diagnostic information as to the likely etiology. Recently, a systematic approach to interpreting delayed-enhanced images in patients with heart failure or cardiomyopathy has been proposed. Step 1 The presence or absence of hyperenhancement is determined.

In the subset of patients with longstanding severe ischemic cardiomyopathy, the data indicate that virtually all patients have prior MI. Step 2 If hyperenhancement is present, the location and distribution of hyperenhancement should be classified as a CAD or non-CAD pattern. Step 3 If hyperenhancement is present in a non-CAD pattern, further classification should be considered. As described above, there is emerging data that suggest certain nonischemic cardiomyopathies have predilection for specific scar patterns.

For example, in the setting of LV hypertrophy, the presence of midwall Table 3. Diagnostic CMR findings of specific cardiomyopathies. Hyperenhancement HE patterns that may be encountered in clinical practice. Additionally, endocardial HE that occurs globally i. From Shah et al. Edelman RR, et al. Clinical Magnetic Resonance Imaging, 3rd ed. Elsevier Press; , with permission hyperenhancement in one or both junctions of the interventricular septum and RV free wall is highly suggestive of hypertrophic cardiomyopathy, whereas midwall or epicardial hyperenhancement in the inferolateral wall is consistent with Anderson-Fabry Disease.

Moreover, instead of there being an infinite variety of hyperenhancement patterns, it appears that a broad stratification is possible into a limited number of common delayed-enhancement phenotypes. Visualization of presence, location, and transmural extent of healed Q-wave and non-Qwave myocardial infarction. Effects of time, dose and inversion time for acute myocardial infarct size measurements based on magnetic resonance imaging—delayed contrast enhancement. Transmural extent of acute myocardial infarction predicts long-term improvement in contractile function.

Delayed contrast-enhanced magnetic resonance imaging for the prediction of regional functional improvement after acute myocardial infarction. The use of contrastenhanced magnetic resonance imaging to identify reversible myocardial dysfunction. N Engl J Med. Nonstress delayed-enhancement magnetic resonance imaging of the myocardium predicts improvement of function after revascularization for chronic ischemic heart disease with left ventricular dysfunction. Viability assessment by delayed enhancement CMR: Assessment of no-reflow regions using cardiac MRI. Prognostic significance of microvascular obstruction by magnetic resonance imaging in patients with acute myocardial infarction.

Microvascular obstruction and left ventricular remodeling early after acute myocardial infarction. Accuracy of contrast-enhanced magnetic resonance imaging in predicting improvement of regional myo- cardial function in patients after acute myocardial infarction. Delayed enhancement and T2-weighted cardiovascular magnetic resonance imaging differentiate acute from chronic myocardial infarction. Value of T2-weighted, first-pass and delayed enhancement, and cine CMR to differentiate between acute and chronic myocardial infarction.

Retrospective determination of the area at risk for reperfused acute myocardial infarction with T2-weighted cardiac magnetic resonance imaging: Coronary magnetic resonance angiography for the detection of coronary stenoses. Whole-heart steady-state free precession coronary artery magnetic resonance angiography.

Assessment of coronary arteries with total study time of less than 30 minutes using whole-heart coronary MR angiography. Differentiation of heart failure related to dilated cardiomyopathy and coronary artery disease using gadolinium-enhanced cardiovascular magnetic resonance. Noninvasive diagnosis of coronary artery disease in patients with heart failure and systolic dysfunction of uncertain etiology, using late gadolinium-enhanced cardiovascular magnetic resonance.

Clinical, imaging, and pathological characteristics of left ventricular thrombus: Detection and characterization of intracardiac thrombi on MR imaging. Utility of cardiac magnetic resonance imaging in the diagnosis of hypertrophic cardiomyopathy. Myocardial scarring in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy. Delayed hyper-enhancement of myocardium in 39 hypertrophic cardiomyopathy with asymmetrical septal hypertrophy: Delayed contrast enhancement of MRI in hypertrophic cardiomyopathy.

Late myocardial enhancement in hypertrophic cardiomyopathy with contrast-enhanced MR imaging. Toward clinical risk assessment in hypertrophic cardiomyopathy with gadolinium cardiovascular magnetic resonance. J Inherit Metab Dis. Prevalence of Anderson-Fabry disease in male patients with late onset hypertrophic cardiomyopathy. Mar 26 ; The histological basis of late gadolinium enhancement cardiovascular magnetic resonance in a patient with Anderson-Fabry disease.

Gadolinium enhanced cardiovascular magnetic resonance in Anderson-Fabry disease. Evidence for a disease specific abnormality of the myocardial interstitium. Mignani R, Cagnoli L. Cardiovascular magnetic resonance in cardiac amyloidosis. MR findings in cardiac amyloidosis. Assessment of restrictive cardiomyopathy of amyloid or idiopathic etiology by magnetic resonance imaging.


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    7. Contribution of magnetic resonance imaging in the differential diagnosis of cardiac amyloidosis 40 3. Spectrum of pathological changes in both ventricles of patients dying suddenly with arrhythmogenic right ventricular dysplasia. Relation of changes to age. Cardiovascular magnetic resonance in arrhythmogenic right ventricular cardiomyopathy revisited: Magnetic resonance imaging of arrhythmogenic right ventricular dysplasia: Noninvasive detection of myocardial fibrosis in arrhythmogenic right ventricular cardiomyopathy using delayed-enhancement magnetic resonance imaging.

    The additional value of gadolinium-enhanced MRI to standard assessment for cardiac involvement in patients with pulmonary sarcoidosis. Effectiveness of delayed enhanced MRI for identification of cardiac sarcoidosis: Diagnostic performance of cardiovascular magnetic resonance in patients with suspected acute myocarditis: Presentation, patterns of myocardial damage, and clinical course of viral myocarditis.

    Magnetic Resonance of Myocardial Viability. Clinical Magnetic Resonance Imaging. Transmural progression of necrosis within the framework of ischemic bed size myocardium at risk and collateral flow. Hemodynamics Similar to other CMR protocols, hemodynamic assessment may comprise one or several pulse sequences, depending on the physiological para- Atrial Septal Defect Ventricular Septal Defect Tetralogy of Fallot Coarctation of the Aorta Transposition of the Great Arteries References meters that should be appraised.

    For example, in valvular stenosis, morphologic characteristics e. Signal voids, which result from the dephasing of spins that occur with turbulent flow, can be used to qualitatively assess valvular regurgitation. First-pass perfusion imaging can be used to follow the transit of contrast media to determine the presence of intracardiac shunts in a manner analogous to a bubble study in echocardiography. Velocity-encoded imaging can be used to estimate pressure gradients and blood flow across an orifice. Then, it discusses a few select pathophysiological conditions as working examples.

    With echocardiography there are two limitations. First, the blood flow profile is not directly measured but assumed to be flat i. Second, the cross-sectional area of the orifice is estimated from a diameter measurement of the orifice at a different time from when Doppler velocity was recorded using a different examination M-mode or 2D imaging.

    Cardiovascular MRI in Practice A Teaching File Approach

    On the other hand, velocity-encoded CMR has some disadvantages. Perhaps most importantly, velocity-encoded CMR is usually not performed in real time because of current technical limitations and requires breathholding to minimize artifacts due to respiratory motion. One consequence is that it is difficult to measure changes in flow that occur with respiration. A comparison of various imaging characteristics between velocity-encoded CMR and Doppler echocardiography is provided in Table 4.

    Aortic Stenosis Several validation studies have demonstrated good agreement of aortic valve area by planimetry on cine CMR images with measures derived using transesophageal and transthoracic echocardiography, and invasive hemodynamic measurements during cardiac catheterization. The correct plane is determined by first, obtaining at least 2 orthogonal long-axis views of the high velocity jet across the valve by either cine or velocity-encoded CMR.

    Then, the short-axis plane is placed at the origin of the jet, and the plane is positioned to be orthogonal to the direction of the jet on all the long-axis views. Importantly, a stack of consecutive, parallel short- Table 4. Comparsion of velocity-encoded CMR and doppler echocardiography. Temporal resolution may be significantly improved for nonbreathhold imaging, but artifacts due to respiratory motion artifact may be prominent. Planimetry for valve area is performed on cine images with higher spatial and temporal resolution than usual for standard imaging.

    A small field-of-view image with high spatial resolution can be obtained with extensive oversampling in the phase encoding direction to prevent wraparound artifact Figure 4. Pulmonic and mitral valve stenosis is evaluated using a similar approach Cases 20 and Regurgitant Valvular Lesions Valvular regurgitation can be evaluated both qualitatively and quantitatively using cine CMR and velocity-encoded flow imaging.

    On cine CMR, regurgitant flow is visualized as a region of spin dephasing and resultant signal loss extending from the valve plane into the cavity into which the jet is directed Case An estimate of the size and extent of the signal loss can be performed by Hemodynamics Figure 4.

    Still-frame during systole from an SSFP cine loop of an aortic valve demonstrating partial fusion of the cusps. A small field-of-view with extensive over-sampling in the phase encoding direction to prevent wraparound artifact was utilized to provide high spatial resolution. Note that planimetry of the valve can be readily performed 43 visual evaluation, and along with an evaluation of chamber sizes and other parameters such as cessation of antegrade flow in the pulmonary veins in the instance of mitral regurgitation, one can get an estimate of the severity of regurgitation.

    For quantitative assessment of regurgitation, the regurgitation fraction may be calculated from data derived from velocity-encoded imaging, sometimes in combination with cine CMR. However, with regurgitant lesions that result in more turbulent flow such as mitral or aortic regurgitation, the calculation of regurgitant volume and regurgitant fraction can be more complex. These errors typically result in an underestimation of the regurgitant Figure 4. Velocity-encoded flow data obtained from a through-plane study of an incompetent pulmonic valve. Hemodynamic Assessment and Congenital Heart Disease volume.

    Therefore, to obtain the most accurate measurements, the regurgitant volume is measured indirectly for both mitral and aortic regurgitation. For example, with aortic regurgitation, the regurgitant volume may be calculated by subtracting the effective forward flow antegrade — retrograde through the pulmonic valve from the antegrade flow through the aortic valve using two separate through-plane velocity-encoded acquisitions. For mitral regurgitation, the regurgitant volume may be obtained by subtracting systolic flow through the aortic valve measured by velocity-encoded CMR from LV stroke volume measured by volumetric quantification of a stack of cine CMR images.

    For all velocity-encoded acquisitions, TE should be minimized to reduce dephasing and signal loss. Congenital Heart Disease Because of its capacity for multiplanar imaging, and the ability to comprehensively survey the heart and great vessels, MR imaging is quite helpful in the evaluation of known or suspected congenital heart disease. Standard morphologic imaging allows assessment of the great vessel relationships, as well as cardiac and abdominal situs. Cine imaging demonstrates global and regional cardiac structure and function.

    Velocity-encoded imaging allows quantitation of flow through the great vessels as well as through areas of possible stenosis. MR angiographic imaging is used to evaluate for the possibility of anomalous vessels, the structure and relationships of the great vessels, and the presence of collaterals. A brief discussion of specific defects follows. Suggested imaging protocols are described in the appendix. Atrial Septal Defect This refers to a group of disorders wherein there is abnormal communication between the atrial chambers.

    These may, however, extend beyond the fossa ovalis to involve a variable portion of the septum. Its superior border is formed by the inferior border of the fossa ovalis and its inferior border is formed by the leaflets of the malformed atrioventricular valve. Although partial anomalous pulmonary venous return is present with increased frequency in ASDs in general, the superior sinus venosus ASD in particular has a frequent association with anomalous drainage, particularly involving the right upper lobe pulmonary vein.

    The left to right shunt occurring as a result of the atrial septal defect will result in right atrial and right ventricular enlargement. Increased volume in the pulmonary circuit may result in prominent main and hilar pulmonary arteries. The CMR examination is often performed prior to anticipated closure of the defect, which currently is often performed using endovascular catheter techniques. A stack of four-chamber cine images as well as extension of the shortaxis acquisitions through the interatrial septum will often allow depiction of secundum atrial septal defects, particularly if large.

    The imaging plane is roughly parallel to the interatrial septum, but should be optimized to account for cardiac cycle interatrial septal motion and ASD flow direction. This en face view also provides excellent depiction of the anteroposterior and craniocaudal dimensions of the septal defect. They often arise as part of more complex congenital Congenital Heart Disease 45 Figure 4.

    Small defects are known to undergo spontaneous closure, while large defects carry the risk of developing irreversible pulmonary hypertension. Morphologically, multiple forms exist and are classified by location inlet, muscular, perimembranous, etc. The defect itself can often be visualized on the cine images Case In cases where pulmonary hypertension has supervened, evaluation of the degree of abnormal interventricular septal curvature can often provide indirect evidence of pulmonary arterial hypertension.

    All of these findings are related to the abnormal embryologic formation of the conal septum, which results in hypoplasia of the pulmonary infundibulum with over-riding of the aorta and a malalignment VSD. The surgical repair is directed to closure of the VSD and relief of the pulmonary outflow tract obstruction using an infundibular or transannular patch repair. Most cases come to imaging after prior surgical repair in early childhood. Since these patients are at risk for postoperative pulmonic insufficiency or residual pulmonic stenosis, detailed evaluation of the right ventricular outflow tract and pulmonary valve is mandatory.

    Velocityencoded imaging can be performed through the great vessels for calculation of any residual shunt. Additionally, given the frequent late presentation of aortic insufficiency, detailed evaluation of the aortic valve should also be performed. In fact, aberrant ductal tissue 46 4. Delayed-enhancement short-axis view of the RV in a post-op Tetralogy patient demonstrating dilatation and hyperenhancement of the outflow tract arrows present in the wall of the coarctation may have a role in its formation.

    Severe forms present in infancy while milder forms may not be discovered until adulthood. Upper extremity hypertension and diminished femoral pulses are frequently found in patients presenting in adulthood. Repair in infancy is most commonly performed surgically, with primary end-to-end anastomosis when feasible. Endovascular repair is often used in cases of recoarctation or residual stenosis following primary repair, but is also sometimes used primarily depending on the center. At the time of CMR examination, many of these patients will have undergone prior surgical or endovascular repair.

    Late sequelae include the development of aneurysms at the site of the prior repair as well as recurrent coarctation. These findings are well evaluated using MR angiographic and cine imaging through the region of the proximal descending aorta Figure 4. Cine A and MR angiographic image B of a patient who has recurrent coarctation status-post correction in childhood.

    Cardiovascular MRI in Practice: A Teaching File Approach

    Note the turbulent flow jet resulting in spin dephasing on cine imaging arrow References Velocity-encoded imaging can be obtained just proximal to the region of coarctation, at the site of narrowing if present, and in the more distal descending thoracic aorta to evaluate for the presence of residual gradient, and for the detection of collateral flow.

    Transposition of the Great Arteries This entity is characterized by the presence of ventriculo-arterial discordance; that is, the aorta arises from the morphologic right ventricle and the pulmonary artery from the left ventricle. As a result, the systemic and pulmonary circuits operate in parallel, instead of in series. Definitive repair is performed in infancy and most patients examined with CMR are status-post prior corrective surgery. The current surgical procedure of choice is the arterial switch Jatene procedure, but many older patients who were repaired using the atrial switch procedures Mustard or Senning are now adults and may present for imaging.

    Velocityencoded information can be obtained through the origins of the great vessels to exclude any residual shunts. In these patients with a systemic right ventricle, cine imaging is helpful for the evaluation of right ventricular function Case Other lesions, including complex defects and univentricular repairs using Fontan shunts can also be evaluated non-invasively with CMR Case MR evaluation of cardiovascular physiology in congenital heart disease: Dorfman AL, Geva T.

    Magnetic resonance imaging evaluation of congenital heart disease: Magnetic resonance to assess the aortic valve area in aortic stenosis: Evaluation of aortic stenosis by cardiovascular magnetic resonance imaging: Magnetic resonance jet velocity mapping in mitral and aortic valve stenosis. Practical value of cardiac magnetic resonance imaging for clinical quantification of aortic valve stenosis: Rapid quantitation of high-speed flow jets. Quantification of shunt volumes in congenital heart diseases using a breath-hold MR phase contrast technique— comparison with oximetry.

    Int J Cardiovasc Imaging. Comparison between phase-velocity cine magnetic resonance imaging and invasive oximetry for quantification of atrial shunts.

    Use of non-invasive phase contrast magnetic resonance imaging for estimation of atrial septal defect size and morphology: Cardiac magnetic resonance imaging evaluation of sinus venosus defects: Interventricular septal configuration at mr imaging 48 4. Hemodynamic Assessment and Congenital Heart Disease and pulmonary arterial pressure in pulmonary hypertension. Corrected tetralogy of Fallot: Aortic root dilatation in tetralogy of Fallot long-term after repair-histology of the aorta in tetralogy of Fallot: Magnetic resonance imaging of congenital abnormalities of the thoracic aorta.

    Simple congenital heart lesions.