5. CARDIAC MRI INDICATONS
Applications of cardiac MRI include the
following:
1.Assessment of myocardial scar,
infiltrative processes, and inflammation.
2.Assessment of myocardial ischemia
3.Assessment of ventricular function
4.Characterization of cardiac chamber
morphology and function
6. CARDIAC MRI INDICATONS
5. Detection and characterization of
congenital heart disease
6. Characterization of cardiac masses
7. Diagnosis of pericardial disease
8. Quantification of valvular disease and
shunt physiology
7. CARDIAC MRI INDICATONS
9. Detection of coronary artery
arteriosclerosis
10. Detection and characterization of
coronary anomalies
11. Detection and characterization of
coronary artery aneurysms
8. CARDIAC MRI SEQUENCES
BRIGHT BLOOD IMAGING
Used to determine flow, motion, aortic
valve diseases
- Cine gradient echo imaging
- FASTCARD
- True fast imaging with steady state
precession (FISP)
9. CARDIAC MRI SEQUENCES
BLACK BLOOD IMAGING
Used to identify Extraluminal aortic pathology,
intramural hematoma, or dissection
- ECG-gated spin echo (SE) or fast-spin echo (FSE)
- ECG-gated db-HASTE
- Can be performed breath-hold or multiple averages
non-breath-hold
10. • MYOCARDIAL DISEASES:
ISCHEMIC
NONISCHEMIC
CARDIAC MRI
- ONLY IMAGING MODALITY WITH PRECISE ASSESSMENT OF
VENTRICULAR FUNCTION AND COMPREHENSIVE TISSUE
CHARACTERIZATION IN A SINGLE EXAMINATION WITHOUT THE USE OF
IONIZING RADIATION.
12. PERFUSION
Myocardial perfusion of the ischemic heart may be studied with MR. Most perfusion
analysis approaches make use of intravenously injected gadolinium-based MR contrast
agents.
This type of contrast medium temporarily reduces the T1-relaxation time and thereby
relatively increases the MR-signal intensity of well-perfused tissues. After contrast
injection, ischemic myocardial regions show up as areas with no or little signal intensity
change as compared to well-perfused myocardium.
13. VIABILITY
At 15 to 30 minutes after contrast injection, washout
will be complete in normal myocardium in contrast to
infarcted or edematous tissue. This phenomenon is the
basis of “delayed enhancement imaging”.
In MR images, the presence of contrast agent can be detected as a
bright area on images acquired with T1-weighted MR pulse
sequences
14. STANDARD SEQUENCE
The typical MRI sequences that are used for the
detection and characterization of myocardial disorders
can be divided into:
A. Functional assessment
B. Tissue characterization
Functional assessment
- can be performed using cine imaging, typically Balanced
steady-state free precession (bSSFP) sequences, acquired in
standard cardiac planes including at multiple levels in the
short-axis plane.
17. STANDARD SEQUENCE
Black blood imaging
- the blood pool is nulled during a double inversion recovery
- Allowing a clear demarcation of the subendocardium
- T1-weighted black blood images allows anatomic evaluation
- T2-weighted black blood sequences can be performed with or without fat
saturation to highlight areas of edema, seen in clinical entities including
acute ischemia, myocarditis, and sarcoidosis.
- Also provides prognostic information after reperfusion in acute ischemia.
18. STANDARD SEQUENCE
T2* imaging
- local magnetic field inhomogeneity present in paramagnetic materials
such as iron.
- Dephasing due to magnetic field inhmogeneity can be detected by
using gradient-echo sequences with low flip angle, long TE, and no
refocusing pulse
- Tissues that contain paramagnetic material T2*, relaxation occurs
faster
- Cardiomyopathy - higher T2* values may also provide prognostic
information for risk of adverse cardiac events
19. STANDARD SEQUENCE
First-pass perfusion imaging
- real time
- Gradient-echo T1-weighted sequences are performed during the
administration of contrast material typically at dedicated levels (i.e., base, mid
ventricle, and apex).
- Perfusion imaging can be useful for identifying
- microvascular obstruction (in post-infarct states)
- hyperemia (in myocarditis)
20. STANDARD SEQUENCE
LGE images ]
- Greatest role in the characterization of
cardiomyopathy into ischemic and nonischemic subtypes
in addition to providing prognostic information.
- The areas of increased extracellular volume (due to
fibrosis, edema, or an infiltrative process), which retain
gadolinium-based contrast material, can be identified
as bright on the background of a black myocardium.
- Images are acquired 10–15 minutes after contrast
administration to optimize peak uptake of contrast
material in the diseased myocardium.
21.
22. ADDITONAL SEQUENCE
T1 contrast-enhanced mapping
- better detection of diffuse disease
- decreased interobserver variability
- production of quantitative data
- Mapping may also be able to provide assessment of therapeutic efficacy in
cases of myocardial disease such as sarcoid.
T1 and T2 mapping are newer methods for the detection of myocardial
disease using alterations in the native T1 or T2 relaxation of the
myocardium.
25. CORONARY ARTERY
DISEASE
MYOCARDIAL
INFARCTION
CMR provides a comprehensive assessment of the spectrum of coronary
artery disease (CAD) using
1. Cine imaging - cardiac structure and function
2. Perfusion imaging - for myocardial blood flow
3. LATE GADOLINIUM ENHANCEMENT (LGE) - for infarction (detects
subendocardial infarction of either the left or the right ventricle, infarct
size, visualization of necrotic and non-necrotic myocardium), and in
patients with acute coronary syndrome
4. T2-weighted or mapping imaging for myocardial edema.
26. DETECTING ACUTE CORONARY SYNDROMES
AND DIFFERENTIATING FROM NON
CORONARY CAUSES
High sensitivity and specificity for detecting acute coronary syndromes and
risk-stratifying patients presenting with acute chest pain.
Acute elevation of serum biomarkers consistent with myocardial injury but with
nonobstructive coronary arteries. It may provide diagnostic information to
direct therapy and improve prognosis.
14
T2-weighted imaging (or T2 mapping) – detects extent of the salvageable
myocardium days after emergent restoration of coronary flow by PCI.
Can capture various noncoronary abnormalities used to diagnose the causes of
chest pain.
27. DETECTING AND QUANTIFYING
MYOCARDIAL ISCHEMIA
Stress CMR imaging is performed using pharmacologic stress agents, and
less often using treadmill exercise
As summarized by the recent AHA/ACCF guidelines for stable ischemic
heart disease, vasodilating stress CMR myocardial perfusion imaging
(MPI)
effective clinical tool in diagnosing CAD and risk-stratifying patients
with suspected myocardial ischemia.
1
28. Compared to single-photon emission tomography
(SPECT) imaging, CMR MPI has several technical
advantages:
• Not limited by attenuation artifacts
• Free from ionizing radiation
• Three- to fourfold higher spatial resolution than
SPECT.
STRESS CMR study that includes stress and rest
perfusion imaging, cine cardiac function, and
29. Dobutamine stress CMR (both perfusion
and cine function):
EXCELLENT SENSITIVITY AND SPECIFICITY
in detecting CAD
Superior to dobutamine stress
echocardiography
30. CARDIOMYOPATHY
OVERALL APPROACH
In patients with valvular disease:
Volumetric cine CMR can assess the loading impact
onto the heart and the resultant ventricular
compensation
Tissue tagging
-resolve any suspected regional wall motion
abnormality at rest or stress or when myocardial
adhesion from pericardial diseases becomes part of
the assessment.
31. HYPERTROPHIC CARDIOMYOPATHY
Echocardiography missed hypertrophic segments and
underestimated the magnitude of hypertrophy in the
basal anterolateral wall by as much as 33% compared
to CMR.
40% of apical aneurysms are missed by
echocardiography.
32. Presence of LGE
Indicative of heterogeneous fibrosis and
myofibril disarray
ventricular arrhythmias and progressive
ventricular dilation.
33. ARRHYTHMOGENIC RIGHT VENTRICULAR
CARDIOMYOPATHY
Distinguishes itself from other cardiomyopathies by:
- predisposition toward ventricular arrhythmia that
precedes overt morphologic abnormalities and
histologic substrate
- diverse phenotypic manifestations
34. CMR offers advantages over
echocardiography
Quantitative and Volumetric assessment of RV
function and its fibrofatty tissue characterization of
myocardium.
35. Value of CMR as an integral component in the workup of
ARVC affirmed by CMR protocols
Major Criteria:
- Localized aneurysms
- Severe global dilation with systolic dysfunction
- Severe segmental dilation of the right ventricle
- Fat infiltration of the RV - limited specificity for
diagnosing ARVC.
36. MYOCARDITIS
CMR targets the three main pathophysiologic
components :
- Myocardial edema by T2-weighted imaging
- Regional hyperemia
- Capillary leak
a. early gadolinium enhancement ratio
(EGEr)
b. myocardial necrosis or fibrosis by LGE
37. T2-weighted images + LGE
high diagnostic accuracy for acute myocarditis
Parvovirus
- subepicardium and midmyocardium of the
inferolateral walls are usually involve
Human Herpesvirus 6
– septal involvement with potentially more serious
sequelae.
38. CARDIAC SARCOIDOSIS
CMR may enhance disease detection in histologic
stages of disease:
• Tissue edema
• Noncaseating granulomatous infiltration,
• Patchy myocardial fibrosis
39. Extracardiac sarcoidosis
LGE and RV dysfunction
high-risk markers for cardiac death or serious
ventricular arrhythmias independent of LVEF
40. CARDIAC AMYLOIDOSIS
The pattern of LGE may differentiate the
subtype of amyloidosis:
ATTR - transmural LGE and
AL subtype - RV involvement
Takotsubo cardiomyopathy:
transient Contractile dysfunction of the apex
41. CARDIAC THROMBUS AND MASS
LGE imaging > echocardiography = in detecting THROMBUS
Common benign cardiac tumors:
Atrial myxomas are often seen as a round or multilobar mass in the left atrium (75%),
right atrium (20%), or ventricles or mixed chambers (5%).
Malignant lesions : cardiac involvement from direct invasion (lung and breast),
lymphatic spread (lymphomas and melanomas), and hematogenous spread (renal cell
carcinoma)
Primary cardiac malignancies:
- Angiosarcoma, barosarcoma, rhabdomyosarcoma, and liposarcoma.
43. ARRHYTHMIAS
IMAGING OF PATIENTS BEFORE
ELECTROPHYSIOLOGIC PROCEDURES
CMR’s ability to identify the potential site of ablation or
scar
provide three-dimensional volume mapping of the atria
or ventricles.
For patients with atrial fibrillation (AF): strong msrkers of AF
recurrence
- Left atrial emptying function
- Evidence of LV fibrosis on CMR
44. Ischemic and Nonischemic ventricular tachycardia (VT)
- Critical isthmus sites: peri-infarct regions identifiable by LGE.
- CMR can provide guidance to critical isthmus sites during VT
ablation.
Pericardial Diseases:
CMR is the test of choice
Differentiating constrictive pericarditis from restrictive cardiomyopathy
Pericardial thickness: aseesed by black-blood FSE or cine imaging (3 mm
is normal.)
45. Pericardial metastases > primary pericardial tumors
Malignant invasion of the pericardium: shows focal
obliteration of the pericardial line and a pericardial
effusion.
Most neoplasms
- appear dark or gray on noncontrast T1-
weighted images, except metastatic melanoma
46. ADULT CONGENITAL HEART DISEASE
CMR key additive data beyond other imaging methods in assessment
of congenital heart disease is based on the ff
- no need for ionizing radiation
- three-dimensional tomographic imaging of thoracic structures
and anatomy
- correlation of complex anatomy with blood flow and physiology
47. ATRIAL AND VENTRICULAR SEPTAL DEFECTS
- less invasive alternative to transesophageal echocardiography (TEE)
and diagnostic catheterization
- detect the presence of an atrial septal defect (ASD)
- assess suitability for transcatheter ASD closure,
- quantify right heart size and function by cine SSFP,
- determine pulmonary-to-systemic shunt ratio (Qp/Qs) using
velocity-encoded phase contrast
- identify any coexisting anomalous pulmonary venous return using
three-dimensional contrast- enhanced MRA.
48. Since most closure devices are MRI compatible, CMR can be used
to assess for residual shunt and proper device deployment.
LGE imaging may help to determine if a VSD developed as a
complication of MI.
Three-dimensional MRA can capture abnormal intrathoracic
structures and vascular dynamics in anomalous pulmonary venous
return.
49. Magnitude of any left-to-right shunt
Direct blood flow measurement in the anomalous pulmonary vein or by
Qp/Qs ratio
In Coarctation of the AORTA:
Cine SSFP in a long-axis “candy cane” view:
- delineates the degree of obstruction, and aortic valvular dysfunction.
- GOLD STANDARD for LV size, LV function, and myocardial mass.
Phase-contrast imaging:
characterize the descending-to-ascending aorta flow ratio
estimate pressure gradient across the coarctation and collateral formation.
50. CONOTRUNCAL ANOMALIES
In patients who have undergone surgery for TOF
- relevant assessment of any RV outflow aneurysm
- pulmonary regurgitation fraction
- biventricular size and function
- residual shunt
LGE imaging- detection of myocardial fibrosis ssociated with:
- ventricular dysfunction, exercise intolerance, and
arrhythmias.
51. Arterial switch operation:
most common corrective surgery.
CMR is useful in monitoring after surgical correction by assessing:
- ventricular size and function
- flow across the postoperative LV and RV outflow tracts
- aortopulmonary collaterals.
LGE CMR : incorporated in risk stratification of these patients.4
52. VALVULAR HEART DISEASE
For aortic regurgitation, CMR phase-contrast imaging has higher
reproducibility in quantifying the regurgitant volume and serial
monitoring.
CMR is a useful before or after transcatheter aortic valve replacement
(TAVR)
CMR is more accurate in sizing the aortic annulus before the
procedure, predicting the severity of aortic regurgitation after TAVR.
This article is simultaneously published in 2005 printed issues of radiology and journal of American college of radiology on use of noninvasive cardiac imaging in diagnosis and evaluation of certain cardiac diseases
Applications of cardiac MRI include but are not limited to the following:
Assessment of myocardial scar, infiltrative processes, and inflammation.
Assessment of myocardial ischemia
Assessment of ventricular function
Characterization of cardiac chamber morphology and function
Fisp fast imaging with steady-state precession
Fastcard fasting cardiac mri
Techniques used are:
ECG-gated spin echo (SE) or fast-spin echo (FSE)
ECG-gated db-HASTE
Can be performed breath-hold or multiple averages non-breath-hold
Myocardial disease is broadly divided into ischemic and nonischemic. Many systemic disorders, genetic conditions, and adaptive states can lead to nonischemic cardiomyopathy (NICM). Imaging plays a critical role in the diagnosis of myocardial disease and risk stratification.
Cardiac MRI is the only imaging modality that allows precise assessment of ventricular function and comprehensive tissue characterization in a single examination without the use of ionizing radiation
The purpose of these MR scans is to image the heart in three dimensions.
The second stepping stone in CVMR is evaluation of cardiac function. The second most frequent indication for cardiac MR is evaluation of myocardial wall motion abnormalities in patients with suspected myocardial ischemia.
Figure 3. Standard versus high-resolution perfusion-CMR: Case Example 3. An inferior scar with thinning of the myocardium is seen in all images (open arrows, A–I). Dark-rim artifact seen on the basal slice (dashed arrows, A) at standard resolution (2.5 mm in-plane spatial resolution) is not present at high resolution (G). By virtue of their identical spatial resolution, LGE imaging and high-resolution perfusion-CMR allow for a better correlation between scar and perfusion than LGE imaging and standard resolution perfusion-CMR. An area of peri-infarct ischemia (small arrows, H) is therefore more clearly identified at high resolution. In this patient, coronary angiography showed a chronic total occlusion of the right coronary artery and the patient's symptoms were relieved by subsequent PCI. CMR indicates cardiovascular MR; LGE, late gadolinium-enhanced imaging; PCI, percutaneous coronary intervention.
However, when the tissue is damaged, for example, due to infarction, the resorption rate of contrast agent will be diminished. At 15 to 30 minutes after contrast injection, washout will be complete in normal myocardium in contrast to infarcted or edematous tissue. This phenomenon is the basis of “delayed enhancement imaging”.
However, when the tissue is damaged, for example, due to infarction, the resorption rate of contrast agent will be diminished. At 15 to 30 minutes after contrast injection, washout will be complete in normal myocardium in contrast to infarcted or edematous tissue. This phenomenon is the basis of “delayed enhancement imaging”.
A–D, Balanced steady-state free precession MR images are obtained in standard cardiac planes: short-axis
(A), four-chamber and horizontal long-axis - The blood pool is bright on cine imaging, allowing clear delineation of the blood pool from the myocardium.
(B), two-chamber and vertical long-axis
(C), and three-chamber
(D) views.
These images allow quantification of ventricular function, volume, and mass; assessment for global and regional wall motion abnormalities; and evaluation of myocardial wall morphology.
Black blood imaging
- can be performed with either T1- or T2-weighting
In black blood sequences, the blood pool is nulled during a double inversion recovery, which allows clear demarcation of the subendocardium
T1-weighted black blood images allow anatomic evaluation including clear depiction of the pericardium.
T2-weighted black blood sequences can be performed with or without fat saturation to highlight areas of edema, which can be seen in various clinical entities including acute ischemia, myocarditis, and sarcoidosis. Edema on a T2-weighted sequence can also provide prognostic information after reperfusion in acute ischemia.
- takes advantage of local magnetic field inhomogeneity that occurs in the presence of paramagnetic materials such as iron. Using gradient-echo sequences with a low flip angle, long TE, and no refocusing pulse, dephasing due to magnetic field inho- mogeneity can be detected. When tissues contain paramagnetic material T2*, relaxation occurs faster, as can be seen in both primary and secondary iron overload states. In patients with cardiomyopathy, higher T2* values may also provide prognostic information for risk of adverse cardiac events
First-pass perfusion imaging
- allows the depiction of contrast distribution in real time. Gradient-echo T1-weighted sequences are performed during the administration of contrast material typically at dedicated levels (i.e., base, mid ventricle, and apex). Images are quickly obtained over the course of the contrast administration so that areas of myocardium with abnormal perfusion can be identified. Aside from vasodilator myocardial perfusion imaging, which is widely used to diagnose ischemia, perfusion imaging can be useful for identifying microvascular obstruction (as can be seen in post-infarct states) and hyperemia (as can be seen in myocarditis)
Of all the cardiac MRI sequences, LGE images play the greatest role in the characterization of cardiomyopathy into ischemic and nonischemic subtypes in addition to providing prognostic information. An inversion recovery gradient sequences nulls the myocardium; hence, the areas of increased extra- cellular volume (due to fibrosis, edema, or an infiltrative process), which retain gadolinium-based contrast material, can be identified as bright on the background of a black myocardium. Typically, images are acquired 10–15 minutes after contrast administration to optimize peak uptake of contrast material in the diseased myocardium
E, Late gadolinium enhancement (LGE) MRI is performed 10 minutes after administration of IV gadolinium. On LGE images like this LGE image, areas of fibrosis, edema, and increased extracellular matrix can be identified as white on background of black myocardium, which has been nulled.
T1 and T2 mapping are newer methods for the detection of myocardial disease using alterations in the native T1 or T2 relaxation of the myocardium.
T1 contrast-enhanced mapping
- benefits of mapping include better detection of diffuse disease, decreased interobserver variability, and production of quantitative data. Mapping may also be able to provide assessment of therapeutic efficacy in cases of myocardial disease such as sarcoid.
CMR provides a comprehensive assessment of the spectrum of coronary artery disease (CAD) using cine imaging for cardiac structure and function, perfusion imaging for myocardial blood flow, LATE GADOLINIUM ENHANCEMENT (LGE) for infarction (detects subendocardial infarction of either the left or the right ventricle, infarct size, visualization of necrotic and non-necrotic myocardium), and in patients with acute coronary syndrome, T2-weighted or mapping imaging for myocardial edema.
CMR imaging has high sensitivity and specificity for detecting acute coronary syndromes and risk-stratifying patients presenting with acute chest pain.
Specifically, CMR is a valuable diagnostic tool in patients who present with acute elevation of serum biomarkers consistent with myocardial injury but with nonobstructive coronary arteries, because it may provide diagnostic information to direct therapy and improve prognosis.14
T2-weighted imaging (or T2 mapping) can detect the extent of the salvageable myocardium days after emergent restoration of coronary flow by percutaneous coronary intervention (PCI).
Furthermore, CMR can capture various noncoronary abnormalities used to diagnose the causes of chest pain.
Stress CMR imaging is performed using pharmacologic stress agents (such as vasodilating or positive inotropic) in many centers, and less often using treadmill exercise in highly specialized centers.
As summarized by the recent AHA/ACCF guidelines for stable ischemic heart disease, vasodilating stress CMR myocardial perfusion imaging (MPI) is an effective clinical tool in diagnosing CAD and risk-stratifying patients with suspected myocardial ischemia.1
Compared to single-photon emission tomography (SPECT) imaging, CMR MPI has several technical advantages: It is not limited by attenuation artifacts, is free from ionizing radiation, and has a three- to fourfold higher spatial resolution than SPECT. A stress CMR study that includes stress and rest perfusion imaging, cine cardiac function, and myocardial viability takes 35 to 45 minutes (versus >2 hours for dual-isotope SPECT).
Dobutamine stress CMR (both perfusion and cine function):
EXCELLENT SENSITIVITY AND SPECIFICITY
in detecting CAD
Superior to dobutamine stress echocardiography
CMR imaging is an invaluable tool for assessing various cardiomyopathies given its multifaceted interrogation of ventricular structure and myocardial physiology in matching arbitrary scan planes.
In patients with valvular disease, volumetric cine CMR can assess the loading impact onto the heart and the resultant ventricular compensation, which determines appropriateness of surgery. Tissue tagging may help to resolve any suspected regional wall motion abnormality at rest or stress or when myocardial adhesion from pericardial diseases becomes part of the assessment.
Compared to echocardiography, CMR provides a more precise three- dimensional pattern of LV hypertrophy and tissue characteristics in patients with hypertrophic cardiomyopathy
Because Echocardiography missed hypertrophic segments and underestimated the magnitude of hypertrophy in the basal anterolateral wall by as much as 33% compared to CMR. In addition, 40% of apical aneurysms are missed by echocardiography.
Presence of LGE is indicative of heterogeneous fibrosis and myofibril disarray and has been associated with ventricular arrhythmias and progressive ventricular dilation.
Arrhythmogenic right ventricular cardiomyopathy (ARVC) distinguishes itself from other cardiomyopathies by (1) a predisposition toward ventricular arrhythmia that precedes overt morphologic abnormalities and even histologic substrate and (2) diverse phenotypic manifestations despite the success in isolating the causative desmosomal mutations
Recent efforts in standardization of CMR protocols have nonetheless affirmed the value of CMR as an integral component in the workup of ARVC (arrythmogenic right ventricular cardiomayopathy).
Currently, task force guidelines consider localized aneurysms, severe global dilation with systolic dysfunction, and severe segmental dilation of the right ventricle as major criteria for ARVC
Fat infiltration of the right ventricle as an isolated finding is of limited specificity for diagnosing ARVC.
CMR targets the three main pathophysiologic components of myocarditis: myocardial edema by T2-weighted imaging, regional hyperemia and capillary leak brought by early gadolinium enhancement ratio (EGEr), and myocardial necrosis or fibrosis by LGE imaging
It is important to note that A combined approach using T2-weighted images and LGE provides high diagnostic accuracy for acute myocarditis
The subepicardium and midmyocardium of the inferolateral walls are usually involved, and Parvovirus has been implicated in these cases, but septal involvement is associated with human herpesvirus 6 with potentially more serious sequelae.
CMR may enhance disease detectionin Cardiac sarcoidosis through the successive histologic stages of disease: tissue edema, noncaseating granulomatous infiltration, and patchy myocardial fibrosis.
In patients with extracardiac sarcoidosis, LGE and RV dysfunction are high-risk markers for cardiac death or serious ventricular arrhythmias independent of LVEF.
The pattern of LGE may differentiate the subtype of amyloidosis: cardiac amyloidosis caused by ATTR is more likely to show transmural LGE and RV involvement than the AL subtype
While in other Cardiomyopaties: Transient LV apical ballooning syndrome, or takotsubo cardiomyopathy, is characterized by a transient contractile dysfunction of the apex, caused by elevated catecholamines from severe emotional or physical stress
Atrial myxomas - typically have inhomogeneous brightness in the center on cine SSFP imaging due to gelatinous contents and may have a pedunculated attachment to the fossa ovalis.
LGE imaging can detect thrombus at a higher sensitivity than echocardiography by depicting high contrast between the dark thrombus and its adjacent structures and by imaging in three dimensions.
Common benign cardiac tumors include atrial myxoma, rhabdomyoma, broma, and endocardial broelastoma. Atrial myxomas are often seen as a round or multilobar mass in the left atrium (75%), right atrium (20%), or ventricles or mixed chambers (5%).
Metastatic cardiac malignancy is much more common than primary cardiac malignancy. Malignant lesions include cardiac involvement from direct invasion (lung and breast), lymphatic spread (lymphomas and melanomas), and hematogenous spread (renal cell carcinoma)
Primary cardiac malignancies occur more often in children or young adults and include angiosarcoma, brosarcoma, rhabdomyosarcoma, and liposarcoma.
Hypereosinophilia, regardless of its cause, has been suggested to lead to cardiomyopathy in three stages: necrosis, thrombosis, and fibrosis. Hypereosinophilia is the hallmark of Löf er endocarditis, whereas it is variable in endomyocardial fibrosis, which has characteristic features on CMR
CMR is helpful in planning electrophysiologic procedures given its ability to identify the potential site of ablation or scar and to provide three-dimensional volume mapping of the atria or ventricles.
For patients with atrial fibrillation (AF): undergoing pulmonary venous isolation (PVI), left atrial emptying function and evidence of LV fibrosis on CMR are strong markers of AF recurrence.
In both ischemic and nonischemic ventricular tachycardia (VT), critical isthmus sites are typically located in peri-infarct regions identifiable by LGE. These findings suggest that CMR can provide guidance to
critical isthmus sites during VT ablation.
CMR is the current test of choice in differentiating constrictive pericarditis from restrictive cardiomyopathy, based on assessing pericardial thickness and constrictive physiology from pericardial disease and the pattern of any myocardial in ltration from restrictive cardiomyopathy
Pericardial thickness is easily assessed by either black-blood FSE or cine imaging, and up to 3 mm is accepted as normal.
Pericardial metastases are much more common (from lung, breast, and lymphomas) than primary pericardial tumors. Malignant invasion of the pericardium often shows focal obliteration of the pericardial line and a pericardial effusion.
Most neoplasms appear dark or gray on noncontrast T1-weighted images, except metastatic melanoma, because its paramagnetic metals are bound by melanin.
CMR can provide key additive data beyond other imaging methods in assessment of congenital heart disease based on (1) no need for ionizing radiation, (2) three-dimensional tomographic imaging of tho- racic structures and anatomy (versus more limited echocardiographic windows with body growth), and (3) correlation of complex anatomy with blood flow and physiology
CMR offers a less invasive alternative to transesophageal echocardiography (TEE) and even diagnostic catheterization for patients presenting with right-sided volume overload from a suspected left-to- right shunt. A CMR study can detect the presence of an atrial septal defect (ASD), assess suitability for transcatheter ASD closure, quantify right heart size and function by cine SSFP, determine pulmonary-to-systemic shunt ratio (Qp/Qs) using velocity-encoded phase contrast, and identify any coexisting anomalous pulmonary venous return using three-dimensional contrast- enhanced MRA.
Since most closure devices are MRI compatible, CMR can be used to assess for residual shunt and proper device deployment.
LGE imaging on the other hand may help to determine if a VSD developed as a complication of MI.
Using a large field of view, three-dimensional MRA can capture abnormal intrathoracic structures and vascular dynamics in anomalous pulmonary venous return.
Generally, it is more accurate than invasive oximetry measurements because of the errors from mixed venous return in the right atrium.
The magnitude of any left-to-right shunt can be assessed by either direct blood flow measurement in the anomalous pulmonary vein or by Qp/Qs ratio described previously, which generally is more accurate than invasive oximetry measurements
Cine SSFP in a long-axis “candy cane” view can further delineate the aortic anatomy, the degree of obstruction, and aortic valvular dysfunction. Cine SSFP is the gold standard for LV size, LV function, and myocardial mass.
Phase-contrast imaging can characterize the descending-to-ascending aorta flow ratio and estimate pressure gradient across the coarctation and collateral formation.
In patients who have undergone surgery for TOF, CMR provides relevant assessment of any RV outflow aneurysm, pulmonary regurgitation fraction (patients who underwent patching of pulmonic valve with postoperative pulmonary regurgitation), biventricular size and function, and any residual shunt. LGE imaging has been proposed for detection of myocardial fibrosis, which is associated with ventricular dysfunction, exercise intolerance, and arrhythmias.
An arterial switch operation is now the most common corrective surgery, although many adult patients have undergone an atrial switch procedure. CMR is useful in monitoring these patients after surgical correction by serially assessing ventricular size and function, flow across the postoperative LV and RV outflow tracts, and aortopulmonary collaterals. Systemic RV LGE is strongly associated with an adverse clinical outcome, especially arrhythmia in TGA. Thus, LGE CMR should be incorporated in risk stratification of these patients.4
For aortic regurgitation, CMR phase-contrast imaging has higher reproducibility than echocardiography in quantifying the regurgitant volume and is more suitable for serial monitoring.
CMR is a useful tool in assessing patients before or after transcatheter aortic valve replacement (TAVR)
Compared to transthoracic echocardiography (TTE), CMR is more accurate in sizing the aortic annulus before the procedure, which predicts the severity of aortic regurgitation after TAVR.
