B P3 C19 Cardiovascular MRI Flashcards
In MRI, after delivery of a radiofrequency pulse, the electromagnetic energy absorbed by the H nuclei will be released back to the environment by two coexisting mechanisms:
Longitudinal magnetization recovery
Transverse magnetization decay
The rates of longitudinal magnetization recovery and transverse magnetization decay are measured by ____ and _______ values, respectively.
T1 and T2 (or T2*)
For qualitative interpretation, ________ is in general preferred in CMR, thus most pulse sequences used in CMR are T1-weighted techniques
Signal enhancement (from T1 effects)
Current common T1-weigh CMR techniques include gradient echo cine, myocardial perfusion, late gadolinium enhancement (LGE), and phase contrast blood flow imaging.
T2-weighted and T2*-weighted CMR are primarily for imaging of _______ and _________, respectively.
Myocardial edema
Iron content
________ the standard pulse sequence for quantifying cardiac volumes and functions, employs a mixed T2/T1 weighting
Cine steady-state free precession (SSFP)
________ are most commonly used in clinical CMR.
Gadolinium-based contrast agents (GBCAs)
When injected as an intravenous bolus, a GBCA transits through cardiac chambers and coronary arteries over 15 to 30 seconds (________) before it diffuses into the extracellular space.
First-pass phase
At approximately 10 to 15 minutes after injection, a ______________ between contrast washing-in into the extracellular space and washingout to the blood pool is reached
Transient equilibrium
____________ are performed during the first-pass phase, whereas __________ are obtained during the equilibrium phase
Myocardial perfusion CMR and most magnetic resonance angiograms (MRAs)
LGE images
An interstitial inflammatory reaction that can lead to severe skin induration, contracture of the extremities, fibrosis of internal organs, and death after exposure of patients with severe renal dysfunction with GBCA
Nephrogenic systemic fibrosis (NSF)
Risk factors to developing NSF include
Estimated glomerular filtration rate (eGFR) <30 mL/ min/1.73 m2
Need for hemodialysis
Acute renal failure
Presence of concurrent proinflammatory events.
To overcome blurring from cardiac motion, data acquisition is synchronized to the electrocardiogram (ECG) signal (cardiac gating), which is either _____________ (ECG triggering follows imaging data acquisition in each cardiac cycle) or ______________ (continuous data acquisition with subsequent reconstruction based on ECG timing).
Prospective
Retrospective
For cine imaging, __________ is preferred because it covers the entire cardiac cycle.
Retrospective gating
CMR uses ___________ imaging to assess cardiac morphology and structure.
Bright-blood cine SSFP imaging or
Dark-blood fast spin-echo (FSE)
_________ can image the heart in motion at a high temporal resolution of 30 to 45 msec during a breath-hold of <10 seconds.
Cine SSFP
For dark-blood techniques, __________ is used for morphology of cardiac chambers, vascular structures, pericardium, and imaging of fat.
T1-weighted FSE
T2-weighted FSE with fat suppressed can image for _______
Myocardial edema
________ is a T1-weighted imaging that detects accumulation of GBCA in the myocardium due to infarction, infiltration, or fibrosis.
LGE
LGE is detected 5 to 15 minutes after an intravenous injection of GBCA (0.1 to 0.2 mmol/ kg) (hence the term “late”). LGE data can be captured in 2D or 3D.
________ is routinely used in LGE imaging to enhance myocardial tissue contrast.
Phase-sensitive inversion recovery (PSIR) reconstruction
________ is routinely used in LGE imaging to enhance myocardial tissue contrast.
Phase-sensitive inversion recovery (PSIR) reconstruction
CMR perfusion imaging examines the ___________ of an intravenous bolus of GBCA as it travels through the coronary circulation.
First-pass transit
Gadolinium provides strong ________ in well-perfused region compared with hypoenhancement (dark regions) in poorly perfused myocardium.
Signal enhancement
At a spatial resolution of approximately 2 mm in-plane, CMR perfusion can provide information of ____________ at the endocardial/epicardial or at a segmental level.
Myocardial blood flow
T2-weighted imaging detects myocardial edema from _________ or __________, and it has been shown to have high correlation to the area-at-risk after acute myocardial infarction (MI)
Ischemic injury or inflammation
CMR perfusion also complements LGE in determining the chronicity of an MI and allowing for accurate measurement of _________ .
Salvageable myocardium
T2* is a transverse relaxation parameter well validated method for measuring tissue _______
Iron content
The normal T2* of the myocardium
∼40 to 50 msec
T2* level of _____ is diagnostic of myocardial iron overload
T2* of <20 msec
T2* of _______ is evidence of severe iron overload.
<10 msec
_____________ allows quantitation of velocities of blood flow and myocardial motion and intravascular flow rates.
Phase contrast imaging
Estimate in quantitative terms the expansion of the extracellular space in the myocardium where GBCA distribute; has good correlation with collagen content of the interstitial space in conditions where diffuse fibrosis or infiltration occurs
T1 Mapping
Noninvasive method in monitoring disease progression or treatment response
Provides quantitation of the spectrum of extracellular volume (ECV) expansion from fibrosis or infiltration; characterized myocardial pathology not visible by LGE imaging.
T1 Mapping
Involves acquisition of a series of images with different T2 weighting, provides a quantitative measurement of regional fraction of free water in the myocardium.
T2 Mapping
_________ renders the detection of myocardial edema more reliable and is less prone to artifacts due to either motion or arrhythmia
T2 mapping
Accurate in diagnosing and risk stratifying for CAD in patients with stable chest pain syndromes; has fewer artifacts, is free from ionizing radiation, and has threefold higher spatial resolution
Stress CMR Perfusion Imaging
Excellent correlation of stress CMR perfusion against invasive measurement of fractional flow reserve (FFR), showcasing its high accuracy in determining the physiologic significance of coronary stenosis
A combined criteria of ___________ and ______________ in CMR has sensitivity and specificity between 85% and 90% in the prediction of segmental contractile recovery after revascularization
End-diastolic wall thickness of >5.5 mm
Cine systolic wall thickening of >2 mm
The ________ detected by LGE imaging accurately depicts a progressive stepwise decrease in functional recovery despite successful coronary revascularization, especially robust in myocardial regions of akinesia or dyskinesia
Transmural extent of myocardial scar
______ cutoff is sensitive in detecting segmental contractile recovery.
50% transmurality
______ can provide a physiologic assessment of the mid-myocardial and subepicardial contractile reserve and may be useful when tissue edema is prominent (e.g., early after an acute coronary syndrome), making infarct transmurality assessment challenging.
Low-dose dobutamine cine imaging
___________ is at present the most sensitive and accurate imaging method in detecting subendocardial infarction and quantifying infarct size, respectively
CMR LGE imaging
CMR is not indicated as a routine first-line imaging after an acute MI, but it is useful in assessing the most common issues after an acute MI, including
Addressing the perfusion status of MI or the extent of noninfarct salvageable myocardium
Complications such as formation of aneurysm, intracavitary thrombus, microvascular obstruction, pericarditis, or ventricular septal defect
The ffg can be quantified by what CMR techniques
Acute reperfused MI, regions of ischemic area-at-risk
Microvascular obstruction (no-reflow)
Intramyocardial hemorrhage
Acute reperfused MI, regions of ischemic area-at-risk - T1 or T2 mapping
Microvascular obstruction (no-reflow) - LGE
Intramyocardial hemorrhage - T2* mapping
Dark-blood LGE imaging improves the detection of subendocardial infarction by enhanced discrimination of the infarct-blood border 1
The noninvasive gold standard for infarct size and microvascular obstruction.
CMR
The _________ continue to demonstrate strong prognostic association with serious ventricular arrhythmias and sudden cardiac death in various types of cardiomyopathies
Presence, pattern, and extent of LGE
CMR has higher sensitivity than echocardiography for diagnosing HCM by capturing ____________ or ___________, which are occasionally missed by echocardiography
Hypertrophy of the basal anterior wall or apical aneurysm
Markedly elevated LV mass index (men >91 g/m2 and women >69 g/m2 ) and maximal wall thickness of ________ have been shown to be sensitive and specific markers of risk of cardiac death, respectively.
> 30 mm
In a large series, the extent of LGE was indicative of ____________ and was associated with ventricular arrhythmias, progressive LV dilation, and cardiac events, regardless of presence of outflow obstruction or prior septal myectomy
Heterogeneous fibrosis
______ by cine CMR, LGE, and regional strain imaging estimates the risk of atrial fibrillation in HCM patient
Quantifying left atrial remodeling
The ________ was shown to have strong association with ventricular arrhythmia independent of presence of fibrosis.
Directionality of myocardial disarray (known as fractional anisotropy)
Identify the pathology
Microvascular obstruction
Left, Short-axis T2*-weighted image from a porcine model of reperfused MI demonstrating intramyocardial hemorrhage in the anteroseptum.
Right, Short-axis phasesensitive inversion recovery LGE image in the same animal demonstrating transmural LGE with a mid-wall region of intramyocardial hemorrhage.
Identify the pathology
Ventricular pseudoaneurysm
Left, A two-chamber long-axis SSFP cine image at end-diastole in a patient 5 years after anterior MI demonstrating a chronic anterior pseudoaneurysm. Note the narrowed neck of the pseudoaneurysm.
Right, Short-axis phase-sensitive inversion recovery LGE image from the same patient demonstrating enhancement of the fibrous outer layer of the pseudoaneurysm, which is lined with thrombus, which appears black.
Identify the pathology
Apical hypertrophic cardiomyopathy with apical thrombus.
CMR in a 36-year-old man with syncope demonstrates “burnt out” apical HCM with evidence of an apical LV thrombus on LGE imaging and cine functional four- and two-chamber imaging
Arrhythmogenic cardiomyopathy distinguishes itself from other cardiomyopathies by
(1) a predisposition toward ventricular arrhythmia that precede overt morphologic abnormalities and even histologic substrate
(2) diverse phenotypic manifestations including LV or biventricular involvement
Major criteria in the diagnosis of ARVC based on 2010 Task Force Criteria
Combination of regional RV akinesia/dyskinesia/ dyssynchronous contraction and significant RV dilation or dysfunction
Areas of predilection in ARVC
Subtricuspid region, basal RV free wall, and LV p terolateral wall. 2
Patients with _______ experienced substantially higher risk of sudden death or arrhythmic events than those with solitary RV involvement, and no events were observed in those with a negative CMR
LV involvement
Identify the pathology
35/F who developed heart failure following birth of her second child.
ECG- LAFB and frequent ventricular couplets
Echo- mild LV and RV dysfunction, with hyperdynamic function of the RV apex relative to the rest of the right ventricle (McConnell’s sign)
The differential diagnosis - peripartum cardiomyopathy, pulmonary embolism, myocarditis, arrhythmogenic cardiomyopathy
Arrhythmogenic cardiomyopathy
A, End-systolic frame from cine CMR (see also Video 19.6) shows “crinkling” or “accordion sign of the RV base (white arrows) and notching of the LV epicardium due to fatty infiltration (yellow arrows).
B, Post-contrast T1-weighted inversion recovery image shows LGE of the RV free wall and LV epicardium (arrows).
CMR targets the three main pathophysiologic components of myocarditis
Myocardial edema by T2-weighted imaging
Regional hyperemia and capillary leak by early gadolinium enhancement ratio (EGEr )
Myocardial necrosis or fibrosis by LGE imaging
The _______ walls have been described in parvovirus-related cases,
Subepicardium and midmyocardium of the inferolateral
________ involvement has been associated with human herpesvirus 6
Septal
__________ has been shown to differentiate acute versus healed stages of myocarditis in cases where chronicity of myocarditis is uncertain.
T2 mapping
Identify the pathology
CMR of a 54-year-old man with fever, chills, rash, and elevated troponin, sedimentation rate, and C-reacti protein revealed dilated cardiomyopathy with a LV ejection fraction of 28%
Acute Myocarditis
There were diffuse inflammatory abnormalities with T1 >1300 msec, T2 >70 msec, ECV ∼50%, and patchy mid-wall enhancement on LGE imaging, consistent with acute myocarditis. He was treated with intravenous immunoglobulin, methylprednisolone, tofacitinib, and tocilizumab.
CMR may enhance disease detection through the successive histologic stages of disease:
Tssue edema
oncaseating granulomatous infiltration
Patchy myocardial fibrosis
Most commonly, cardiac infiltration based on LGE imaging is seen in multiple locations involving the ______ and _______ part of the right ventricle.
Septum and basal anterior
Typical cases demonstrate __________ and occasionally high signal on T2-weighted imaging indicative of edema
Expansion of the wall thickness matched with LGE infiltration
In patients with known cardiac sarcoidosis, current evidence suggests that _______ are the strongest risk markers for mortality or significant ventricular arrhythmias
Presence, multiple foci, extent of LGE
RV systolic dysfunction
RV LGE
Per current A can College of Cardiology (ACC)/American Heart Association (AHA) guideline, patients with cardiac sarcoidosis, the presence of LGE is a _________ for ICD therapy in patients with an expected meaningful survival >1 year.
Class IIa indication
48-year-old woman with new-onset complete heart block and history of pulmonary sarcoidosis
Identify
Cardiac sarcoidosis
Extensive LV subepicardial late gadolinium enhancement in short axis (A) and long axis (B) images, consistent with cardiac involvement, and myocardial edema on T2-weighted imaging suggesting active inflammation
Typically demonstrates morphologic changes of a restrictive cardiomyopathy, circumferential and diffuse LGE in the LV with possible RV subendocardial involvement, and in some cases microvascular dysfunction on first-pass perfusion matching the LGE regions.
Cardiac amyloidosis
Cardiac amyloidosis from _______ appears to show more ventricular remodeling of increased myocardial mass, transmural LGE, and RV involvement
ATTR Amyloidosis
The transmurality and extent of LGE represent advanced cardiac amyloidosis, and these findings are associated with patient mortality incremental to common risk markers including systolic and diastolic function
However, ____________ has become a part of the standard diagnostic algorithm because it offers a more complete quantitation of the regional and global severity of amyloid infiltration
Myocardial ECV quantitation
75-year-old man with worsening heart failure with persevered ejection fraction with the ffg CMR
Identify
Cardiac amyloidosis
Extensive mid-wall LV (A and B) and left atrial (C) LGE consistent with cardiac amyloidosis. Subsequent RV biopsy confirmed the diagnosis of transthyretin (ATTR) amyloidosis.
In about 30% of patients with idiopathic dilated cardiomyopathy, a _________ has been reported and its extent is associated with a lack of response to medical therapy, sudden death, and inducible ventricular tachycardia, independent of LV size and function.
Patch or linear mid-wall striae septal LGE
In patients with reduced ventricular function, a _______ (at 1.5T) is consistent with iron overload, whereas a myocardial ________ indicates a high risk of clinical heart failure, despite normal LV function, within 1 year.
T2* <20 msec
T2* <10 msec
___________ precipitated by elevated catecholamines from severe emotional or physical stress, is characterized by a transient circumferential contractile dysfunction of the apex, which is in stark contrast to basal hyperkinesia.
Transient LV apical ballooning syndrome (or Takotsubo cardiomyopathy)
CMR findings in Takotsubo CMP
Myocardial edema
Perfusion defects consistent with microvascular dysfunction, matching the segments with severe systolic dysfunction
LGE imaging in most cases are negative showing only a low-intensity diffuse enhancement
Indeed, significant LGE should raise the suspicion for an alternative diagnosis of an acute coronary event.
63-year-old man with fatigue, elevated eosinophil count, and echocardiogram suggestive of LV apical thrombus
Identify
Loeffler’s cardiomyopathy
Normal LV and RV systolic function with obliteration of the LV apex on SSFP cine sequences in four-chamber and twochamber projections (Above)
Bottom, LGE imaging with phase-sensitive inversion recovery revealed subendocardial LGE at the LV apex (arrows) with overlying apical thrombus (asterisk). Collectively these findings are consistent with endomyocardial fibrosis (Loeffler’s endocarditis
55 male with HF symptoms, LVEF 30%
Identify
Nonischemic dilated CMP
There was absence of both stress perfusion defect (middle) and LGE (right) so that infarction and infiltration were ruled out. In approximately 30% of patients with idiopathic cardiomyopathy, there is a characteristic mid-wall striate of LGE.
__________ often coexist in the pressure-loaded LV myocardium in patients with severe aortic stenosis.
Diffuse (patchy LGE) or replacement (endocardial) myocardial fibrosis
In elderly patients, coexistence of ________ was noted by CMR in 8% of patients manifesting a low-flow low-gradient pattern, and it has poor prognosis
Amyloidosis
Pericardial thickness can be shown on either black-blood FSE or cine imaging, where up to ______ is considered normal; however, minimal but diffuse increased thickness is observed in 20% of patients with significant pericardial constriction.
2 mm
Pericardial LGE after the administration of GBCA indicates _________ and has been shown to complement C-reactive protein levels in diagnosing active pericarditis and predicting reversibility of pericardial inflammation and even constrictive physiology in response to anti-inflammatory medical therapies
Active pericardial inflammation
________ usually have thin smooth walls without internal septa and their transudative contents appear homogeneous dark on T1-weighted images and bright on T2weighted images, with no enhancement after contrast.
Simple pericardial cysts
Findings on T1 and T2 weighted images of the ffg:
Simple pericardial cysts
Proteinaceous cysts
Exudative pericardial fluid
Hemorrhagic pericardial fluid
Simple pericardial cysts - dark T1, bright T2, no enhancement after contrats
Proteinaceous cysts - bright T1, dark T2
Exudative pericardial fluid - medium T1
Hemorrhagic pericardial fluid - bright T1 and T2 (but darkens as hemosiderin deposition occurs as it develops into a hematoma)
Malignant invasion of the pericardium often shows _________ of the pericardial line and a pericardial effusion.
Focal obliteration
Most neoplasms appear ______ on noncontrast T1-weighted images except metastatic melanoma owing to its paramagnetic metals bound by melanin.
Dark or gray on T1
CMR contributes to assessment of patients at risk of sudden death (SD) by
Quantitation of LV ejection fraction
RV pathology
Detection of myocardial scar using LGE
Anomalous coronary arteries
Less commonly T2* mapping for iron overload.
LGE _________ of LV mass has been reported to be a risk marker in both ischemic and nonischemic cardiomyopathies
Larger than 5%
76 male with HF symptoms with hx of CAD
Identify
Ischemic CMP
B and C, LGE images showed a lateral wall transmural myocardial infarction (yellow arrows) together with tethering of the posterior mitral leaflet. In addition, midwall septal fibrosis (white arrows) suggested mixed ischemic and nonischemic cardiomyopathy.
66-year-old woman with recent acute pericarditis and worsening pain and dyspnea despite anti-inflammatory therapy
Identify
Constrictive Pericarditis
Both SSFP cine (A) and T1-weighted fat suppressed (B) sequences revealed diffuse pericardial thickening (asterisks).
(C) Both pericardial layers exhibited diffuse hyperintensity on T2-weighted images consistent with pericardial edema (asterisks)
D, The pericardium enhanced on first-pass perfusion images (Video 19.25) and demonstrated severe concentric LGE (asterisks) signaling pericardial inflammation.
Identify
Scimitar syndrome
Identify
Coarctation of the Aorta
Cine SSFP in a longaxis “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.
Black-blood FSE is useful to evaluate the entire aorta because it is less affected by metallic artifacts from implanted endovascular stent than gradient-echo techniques.
Phase-contrast imaging can characterize the descendingto-ascending aorta flow ratio and estimate pressure gradient across the coarctation and collaterals formation
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 3D.
__________ does not enhance on first-pass perfusion and often has a characteristic “etched” appearance on LGE imaging
Mural thrombus
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.
Often seen as a round or multilobar mass in the left atrium (75%), right atrium (20%), and ventricles or mixed chambers (5%)
Atrial Myxoma
Identify
66-year-old woman with factor V Leiden mutation and antiphospholipid syndrome and finding of a mass on echocardiography
Cardiac thrombus
(A) Steady-state free precession image, four-chamber view demonstrates an isointense mass in the left atrium posterior wall (asterisk).
(B) T1-weighted black-blood image, short-axis view demonstrates an isointense mass attached to the left atrial wall (arrows). There is another small mass in the posterior wall of the atrium (asterisk), which suggests presence of multiple thrombi.
(C) On LGE image, short-axis view, the mass appears to be heterogeneously hyperintense, while
(D) on LGE, long inversion time (T1) image (T1 = 600 ms), short-axis view, the mass was nulled completely suggesting lack of enhancement.
Identify
24-year-old woman with and suspicion of a left atrial mass on echocardiography
Cardiac myxoma
B, Tissue characterization revealed hyperintense signal on T2-weighted sequence suggestive of tissue edema. C, There was heterogenous signal intensity on LGE imaging.
Identify based on LGE pattern
Subendocardial or
Transmural
Ischemic/Coronary Pattern
Identify based on LGE pattern
Global or patchy subendocardial (non coronary)
More extensive and diffuse LGE, often more diffuse and transmural pattern, QALE score ≥ 13
Cardiac Amyloidosis - ATTR
Identify the LGE pattern:
Mid-wall or subepicardial septal LGE
Dilated cardiomyopathy
Identify the LGE pattern
Focal (mid-wall) LGE of anterior and posterior RV insertion points (hinge points) and of hypertrophied segments
Hypertrophic cardiomyopathy
Identify the LGE pattern
Basal to mid-interventricular septum and RV insertion points or diffuse patchy LGE
Systemic Sclerosis
Identify the LGE pattern
Lateral, typically inferolateral or inferior wall with a mid-wall to subepicardial enhancement
Myocarditis
Identify the LGE pattern
Subepicardial/midwall, basal and mid-interventricular septum but also patchy LGE
Sarcoidosis
Identify the LGE pattern
Diffuse LGE of RV (and occasionally LV) wall
ARVC
CMR criteria for LV noncompaction
NC/C ratio > 2.3 measured end diastole
MRI predictors of segmentile contractile recovery after revascularization:
End diastolic wall thickness >5.5 mm
Cine systolic wall thickening >2 mm
<50% transmurality
