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
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
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).
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.
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
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.
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.
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
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.
