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