CARDIAC MAGNETIC RESONANCE IMAGING Flashcards
What is cardiac magnetic resonance (CMR)?
A non-invasive imaging technique that uses a strong magnet, radiofrequency pulses, and gradient magnetic fields to produce detailed images of the heart.
CMR is essential for evaluating various cardiac conditions without ionizing radiation.
What strength of magnet does CMR typically use?
1.5 to 3.0 Tesla
This is equivalent to 30,000–60,000 times the strength of the earth’s magnetic field.
What fundamental process allows CMR to produce images?
The alignment of positively charged protons in a magnetic field, followed by relaxation and signal emission.
This involves T1 and T2 relaxation components.
What is k-space in CMR?
A data space where collected signals are organized before creating an image.
It is essential for image reconstruction in CMR.
How does CMR differ from echocardiography?
CMR does not expose patients to ionizing radiation and has superior contrast-to-noise and signal-to-noise ratios.
This allows better delineation of tissue borders.
What are some limitations of CMR?
Availability, portability, contraindications, difficulty with irregular rhythms, and claustrophobia.
CMR requires specialized facilities and trained personnel.
What are common indications for CMR?
- Evaluation of chest pain syndrome
- Assessment of coronary anomalies
- Evaluation of LV function after myocardial infarction
- Assessment of myocardial viability
- Evaluation of myocarditis
- Evaluation of specific cardiomyopathies
- Characterization of cardiac valve dysfunction
- Evaluation of cardiac masses
- Assessment of congenital heart disease
- Evaluation for aortic dissection
These indications highlight CMR’s versatility in cardiac assessment.
What pulse sequences are commonly used in CMR?
- Bright blood gradient echo sequences
- Dark blood spin echo sequences
- Steady-state free precession sequences
- Inversion recovery sequences
These sequences help in visualizing different aspects of cardiac structures.
What is late gadolinium enhancement (LGE) imaging?
A CMR technique used to identify myocardial scar/fibrosis by administering gadolinium-based contrast agents.
LGE imaging helps in assessing areas of scar after myocardial infarction.
Can CMR be used for stress testing in patients with chest pain?
Yes, CMR stress testing can assess flow-limiting coronary stenosis in patients with intermediate pretest probability of CAD.
Methods include vasodilator perfusion CMR and dobutamine stress function CMR.
What is the role of CMR in evaluating ventricular function?
CMR is the reference standard for assessing ventricular volumes, ejection fraction, and ventricular mass.
It is particularly useful after myocardial infarction or in heart failure.
What specific cardiomyopathies can CMR assess?
- Infiltrative diseases (e.g., amyloid, sarcoid)
- Hypertrophic cardiomyopathy
- Arrhythmogenic right ventricular cardiomyopathy
CMR can reveal unique LGE patterns associated with various cardiomyopathies.
What is the importance of T1 and T2 mapping in CMR?
They provide direct quantification of myocardial tissue properties, aiding in the assessment of conditions like edema and fibrosis.
These mapping techniques are evolving for better accuracy in diagnoses.
How can CMR be used in the context of myocardial infarction?
CMR identifies myocardial necrosis, microvascular obstruction, and myocardial thrombus using LGE imaging.
It also assesses the likelihood of recovery of function with revascularization.
What role does CMR play in assessing valvular disease?
CMR assists in evaluating valve lesions when echocardiographic images are technically limited and provides quantitative assessments of stenosis and regurgitation.
Techniques such as phase-contrast imaging are utilized for flow measurements.
