Cardiac MRI > Technique > Review Questions 2

Review Question Answers

    1)  Which of the following can interfere with ECG gating?

    1. Arrhythmias
    2. COPD
    3. Large T waves
    4. Magnetohydrodynamic effects
    5. All of the above

    Answer: E. Arrhythmias have a variable R-R interval, thus making gating difficult. COPD patients may have a low ECG signal due to increased distance from the chest wall to the heart. Large T waves may mimic R waves. Magnetohydrodynamic effects can be solved with vectocardiogram gating.

    2)  True or False: All of the information for a segmented cine can be acquired during a single heart beat.

    Answer: False. A segmented cine is a collection of images aquired over multiple heartbeats. Each individual image in the cine is the result of data from same phase in the cardiac cycle over multiple heartbeats.

    3)  True or False: Myocardial tagging can be used to assess myocardial function because the tag lines move with the myocardium.

    Answer: True. Tag lines are applied prior to image aquisition by modulating the magnization gradient such that there is no signal coming from the tagged myocardium. Hence, the tag lines move with the initially tagged myocardium throughout the cardiac cycle.

    4)  What techniques are crucial to MRI coronary angiography?

    1. Cardiac gating
    2. Navigator
    3. Imaging during mid-diastole
    4. All of the above

    Answer: D. All of the above. Cardiac gating is used in all Cardiac MRI, but is especially important in coronary angiography due to the small size of the coronary arteries. Navigator echoes decrease the motion effect of breathing. The least amount of heart motion is during mid-diastole, so imaging is done at this point.

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