Quiz: Cardiovascular: Cardiac Function 1

The workhorse sequence for assessing cardiac function is:
- Spoiled gradient recalled echo because it has high signal to noise ratio and is robust to artefacts.
- Balanced steady state free precession as it has high signal to noise ratio and has contrast determined by the ratio of T2 to T1.
- Turbo-spin echo as it is very fast and robust to off-resonance artefacts.
- MR fingerprinting as it provides all the information you could ever want.
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When contouring the left ventricle for functional assessment:
- The trabeculations and papillary muscles are excluded from the myocardial mass as it is more reproducible.
- The trabeculations and papillary muscles are included in the myocardial mass as it is more accurate.
- Some centres include papillary muscles and some leave them out of the myocardial mass estimates as there is no current consensus.
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Feature tracking:
- Tracks the tag intersections from tagged cine data to measure myocardial velocity
- Provides blood flow velocity by tracking blood throughout the cardiac cycle.
- Tracks the movement of the heart valves to identify regurgitation
- Tracks the myocardium through the cardiac cycle from cine images to produce a model of myocardial motion.
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Tagging:
- Provides measures of tissue deformation calculated from images where a spatial variation in signal intensity is applied at the beginning of each cardiac cycle.
- Provides displacement information via the phase images, where the image phase is proportional to the displacement of the myocardium relative to the beginning of the cardiac cycle.
- Is a method for assessing through-plane motion via the image phase.
- Tracks the displacement of the epi and endocardial borders on balanced steady state free precession cine images to provide models of myocardial deformation.
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Displacement encoding with stimulated echoes (DENSE):
- DENSE typically requires shorter breath hold durations than tagging and does not suffer from tag fade.
- DENSE typically provides higher spatial resolution displacement (and therefore strain information) than tagging, but is a more complicated pulse sequence.
- It is straightforward to acquire tagging data with encoding in three directions for estimating 3D strains, whereas DENSE is intrinsically only a 2 direction encoding method.
- DENSE analysis automatically tracks the epi and endocardial borders to provide a model of ventricular deformation.
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Global (whole slice) strains are similar when obtained from feature tracking strain results and from tagged images, but regional strains differ between the two techniques because:
- Feature tracking algorithms effectively track the epi and endocardial borders and through plane motion artefactually affects the measured regional strains.
- Tags fade through the cardiac cycle, but feature tracking is consistent throughout the cardiac cycle, therefore regional peak systolic strains obtained from tagging are under-estimated.
- The high velocities typically present in the septal wall cannot be accurately tracked with feature tracking result in over-estimation of regional strains relative to tagging results.
- The cyclical boundary conditions imposed by feature tracking analysis software result in artefacts in the regional strain values produced.
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