Resources/Protocols
Cardiac MRI protocols
The most sequence-intensive exam in MRI — morphology, function, flow and tissue characterisation in a single sitting.
Cardiac MRI asks the radiographer to combine two synchronisations at once: the cardiac cycle and the respiratory cycle. Everything else follows from getting those right. Planning is built from the heart's own oblique axes rather than the body's, and each sequence family answers a different clinical question.
Deep-dive protocol guides
Full step-by-step protocols — positioning, per-sequence planning, parameters, artifacts and a review checklist for each study:
Studies in this region
- Dark-blood morphology
- White-blood imaging
- Cine function
- Ejection fraction
- Flow quantification
- 3D and 4D flow
- Venc scout
- Perfusion
- Late enhancement / viability
- T1 mapping
Planning
- Establish reliable ECG gating before scanning — a poor trace corrupts every subsequent sequence.
- Build the cardiac axes in sequence: from axial localizers to vertical long axis, horizontal long axis, then true short axis.
- Plan the short-axis stack perpendicular to the interventricular septum, covering base to apex without gaps.
- Set the velocity encoding for flow sequences just above the expected peak velocity — too low aliases, too high loses sensitivity.
- Keep breath-hold instructions consistent so short-axis slices stack correctly for volume calculation.
Sequences by study
| Family | Typical use | Why |
|---|---|---|
| Dark-blood morphology | Anatomy and tissue overview | Blood suppressed for clear wall definition |
| Cine (white blood) | Wall motion, volumes, ejection fraction | Function across the cardiac cycle |
| Flow quantification | Valve and shunt flow | Velocity-encoded phase contrast |
| 4D flow | Complex flow patterns | Volumetric velocity data over time |
| Perfusion | Myocardial blood supply during stress and rest | First-pass contrast imaging |
| Late enhancement | Infarct and fibrosis (viability) | Scar retains contrast longer than healthy myocardium |
Mistakes that cost repeats
- Accepting a marginal ECG trace — gating failure invalidates the whole study, not one sequence.
- A short-axis stack angled to the body rather than perpendicular to the septum, corrupting volume measurements.
- Velocity encoding set too low, producing aliased flow that cannot be quantified.
- Inconsistent breath-holds across the short-axis stack, leaving gaps or overlaps between slices.
Common questions
- Why is ECG gating essential in cardiac MRI?
- The heart moves throughout every cardiac cycle. Gating synchronises data collection to the same cardiac phase across heartbeats, so the images represent a consistent moment rather than a blur of the whole cycle.
- How are the cardiac imaging planes derived?
- They are built stepwise from the heart's own geometry: axial localizers give the vertical long axis, which gives the horizontal long axis, which in turn defines the true short axis perpendicular to the septum.
- What does late gadolinium enhancement show?
- Scarred or fibrotic myocardium washes contrast out more slowly than healthy tissue, so it appears bright on delayed imaging — the basis for assessing infarct extent and viability.
- How is velocity encoding chosen for flow imaging?
- Set it just above the expected peak velocity. Too low and the flow signal aliases and cannot be measured; too high and low velocities are encoded with poor sensitivity.
Try it in ScanFlo: Plan a short-axis stack perpendicular to the septum, then a second angled to the body axis, and compare the ventricular cross-sections. The second one is why volume measurements go wrong.