Why is ECG gating essential in cardiac MRI?

The heart moves continuously, so images must be synchronised to the cardiac cycle. ECG gating tells the scanner when to acquire each phase; without a clean trace, the images mistrigger and blur, and the study fails.

What does late gadolinium enhancement show?

It distinguishes viable muscle from scar. Ten to fifteen minutes after contrast, normal myocardium washes out and appears black, while scarred tissue retains contrast and stays bright. This 'dead or alive' test guides revascularisation decisions.

How can you tell ischaemic scar from myocarditis on LGE?

Ischaemic scar enhances from the inner (subendocardial) wall outward and follows a coronary-artery territory. Myocarditis and many cardiomyopathies enhance in the mid-wall or epicardium and do not respect coronary territories.

Cardiac MRI protocol

Imaging that freezes a beating heart, in three dimensions of space plus time. You assess structure, function and viability, and everything depends on two things working: a clean ECG trace and a reproducible breath-hold.

By the ScanFlo Editorial Team · Updated 12 October 2026

In this section · Protocols

Protocols/Cardiac

When this study is used

Ventricular function and ejection fraction (cardiomyopathy, heart failure).
Myocardial viability and scar after infarction.
Suspected myocarditis, infiltration or intracardiac thrombus.

Patient & coil positioning

Head-first supine in a cardiac/torso array coil; place ECG leads in the 'vector' arrangement, close together on the left chest, to limit the magnetohydrodynamic effect that distorts the T-wave.
Verify a clean, well-triggered ECG before scanning. A bad trace makes the exam impossible.
Rehearse the breath-hold at end-expiration ('breathe in, blow out, small breath in, hold'); expiratory holds are the more reproducible.

Localizer

Axial/coronal localizer to find the left ventricle, then build the cardiac planes step by step. Cardiac geometry follows the heart, not the body.

Sequence planning

For each sequence below you get the reference line the slice group follows, how much it covers, and why the sequence is in the protocol at all. Plan against the localizer, not by eye.

Cine bSSFP (TrueFISP / FIESTA)

2-ch, 4-ch, short-axis

Planning: Build via the double-oblique technique (below); stack short-axis slices across the ventricle like a loaf.

Why: Bright-blood cine for wall motion and ejection fraction, with volumes measured from the short-axis stack.

Late gadolinium enhancement (LGE)

Short-axis + long-axis

Planning: Acquire 10–15 minutes after contrast, matched to the cine slices; set the inversion time to null normal myocardium.

Why: The dead-or-alive test: normal muscle goes black, while scar retains contrast and stays bright.

T2 / T2-STIR (oedema)

Short-axis

Planning: Match the cine coverage.

Why: Myocardial oedema in acute injury and myocarditis.

Early post-contrast (thrombus)

Long-axis

Planning: Through the LV apex.

Why: Non-enhancing thrombus stands out dark against enhancing blood and scar.

Representative parameters

Treat these as ranges. Field strength, coil and vendor all move the numbers. What must not move is understanding why each sits where it does.

Sequence	Gating	Notes
Cine bSSFP	ECG, breath-hold	Function, EF from short-axis stack
LGE	ECG, breath-hold	TI nulls normal myocardium; 10–15 min post-contrast
T2-STIR	ECG, breath-hold	Oedema

Artifacts & how to fix them

Artifact	Typical cause	Mitigation
ECG mistrigger	Magnetohydrodynamic T-wave distortion	Vector lead placement; re-attach; check trace before scanning
Breathing blur	Inconsistent breath-holds	Rehearse; end-expiration holds; real-time cine if needed
Dark-rim / off-resonance	bSSFP banding	Shim carefully; adjust frequency
Wrong LGE nulling	Inversion time not matched	Run a TI-scout; set TI to null normal myocardium

What am I looking at?

You are not reporting the study, but recognising pathology helps you keep it in the field of view and know when to add a sequence or contrast. How the common findings read on the console:

Finding	Sequence to check	How it reads
Ischaemic infarct	Short-axis LGE	Subendocardial bright enhancement following a coronary territory
Myocarditis / cardiomyopathy	Short-axis LGE	Mid-wall or epicardial patchy enhancement, not coronary-territory
Apical thrombus	Cine + LGE	Dark, non-enhancing mass in the LV apex

Review checklist

Clean ECG trace throughout acquisition.
Short-axis cine stack covers base to apex for volume measurement.
LGE inversion time correctly nulls normal myocardium.
Enhancement pattern classified as ischaemic (subendocardial) or non-ischaemic.

Mistakes that cost repeats

Scanning on a poor ECG trace and getting blurred, mistriggered cines.
LGE with the wrong inversion time, so scar and normal muscle look alike.
Inconsistent breath-holds shifting the heart between slices.
Skipping the short-axis stack needed to compute ejection fraction.

Common questions

Why is ECG gating essential in cardiac MRI?: The heart moves continuously, so images must be synchronised to the cardiac cycle. ECG gating tells the scanner when to acquire each phase; without a clean trace, the images mistrigger and blur, and the study fails.
What does late gadolinium enhancement show?: It distinguishes viable muscle from scar. Ten to fifteen minutes after contrast, normal myocardium washes out and appears black, while scarred tissue retains contrast and stays bright. This 'dead or alive' test guides revascularisation decisions.
How can you tell ischaemic scar from myocarditis on LGE?: Ischaemic scar enhances from the inner (subendocardial) wall outward and follows a coronary-artery territory. Myocarditis and many cardiomyopathies enhance in the mid-wall or epicardium and do not respect coronary territories.

Try it in ScanFlo: Build the cardiac planes with the double-oblique method (axial to 2-chamber to 4-chamber to short axis), each planned off the last. Watch how the heart's own geometry emerges step by step. That sequence of obliques is the whole skill of cardiac planning. See ScanFlo MRI →

← All cardiac studies

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