MRI Workup of Ischemic Heart Disease — Insights and Innovations
MRI Workup of Ischemic Heart Disease — Insights and Innovations
Source: Medscape (Supported by Bayer)
Date: 21, October 2025
Keynotes:
1. Purpose
Cardiac Magnetic Resonance (CMR) is a specialized, non-invasive test used to assess heart muscle structure, function, perfusion, and scarring.
It complements coronary CT angiography (CCTA), which focuses mainly on coronary artery visualization.
2. Cine Imaging
Cine imaging acts like a moving video of the beating heart, synchronized with the ECG.
It shows ventricular wall motion, contractility, and ejection fraction, allowing detection of ischemic wall motion abnormalities and stunned myocardium.
3. Perfusion Imaging
Perfusion sequences evaluate blood flow to the myocardium at rest and under stress.
They identify ischemic or underperfused regions and guide treatment or revascularization decisions.
4. Late Gadolinium Enhancement (LGE)
LGE detects fibrosis and scarring caused by prior infarction or inflammation.
It distinguishes viable from non-viable myocardium, predicting the likelihood of recovery after PCI or CABG.
LGE imaging is typically performed 10–15 minutes after contrast injection.
5. T2 Imaging
T2-weighted sequences reveal myocardial edema, a sign of acute injury or inflammation.
• In acute MI, T2 and LGE follow a coronary distribution (subendocardial or transmural).
• In myocarditis, edema appears patchy or lateral, often with subepicardial or mid-wall enhancement.
Combining T2, LGE, and cine data helps distinguish inflammation from ischemic necrosis.
6. MR Angiography (MRA)
CMR can incorporate Magnetic Resonance Angiography (MRA) to visualize major vessels — such as the aorta, pulmonary arteries, carotid, renal, and limb arteries — without radiation.
It helps detect aneurysm, dissection, thrombosis, stenosis, or congenital anomalies, providing a radiation-free vascular map.
MRA is ideal for imaging large-vessel anatomy in the chest, neck, abdomen, and extremities, but not for coronary arteries, where CT angiography remains superior.
7. Contrast Use and Kidney Safety in MRA
MRA does not use iodine-based contrast like CT angiography.
Instead, it employs Gadolinium-based contrast agents (GBCA) — lighter, safer, and rarely nephrotoxic.
They are safe for most patients except those with severe renal failure (eGFR < 30 mL/min).
In such cases, non-contrast MRA techniques can still be performed effectively.
Both MRI and MRA use the same Gadolinium contrast — the difference lies in how it is injected: slowly for tissue imaging (MRI) and rapidly for vascular mapping (MRA).
8. Standard CMR Protocol
A full CMR study includes:
• Cine imaging (2-, 3-, and 4-chamber + short-axis views).
• Gadolinium contrast (0.1–0.2 mmol/kg).
• LGE imaging 10–15 minutes post-contrast for scar or fibrosis visualization.
A rapid protocol may combine cine and LGE, with optional stress perfusion for ischemia detection.
9. Acute vs. Chronic MI on CMR
• Acute MI: T2 detects edema; LGE shows acute injury.
• Chronic MI: CMR measures scar depth — < 50% wall thickness scarred suggests viable myocardium.
• True aneurysm: wide neck; false aneurysm: narrow neck (contained rupture).
10. CT vs. CMR — Complementary Tools
• CT (CCTA): best for coronary arteries — answers “Are the arteries blocked?”
• CMR: best for myocardial tissue and function — answers “How healthy is the heart muscle?”
Used together, they offer a complete anatomy + function + tissue approach.
11. How to Write a CMR Request in Clinical Practice
When a physician writes only “CMR” or “Cardiac MRI”, the radiologist interprets it as a standard comprehensive cardiac study including cine, LGE, and basic perfusion imaging.
However, the best practice is to specify the goal of the scan clearly, for example:
• “CMR – LV function and wall motion (cine imaging).”
• “CMR – Stress/rest perfusion to rule out ischemia.”
• “CMR – LGE for viability and scar evaluation.”
• “CMR – T2 mapping for acute injury or myocarditis.”
• “CMRA – Evaluate aorta, pulmonary arteries, and proximal coronary arteries (though less precise than CT angiography)”
• “Cardiac MRI (CMR) including MR Angiography if clinically indicated.”
12. Clinical Value
CMR and CCTA together provide a complete understanding of ischemic heart disease — one defines arterial anatomy, the other evaluates myocardial health.
This integrated approach improves diagnostic precision, guides therapy, and enhances long-term outcomes.
