Cardiovascular magnetic resonance imaging (cardiac MRI)
Cardiac MRI is one of the most important non-invasive diagnostic techniques available. A cardiac MRI does not only provide a clear insight into the processes taking place inside the heart, but can also be used to help differentiate between different types of tissues, as well as allowing an assessment of heart function.
What is meant by cardiovascular magnetic resonance imaging (cardiac MRI)?
Cardiac MRI uses strong magnetic fields and specific radiofrequency pulses that excite molecules inside the patient's body (mainly hydrogen atoms), causing them to emit energy. This energy is then measured and converted into a digital signal, which is used to produce an image.
The main advantage of this technology is that it does not require ionizing radiation or iodine-based contrast media. A cardiac MRI usually takes between 45-60 minutes. Aside from using ECG triggering, the technology also requires the patient to hold their breath at certain stages during the process. Depending on the type of condition involved, cardiac MRI investigations may require contrast agents (gadolinium) to be injected via a peripheral IV access.
Possible applications
Coronary heart disease
- Assessment of cardiac vitality (see Fig. 1: Visualization of scarring following myocardial infarction)
- Evaluation of myocardial ischemia (adenosine/dobutamine stress MRI)
While cardiac MRI does not currently have a role in the assessment of coronary stenosis, it is sometimes used in the diagnosis of congenital vascular malformations.
Congenital heart defects
- Morphology
- Assessment of the severity of cardiac shunting
- Monitoring of patient progress following corrective surgery (due to the nature of our patient pool this is a very rare indication)
Heart valve disease
Although an evaluation of valve regurgitation and valve stenosis is possible, this is usually already covered by echocardiography-based investigations.
Cardiac neoplasms
- Cardiac tumors - benign; malignant (see Fig. 2)
- Thrombi
Pericardial disease
- Pericardial effusion
- Pericardial thickening
Cardiomyopathies
All types, including:
- Hypertrophic obstructive/non-obstructive
- cardiomyopathy
- DCM - dilated cardiomyopathy
- ARVC - arrhythmogenic right ventricular cardiomyopathy
- Non-compaction cardiomyopathy
Inflammatory myocardial diseases, e.g.:
- Acute and chronic myocarditis
- Churg-Strauss syndrome
- Sarcoidosis
Systemic diseases, e.g.:
- Amyloidosis (see Fig. 4)
- Hemochromatosis
- Fabry disease
Contraindications
- Non-MRI compatible pacemaker or ICD
- Neurostimulator
- Insulin pump
- Cochlear implants
- Penile implant
- Metallic splinters/shrapnel within the area of interest (thoracic vessels, eye)
- Ferromagnetic metal clips after carotid endarterectomy or neurosurgery
- 1. trimester of pregnancy
This procedure is not usually contraindicated (except in extremely rare cases) in patients with prosthetic heart valves, endovascular stents, joint prostheses or metal implants that are used to stabilize bones.
Preparation
Only a stress MRI requires some form of special preparation. Patients should stop taking beta blockers on the day of the procedure. If an adenosine stress MRI has been scheduled, patients must also avoid the following for 12 hours prior to surgery: coffee, caffeinated fizzy drinks, chocolate, tea.
Specialist publications
Konsensusempfehlungen von DRG/DGK/DGPK zum Einsatz der Herzbildgebung mit Computertomografie und Magnetresonanztomografie [DRG/DGK/DGPK consensus recommendations on the use of cardiac imaging using computed tomography and magnetic resonance imaging]
Deutschen Gesellschaft für Kardiologie – Herz- und Kreislaufforschung (German Cardiac Society)
dgk.org
