The cardiac MRI ARVC protocol encompasses a set of different MRI sequences for the cardiac assessment in case of suspected arrhythmogenic right ventricular cardiomyopathy.
Note: This article aims to frame a general concept of a cardiac MRI protocol in the above setting.
Protocol specifics will vary depending on additional clinical questions, differential diagnosis, MRI scanner type, specific hardware and software, radiologist and perhaps referrer preference, patient factors e.g. arrhythmia or breathing problems or implants, specific indications and time constraints.
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Indications
1.5 vs 3 tesla
Cardiac MRI examinations can be generally performed on both 1.5 and 3 tesla.
The acquisition at a 3 tesla system requires a lot of adjustments and careful shimming to avoid flow and dark banding artifacts, especially concerning steady-state free precession cine imaging.
Due to potential problems with cine imaging at 3T, a cardiac MRI for the assessment of arrhythmogenic right ventricular cardiomyopathy might be preferably conducted on a 1.5 tesla system.
Applications that may benefit from increased field strength is late gadolinium enhancement 1,2.
Patient preparation
Checking indications, contraindications, explanation of the examination and obtaining informed consent is obvious as in other examinations.
Beyond that patient preparation for cardiac MRI includes the following:
instruction how to breathe
an electrocardiogram signal need to be acquired
Patient positioning
A cardiac MRI is conducted in the supine position.
Technical parameters
Coil
Multi-phased array coils are recommended.
anterior surface coil, posterior coil
cardiac coil
Scan geometry
in-plane spatial resolution: will vary with the sequence
field of view (FOV): will vary, for most planes a FOV ≤320 mm is recommended
slice thickness: for cine images especially right ventricular stack consider 5-6 mm
Planning
The cardiac imaging planes differ from the normal axial, coronal and sagittal body planes 1-4:
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overview
angulation: strictly axial
volume: from the thoracic inlet to the diaphragm
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horizontal long axis view or 4-chamber view (4ch)
angulation: along the left ventricular long axis through the apex and the centers of the mitral and tricuspid valves
volume: including the anterior and inferior wall or a single slice
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left ventricular vertical long axis view or 2-chamber view (2ch)
angulation: along the left ventricular long axis through the left ventricular apex and the center of the mitral valve
volume: including septum and left ventricular free wall or single slice
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sagittal left ventricular outflow tract (LVOT) or 3-chamber view (3ch)
angulation: through the left ventricular apex, the center of the mitral valve and the left ventricular outflow tract and aortic valve
volume: including the anterolateral and inferoseptal left ventricular wall
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short-axis view (sax)
angulation: perpendicular to the left ventricular long axis
volume: stack usually including the atrioventricular valves and the cardiac apex or 3 single slices through basal, midventricular and apical zones
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right ventricular vertical long axis view or 2-chamber view (2ch)
angulation: along the right ventricular long axis through the apex, the center of the tricuspid valve and the right ventricular outflow tract
volume: single slice, or a stack including the septum and right ventricular free wall
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right ventricular transaxial view
angulation: strictly axial to the body axis
volume: including the whole right and left ventricles and the pulmonary valve
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sagittal right ventricular outflow tract (RVOT)
angulation: sagittal oblique along the axis of the main pulmonary artery
volume: consider a stack
Sequences
Standard sequences
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T2 black-blood or SSFP
purpose: overview, depiction of the cardiac surroundings and great vessels
technique: T1 black-blood, T2 black-blood, SSFP ideally over 1-2 breath-holds
planes: axial (increased FOV)
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cine imaging
purpose: left ventricular wall motion, left ventricular volumetry
technique: cine SSFP or spoiled GRE
planes: 2ch, 4ch, 3ch and short-axis views, RV VLA, transaxial stack, sRVOT
Optional sequences
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T1 weighted imaging
purpose: for the evaluation of fatty deposits
technique: T1 black-blood with and without
planes: transaxial stack
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late gadolinium enhancement (C+)
purpose: for the evaluation of myocardial fibrosis
technique: 2D and 3D IR GRE, PSIR
planes: 2ch, 4ch, 3ch and short-axis views
TI as determined by TI scout (Look-Locker) or fixed TI (PSIR)
(*) indicates optional planes
Practical points
The following considerations can be made in certain conditions:
single-shot modules or free breathing with real-time image acquisition in patients with difficulties holding their breath
abdominal bands in profound respiratory motion
peripheral pulse gating in patients with a weak ECG signal
postponing the exam in patients with severe pleural effusion and related ghosting artifacts and breathing problems until after pleural drainage
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cine imaging
volumes need to be obtained for both ventricles
a stack of sagittal cine images through the right ventricular outflow tract can be considered
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late gadolinium enhancement
inversion time (TI) should be nulled for the right ventricle