To obtain standardized cardiac imaging planes in the shortest number of steps possible. The standard planes include Vertical Long Axis (VLA) or 2 Chamber view (2C), Horizontal Long Axis (HLA) or 4 Chamber view (4C) and multiple, contiguous short axis views.
CARDIAC MRI SEQUENCES
- SS-FSE TR-700-1,000
- SSFP TR-40
- MPGE TR-700-1,000
- CE-IRG
- Phase Contrast
- MRA/CE-MRA(CEMRA = contrast-enhanced MR angiography)
- Delayed Enhancement Study:10–30 minutes later by a cardiac-gated T1-weighted pulse sequence-The typical pulse sequence for myocardial delayed enhancement is a segmented inversion-recovery–prepared fast gradient-echo sequence. Imaging occurs over nine to 12 heartbeats, in a breath hold. In patients who have difficulty holding their breath, navigator-assisted free-breathing techniques can be used without breath holding.The purpose of this protocol is to evaluate the myocardium for scar which can be secondary to prior infarct, infiltrative disease, myocarditis, or ardiomyopathy.An inversion-recovery sequence is used to optimize the contrast between gadolinium-retaining infarcted or scar tissue and healthy or viable myocardium.
single-shot, fast spin echo (SS-FSE)Fast spin echo sequences often known as “black blood” double inversion recovery (DIR) technique sequences are typically used to asses the heart Morphology.These sequences are typically used in conjunction with double inversion recovery prepulses. The “bright blood” SSFP sequence can also be used to assess cardiac morphology if it is altered to produce images of the entire heart (rather than a cine loop at a single location)
Magnetization-prepared gradient echo sequences-MPGE- are used to assess myocardial perfusion
Contrast enhanced Inversion Recovery GRE-CE IRGevaluation of myocardial viability utilizes inversion recovery gradient echo sequences, with the inversion time set to null viable myocardium. Either spoiled gradient echo or SSFP sequences can be used in conjunction with the inversion recovery prepulse. These sequences typically utilize segmented k-space acquisition.
MR CARDIAC Angiography-Many different sequences have been used to image the coronary arteries. These sequences are typically used in conjunction with segmented k-space acquisition. Two-dimensional (2D), segmented, gradient echo sequences can be used to evaluate coronary artery anomalies. Three-dimensional (3D) techniques are used to evaluate the arteries for stenosis. Images can be acquired during breath-holding or free breathing. Images can be obtained with or without intravenous contrast. A 3D, segmented SSFP sequence without intravenous contrast is well suited to evaluate the coronary arteries. If intravenous contrast is employed, intravascular contrast agents are the most useful.Standard 3D, spoiled gradient echo sequences with intravenous contrast are used to evaluate the aorta and great vessels.
Phase Contrast-This is a gradient echo sequence used to measure blood velocity. By integrating pixel velocities across a vessel volume flows can be calculated. Velocity measurements are used to estimate pressure gradients.
Magnetization-prepared gradient echo sequences-MPGE- are used to assess myocardial perfusion
Contrast enhanced Inversion Recovery GRE-CE IRGevaluation of myocardial viability utilizes inversion recovery gradient echo sequences, with the inversion time set to null viable myocardium. Either spoiled gradient echo or SSFP sequences can be used in conjunction with the inversion recovery prepulse. These sequences typically utilize segmented k-space acquisition.
MR CARDIAC Angiography-Many different sequences have been used to image the coronary arteries. These sequences are typically used in conjunction with segmented k-space acquisition. Two-dimensional (2D), segmented, gradient echo sequences can be used to evaluate coronary artery anomalies. Three-dimensional (3D) techniques are used to evaluate the arteries for stenosis. Images can be acquired during breath-holding or free breathing. Images can be obtained with or without intravenous contrast. A 3D, segmented SSFP sequence without intravenous contrast is well suited to evaluate the coronary arteries. If intravenous contrast is employed, intravascular contrast agents are the most useful.Standard 3D, spoiled gradient echo sequences with intravenous contrast are used to evaluate the aorta and great vessels.
Phase Contrast-This is a gradient echo sequence used to measure blood velocity. By integrating pixel velocities across a vessel volume flows can be calculated. Velocity measurements are used to estimate pressure gradients.
IMAGING PLANES OF CARDIAC MRI
sagittal single-shot fast spin-echo image is used as an initial localizer for coronal imaging
Coronal single-shot fast spin echo-aortic valve
Four-chamber gradient-echo image oblique axial plane serves as a localizer for the short-axis view
Coronal single-shot fast spin-echo image obtained off the sagittal plane. To localize the atrioventricular valve level, an imaging plane is prescribed along a line connecting the cardiac apex and the level of the middle of the atrioventricular valve, as shown.
Four-chamber gradient-echo image-cross sectional depiction of the atrioventricular valves
The 3-chamber view can be prescribed from the left ventricular outflow tract view of a short-axis view. This view displays the aortic and mitral valves immediately adjacent to one another.
Left ventricular outflow view: Steady-state gradient echo (SSFP [steady-state free precession]) left ventricular outflow view demonstrates a bicuspid aortic valve and an aortic jet secondary to aortic stenosis.
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