6/18/2014 1 Cardiac MRI Cardiac Anatomy Follow the arrows. Starting at the superior and inferior Vena Cava. Common indications for MR imaging of the heart include the following: Why Cardiac MRI? •Diagnosis of arterial and ventricular septal defects. •Assess congenital abnormalities. •Visualization of the papillary muscles and valves. •Cardiac Perfusion Cardiac Coils Regular MRI Coils Multi channel coil technology placed anterior and posterior in close proximity to the heart produces better image resolution and better signal.
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6/18/2014
1
Cardiac MRI Cardiac Anatomy
Follow the arrows.
Starting at the
superior and
inferior Vena Cava.
Common indications for MR
imaging of the heart include the
following:
Why Cardiac MRI?
•Diagnosis of arterial and ventricular septal defects.
•Assess congenital abnormalities.
•Visualization of the papillary muscles and valves.
•Cardiac Perfusion
Cardiac Coils
Regular MRI Coils
Multi channel coil technology
placed anterior and posterior
in close proximity to the heart
produces better image
resolution and better signal.
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ECG Prep and Triggering
MRI Electrocardiogram
(ECG) helps to trigger (or
time) the MRI pulse sequence
to reduce motion artifact.
Cardiac Gating
Normal Cardiac
Cycle:
P wave to P wave.
R to R Interval:
R wave to R wave.
Cardiac Gating
Trigger window
starts at the p
wave (orange)
Delay window starts
at the R wave
(yellow)
Available imaging
time is between
the T wave and P
wave (green)
Cardiac Gating
Image slice
acquisition
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MRI Positioning
A. Two-Chamber
view positioning
B. Four-Chamber
view positioning
C. Four-Chamber
view
Two-Chamber View
Center parallel to long axis
of left ventricle
Always center from breath-
hold (BH) transverse
The resultant image will
demonstrate the left
ventricle, left atrium, left atrial
appendage (LAA)
and mitral valve (MV)
Also called vertical long
axis view LV
MV
LA
LAA
Two-Chamber View
Notice the left atrial appendage?
Mitral valve regurgitation?
MRI Cine (Movie):
Aliased Two-Chamber View
The field of view (FOV)
that was selected was
too small for body
habitus; therefore fold
over or wrap has
degraded this image
Wrap
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Four-Chamber View
Center parallel to the two-
chamber view
Center in between the papillary
muscles on short axis (SA)
image
The resultant image will
demonstrate the right and left
atrium, the right and left
ventricle, and MV and tricuspid
valve
Also known as horizontal long
axis
LV
MV
LA
RA RV
TV
Four Chamber View
MRI Cine (Movie):
Malpositioned Four-Chamber
View This image was positioned
too superior on the two-
chamber view
The resultant image has
the aortic valve (AV) in
the view making it a five-
chamber image
Aortic
root
Malpositioned Four-Chamber
View MRI Cine (Movie):
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Short Axis Center perpendicular
to the septum on the
four-chamber view
The resultant image
demonstrates the left
and right ventricle in a
nice round shape
(donuts)
Left ventricle (LV) has
a thicker myocardial
wall.
LV RV
Short Axis
MRI Cine (Movie):
Short Axis with Motion Artifact
Impaired image
quality because patient
had difficulty holding
their breath
Motion artifact
Left Ventricular Outflow
Tract of Aorta
Center perpendicular to
the aorta
The resultant image
demonstrates the left
ventricle, AV and
outflow tract
Also known as coronal
view RV LV
RA
LVOT & AV
PA
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Left Ventricular Outflow
Tract of Aorta MRI Cine (Movie):
The black line in the
left ventricle represents
regurgitation of the
aortic valve.
Flow Artifact
Turbulent flow in the
aorta causing a flow
artifact on left
ventricular outflow
tract (LVOT) image Flow artifact
Flow Artifact
MRI Cine (Movie):
Para-Axial Aorta
Center parallel to the
aortic valve (AV)
using the LVOT
image
The resultant image
demonstrates the
cusps
of the aortic valve
(AV)
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Aortic Valve Three-Chamber View
Center parallel to the
long axis of the left
ventricle and aorta
This image
demonstrates the AV,
MV, and right and left
ventricle LA MV
LV
RV
AV
Parasagittal Aorta
Center parallel to the
ascending and
descending aorta
The resultant image
shows the aorta in a
candy cane view
Ascending
aorta
Descending
aorta
Descending
aorta
Ascending
aorta
RPA
Parasagittal Aorta
MRI Cine (Movie):
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Hypertrophic Cardiomyopathy Right Ventricle Perforation: 85 YO Un
Life threatening rupture on CMR
MRI
Perfusion
Myocardial Perfusion
Normal – Myocardium enhances
homogeneously in both rest and stress scans
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Myocardial Perfusion
Myocardial Perfusion Defect
Ischemia – myocardial defect presents at stress,
disappears at rest.
Necrosis – myocardial defect presents at stress and
at rest.
Myocardial Perfusion
Intramural – perfusion defect is placed in the
inner layers of myocardium
Transmural – perfusion defect is located in the
entire myocardial wall
Subendocardial – perfusion defect is placed in
the subendocardial myocardium.
Usually this is not well identified by Single Photon
Emission Computed Tomography (SPECT) studies.
Heart Wall Why MRI Perfusion?
Better resolution than other modalities CT and
Nuclear Medicine (Resolution < 2mm)
No radionuclide
Visualize subendocardial defects. This helps the
cardiologist determine if coronary stenosis
should be treated by angioplasty or coronary
bypass surgery. Cardiac viability or damage.
Morphology and of the heart is included.
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Comparisons
Nuclear(including PET) MRI
Spatial
Resolution 1.0 – 1.3 cm 1.0 – 1.5 mm
Voxel resolution 3 – 5 cm 8 – 10 mm
SNR 6 20
CNR 8 >100
Difference in
resolution 1 60 – 80
PET, position – emission tomography
CNR, Contrast – to – noise ratio
SNR, signal – to – noise ratio
41 YO M with 1-mm ST Elevation Myocardinal
Infarction 1 Week Ago
and Negative Nuclear Scan Yesterday
A very thin lateral wall subendocardial infarction below the limits for detection by standard nuclear
imaging well visualized by the high spatial resolution afforded by cardiovascular magnetic
resonance (CMR). Note, the high CMR resolution to demonstrate the dual supply of the posterior
lateral papillary muscle suggested by variable scar (middle arrow).
MRI Challenges
Claustrophobia
Motion
Cardiac Triggering (arrhythmias)
Coil selection
Pacemakers
Gradient strength (faster imaging)
Coronary Arteries/Stents
The End
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References:
Westbrook, Catherine and Kaut, Carolyn (1998). MRI In Practice, 3rd ed.,
Blackwell Science, Inc. Malden, Ma.
Biederman, Robert et al. (2008). Cardiovascular MRI Tutorial: Lectures and
Learning. Lippincott Williams & Wilkins. Philadelphia, Pa.
Haaga, John et al. (2009). CT and MRI of the Whole Body. Mosby Elsevier.