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© Springer International Publishing 2016
M.J. Budoff, J.S. Shinbane (eds.), Cardiac CT Imaging: Diagnosis of Cardiovascular Disease,
DOI 10.1007/978-3-319-28219-0_4
Orientation and Approach
to Cardiovascular Images
Jerold S. Shinbane and Antreas Hindoyan
Abstract
Mastery of conventional anatomy and physiology is essential as a template for understanding
of cardiovascular variation and pathology. A multitude of analysis and reconstruction tools
including orthogonal, double oblique, and curved multiplanar reformatted 2-D, and volumerendered 3-D views can be utilized for comprehensive diagnosis of cardiovascular pathology.
The goal of this chapter is orientation to review and analysis of cardiovascular structure from
CCTA image sets using a systematic approach.
Keywords
Cardiovascular Computed Tomographic Angiography • Computed Tomography •
Curved Multiplanar Reformatted • Double-Oblique • Orientation • Orthogonal Views •
Volume-Rendered
Abbreviations
AAO Ascending Aorta
DAO Descending Aorta
AV Aortic Valve
CS Coronary Sinus
GCV Great Cardiac Vein
IVC Inferior Vena Cava
LA Left Atrium
LAA Left Atrial Appendage
LAD Left Anterior Descending Coronary Artery
LV Left Ventricle
LCx Left Circumfl ex Coronary Artery
LIMA Left Internal Mammary Artery
LM Left Main Coronary Artery
LS Left Sinus of Valsalva
MV Mitral Valve
PA Pulmonary Artery
PDA Posterior Descending Coronary Artery
PV Pulmonary Vein
RA Right Atrium
RAA Right Atrial Appendage
RCA Right Coronary Artery
RIMA Right Internal Mammary Artery
RV Right Ventricle
TV Tricuspid Valve
Introduction
A systematic and comprehensive approach to analysis of
visualized structures is essential to interpretation of CCTA
utilizing the multitude of analysis and reconstruction tools.
The underpinning of this approach is an understanding of
the 3-D anatomy and physiology of structures and their
J. S. Shinbane , MD, FACC, FHRS, FSCCT (*) • A. Hindoyan , MD
Division of Cardiovascular Medicine, Department of Internal
Medicine , Keck School of Medicine of the University
of Southern California , 1520 San Pablo Suite 300 ,
Los Angeles , CA 90033 , USA
e-mail: shinbane@usc.edu
4
Electronic supplementary material The online version of this
chapter (doi: 10.1007/978-3-319-28219-0_4 ) contains supplementary
material, which is available to authorized users.
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interrelation in the acquired tomographic data cube. Imagers
will ultimately fi nd their own individualized algorithm for
image analysis, but this approach ultimately needs to be
complete, methodical, and effi cient. The goal of this chapter
is orientation to viewing and analyzing cardiovascular structure from CCTA image sets, with mastery of conventional
anatomy and physiology serving as a template for understanding of cardiovascular variation and pathology.
An important factor prior to image analysis is review of
relevant clinical history and questions to be answered by the
study. Before evaluation of individual structures, the image
set needs to be assessed for limitations to analysis due to the
fi eld of view, percentage of the cardiac cycle imaged, and
image quality based on degree of target region of interest
contrast opacifi cation and artifacts. Analysis should be systematic rather than focused on the most prominent fi ndings.
One systematic approach to analysis involves comprehensive
evaluation through serial assessment of: (1) Non-coronary
artery cardiovascular structure cranial to caudal with axial
scrolling followed by additional 2- and 3-D analysis, (2)
Coronary artery cardiovascular structure cranial to caudal
with axial scrolling as an anchor followed by additional 2and 3-D analysis, and (3) Non-cardiovascular structures in
the available fi eld of view by physicians with expertise in
evaluation of these structures.
Image Views
Orthogonal Views: Axial, Sagittal and Coronal
Planes (Figs. 4.1 – 4.134 shown at the end
of the chapter; Videos 1, 2, and 3)
Even with the advent of a multitude of imaging software
options, the axial images remain an anchor for analysis with
additional information obtained from 2-D coronal sagittal,
double oblique, curved multi-planar, and 3-D reconstructions useful for confi rmation and specialized analysis of specifi c structures. In addition to structure, tissue characteristics
related to the radiodensity of the tissue can be assessed
through measurement of HUs (Fig. 4.135 ). The Hounsfi eld
unit (HU) is based on an attenuation scale in which the
radiodensity of water is 0 HU and air 1000 HU. Tissues have
a spectrum of HU ranges depending on their radiodensity
with approximate values for fat of −50 to −100 HU, muscle
10–40 HU, and wide spectrum for bone of 400–3000 HU
based on architecture.
Analysis of CCTA relies signifi cantly on evaluation of the
axial plane images. In the axial plane, the thorax is viewed in
serial cranial to caudal slices, with visualization of thinner
slices enabling evaluation with greater resolution than thicker
slices. If the CT system used does not provide true isotropic
voxels due to limited Z axis resolution, the axial plane provides
resolution superior to other planes. This is not the case for
scanners providing imaging with isotropic voxels, as the voxels possess uniform resolution in all axes. The reader should
visualize the patient in the supine position with the patient’s
feet coming out towards the reader. The sternum (anterior) and
spine (posterior) can also be used to orient the reader in the
axial plane (Fig. 4.136 ). The reader should never try to analyze
a structure using one axial slice. Assessment of adjacent axial
slices to establish anatomic continuity should be performed
for comprehensive identifi cation of a structure and its
connections.
Non-coronary artery cardiovascular structure analysis
includes: the size and architecture of the aorta and branch
vessels at all visualized levels, the size and architecture of
the main pulmonary artery and pulmonary artery branches,
the 3-D relationships between the aorta and the pulmonary
arteries, presence of anomalous thoracic vascular anatomy,
location, number, and course of the pulmonary veins, atrioventricular and ventriculo-arterial concordance, continuity
of the atrial septum, continuity of the ventricular septum,
the presence of fi lling defects or masses in the left atrial
appendage, atria and ventricles, valvular structure, myocardial thickness and tissue attenuation, and pericardial thickness and presence of effusion.
The thorax is viewed from anterior to posterior by scrolling through serial coronal images (Fig. 4.137 ) and from right
to left on sagittal images (Fig. 4.138 ). In these reconstruc-
tions, multiple stacks of images are viewed at once, and
therefore thin collimation lines can be seen. If the data sets
are not aligned properly due to motion, step artifacts can
occur. These artifacts would not be present using scanners
which have an acquisition volume imaging the fi eld of view
in one gantry rotation, allowing single beat imaging.
Respiratory motion artifacts are well seen on sagittal views.
In the sagittal and coronal views, assessment of contrast
opacifi cation of the descending aorta can be used as a
marker of the adequacy of timing for contrast opacifi cation
of the distal coronary arteries. Measurement of contrast density and homogeneity measured by HU at serial levels of the
descending aorta can be performed. If the HUs decrease signifi cantly as the aorta descends, the distal coronary arteries
may be poorly opacifi ed and more diffi cult to analyze
(Fig. 4.139 ).
The sagittal and coronal views display certain structures
well in their natural planes. Sagittal images are helpful for
viewing the right ventricular outfl ow tract, aorta in a “candy
cane” view, and origins of venous coronary artery bypass
grafts off of the aorta (Fig. 4.140 ). Coronal images facilitate
display of the sternum, course of the left and right internal
mammary arteries, mid-segment of the right coronary artery,
left ventricular outfl ow tract, pulmonary veins and atrial
appendage entering the left atrium, and descending aorta
(Fig. 4.141 ).
J.S. Shinbane and A. Hindoyan
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Fig. 4.136 A 2-D axial view showing anterior (sternum), posterior
(spine), right and left orientation
Fig. 4.137 2-D coronal view showing cranial, caudal, left and right
orientation. Motion artifacts are seen as thin collimation lines ( arrows )
Fig. 4.135 Panel ( a ): A 2-D non-contrast axial view showing the
Hounsfi eld Units of various tissues including subcutaneous fat, air in
the lungs, bone, skeletal muscle and left ventricular myocardium. Panel
( b ): A 2-D contrast-enhanced axial view showing the Hounsfi eld Units
of various tissues including subcutaneous fat, air in the lungs, bone,
skeletal muscle, and left ventricular myocardium, and contrast enhanced
right atrium (with inhomogeneity due to mixing of contrast enhanced
and non-contrast enhanced blood), right ventricle, left atrium, left ventricle, and aorta. Ao aorta, HU Hounsfi eld units, LA left atrium, LV left
ventricle, RA right atrium, RCA right coronary artery, RV right
ventricle
ab
4 Orientation and Approach to Cardiovascular Images
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ab
Fig. 4.138 2-D sagittal views showing anterior (sternum) and posterior (spine) orientation. Panel ( a ) Respiratory motion artifacts are seen as
discontinuity of the sternum with thin collimation lines ( arrows ). Panel ( b ) Sternum with no evidence of respiratory motion ( arrow )
ab
Fig. 4.139 Panel ( a ): A 2-D contrast-enhanced sagittal view showing
decreased contrast density and homogeneity at serial levels of the
descending aorta ( arrow ) as a marker of inadequate timing and contrast
dose to visualize the distal segments coronary arteries. Panel ( b ): A 3-D
contrast-enhanced reconstruction with lack of visualization of the mid
to distal left anterior descending coronary artery ( arrow )
Double Oblique 2-D Views
The axial, coronal, or sagittal views can be used as a starting
point for rotation into planes providing coaxial long and
short axis views of specifi c vascular structures (Fig. 4.142 ).
“En face” measurements at various levels of the aorta (aortic annulus, sinus of Valsalva, sinotubular junction, ascending, arch, and descending aorta), pulmonary arteries,
pulmonary vein ostia, and atrial or ventricular septal defects
are important, as these structures often have ovoid rather
than circular shapes, allowing the maximum and minimum
diameters as well as the area of these structure to be
quantifi ed.
Curved Multiplanar Reformatted Views
Curved MPR images can evaluate an entire vascular structure in one view (Fig. 4.143 ). The plane of a specifi c artery
can be chosen and displayed as a “curved surface” from
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abc
Fig. 4.140 Panel ( a ): A 2-D sagittal view displaying aorta in a “candy
cane” view in a patient with atherosclerotic disease of the aorta. Panel
( b ): A 2-D sagittal view showing the origin of a saphenous venous
coronary artery bypass graft off of the aorta in a patient with coronary
artery bypass graft surgery ( arrow ). Panel ( c ): Axial view demonstrat-
ing the same saphenous vein graft ( arrow )
a
de
bc
Fig. 4.141 Serial 2-D coronal images. Panel ( a ): Sternum with left and
right internal mammary arteries ( arrow ). Panel ( b ): Mid-segment of the
right coronary artery ( arrow ). Panel ( c ): Left ventricular outfl ow tract
( arrow ). Panel ( d ): Left atrium ( arrow ), pulmonary veins and left atrial
appendage. Panel ( e ): Descending aorta ( arrow )
4 Orientation and Approach to Cardiovascular Images
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within the 3D volume. This view also creates cross sectional
cuts of each vascular segment. The thickness of the cross
sectional cuts can be adjusted using workstation software.
All other structures are automatically eliminated, including
the side branches, and separate reconstructions can be rendered for each side-branch.
Volume-Rendered 3-D Views
The volume rendered technique relies on identifi cation of all pixels within a specifi ed attenuation range. The 3-D views may be
helpful to obtain an overall sense of 3-D cardiovascular anatomy,
but measurements related to structure should be performed using
Fig. 4.142 Long ( a ) and short axis ( b ) 2-D double oblique views for coaxial assessment of the aorta at the sinuses of Valsalva ( arrows )
Fig. 4.143 Curved multiplanar reformatted views of the aorta with long axis ( a ) and serial coaxial cross sectional views ( b )
J.S. Shinbane and A. Hindoyan
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2-D images in the appropriate plane. A variety of automatic and
manual editing softwares allow visualization of specifi c structures and relationships in the 3-D data cube, but require care in
utilization in order to avoid over or under editing of structures
(Fig. 4.144 ).
Orientation to Analysis of Cardiovascular
Structure
Orientation of the Great Vessels
Review of the spatial relationship between the aorta and
main pulmonary artery is essential for analysis of rotational
abnormalities of the great vessels. In the normal relationship
of the aorta and main pulmonary artery, these vessels are perpendicular with the aorta rightward and posterior to the main
pulmonary artery (Fig. 4.145 ). In D-transposition of the
great arteries, the aorta is usually anterior to the main pulmonary artery, while in L-transposition, the aorta is usually
anterior and rightward to the main pulmonary artery. In the
setting of transposition of the great arteries, these vessels can
be parallel with coaxial visualization in the same plane leading to a “double barrel shotgun” appearance.
Aorta
The aorta can be followed in the axial plane from the aortic
root through the ascending aorta, arch and descending por-
tions for morphology, atherosclerotic and non- atherosclerotic
plaque, mural thrombus, penetrating ulcer, dissection, aneurysm and pseudoaneurysm. After review of the aorta in the
axial position, double oblique views can be created so that
coaxial measurements can be made at multiple levels including: the aortic annulus, sinuses of Valsalva, sinotubular junction, ascending aorta, arch, descending thoracic aorta, and
potentially the upper abdominal aorta (Fig. 4.146 ). Due to
limitation of the fi eld of view for radiation dose reduction,
portions of the aorta may not visualized. Recognition of the
segments of the aorta not visualized is therefore important
for analysis and reporting of fi ndings.
Pulmonary Arteries
The initial axial assessment of the aortic to pulmonary artery
relationship will bring the main pulmonary artery into view.
The main pulmonary artery as well as proximal right and
left pulmonary arteries can subsequently be assessed for
morphology and measured coaxially using double oblique
views, assessing for evidence of pulmonary arterial hypertension or aneurysm (Fig. 4.147 ). The pulmonary arterial
tree is then assessed on the available full fi eld of view on
serial slices for vessel caliber and any evidence of fi lling
defects, recognizing limitations if the contrast bolus has
been focused on left-sided structures. Again, due to limited
fi eld of view for radiation dose reduction in studies performed for purposes such as coronary artery analysis, portions of the pulmonary arterial tree may not be visualized or
Fig. 4.144 Volume rendered 3-D reconstructions of the thorax with serial editing from thorax to cardiovascular structures to coronary arteries
4 Orientation and Approach to Cardiovascular Images
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adequately contrast opacifi ed and therefore analysis is limited. Recognition of the portions of the pulmonary arterial
tree not visualized is therefore important to analysis and
reporting of fi ndings.
Cardiac Chambers
Axial images should be reviewed for the spatial relationship
between the heart and the thorax (Fig. 4.148 ). With normal
anatomy, the heart is in the left hemithorax (levocardia), as
opposed anomalous location in the right hemithorax (dextrocardia), or midline (mesocardia). The ventricles are normally D-looped, with the right ventricle rightward and
anterior to the left ventricle, whereas in L-looped ventricles
the relationship is inverted.
Right Atrium/SVC/IVC/Coronary Venous System
Visualization of the right atrium is dependent on the injection protocol. Even in circumstances where there is signifi cant contrast bolus in the right atrium, there is still
non-contrast enhanced blood fl ow from the contralateral
arm venous drainage as well as the inferior vena cava. The
presence of contrast and non-contrast enhanced blood
causes Hounsfi eld Unit heterogeneity in the right atrium
making endocardial assessment more challenging. The right
atrium has a triangular shaped appendage as opposed to the
ab
Fig. 4.145 2-D axial views demonstrating the spatial relationship
between the aorta and main pulmonary artery for assessment of rotational abnormalities of the great arteries. Panel ( a ): Normal relationship
of the aorta and main pulmonary artery with the aorta rightward and
posterior to the main pulmonary artery. Panel ( b ): D-transposition of
the great arteries, with parallel relationship of the great arteries with the
aorta anterior and rightward to the main pulmonary artery. Ao aorta, PA
pulmonary artery
a
b
Fig. 4.146 2-D double oblique views demonstrating coaxial display of
the aorta at multiple levels. Panel ( a ): The aortic annulus, sinuses of
Valsalva, sinotubular junction, ascending aorta, Panel ( b ): Descending
thoracic aorta and upper abdominal aorta. Ao aorta, Ao V aortic valve,
ST sinotubular
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vermicular, “worm like”, morphology of the left atrial
appendage (Fig. 4.149 ). Familiarity with the division of the
right atrium into a trabeculated lateral portion separated by
the crista terminalis from a smooth walled septum is essential to avoid misinterpretation of structures as masses.
Characteristics of the septum such as lipomatous hypertrophy (Fig. 4.150 ), atrial septal aneurysm, patent foramen
ovale, and atrial septal defect require analysis of the entire
septum. The size, shape and morphology of atrial septal
defects including the surrounding rim require detailed
assessment in double oblique views. Analysis for the presence, morphology and patency of the superior and inferior
vena cavae should also include a search for any anomalous
connections from the pulmonary veins as well as for the
presence of other venous connection to the right atrium. The
coronary sinus ostium is usually seen in the inferoposterior
right atrium. The coronary sinus/great cardiac vein should
be evaluated for continuity throughout course as well as for
evidence of enlargement due to either right-sided pressure
and volume overload or a left-sided superior vena cava with
aneurysmal coronary sinus connection. The coronary sinus
ostium may have a variable degree of presence of a remnant
ab
c
Fig. 4.147 2-D axial view of the main pulmonary artery. Panel ( a ): Pulmonary artery enlargement associated with pulmonary arterial hyperten-
sion. Panels ( b , c ): Large pulmonary artery emboli ( arrows ). Ao aorta, PA pulmonary artery
Fig. 4.148 2-D axial views of the normal orientation of the heart in the
thorax (levocardia).
4 Orientation and Approach to Cardiovascular Images
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Thebesian valve. Evaluation of the entire coronary venous
system necessitates a delay in timing of image acquisition
from contrast injection as contrast-enhanced blood must
fl ow back from the myocardium through the coronary
venous branches, great cardiac vein and then to the coronary
sinus. Adequate opacifi cation of a left-sided superior vena
cava requires images obtained with a left arm venous contrast injection.
Left Atrium/Pulmonary Veins
The left atrium and its relationship to the pulmonary
veins and other thoracic structures can be characterized
with multiple CCTA reconstruction modalities
(Figs. 4.151 and 4.152 ). The left atrium is often trapezoi-
dal in shape and becomes progressively more spherical
when enlarged. The complex shape makes single plane
assessment challenging and therefore volumetric assessment more completely characterizes size. The left atrial
volume can be quantitated at end systole and end-diastole. The left atrial appendage is a complex structure,
with variation in shape, size, lobulation, and the presence
of pectinate muscles. Characterization of the left atrial
appendage ostial characteristics, length of the main body,
and number and morphology of lobes can be important to
procedures such as left atrial appendage occlusion
devices. Assessment should be made for filling defects in
the left atrial appendage. Filling defects can be due to
thrombus, mass, or inadequate opacification due to
decreased left atrial appendage velocity. The left atrium
should be assessed for masses as well as other anomalies
Fig. 4.149 Views of the triangular shaped, wide based right atrial appendage. Panel ( a ): 3-D reconstruction. Panel ( b ): 2-D double oblique image.
RAA right atrial appendage
Fig. 4.150 2-D axial view of the atrial septum demonstrating lipomatous hypertrophy ( arrows )
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