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Fig. 11.10 Short axis images of
the LV ( right ) and RV (right
ventricle, left ) from an 18 year
old woman with syncope and
ARVD (arrhythmogenic RV
dysplasia). Note the enlargement
of the RV compared to the LV
and the presence of wide
trabeculations in the RV, both
major criteria for diagnosis of
ARVD
Fig. 11.11 Cardiac CT Images of two patients with ARVD (arrhythmogenic right ventricular dysplasia). The arrows demonstrate “fatty
infi ltration” of the RV wall, a major diagnostic criteria for the diagnosis of ARVD
11 Assessment of Cardiac Structure and Function by Computed Tomography Angiography
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make quantitation of LV function with MDCT diffi cult, and
individuals with pacemakers should have the ventricular rate
set to 60 beats per minute. The presence of atrial fi brillation
is not a contraindication, but, with uncontrollable rapid ventricular response, will likely result in sub-optimal data.
Strengths
A properly planned 64+slice, retrospectively ECG-gated,
MDCT examination can provide quantitative data on LV/RV
systolic (and diastolic function) both globally and regionally. It can also provide quantitative data on chamber sizes,
valve (both natural (Fig. 11.16 ) and prosthetic) valve motion
and cross-sectional areas, visualization of intra-cardiac
shunts, defi nition of cardiac tumors and thrombi, quantitation of LV muscle mass, regional wall thicknesses and
thickening, myocardial infarct size, and the gross physiologic consequences of pericardial effusions and pericardial
constriction.
Limitations
Sub-optimal assessment of cardiac structures and function
can occur due to cardiac dysrhythmias, inadequate heart rate
control during imaging, and poor chamber contrast timing/
administration. Defi nition of end-diastole is straight-forward
by noting the timing of the R-wave on the ECG and the
appropriate CT reconstructed phase. Defi nition of endsystole is more diffi cult. Although using a 10-phase retrospective reconstruction usually assigns end-systole to the
smallest chamber volume, recent data suggest that at least a
15 phase reconstruction might be more appropriate for timing of this event [ 38 ]. The number of phases reconstructed
from a 64+-slice MDCT retrospectively ECG gated cardiac
CT is a choice made by the physician, and going from a
10-phase to a 20-phase reconstruction only results in more
images to review for analysis and the subsequent increase in
fi le size and image storage requirements. Also, many of the
available image processing workstations have a limit to the
number of images that can be placed into active memory for
review.
Comparison to Other Imaging Modalities
EBT and by inference 64+slice MDCT has been validated
for assessment of cardiac function in comparison to SPECT
imaging, MRI, contrast-ventriculography, and twodimensional echo.
Future Directions
The quantitation of cardiac structure and function by cardiac CT has been evolving for more than 25 years.
Improvements in cardiac edge-detection methods have
Fig. 11.12 Cardiac CT in a patient with “non-compaction” of the LV.
Left : Long axis showing dilation of the lower (apical) one-half of the
LV chamber. Right : a mid-LV short axis demonstrating dilation of the
LV chamber and the presence of deep “sinusoids” (fenestrations) of the
LV chamber
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essentially eliminated the need to laboriously trace images
from each tomographic plane and apply a modifi ed
Simpson’s (stack of coins) rule. All current workstations
allow for straight-forward information on EF, regional wall
thickening, regional wall motion, and LV volumes from
64+-slice MDCT cardiac examinations. Semi-quantitative
information on left/right atrial volume/dimensions and RV
volume/dimensions are also in development.
Fig. 11.13 Cardiac CT of a patient with severe pulmonary hypertension as a consequence to severe, chronic mitral valve regurgitation. The
horizontal ( left ) and vertical ( middle ) long axis images demonstrate the
dilation of the right ventricle (RV) and right atrium (RA)/left atrium; the
short ( right ) axis image demonstrates a common characteristic of pul-
monary hypertension and a “D” shaped interventricular septum (IVS)
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a
b
c
Fig. 11.14 Measurement of cardiac and chamber dimensions in cardiac CT. ( a ) Long axis and short axis dimensions of the left ventricular
long axis and at mid ventricle short axis. ( b ) Measurements of septal,
apical, and lateral wall thicknesses at end-diastole in a patient with
severe cardiac hypertrophy. ( c ) Representative measurements of the
aortic root and left atrium as measured mimicking a para-sternal measurement that might be done using two-dimensional echocardiography
(direction indicated by arrow )
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Fig. 11.15 Evaluation of the pericardium by cardiac CT. ( a ) Left –
Concentric, densely calcifi ed pericardium in a patient with constrictive
pericarditis as a consequence to tuberculosis. Right – Images from a
patient with pericardial tamponade from a concentric pericardial
effusion. ( b ) Top left – Volume rendered image demonstrating entire
cardiac volume; Top right : Volume rendered image demonstrating only
the cardiac epicardial surface; this was performed by changing the CT
display window and level settings on the image presented in b , top left ;
Bottom : a maximum intensity projection of the horizontal cardiac long
axis demonstrating the opacifi ed cardiac chambers and the surrounding
low intensity circumferential pericardial effusion
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Fig. 11.15 (continued)
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LV long axis and short axis images demonstrating thickened mitral
valve leafl ets ( arrow ) and dilated left atrium and measurement of mitral
valve area in a patient with moderate mitral valve stenosis. ( b )
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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_12
Cardiovascular CT for Perfusion
and Delayed Contrast Enhancement
Imaging
Ravi K. Sharma , Ilan Gottlieb , and João A. C. Lima
Abstract
Recent advancements in multi-detector computed tomography (MDCT) imaging have demonstrated the ability of MDCT to be a comprehensive imaging modality, which in a single
scan setting could provide a wide array of complementary information. Advent of MDCT
system with faster scan acquisition of entire myocardial volume has allowed assessment of
stress myocardial perfusion that has shown to provide incremental diagnostic accuracy over
coronary CT angiography (CTA) in assessing hemodynamically signifi cant stenosis.
Detection of fi brosis by Delayed Enhanced MDCT (DE-MDCT) has been validated
against gold standards such as histology and contrast enhanced MRI. DE-MDCT can accurately identify and characterize morphological features of acute and healed myocardial
infarction, including infarct size, transmurality, and the presence of microvascular obstruction and collagenous scar. In addition, recent studies have also substantiated the utility of
contrast enhanced MDCT in assessment of extracellular volume fraction (ECV) which corresponds to diffuse myocardial fi brosis. This has allowed comprehensive evaluation of
myocardial tissue characteristics with signifi cant bearing on the management, prognosis
and follow- up of a myocardial disease process.
Keywords
Computed tomography perfusion • Stress CT perfusion • Delayed enhanced MDCT
• MDCT myocardial viability • Myocardial fi brosis
Abbreviations
CAD Coronary Artery Disease
CTA Coronary CT Angiography
DE-MDCT Delayed enhanced MDCT
ECV Extracellular Volume Fraction
LAD Left Anterior Descending
LV Left Ventricle
MDCT Multi-Detector Computed Tomography
MRI Magnetic Resonance Imaging
PET Positron Emission Tomography
SPECT Single Photon Emission Computed Tomography
R. K. Sharma , MD • J. A. C. Lima , MD (*)
Division of Cardiology, Johns Hopkins Hospital ,
Blalock 524D, 600 N. Wolfe St , Baltimore , MD 21287 , USA
e-mail: rsharm25@jhmi.edu; jlima@jhmi.edu
I. Gottlieb , MD Msc, PhD
Casa de Saúde São José – Radiologia ,
R. Macedo Sobrinho, 21 – Humaitá , Rio de Janeiro ,
RJ 22271-080 , Brazil
e-mail: ilangottlieb@gmail.com
Electronic supplementary material The online version of this chap-
ter (doi: 10.1007/978-3-319-28219-0_12 ) contains supplementary
material, which is available to authorized users.
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Subject Overview
A 54 year old male with diabetes and family history of coronary artery disease (CAD) comes to a cardiologist for the
fi rst time for atypical chest pain. The patient reports “having
to grasp for air” while in chest pain. A rest electrocardiogram (ECG) is done at the offi ce, in which non-specifi c T
wave changes were the only abnormality. Besides blood
tests, the cardiologist orders an echocardiogram that shows
reduced left ventricle (LV) function and akinesis of the mid
and apical anterior-septal walls and a stress single photon
emission computed tomography (SPECT) study that shows
a perfusion defect in the same regions, with little reversibility on the rest images. Thinking this is most likely ischemic
coronary disease, the cardiologist orders a cardiac magnetic
resonance imaging (MRI) for viability evaluation prior to
the invasive coronary angiography, which showed an
occluded mid left anterior descending (LAD) artery with
distal fi lling via collaterals. Given the presence of viability
on the MRI scan, the patient successfully underwent percutaneous coronary intervention of the mid-LAD lesion and
two months later LV function shows improvement and the
patient is asymptomatic.
Cardiologists are familiar with relying on a number of different imaging modalities for a thorough assessment of cardiovascular diseases and further decision making. Coronary
anatomy evaluation is usually performed using invasive catheterization or more recently by non-invasive MDCT scans.
Global and regional myocardial function as well as structural
abnormalities can be assessed with echocardiography, MRI
and MDCT. Subclinical atherosclerosis is usually assessed
via detection of coronary calcium using MDCT or electron
beam CT scanners or via measuring carotid intima-media
thickness with ultrasound; while ischemia detection and
quantifi cation at stress are usually performed with nuclear
SPECT or positron emission tomography (PET), echo or
MRI imaging. Finally myocardial fi brosis for viability and
prognosis assessment is usually detected and quantifi ed by
MRI and nuclear techniques.
Recent advancements in MDCT imaging have demonstrated the feasibility of MDCT to be a comprehensive imaging
modality, which in a single scan setting could provide a wide
array of complementary information. Ideally, using one imaging modality to perform all these assessments during a single
scan setting could have substantial economic implications, may
serve to reduce patient anxiety, and improve workfl ow.
Ischemia Detection by MDCT
The notion that CT could provide information on myocardial
perfusion has been documented in the past by investigators
using electron beam CT [ 1 ]. However, the combination of a
reliable coronary angiogram with stress-induced myocardial
perfusion assessment had to wait until spiral CT technology
progressed suffi ciently to enable the acquisition of 64 slices
simultaneously [ 2 ]. Advent of wide array single source (256
or 320) and dual source detector scanning system with faster
gantry rotation time has allowed rapid acquisition of entire
cardiac volume with low radiation exposure, making MDCT
perfusion imaging more feasible and safe to perform.
Currently, the greatest limitations to CT coronary angiography are the presence of severely calcifi ed coronary segments, stents, or other artifacts that limit luminal visualization.
Patients with calcifi ed arteries tend to be older and/or have
advanced CAD. Their studies are challenging from a diagnostic viewpoint because vulnerable plaques and stenotic lesions
may be hidden underneath large amounts of calcium accumulated in the atherosclerotic plaques encompassing one or
more segments. While progress in multidetector technology
has improved our ability to study such patients, greater coverage and improved temporal resolution are unlikely to eliminate the problem, which is in large part intrinsic to the
pathogenesis of atherosclerosis, namely, plaques grow outwardly fi rst and tend to accumulate calcium as part of the
healing process, therefore creating a natural shield to X-ray
penetration. That is a particular limitation to the study of
older persons, patients with advanced CAD, and patients who
underwent coronary artery bypass graft surgery or multiple
stent implantation, as well as patients with diseases such as
chronic renal failure that accelerate plaque calcifi cation.
Furthermore, coronary anatomic information is much
more valuable when combined with a functional test, since
some decisions regarding treatment are based on the detection of myocardial ischemia [ 3 ]. Corresponding perfusion
defi cit related to an anatomic stenosis also confers worse
clinical prognosis [ 4 ]. The poor correlation between ana-
tomic modalities such as invasive coronary angiography [ 5 ,
6 ] and MDCT [ 7 ] with stress perfusion tests underscores the
fact that one cannot substitute for the other.
Myocardial perfusion measurements by MDCT are
derived from the upslope differences in contrast enhancement between the ischemic and remote areas (Fig. 12.1 ).
Previous generation 64-detector scanners had limited coverage of the heart, resulting in the base of the heart being
scanned earlier in time than the apex, making comparisons in
signal intensities between the two areas problematic. In this
regard, the introduction of wide coverage MDCT technology
allowed the entire heart to be imaged in one gantry rotation
(Fig. 12.2 ) combined with the capability of programming
such gated image acquisitions to occur only during specifi c
portions of a given cardiac cycle (Fig. 12.3 ). This created a
brand new horizon of possibilities to reduce radiation exposure enough to enable the performance of combined angiography and myocardial perfusion assessment during stress,
which associated with the angiographic and delayed
enhanced images, should provide a comprehensive cardiac
assessment. Also, with more coverage and faster acquisition,
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