Non-Invasive Coronary Angiography;
The Future Is Here “Fast MSCT”!
Alireza Zarrabi, M.D.
Center for Vulnerable Plaque Research,
Texas Heart Institute and University of Texas - Houston
VP Watch – October 16, 2002 - Volume 2, Issue 41
1979 Nobel Prize in Medicine and
Physiology went to Hounsfield and
McCormack for invention of computed
Godfrey Hounsfield Allan MacLeod Cormack
Non-invasive imaging of coronary arteries has
been a dream for cardiovascular medicine that
is now coming close to reality.
However, imaging of small arteries
(coronaries) on a moving target body (heart) is
a complicated and challenging situation.
There is no time in which all portions of the
heart are at rest and this fact contributes to
limitations for any tomographic imaging
method that requires fixed exposure time.
CT, EBCT, and MRI are competing techniques
for non-invasive imaging of coronary arteries.
Each of the above technology has some
advantages and disadvantages that prevent
them from being a unique solution superior to
the others to completely serve the purpose of
non-invasive diagnosis of future culprit lesions
(vulnerable plaque) as a widely available
MR angiography has been a progressive process in recent years.
n Sensitivity Specificity
Post et al 1996 20 38% 95%
Müller et al 1997 30 83% 94%
Achenbach et al 1997 73 65% 88%
Sandstede et al 1999 30 81% 89%
van Geuns et al 1999 32 50% 91%
Leithmonnier et al 1999 20 65% 93%
Sardanelli et al 2000 42 82% 89%
Regenfus et al 2001 50 87% 91%
Kim et al 2001 107 83% 73%
The feasibility of MRI to quantify plaque morphology has been demonstrated
ex vivo in human carotid tissue and in vivo in animal models. 1,2
MR Imaging and MR Angiography :
No need for contrast media
Detailed plaque characterization
Poor spatial resolution
Inadequate temporal resolution
Milestone in CT
1967 Pattern recognition and reconstruction techniques using computer – G.
1971 The first clinical prototype CT brain scanner – Ambrose
1974 The first whole-body CT scanner – Robert Ledley
1979 Nobel Prize in Medicine and Physiology – Hounsfield and MacLeod Cormack
1979 The first principle and operation of the electron beam CT (EBCT) scanner –
1983 The first EBT scanner developed by Imatron and named cardiovascular
1988 The first coronary calcium study
1989 The first report of a practical spiral CT scanner (single-slice spiral CT)– Willi
1992 Dual-slice spiral CT scanner
1995 The first CT coronary angiography
1998 Multi-slice CT scanner
In old conventional CT the x-ray tube and detectors
rotate for 360 degrees or less to scan one slice while the
table and patient were stationary which was time
In next generation In 1989 the first report of a practical
spiral CT scanner was presented at RSNA meeting by
Dr. Willi Kalender.
The next step forward has been the introduction of
multi-slice CT (MSCT) scanner at the RSNA 1998.
CT screening has been the center of attention in the
field of clinical diagnostic imaging during the past
few years for different purposes such as coronary
artery calcification, lung cancer, colonoscopy, and
whole body scan.
CT claims several applications in the field of
Coronary calcium imaging
Assessment of cardiac function
Electron beam computed tomography
(EBT) can accurately identify presence
of calcification in the coronary tree non-
Coronary calcification is not normal and
clearly indicates presence of
Rumberger et al. stated important conclusion
for using EBT: 6,7
Coronary calcium area per individual
coronary artery and/or per whole heart as
defined by EBT is highly correlated with
histologically quantified coronary plaque
Guerci, Arad, and colleagues also found that
in asymptomatic adults, EBCT of coronary
arteries predicts coronary death and nonfatal MI
and the need for revascularization procedures. 4
Rumberger and others showed the ranges for
EBT coronary calcium score cutpoints that
predict the likely severity of associated maximal
angiographic stenosis severity to a high
sensitivity, high specificity or optimal
Budoff, Raggi, and colleagues showed
that EBT calcium scanning provides
incremental and independent power in
predicting the severity and extent of
angiographically significant CAD in
symptomatic patients, in conjunction with
pretest probability of disease. 3
# of patients Sens. Spec.
Nakanishi et al. 1997 37 74% 91%
Schmermund 1998 28 82% 88%
Achenbach 1998 125 92% 94%
Ropers 2000 118 90% 82%
Achenbach 2000 36 92% 91%
Achenbach 1999 56
Occlusion 100% 100%
Stenosis 100% 97%
Sensitivity and Specificity of EBCT for Obstructive
Coronary Disease As Compared With Invasive
Achenbach et al. for the first time established
protocol for the visualization of coronary
arteries by EBT. 8
EBT has been used as a noninvasive 3D
arteriography of the large epicardial coronary
arteries, to visualize coronary artery bypass
grafts, and also to characterize coronary artery
True temporal resolution 50-100 ms 230-1000 ms
Spatial resolution 1.5 mm vessels 1.0mm vessels
Practical heart rate
limitations for a Dx study
50-100 bpm <60-65 bpm
Cardiac function &
Radiation exposure, mSv 1-2 2-10
Clinical availability Increasing slowly Expanding rapidly
Yes, extensively validated Yes, limited validation
EBT vs. MSCT
Adapted from: Noninvasive Coronary Angiography Using Computed Tomography: Ready to Kick It Up Another
Notch? Circulation. 2002 Oct 15;106(16):2036-2038
Comparing MSCT and Invasive
n Sens Spec
Nieman et al 2001 31 81% 97%
Achenbach et al. 2001 64 91% 84%
Knez et al. 2001 42 78% 98%
Nieman et al. 2002 59 95% 86%
As reported in VP Watch of this week,
Nieman and colleagues performed ECG-gated MSCT
angiography with a 16-slice MSCT scanner (0.42-s
rotation time, 12x0.75-mm detector collimation) in
selective patients with suspected obstructive coronary
Additional ß-blockers were given 1 hour before the
procedure to those patients with a resting heart rate
>65 beats/minute. Average heart rate during study
was 56 beats/min.
MSCT scanner used for this study has a rotational
speed of 440 ms and can achieve cardiac tomographic
slice thicknesses of <1.0 mm.
They showed the overall sensitivity and specificity to
detect significantly stenosed coronary arteries was 95%
The predictive value of MSCT angiography to detect
patients with no, single, or multivessel disease in this
study was 100%, 75%, and 74%, respectively.
The use of 16-slice CT scanner with 400ms
rotation time, combined with ß-blocking agent
has significantly improved the diagnostic
accuracy of MSCT to non-invasive detection
of coronary stenosis.
Fast MSCT is moving fast to become the first
screening imaging technique for detection of
coronary artery disease.
Which one of the following should be
considered as first step imaging in
screening for vulnerable plaques in
MRI / MRA
Despite improvements in rotational
acquisition speed above most current
helical scanners, resting heart rate
would still be a major factor in image
quality by MSCT. What is the next step:
Faster CT (decrease rotation time)?
Larger detectors (32, 64, or more slices)?
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