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What is cardiac
scoring?
Cardiac scoring (or coronary
artery calcium scoring) is a noninvasive, painless screening
of the heart for calcium deposits in the coronary arteries,
which are the blood vessels that bring oxygen and nutrients
to the heart. As calcium deposits build up, the blood vessels
narrow, allowing less blood and oxygen to the heart. Coronary
calcium can develop as early as the second decade of life.
Although it is more common in advanced age, coronary calcium
is not an inevitable part of aging. Calcium deposits can be
absent in normal vessel walls, regardless of age.
Cardiac scoring is performed
in just 20 seconds on a multislice computed tomography (CT)
scanner and is extremely accurate in detecting the presence,
extent, and severity of hard plaque burden within the
coronary arteries. Hard plaque is a known indicator of
coronary artery disease (CAD). Prior to advancements in CT
scanning, it was extremely difficult to detect the very small
calcium deposits that form in the early stages of heart
disease. However, with multislice CT scanning, even miniscule
calcium deposits can be detected easily.
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Why is
getting a cardiac score important?
Coronary artery disease (CAD)
or atherosclerosis is the #1 cause of death of both men and
women, claiming over 500,000 lives each year. Over 400 people
under age 65 die each day from cardiac events (ie, death,
myocardial infarction, congestive heart failure, and stroke)
related to CAD, many without prior symptoms or warning.
Typically, patients are diagnosed with CAD when they have
already shown symptoms (eg, chest pain, fatigue), responded
abnormally to stress testing, or undergone cardiac
angiography. This means that the opportunity for prevention
is lost and the patient may have already suffered
irreversible consequences or a cardiac event.
Cardiac scoring can detect
coronary calcium in its early stages. Early detection allows
for positive lifestyle changes to be made that will help
prevent or minimize further progression of CAD or cardiac
events. Currently, preventive therapies for heart disease
include blood pressure and lipid control, smoking cessation,
diet, and regular exercise. The use of statins to reduce
blood cholesterol has been shown to decrease the risk of
heart attack by one third.
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Who should have
cardiac scoring?
Cardiac scoring is recommended
for generally healthy, asymptomatic males over age 45 and
females over age 55 who are at risk for CAD. Individuals with
a strong family history of heart disease may want to undergo
cardiac scoring as early as age 35 or 45. The following are
major risk factors for CAD:
- Family history of
coronary artery disease
- High blood
pressure
- High
cholesterol
- History of
smoking
- Diabetes
- Obesity
- Sedentary
lifestyle
- High level of
stress
Cardiac scoring is not
recommended for persons with arrhythmias or with relative
resting tachycardia (heart rate greater than 90 beats per
minute). A high or irregular heart rate makes ECG gating of
the heart difficult, resulting in poor image quality.
However, these conditions can be treated, making a cardiac
scoring examination possible.
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How does cardiac
scoring work?
Figure 1. As with a loaf of bread that is cut
into many slices, computed tomography can make pictures of
"slices" of the body’s internal structures.
Cardiac scoring and all other
virtual studies at Diagnostic Imaging Associates are
performed on the multislice GE LightSpeed Plus CT scanner. CT
stands for computed tomography, a process by which a digital
picture is made by a computer after low-dose x-rays record a
slice or cross section of the body. A CT scanner is a
diagnostic tool which, for cardiac scoring, allows
visualization of the heart and its internal structures. The
word "slice" is often used to explain the images taken of
patient anatomy because they are similar to a single slice of
bread taken from a whole loaf (Figure 1).
During the cardiac scoring
procedure, the patient is asked to lie on the table of the CT
scanner. This tabletop moves the patient’s body through the
CT scanner’s gantry (Figure 2) which houses an x-ray
tube and detectors. The tube rotates around the patient as
x-rays pass through the body to the detectors, where
thousands of x-ray measurements are recorded. Next, the
computer processes this information and displays the
corresponding images on a computer screen. This imaging
technique avoids any overlap of organs or tissues.
Our multislice GE scanner can
capture these images of the heart during a single
breath-hold, which means less stress and discomfort for the
patient and a faster examination time. The cardiac scoring
procedure takes only 5 minutes because the LightSpeed Plus CT
scanner can take eight thin slices of the heart per second.
This high scanning speed allows for clearer, sharper images
with fewer artifacts (false images due to blurring)
caused by movement of the body.
Figure 2.
Patient being moved into the
gantry of the GE LightSpeed Plus CT scanner.
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What
preparation is needed for a cardiac scoring
examination?
Only two things must be done
before undergoing cardiac scoring: no caffeine and no
smoking 4 hours before
the examination. Drinking caffeine and smoking before
the test increases your heart rate. In order to have an
accurate study, your heart rate should be below 80 beats per
minute (bpm). As the heart rate increases over 80 bpm, it is
more difficult to take images of the heart in diastole (ie,
period of relaxation) which decreases the accuracy of the
test results. If the heart rate is too elevated (ie, over 90
bpm), it may be necessary to reschedule your test for another
day. If you anticipate your heart rate being a problem during
cardiac scoring, a beta-blocker can be prescribed to help
lower your heart rate for the examination.
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What
should I expect when I arrive for my cardiac scoring
examination?
When you arrive at Diagnostic
Imaging Associates for your cardiac scoring study, you will
be greeted by our staff at the front desk and then taken to a
private waiting room. At this time, our Virtual Screening
Manager will conduct a personal interview with you that will
include questions about your family medical history and risk
factors you may have for specific diseases or cancers. If
time allows, a 5-minute movie outlining the steps of the
cardiac scoring examination will be shown.
Next, you will be taken to a
dressing room and asked to change into an examination gown.
You will then be led to the CT suite where a radiologic
technologist will position you on the table of our multislice
GE scanner. Four electrodes will be attached to the chest
area—two high on the anterior chest and two low on the sides
of the chest. These electrodes are connected to a special ECG
monitor that signals the CT scanner to take pictures of the
heart in diastole. This assures a clearer, more accurate
image. A slower heart rate makes it easier for the CT scanner
to take pictures of the heart in diastole. If your heartbeat
is too fast, your cardiac scoring examination may have to be
rescheduled.
Two scout views will be taken
to locate your heart within your chest. During these scout
views, the technologist will enter your patient information
(ie, name, patient number, examination date) into the
computer workstation. These two scout views will then
be used to plot the slices of the heart that will be recorded
by the CT scanner. The third scan will obtain the slices of
the heart that will be used to detect and measure the calcium
in your coronary arteries. You will be asked by the
technologist to hold your breath for 20 to 30 seconds.
Holding your breath is very important because it eliminates
artifacts on the image that are due to motion of the chest
during breathing. Approximately 180 to 200 images of your
heart will be taken at this time. The data from the x-rays
will appear immediately on the computer screen, completing
your examination.
The results of your cardiac
scoring examination will be mailed to you in three business
days. Your report will include a summary of the radiologist’s
findings and recommendations for further follow-up. Results
will also be sent to your primary care physician upon
request. Because of the volume of images that must be
analyzed, immediate results from the radiologist are not
possible. Three working days allows the radiologist to take
the proper amount of time to review your study, to report
accurate findings, and if necessary, to seek consultation
with other physicians regarding any unusual
findings.
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What does a cardiac
score mean?
A cardiac score can range from
zero to several thousand and is based on the amount of
calcification detected in the coronary arteries. The more
calcium that is seen in the coronary arteries, the greater
the score. This score is an indicator of your level of hard
plaque burden. A very low score means that there is virtually
no obstructive disease in the coronary arteries, whereas a
high score indicates that the level of hard plaque burden is
extensive and the risk of a future cardiac event is
significant. The following chart outlines what specific
ranges of scores mean and the recommendations a physician is
likely to make based on these scores.
Score
|
Level of Hard Plaque
Burden
|
Level of Significant Risk of
CAD
|
Recommendations
|
0
|
None
|
Extremely low
|
Patient should maintain a healthy diet
that is low in saturated fat and cholesterol, refrain
from smoking, maintain ideal body weight, and
exercise regularly.
|
1–10
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Minimal
|
Very unlikely
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All of the above PLUS close control of
diabetes and high blood pressure, and possibly the
use of statins for high cholesterol.
|
11–100
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Mild
|
Mild to moderate
|
All of the above PLUS daily aspirin,
statins for high cholesterol, and estrogen for
postmenopausal women.
|
101–399
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Moderate
|
Moderate to high
|
All of the above PLUS use of folic acid,
and possibly stress testing for further risk
assessment.
|
400 or greater
|
Extensive
|
High to very high
|
All of the above PLUS stress testing to
assess extent of obstructive disease, and possibly
cardiac angiography.
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The odds ratios for developing
symptomatic CAD based on cardiac scoring are as follow: 7:1
for scores greater than 50, 20:1 for scores greater than 100,
and 35:1 for scores above 160. This means that a person with
a calcium score greater than 50 is 7 times more likely to
experience symptoms of CAD compared with a completely healthy
individual. The ability of calcium scores to predict the risk
of developing symptomatic CAD is particularly striking when
compared with the predictive powers of traditional risk
factors. For example, the likelihood of experiencing symptoms
of CAD is 3.6 times greater for an individual with a smoking
history and 1.8 times greater for a person with high
cholesterol, compared with a healthy individual.
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What score
is typical for a person my age?
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AGE
|
| |
40–45
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46–50
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51–55
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56–60
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61–65
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66–70
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71 and older
|
PERCENTILE
|
|
|
|
|
|
|
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MEN
|
|
|
|
|
|
|
|
10%
|
0
|
0
|
0
|
1
|
1
|
3
|
3
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25%
|
0.5
|
1
|
2
|
5
|
12
|
30
|
65
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50%
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2
|
3
|
15
|
54
|
117
|
166
|
350
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75%
|
11
|
36
|
110
|
229
|
386
|
538
|
844
|
90%
|
69
|
151
|
346
|
588
|
933
|
1151
|
1650
|
WOMEN
|
|
|
|
|
|
|
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10%
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
25%
|
0.1
|
0.1
|
0.1
|
0.2
|
0.5
|
1
|
4
|
50%
|
0.1
|
0.1
|
1
|
1
|
3
|
25
|
51
|
75%
|
1
|
2
|
6
|
22
|
68
|
148
|
231
|
90%
|
3
|
21
|
61
|
127
|
208
|
327
|
698
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Percentile rank is calculated
by adjusting calcium scores for age and sex. The following
example illustrates how to read the above table: a
57-year-old man with a calcium score of 54 would be in the
50th percentile. This means that, in his age- and sex-matched
group, 50% of men have calcium scores greater than his and
50% have scores less than his score. A 46-year-old woman with
a calcium score of 2 would be in the 75th percentile. This
means that compared with her age- and sex-matched peers, 75%
have calcium scores less than hers and 25% have scores above
her score of 2.
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What
do the images from cardiac scoring look
like?
  
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What are
the limitations of cardiac scoring?
One of the limitations of
cardiac scoring is that even though calcium deposition occurs
early in the process of atherosclerosis, plaque material in
its earliest stage is not yet calcified. Thus, despite
cardiac scoring being a more powerful tool for detecting
atherosclerosis at an earlier stage than other x-ray
techniques, soft plaque material cannot be
detected.
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Is
multislice CT scanning as good as EBCT for cardiac
scoring?
Several studies published in
the past year have concluded that multislice CT (MSCT) and
electron beam computed tomography (EBCT) are equal in their
ability to accurately detect hard plaque deposits in the
coronary arteries. Some studies have shown that MSCT has a
better contrast-to-noise ratio and superior spatial
resolution— two key elements in producing clear, accurate
images. Due to these results and because MSCT is less
expensive and more widely available, this technique is
gaining in popularity.
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Is cardiac scoring
safe?
A concern with any study that
exposes the patient to x-rays is radiation exposure. It is
estimate that the amount of radiation received from a cardiac
scoring examination is equal to the background radiation
received from a standard chest x-ray.
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How much does
cardiac scoring cost?
A cardiac
scoring examination at Diagnostic Imaging Associates costs
$375. At this time insurance plans do not cover the cost of
this screening test. Diagnostic Imaging Associates accepts
cash, check, and Visa and MasterCard. Payment is required at
the time of your screening examination.
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Where
can I get a cardiac scoring examination?
Diagnostic
Imaging Associates is the first radiology provider in Delaware
to offer Virtual Check-Up™ and requires no referral from a
doctor or insurance plan. All virtual screening studies can be
performed at three of our seven convenient locations –
Omega
Imaging & MRI, Brandywine , and Glasgow.
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