CT calcium scoring can detect asymptomatic coronary artery disease by identifying coronary artery calcification. Calcium starts accumulating early in atherosclerosis and increases as the disease progresses. While a calcium score of zero does not rule out disease, it is associated with a very low risk of cardiac events. Higher calcium scores correlate with increased risk. CT calcium scoring provides individualized risk assessment and can guide aggressive risk factor modification in high-risk patients.

1. CT Calcium ScoringCT Calcium Scoring
Dr.Sahar Gamal El-Din , CBCCTDr.Sahar Gamal El-Din , CBCCT

2. Background
• Approximately 50% of acute MI occur inApproximately 50% of acute MI occur in
people without any history of CAD.people without any history of CAD.
• Coronary atherosclerosis is a slow progressiveCoronary atherosclerosis is a slow progressive
disease that often goes unrecognized until thedisease that often goes unrecognized until the
person develops symptoms.person develops symptoms.
• What is needed is a way to identifyWhat is needed is a way to identify
asymptomatic people who are at high risk forasymptomatic people who are at high risk for
CV events early in their disease process.CV events early in their disease process.

3. • MI usually occurs in patients who have aMI usually occurs in patients who have a
mild or moderate CA stenosis thatmild or moderate CA stenosis that
develops plaque rupture & leads to andevelops plaque rupture & leads to an
acute thrombosis.acute thrombosis.
• These mild to moderate coronary lesionsThese mild to moderate coronary lesions
may not cause symptoms and/or may notmay not cause symptoms and/or may not
cause enough ischemia to be picked upcause enough ischemia to be picked up
during a routine stress test.during a routine stress test.

4. • During the early stages of coronaryDuring the early stages of coronary
atherosclerosis calcium starts toatherosclerosis calcium starts to
accumulate within the plaque.accumulate within the plaque.
• As the atherosclerotic process progressesAs the atherosclerotic process progresses
the amount of calcification increases.the amount of calcification increases.
• During the advanced stages ofDuring the advanced stages of
atherosclerosis a large amount ofatherosclerosis a large amount of
coronary calcification may be present.coronary calcification may be present.

5. Coronary Disease Progression
Calcified Plaque Detected by CT

6. • Atherosclerosis is the only diseaseAtherosclerosis is the only disease
process known to cause calcium toprocess known to cause calcium to
deposit in coronary artery walls.deposit in coronary artery walls.
• Calcification is not a degenerativeCalcification is not a degenerative
disease, it is not a part of the “normal”disease, it is not a part of the “normal”
aging process.aging process.
• Calcium is not found in normal CA.Calcium is not found in normal CA.

7. • Since calcium deposits start to developSince calcium deposits start to develop
during the early stages of atherosclerosisduring the early stages of atherosclerosis
and if we are able to identify theand if we are able to identify the
presence of calcium we are able topresence of calcium we are able to
identify preclinical coronary arteryidentify preclinical coronary artery
disease during the asymptomatic stage.disease during the asymptomatic stage.
• This can allow for the implementation ofThis can allow for the implementation of
early aggressive risk factor reduction.early aggressive risk factor reduction.

8. • Calcification can be seen with fluoroscopyCalcification can be seen with fluoroscopy
and on chest x-ray.and on chest x-ray.
• Computed tomography allowsComputed tomography allows
quantification of this calcium.quantification of this calcium.

9. • The amount of calcium deposited inThe amount of calcium deposited in
coronary arteries is added up and a “score” iscoronary arteries is added up and a “score” is
given.given.
• The amount of calcium in the coronaryThe amount of calcium in the coronary
arteries varies considerably with age andarteries varies considerably with age and
gender.gender.
• For this reason, coronary calcium scores areFor this reason, coronary calcium scores are
presented as percentile scores that can tellpresented as percentile scores that can tell
how much calcium you have compared tohow much calcium you have compared to
other men or women of your age.other men or women of your age.

10. • higher than the 75th percentile ishigher than the 75th percentile is
considered high risk, irrespective of theconsidered high risk, irrespective of the
score, and indicates prematurescore, and indicates premature
atherosclerosis.atherosclerosis.

11. • Unlike global risk scores such as theUnlike global risk scores such as the
Framingham Risk Score, which provide cardio-Framingham Risk Score, which provide cardio-
vascular risk estimates based on mean risk factorvascular risk estimates based on mean risk factor
distributions across a population, the CCS is adistributions across a population, the CCS is a
direct marker of atherosclerosis in an individualdirect marker of atherosclerosis in an individual
patient.patient.
• As such, it provides an assessment of the burdenAs such, it provides an assessment of the burden
of coronary atherosclerosis, reflecting theof coronary atherosclerosis, reflecting the
integrated lifetime effect of all risk factors in anintegrated lifetime effect of all risk factors in an
individual patient.individual patient.

12. CCS Protocol
• CAC is detected using a standardized protocolCAC is detected using a standardized protocol
involving :involving :
• Prospective ECG-triggered axial scanning, withProspective ECG-triggered axial scanning, with
a slice thickness of 3mm.a slice thickness of 3mm.
• Standard tube voltage is 120 kV, with tubeStandard tube voltage is 120 kV, with tube
current set at 120 to 150 mAs, which shouldcurrent set at 120 to 150 mAs, which should
result in acceptably low levels of radiationresult in acceptably low levels of radiation
exposure (1 to 2 mSv).exposure (1 to 2 mSv).

13. MethodsMethods
• Agatston Score :Agatston Score :Traditional methodTraditional method
(EBCT : MDCT)(EBCT : MDCT)
• Volume Score :Volume Score : Plaque area x slicePlaque area x slice
thickness (mmthickness (mm³³))
• Mass Score :Mass Score : Plaque volume x meanPlaque volume x mean
plaque density .plaque density .

14. • The method is based on the maximum x-ray
attenuation coefficient, or CT number
(measured in Hounsfield units [HU]), and
the area of calcium deposits.
• First, calcified lesions are identified on CT
images by applying a threshold of 130 HU
to the entire image set; tissues with
densities equal to or greater than the
threshold are considered to correspond to
calcium.
Agatston ScoreAgatston Score

15. • For each coronary artery, i, a region of
interest (ROI) is drawn around each
calcified lesion, j.
• The maximum CT number, CTmax ij , of
the ROI is determined and used to assign
a weighting factor, wij.
• The area, Aij, of the ROI is also
determined.

16. • The Agatston score, Sij, is computed as
the product of the weighting factor and
the area:
Sij = wij x Aij
Where :
• w ij = 1 if CTijmax 130 - 199 HU
2 if CTijmax 200 - 299 HU
3 if CTijmax 300 - 399 HU
4 if CTijmax > 400 HU

17. • The score for all lesions in all coronary
arteries is summed to determine the total
calcium burden:
Stot = Σ Sij

19. The Calcium ScaleThe Calcium Scale
The calcium scale is a linear scale with 4The calcium scale is a linear scale with 4
calcium score categories:calcium score categories:
00 NormalNormal
1–991–99 MildMild
100–400100–400 ModerateModerate
>400>400 SevereSevere

21. • Variations according to sex and ethnicity haveVariations according to sex and ethnicity have
been described.been described.
• In the Multi-Ethnic Study of AtherosclerosisIn the Multi-Ethnic Study of Atherosclerosis
(MESA)(MESA) of 6,110 asymptomatic patients, menof 6,110 asymptomatic patients, men
had higher calcium levels than women, and thehad higher calcium levels than women, and the
amount and prevalence of calcium continuallyamount and prevalence of calcium continually
increased with increasing age .increased with increasing age .
• A calcium score of 175 may be average for a 65A calcium score of 175 may be average for a 65
year old male but grossly abnormal for a 55year old male but grossly abnormal for a 55
year old female.year old female.
Circulation 2006;113:30–7Circulation 2006;113:30–7

22. Distribution - menDistribution - men
Age Ca Score
< 40 0
40 -49 0
50-54 5
55-59 36
60-64 95
65-69 201
70-74 302
> 74 521

23. Distribution - womenDistribution - women
Age Ca Score
< 40 0
40 -49 0
50-54 0
55-59 0
60-64 0
65-69 8
70-74 28
> 74 149

24. • In men, Caucasians and Hispanics had the firstIn men, Caucasians and Hispanics had the first
and second highest scores, respectively; blacksand second highest scores, respectively; blacks
had the lowest scores at the younger ages, andhad the lowest scores at the younger ages, and
Chinese had the lowest scores at the older ages.Chinese had the lowest scores at the older ages.
• In women, Caucasians had the highest scores,In women, Caucasians had the highest scores,
Chinese and blacks had intermediate scores, andChinese and blacks had intermediate scores, and
Hispanics had the lowest score except for ChineseHispanics had the lowest score except for Chinese
in the oldest age group.in the oldest age group.

25. •What does CCS “0” mean?
• One may still have non-calcifiedOne may still have non-calcified
atherosclerotic plaque .atherosclerotic plaque .
• Multiple studies have shown only a 0.11 %Multiple studies have shown only a 0.11 %
annual event rate and 1.1% 10 year risk inannual event rate and 1.1% 10 year risk in
asymptomatic patients with 0 CCS.asymptomatic patients with 0 CCS.

26. •Advantages of CCS
• Rapid .Rapid .
• Does not require contrast.Does not require contrast.
• Low radiation dose .Low radiation dose .
• Reproducible.Reproducible.
• Powerful prognostic data.Powerful prognostic data.
• Disadvantages of CCS :Disadvantages of CCS :
• CostCost
• Radiation exposureRadiation exposure

27. Coronary Calcium and Clinical OutcomesCoronary Calcium and Clinical Outcomes
• OVERALL:OVERALL:
– 15 studies published15 studies published
– Age range 41- 85 years oldAge range 41- 85 years old
– Approximately 15,000 patientsApproximately 15,000 patients
– All studies have reported that coronaryAll studies have reported that coronary
calcium predicts CV disease eventscalcium predicts CV disease events
independently of and more accuratelyindependently of and more accurately
than traditional risk factors.than traditional risk factors.

28. • At 2004 a study was carried out inAt 2004 a study was carried out in
Netherlands:Netherlands:
• From 2,032 people ages 55 to 85, with aFrom 2,032 people ages 55 to 85, with a
mean age of 77, who underwent CTmean age of 77, who underwent CT
calcium scoring between 1997 and 2000calcium scoring between 1997 and 2000
• 0 -100 : 47%0 -100 : 47%
• 100 -500 : 26%100 -500 : 26%
• >500 : 27%>500 : 27%
• The mean duration of follow-up was 2.7The mean duration of follow-up was 2.7
years, during which time 92 subjectsyears, during which time 92 subjects

30. • Calcium scores 101-500 :Calcium scores 101-500 : double risk ofdouble risk of
mortality.mortality.
• Calcium scores over 500 :Calcium scores over 500 : 2.7 times2.7 times
increased risk of mortality.increased risk of mortality.
• The increase in mortality :The increase in mortality :
between the lowest and the middlebetween the lowest and the middle
category of calcium scores (0-100 and 101-category of calcium scores (0-100 and 101-
500) : 12.3%500) : 12.3%
 between the middle and the highestbetween the middle and the highest
scores (101-500 and >500) : 23.7%scores (101-500 and >500) : 23.7%

31. Integrating the Calcium Score withIntegrating the Calcium Score with
the Framingham Risk Score (FRS)the Framingham Risk Score (FRS)
• 2004, Johns Hopkins University2004, Johns Hopkins University
calculated the Framingham scores of 5,324calculated the Framingham scores of 5,324
asymptomatic individualsasymptomatic individuals
• Stratified into low-risk, intermediate-risk, andStratified into low-risk, intermediate-risk, and
high-risk groupshigh-risk groups
― Low-riskLow-risk is defined as a 10 year risk of < 10%,is defined as a 10 year risk of < 10%,
― intermediate-riskintermediate-risk is defined as a 10 year risk of 10is defined as a 10 year risk of 10
to 20%to 20%
― high-riskhigh-risk is defined as a 10 year risk > 20%is defined as a 10 year risk > 20%
• Underwent CT coronary artery scanningUnderwent CT coronary artery scanning

32. Framingham Score 10 yr. event riskFramingham Score 10 yr. event risk
recalculated according to CCS rangerecalculated according to CCS range

33. • CLASS IIaCLASS IIa
• Measurement of CCS is reasonable forMeasurement of CCS is reasonable for
cardiovascular risk assessment in asymptomaticcardiovascular risk assessment in asymptomatic
adults at intermediate risk (10% to 20% 10-yearadults at intermediate risk (10% to 20% 10-year
risk).risk). (Level of Evidence: B) .(Level of Evidence: B) .
2010 ACCF/AHA Guideline2010 ACCF/AHA Guideline
RECOMMENDATIONS FOR CALCIUMRECOMMENDATIONS FOR CALCIUM
SCORING METHODSSCORING METHODS

34. • CLASS IIbCLASS IIb
• Measurement of CCS may be reasonable forMeasurement of CCS may be reasonable for
cardiovascular risk assessment in persons atcardiovascular risk assessment in persons at
low to intermediate risk (6% to 10% 10-yearlow to intermediate risk (6% to 10% 10-year
risk).risk). (Level of Evidence: B)(Level of Evidence: B)
• CLASS III: NO BENEFITCLASS III: NO BENEFIT
• Persons at low risk (<6% 10-year risk) shouldPersons at low risk (<6% 10-year risk) should
not undergo CCS measurement fornot undergo CCS measurement for
cardiovascular risk assessment.cardiovascular risk assessment.
(Level of Evidence: B).(Level of Evidence: B).

35. Detection of CAD/Risk Assessment inDetection of CAD/Risk Assessment in
Asymptomatic Patients Without Known CADAsymptomatic Patients Without Known CAD
IndicationIndication Appropriate Use Score (1–9)Appropriate Use Score (1–9)
Global CHDGlobal CHD
Risk EstimateRisk Estimate
LowLow IntermediateIntermediate HighHigh
Family history of
premature CHD
A (7)A (7)
Asymptomatic
No known CAD
I (2)I (2) A (7)A (7) U (4)U (4)
JCCT (2010) 4, 407.e1–407.e33JCCT (2010) 4, 407.e1–407.e33
ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI
/SCMR 2010 Appropriate Use Criteria

36. The 2013 ACC/AHA CholesterolThe 2013 ACC/AHA Cholesterol
and the 2013 ACC/AHA Risk Guidelinesand the 2013 ACC/AHA Risk Guidelines
• Created an entirely risk factor–basedCreated an entirely risk factor–based
pooled cohort equation untested bypooled cohort equation untested by
randomized clinical trials, using the samerandomized clinical trials, using the same
risk factors as the 2010 version but withrisk factors as the 2010 version but with
different weightings, now modified bydifferent weightings, now modified by
race.race.
• They downgraded CCS to a Class IIbThey downgraded CCS to a Class IIb
recommendation.recommendation.

37. ConclusionConclusion
• Despite the remarkable data supporting the prime
role of CCS in risk assessment of the
intermediate-risk population & considering it a
more potent predictor of CAD than risk factors for
atherosclerosis , CCS has not been incorporated
into the mainstream of clinical cardiology and has
been downgraded in the 2013 guidelines.
• As the data continue to accumulate with follow-
up periods up to 15 years, accompanied by
increasing public & physician awareness, the
importance of CCS will be more universally
accepted