Ct calcium scoring 1
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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.
![• 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](https://image.slidesharecdn.com/ctcalciumscoring1-190130102035/85/Ct-calcium-scoring-1-14-320.jpg)
Ct calcium scoring 1
- 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