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Interscan variation in coronary artery calcium quantification in a large asymptomatic patient population
H C Yoon1, J G Goldin, L E Greaser
1Department of Radiology, 1A71 School of Medicine, University of Utah School of Medicine, Salt Lake City 84132, USA.
Insights
Electron beam CT (EBCT) shows significant interscan variation in coronary artery calcium scores, particularly in men. Repeat scans may improve risk stratification for asymptomatic individuals with detected calcification.
Area of Science:
- Cardiovascular imaging
- Radiology
- Preventive cardiology
Background:
- Coronary artery calcium (CAC) scoring is used for cardiovascular risk stratification.
- Electron beam CT (EBCT) is a modality for CAC assessment.
- Understanding interscan variability is crucial for accurate risk assessment.
Purpose of the Study:
- To evaluate interscan variation in CAC scores using EBCT.
- To assess the impact of age, sex, and average calcium score on this variability.
Main Methods:
- 1000 asymptomatic patients underwent two consecutive EBCT scans.
- Scans used ECG gating, breath-hold, 3-mm collimation, and 100-msec exposure.
- Calcific lesions defined by >130 HU density; scores calculated vessel-by-vessel.
Main Results:
- Interscan differences in CAC scores were 28.4% for women and 43.0% for men.
- Individual artery score differences ranged from 20.2-44.9% by sex.
- 31% of patients showed differences in at least one coronary artery between scans.
Conclusions:
- Interscan variability in CAC scores is significant and may affect risk stratification.
- Consideration of repeat scans for subjects with non-zero CAC scores could enhance initial risk assessment.
Objective:
We evaluated interscan variation in coronary artery calcium scores in a large screening population as determined by electron beam CT.
Materials And Methods:
One thousand patients (average age, 53 years; age range, 18-85 years) who were asymptomatic for coronary artery disease underwent two consecutive scans of the heart on an electron beam CT scanner. Scans were performed with ECG gating, breath-hold, 3-mm collimation, and 100-msec exposure. Two contiguous pixels with density values greater than 130 H were used as the minimum criterion for a calcific lesion. The calcium score was determined on a vessel-by-vessel basis for both scans of each patient. Interscan variation in calcium and vessels involved with calcification was evaluated on the basis of age, sex, and average calcium score.
Results:
The percentage of difference between calcium scores in scans was 28.4% and 43.0% for women and men, respectively. For the individual epicardial arteries (left main, left anterior descending, circumflex, and right coronary), the percentage of difference for calcium scores was 20.2-24.2% for women and 30.5-44.9% for men. A difference between the two scans in at least one vessel of the total coronary arteries identified with calcium was noted in 31% of patients.
Conclusion:
Interscan variability in calcium scores may be important in the determination of risk stratification. Subjects with a nonzero calcium score may benefit from undergoing two scans at the time of initial imaging.