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Updated: Aug 16, 2026
Identifying Coronary Artery Calcification on Non-gated Computed Tomography Scans
Published on: August 28, 2018
Coronary artery calcium measurement with multi-detector row CT and low radiation dose: comparison between 55 and 165
Joseph Shemesh1, Rami Evron, Nira Koren-Morag
1Grace Ballas Research Unit of the Cardiac Rehabilitation Institute, Chaim Sheba Medical Center, Sackler School of Medicine and Division of Epidemiology and Preventive Medicine, Tel-Aviv University, Tel-Hashomer 52621, Israel. dshemesh@netvision.net.il
Insights
Lowering radiation dose in coronary artery calcium (CAC) scans using 55 mAs computed tomography (CT) yields results comparable to 165 mAs. This reduction in radiation exposure is effective for CAC detection and measurement.
Area of Science:
- Radiology
- Cardiovascular Imaging
- Medical Physics
Background:
- Coronary artery calcium (CAC) scoring is crucial for cardiovascular risk assessment.
- Multi-detector row computed tomography (CT) is a standard imaging modality for CAC.
- Optimizing radiation dose while maintaining diagnostic accuracy is a key concern in CT imaging.
Purpose of the Study:
- To prospectively compare CAC measurements using 55 mAs versus 165 mAs with electrocardiographically gated multi-detector row CT.
- To evaluate the diagnostic performance and radiation dose implications of lower mAs settings for CAC scoring.
Main Methods:
- Fifty-one subjects underwent CT scans at both 165 mAs and 55 mAs.
- Coronary artery calcium (CAC) number of lesions, total calcium score (TCS), and calcium mass were measured.
- Image noise and volume CT dose index were quantified and compared between the two settings.
Main Results:
- CAC detection and measurements (TCS, calcium mass) were comparable between 55 mAs and 165 mAs (P > 0.05).
- A significant high correlation (r > 0.90, P < .01) was observed for all CAC measures between the two techniques.
- Image noise increased at 55 mAs, but the volume CT dose index decreased significantly (12 mGy to 4 mGy).
Conclusions:
- Radiation dose for CAC detection and measurement can be effectively reduced using 55 mAs multi-detector row CT.
- The 55 mAs technique provides diagnostic results comparable to the standard 165 mAs protocol.
- Lowering radiation dose with 55 mAs is a viable option for CAC scoring without compromising diagnostic accuracy.
Purpose:
To prospectively compare the results of coronary artery calcium (CAC) measurements obtained with 55- and 165-mAs electrocardiographically gated multi-detector row computed tomography (CT).
Materials And Methods:
Institutional clinical study review board approval and written informed consent were obtained. Fifty-one consecutive subjects (mean age, 59 years +/- 10) were scanned consecutively by using 165 and 55 mAs. For each examination, the number of lesions, total calcium score (TCS) calculated with Agatston algorithm (130-HU threshold), and calcium mass (in milligrams) were measured. Noise was measured by averaging 1 standard deviation of the CT attenuation values in five consecutive transverse sections of the ascending aorta. Paired t test and Pearson correlation were used to compare measurements between the examinations.
Results:
By using 55 mAs, CAC was detected (TCS > 0) in all 33 subjects in whom CAC was initially detected with 165 mAs. The mean values of CAC measures with 165 and 55 mAs, respectively, were as follows: number of lesions, 6.2 +/- 9.6 and 6.1 +/- 9.4; TCS, 123 +/- 223 and 126 +/- 225; and calcium mass, 23.25 mg +/- 43 and 24.25 mg +/- 44 (P value was not significant for all parameters). Significant high correlation was found between the two methods for all measures (r > 0.90, P < .01). Similar results were obtained with analysis by coronary vessel. Image noise was 9.3 HU +/- 2.1 with 165 mAs and 14.7 HU +/- 3.9 with 55 mAs (P < .001), with a parallel decrease in the volume CT dose index from 12 to 4 mGy.
Conclusion:
Radiation dose can be reduced (eg, 55 mAs) for CAC detection and measurement at multi-detector row CT and provides results comparable to those obtained with 165 mAs.
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