Agatston score is a semi-automated tool to calculate a score based on the extent of coronary artery calcification detected by an unenhanced low-dose CT scan, which is routinely performed in patients undergoing cardiac CT. Due to an extensive body of research, it allows for early risk stratification as patients with a high Agatston score (>160) have an increased risk for a major adverse cardiac event (MACE) 2. Although it does not allow for the assessment of soft non-calcified plaques, it has shown a good correlation with contrast-enhanced CT coronary angiography 1.
Method of calculation
The calculation is based on the weighted density score given to the highest attenuation value (HU) multiplied by the area of the calcification speck.
- 130-199 HU: 1
- 200-299 HU: 2
- 300-399 HU: 3
- 400+ HU: 4
For example, if a calcified speck has a maximum attenuation value of 400 HU and occupies 8 sq mm area, then its calcium score will be 32.
The score of every calcified speck is summed up to give the total calcium score.
Grading of coronary artery disease (based on total calcium score)
- no evidence of CAD: 0 calcium score
- minimal: 1-10
- mild: 11-100
- moderate: 101-400
- severe: >400
Guidelines for coronary calcium scoring by 2010 ACCF task force
These guidelines are latest at time of writing (July 2016):
- intermediate cardiovascular risk and asymptomatic adults (class IIa)
- low-to-intermediate risk and asymptomatic adults (class IIb)
- low risk and asymptomatic (class III)
- asymptomatic adults with diabetes mellitus, 40 years of age and older (class IIa)
Cardiovascular risk calculator
Many risk calculators are available. Framingham cardiovascular risk calculator uses age, gender, total cholesterol, HDL cholesterol, smoking history, systolic blood pressure, and antihypertensive medication use 5.
In one retrospective study, a semi-automated, modified Agatston score applied to the abdominal aorta in non-contrast CT outperformed the Framingham score 8.
- 1. van der Bijl N, Joemai RM, Geleijns J et-al. Assessment of Agatston coronary artery calcium score using contrast-enhanced CT coronary angiography. AJR Am J Roentgenol. 2010;195 (6): 1299-305. doi:10.2214/AJR.09.3734 - Pubmed citation
- 2. Arad Y, Spadaro LA, Goodman K et-al. Prediction of coronary events with electron beam computed tomography. J. Am. Coll. Cardiol. 2000;36 (4): 1253-60. Pubmed citation
- 3. Thelen M, Erbel R. Cardiac Imaging. Thieme. (2011) ISBN:3131493313. Read it at Google Books - Find it at Amazon
- 4. Greenland P, Alpert JS, Beller GA et-al. 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J. Am. Coll. Cardiol. 2010;56 (25): e50-103. doi:10.1016/j.jacc.2010.09.001 - Pubmed citation
- 5. http://cvdrisk.nhlbi.nih.gov/
- 6. Detrano R, Guerci AD, Carr JJ et-al. Coronary calcium as a predictor of coronary events in four racial or ethnic groups. N. Engl. J. Med. 2008;358 (13): 1336-45. doi:10.1056/NEJMoa072100 - Pubmed citation
- 7. Agatston AS, Janowitz WR, Hildner FJ et-al. Quantification of coronary artery calcium using ultrafast computed tomography. J. Am. Coll. Cardiol. 1990;15 (4): 827-32. Pubmed citation
- 8. O’Connor SD, Graffy PM, Zea R, Pickhardt PJ. Does Nonenhanced CT-based Quantification of Abdominal Aortic Calcification Outperform the Framingham Risk Score in Predicting Cardiovascular Events in Asymptomatic Adults? Radiology. 2018;180562. Available at https://pubs.rsna.org/doi/full/10.1148/radiol.2018180562