An Agatston score from a gated non-contrast scan, given with the MESA or age/sex percentile and a CAC-DRS category; on a non-gated chest CT, coronary calcium is still reported (none, mild, moderate, severe).
Orient first
- Agatston score: area × peak-density weighting (130 HU threshold) summed over all lesions.
- CAC-DRS categories 0, 1 (1–99), 2 (100–299), 3 (≥ 300) guide preventive therapy (verify the version your cardiologists use).
- A score of zero lowers but does not abolish risk; non-calcified plaque is invisible on this scan.
Acquire the study
- Prospectively ECG-gated non-contrast CT, 3 mm slices at 120 kVp, from the carina to the cardiac apex.
The manoeuvre
- Calcium scoring software: mark each lesion ≥ 130 HU by vessel — left main, LAD, circumflex, RCA.
- Exclude aortic, valve and mitral annular calcium from the coronary score (report separately).
- Report the total Agatston score, per-vessel scores and number of vessels.
- Convert to the percentile for age, sex and ethnicity (MESA calculator) and a CAC-DRS category.
- Non-gated chest CT: visual grading — none, mild, moderate, severe — in the lung and mediastinal window review.
What confirms it
- Calcified coronary plaque quantified on a gated 3 mm non-contrast scan.
What licenses you to exclude it
- A score of zero excludes calcified plaque; it does not exclude non-calcified plaque or stenosis.
The classic misread
- Scoring mitral annular or aortic root calcium as coronary.
- Omitting incidental coronary calcium on a routine chest CT — it is actionable.
- Scoring on thin contrast-enhanced images, which are not comparable with Agatston.