Cardiovascular

Opportunistic Assessment of Coronary Artery Calcium Volume and Density From Non-Electrocardiogram-Gated Chest CT Using Artificial Intelligence: Prognostic Implications in a Screening Cohort.

TL;DR

CAC density derived from chest CT using automated AI quantification was independently and inversely associated with MACE, providing additional prognostic value when added to CAC volume.

Key Findings

CAC volume was independently associated with significantly increased risk of MACE after adjusting for clinical covariates.

  • Hazard ratio per increase by one standard deviation: 2.608 (95% CI, 2.016–3.374; P < 0.001)
  • Analysis performed using multivariable Cox proportional hazards models
  • CAC volume was obtained using AI software on non-ECG-gated chest CT
  • Among 1,109 participants with nonzero CAC, 207 experienced MACE during a median follow-up of 7.7 years

CAC density demonstrated a significant, independent, inverse association with MACE after adjusting for CAC volume and clinical covariates.

  • Hazard ratio per increase by one standard deviation: 0.786 (95% CI, 0.659–0.936; P = 0.007)
  • CAC density was derived by back-calculation from the Agatston score and CAC volume
  • The inverse association indicates that higher CAC density was associated with lower MACE risk
  • This relationship held after adjustment for CAC volume, demonstrating independent prognostic value

Ten-year restricted mean survival times (RMSTs) differed across four combined CAC volume-density groups.

  • Low-volume-high-density group: 9.45 years
  • Low-volume-low-density group: 9.07 years
  • High-volume-high-density group: 8.03 years
  • High-volume-low-density group: 7.68 years
  • Differences in time to MACE were predominantly driven by CAC volume, with no significant density-related differences within the volume strata

Differences in time to MACE were predominantly driven by CAC volume rather than CAC density when examined within volume strata.

  • No significant density-related differences were found within the low-volume stratum or high-volume stratum
  • Kaplan-Meier curves and RMST analyses were used to assess group differences
  • Despite this, CAC density retained independent statistical significance in multivariable Cox models
  • The finding suggests volume is the dominant driver of event-free survival differences at the group level

The study analyzed 1,109 asymptomatic adults with detectable CAC identified from a national health screening chest CT program.

  • 7,552 asymptomatic adults were examined for eligibility between 2007 and 2014 at two tertiary hospitals
  • 1,109 participants with nonzero CAC were included in the analysis
  • Median age was 60.3 years; 87% were men
  • Median follow-up duration was 7.7 years
  • Chest CTs were non-ECG-gated, making standard CAC scoring protocols inapplicable without AI assistance

AI software was used to automatically quantify CAC Agatston score and volume from non-ECG-gated chest CT scans.

  • Non-ECG-gated chest CTs are routinely acquired without cardiac synchronization, introducing motion artifact not present in dedicated CAC scoring scans
  • CAC density was derived by back-calculation from the AI-generated Agatston score and CAC volume
  • This opportunistic approach leverages existing chest CT data without requiring additional dedicated cardiac imaging
  • The retrospective design utilized scans performed as part of a national health screening program

What This Means

This research suggests that artificial intelligence can extract meaningful heart disease risk information from routine chest CT scans that were not specifically designed for cardiac imaging. Normally, measuring calcium buildup in the coronary arteries (a strong predictor of heart attack and stroke) requires a special heart scan timed to the heartbeat. This study showed that AI software can measure both the amount (volume) and the hardness (density) of these calcium deposits from standard chest scans taken during health check-ups, and that both measurements carry useful risk information. Among more than 1,100 adults followed for nearly 8 years, those with more calcium had substantially higher rates of major cardiovascular events like heart attacks. Importantly, the density of the calcium also mattered independently: people with denser (harder) calcium deposits had lower risk than those with the same amount of softer calcium. The group with high calcium volume and low density had the worst outcomes (average 7.68 years free from events over 10 years), while the group with low volume and high density had the best outcomes (9.45 years free from events). This research suggests that the millions of chest CT scans already performed annually for lung cancer screening or other health checks could be 'opportunistically' analyzed by AI to provide heart disease risk information at no additional cost or radiation exposure to the patient. Adding calcium density to the commonly used calcium volume measurement may help doctors better identify who is at highest risk and who might benefit most from preventive treatments.

Have a question about this study?

Citation

Kim N, Kim Y, Lee J, Suh Y. (2026). Opportunistic Assessment of Coronary Artery Calcium Volume and Density From Non-Electrocardiogram-Gated Chest CT Using Artificial Intelligence: Prognostic Implications in a Screening Cohort.. Korean journal of radiology. https://doi.org/10.3348/kjr.2025.1614