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

Figures

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  Fig. 1. Flowchart of the study population selection and group stratification. Participants were stratified into four groups according to CAC volume and CAC density, categorized as high (top quartile) or low (lower three quartiles). The top-quartile cutoffs were 173 mm3 for CAC volume and 3.4 for CAC density. CAC = coronary artery calcium, ECG = electrocardiogram, CVD = cardiovascular disease, AI = artificial intelligence

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  Fig. 2. Representative cases of CAC with high and low densities. A: High-volume-high-density CAC in a 65-year-old male, showing diffuse calcification from the left main to the left anterior descending artery (blue areas). The Agatston score was 2,978, CAC volume was 2,343 mm3, and density was 3.8. The participant did not experience MACE during the follow-up period of 3,291 days. B: High-volume-low-density CAC in a 70-year-old male, showing scattered calcifications in the left anterior descending artery, diagonal branch, ramus intermedius, and left circumflex artery (red areas). The Agatston score was 853, CAC volume was 967 mm3, and density was 2.6. The participant experienced MACE 3,156 days after the baseline CT scan. CAC = coronary artery calcium, MACE = major adverse cardiovascular events

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  Fig. 3. Kaplan–Meier curves for the probability of freedom from MACE stratified by CAC volume and density. High CAC volume and density were defined as values within the top quartile of each respective measure (≥173 mm3 for CAC volume and ≥3.4 for CAC density). The number at risk at selected time points is displayed below the x-axis. The truncation times for calculating the restricted mean survival times were 5 and 10 years. MACE = major adverse cardiovascular events, CAC = coronary artery calcium

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  Fig. 4. Restricted cubic spline plots for HRs for MACE according to CAC volume and density. A: Adjusted HRs for MACE across the range of log-transformed CAC volume (Z-scores). B: Time-varying HRs for log-transformed CAC volume estimated from a Cox model with a time interaction term. The HR at time t is modeled as: HR(t) = 2.608 × 0.922t. C, D: Unadjusted and adjusted HRs across the range of CAC density, respectively. HR = hazard ratio, MACE = major adverse cardiovascular events, CAC = coronary artery calcium, CI = confidence interval