From the Guidelines
Interpreting plaque volume on coronary computed tomography angiography (CCTA) requires careful analysis of the plaque characteristics, distribution, and composition, with a focus on identifying high-risk features such as positive remodeling, low-attenuation plaque, spotty calcification, and the napkin-ring sign, as described in the CAD-RADS 2.0 guidelines 1. To accurately assess plaque volume, first examine the cross-sectional images of the coronary arteries, identifying areas of plaque as regions with lower density than the contrast-enhanced lumen but higher density than surrounding tissues. Quantitative assessment involves measuring the total plaque volume in cubic millimeters across the entire coronary tree or within specific segments. Pay attention to plaque composition by differentiating between calcified plaque (>130 Hounsfield Units), non-calcified plaque (30-130 HU), and low-density plaque (<30 HU), as low-density plaques carry higher risk for acute coronary events, as noted in the CAD-RADS 2.0 guidelines 1. Modern CCTA software can automatically calculate plaque volumes and provide color-coded displays to visualize different plaque components. The clinical significance of plaque volume relates directly to cardiovascular risk assessment, with larger volumes and higher proportions of non-calcified or low-density plaque indicating increased risk for future cardiac events, as demonstrated in studies such as the one published in JACC: Cardiovascular Imaging 1. Serial CCTA examinations can track changes in plaque volume over time to evaluate treatment effectiveness. For optimal interpretation, ensure high-quality images with minimal motion artifacts and appropriate contrast timing. Some key points to consider when interpreting plaque volume on CCTA include:
- Identifying high-risk plaque features, such as positive remodeling, low-attenuation plaque, spotty calcification, and the napkin-ring sign, which are associated with a higher risk of future acute coronary events, as described in the CAD-RADS 2.0 guidelines 1.
- Measuring the total plaque volume in cubic millimeters across the entire coronary tree or within specific segments, as noted in the study published in the Journal of the American College of Radiology 1.
- Differentiating between calcified plaque, non-calcified plaque, and low-density plaque, as low-density plaques carry higher risk for acute coronary events, as demonstrated in the study published in JACC: Cardiovascular Imaging 1.
- Using modern CCTA software to automatically calculate plaque volumes and provide color-coded displays to visualize different plaque components, as described in the study published in the Journal of the American College of Radiology 1.
- Tracking changes in plaque volume over time to evaluate treatment effectiveness, as noted in the study published in JACC: Cardiovascular Imaging 1. It is also important to consider the overall amount of coronary plaque, as well as the presence of high-risk features, when interpreting plaque volume on CCTA, as described in the CAD-RADS 2.0 guidelines 1. By carefully analyzing the plaque characteristics, distribution, and composition, and considering the clinical significance of plaque volume, clinicians can use CCTA to inform treatment decisions and improve patient outcomes, as demonstrated in studies such as the one published in the Journal of the American College of Radiology 1.
From the Research
Interpretation of Plaque Volume on CCTA
To interpret plaque volume on clearly visible coronary computed tomography angiography (CCTA), several factors must be considered, including the type of plaque, its volume, and associated features such as calcification and remodeling.
- Plaque Characteristics: Studies have shown that high-risk plaque features, including non-calcified plaque (NCP), spotty calcified plaque (SCP), and increased remodeling index (RI), are associated with an increased risk of acute coronary syndrome (ACS) 2.
- Plaque Volume: The total plaque volume (TPV) and the volume of specific types of plaque, such as NCP and calcified plaque (CP), can provide valuable information about the burden of atherosclerosis and the risk of future cardiovascular events 3, 4.
- Association with Cardiovascular Risk: Research has demonstrated that plaque burden, as assessed by CCTA, adds incremental prognostic value over established measures of coronary artery disease (CAD) and can identify patients at increased risk of cardiovascular events 4, 5.
- Monitoring Plaque Progression: Serial CCTA can be used to monitor changes in plaque volume and composition over time, providing insights into the effectiveness of treatments and the progression of atherosclerosis 6.
- Clinical Implications: The evaluation of coronary atherosclerosis by CCTA, including the measurement of plaque volume and features, has been recognized as a valuable tool for cardiac risk stratification and management, with recent guidelines recommending its use in the assessment of patients with stable CAD 5.