Intravascular optical coherence tomography method for automated detection of macrophage infiltration within
Jose J Rico-Jimenez1, Daniel U Campos-Delgado2, L Maximillan Buja3
1Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA.
Insights
A new intravascular optical coherence tomography (IV-OCT) method, NSDRatio, accurately detects macrophage infiltration in coronary plaques. This advance improves sensitivity and specificity for identifying patients at risk of acute coronary events.
Area of Science:
- Cardiovascular Imaging
- Biomedical Engineering
- Pathology
Background:
- Macrophage infiltration in atherosclerotic plaques is a key driver of acute coronary events.
- Clinical imaging of macrophage content can identify high-risk patients.
- Current imaging methods for macrophage infiltration require improvement.
Purpose of the Study:
- To develop and validate a simple, automated, accurate, and fast intravascular optical coherence tomography (IV-OCT) image processing method for detecting macrophage infiltration in coronary atherosclerotic plaques.
- To compare the performance of the novel method against the standard IV-OCT signature for macrophages.
Main Methods:
- A novel method calculating the normalized-intensity standard deviation ratio (NSDRatio) over adjacent regions of interest in IV-OCT B-scans.
- Application of the NSDRatio method to entire IV-OCT B-scans to highlight areas with high macrophage infiltration.
- Validation using postmortem coronary segments with known macrophage content.
Main Results:
- The NSDRatio method achieved ~88% sensitivity and specificity in detecting coronary plaque macrophage infiltration.
- The standard normalized-intensity standard deviation (NSD) method showed only ~55% sensitivity and specificity.
- The NSDRatio method demonstrated a significant improvement over the standard NSD method.
Conclusions:
- The proposed NSDRatio method significantly enhances sensitivity and specificity for detecting coronary plaque macrophage infiltration compared to the standard NSD method.
- This computationally efficient method is suitable for real-time in-vivo IV-OCT imaging.
- The NSDRatio method holds potential for identifying patients at higher risk of future acute coronary events.
Background And Aims:
Significant macrophages infiltration in advanced atherosclerotic plaques promotes acute coronary events. Hence, the clinical imaging of macrophage content in coronary atherosclerotic plaques could potentially aid in identifying patients most at risk of future acute coronary events. The aim of this study was to introduce and validate a simple intravascular optical coherence tomography (IV-OCT) image processing method for automated, accurate and fast detection of macrophage infiltration within coronary atherosclerotic plaques.
Methods:
This method calculates the ratio of the normalized-intensity standard deviation (NSD) values estimated over two axially-adjacent regions of interest in an IV-OCT cross-sectional image (B-scan). When applied to entire IV-OCT B-scans, this method highlights plaque areas with high NSD ratio values (NSDRatio), which was demonstrated to be correlated with the degree of coronary plaque macrophage infiltration.
Results:
Using an optimized NSDRatio threshold value, coronary plaque macrophage infiltration could be detected with ~88% sensitivity and specificity in a database of 28 IV-OCT scans from postmortem coronary segments. For comparison, using an optimized NSD threshold value, considered the standard IV-OCT signature for macrophages, coronary plaque macrophage infiltration could be detected with only ~55% sensitivity and specificity.
Conclusions:
The proposed NSDRatio method significantly increases the sensitivity and specificity for the detection of coronary plaque macrophage infiltration compared to the standard NSD method. This computationally efficient method can be seamlessly implemented within standard IV-OCT imaging systems for in-vivo real-time imaging of macrophage content in coronary plaques, which could potentially aid in identifying patients most at risk of future acute coronary events.
