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Published on: September 26, 2018
Automated detection of superficial macrophages in atherosclerotic plaques using autofluorescence lifetime imaging
Jose J Rico-Jimenez1, Michael J Serafino1, Sebina Shrestha1
1Department of Biomedical Engineering, Texas A& M University, College Station, TX, USA.
Background And Aims:
Macrophages play an important role in the development and destabilization of advanced atherosclerotic plaques. Hence, the clinical imaging of macrophage content in advanced plaques could potentially aid in identifying patients most at risk of future clinical events. The lifetime of the autofluorescence emission from atherosclerotic plaques has been correlated with lipids and macrophage accumulation in ex vivo human coronary arteries, suggesting the potential of intravascular endogenous fluorescence or autofluorescence lifetime imaging (FLIM) for macrophage imaging. The aim of this study was to quantify the accuracy of the coronary intima autofluorescence lifetime to detect superficial macrophage accumulation in atherosclerotic plaques.
Methods:
Endogenous FLIM imaging was performed on 80 fresh postmortem coronary segments from 23 subjects. The plaque autofluorescence lifetime at an emission spectral band of 494 ± 20.5 nm was used as a discriminatory feature to detect superficial macrophage accumulation in atherosclerotic plaques. Detection of superficial macrophage accumulation in the imaged coronary segments based on immunohistochemistry (CD68 staining) evaluation was taken as the gold standard. Receiver Operating Characteristic (ROC) curve analysis was applied to select an autofluorescence lifetime threshold value to detect superficial macrophages accumulation.
Results:
A threshold of 6 ns in the plaque autofluorescence lifetime at the emission spectral band of 494 ± 20.5 nm was applied to detect plaque superficial macrophages accumulation, resulting in ∼91.5% accuracy.
Conclusions:
This study demonstrates the capability of endogenous FLIM imaging to accurately identify superficial macrophages accumulation in human atherosclerotic plaques, a key biomarker of atherosclerotic plaque vulnerability.
Insights
Autofluorescence lifetime imaging accurately detects macrophages in atherosclerotic plaques. This technique identifies vulnerable plaques, aiding in risk assessment for cardiovascular events.
Area of Science:
- Cardiovascular Research
- Biomedical Imaging
- Pathology
Background:
- Macrophages are key players in the development and destabilization of advanced atherosclerotic plaques.
- Identifying macrophage content in plaques can help identify patients at high risk of future clinical events.
- Intravascular autofluorescence lifetime imaging (FLIM) shows potential for in vivo macrophage imaging.
Purpose of the Study:
- To quantify the accuracy of coronary intima autofluorescence lifetime for detecting superficial macrophage accumulation in atherosclerotic plaques.
Main Methods:
- Endogenous FLIM imaging was performed on 80 human coronary segments.
- Autofluorescence lifetime at 494 nm ± 20.5 nm was used to detect macrophage accumulation.
- Immunohistochemistry (CD68 staining) served as the gold standard for comparison.
Main Results:
- A threshold of 6 ns in autofluorescence lifetime accurately detected superficial macrophages.
- The method achieved approximately 91.5% accuracy in identifying macrophage accumulation.
Conclusions:
- Endogenous FLIM imaging accurately identifies superficial macrophages in human atherosclerotic plaques.
- This technique offers a promising method for imaging macrophage accumulation, a biomarker of plaque vulnerability.
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