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Relation of coronary calcium determined by electron beam computed tomography and lumen narrowing determined by
J A Rumberger1, R S Schwartz, D B Simons
1Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota 55905.
Insights
Electron beam computed tomography (CT) can predict coronary artery disease. Coronary calcium area measured by CT accurately identifies histopathologic atherosclerotic disease in both men and women.
Area of Science:
- Cardiovascular Imaging
- Pathology
- Radiology
Background:
- Coronary calcium assessment by electron beam computed tomography (CT) lacks systematic evaluation for predicting histopathologic atherosclerotic disease.
- Gender-specific differences in the predictive value of coronary calcium for atherosclerosis have not been thoroughly examined.
Purpose of the Study:
- To evaluate the predictive capability of coronary calcium, measured by electron beam CT, for histopathologic atherosclerotic disease.
- To investigate potential gender differences in this predictive relationship.
Main Methods:
- Autopsy examination of 13 hearts (5 women, 8 men), dissecting major epicardial arteries.
- Electron beam CT scanning of straightened arteries followed by histologic preparation at corresponding intervals.
- Planimetry for luminal area obstruction and CT analysis for coronary calcium area (>130 Hounsfield units).
- Receiver-operating characteristic (ROC) analysis to assess the site specificity of calcium area for predicting atherosclerosis.
Main Results:
- A total of 522 histologic specimens were analyzed, paired with corresponding CT scans.
- ROC curve areas indicated good predictive performance for CT-detected calcium in identifying mild, moderate, and severe atherosclerosis in both genders.
- Specific calcium area thresholds (e.g., 1 mm²/segment for mild, >3 mm²/segment for severe disease) were identified for predicting atherosclerosis with 100% specificity.
Conclusions:
- Coronary artery calcium area, as quantified by electron beam CT, demonstrates significant potential for predicting segmental histopathologic coronary artery disease.
- The findings suggest that electron beam CT-derived coronary calcium is a valuable tool for non-invasively assessing the extent of coronary atherosclerosis.
Abstract:
Coronary calcium determined by electron beam computed tomography (CT) has not been systematically evaluated regarding prediction of histopathologic atherosclerotic disease. Furthermore, gender specificity has not been examined. The 3 major epicardial arteries were dissected from 13 consecutive hearts (5 women and 8 men) after autopsy. Each artery was straightened and scanned using CT in contiguous 3 mm thick cross sections. After imaging, histologic sections were prepared at corresponding intervals and luminal area obstruction determined by planimetry. Electron beam CT scans were analyzed to determine coronary calcium area (i.e., tomographic area with CT density > 130 Hounsfield units). A total of 522 histologic specimens were examined and paired with corresponding CT scans (182 in women, 340 in men). Receiver-operating characteristic (ROC) analysis was used to define site specificity of calcium area for luminal area narrowing by atherosclerosis. ROC curve areas for segmental CT calcium and prediction of atherosclerosis representing mild, moderate, or severe disease were, respectively, 0.712, 0.843, and 0.857 for women and 0.732, 0.793, and 0.841 for men. Curves relating false-positive rate (1-specificity) to predefined degrees of atherosclerotic narrowing versus calcium area were curvilinear. In both women and men, calcium areas on the order of 1 mm2/coronary segment were necessary to predict at least mild atherosclerosis with a false-positive rate of 0% (i.e., 100% specificity), whereas a calcium area > 3 mm2 was necessary to predict the same result for severe disease. In conclusion, coronary artery calcium area as determined by electron beam CT has the potential to predict segmental histopathologic coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)