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Intravenous electron-beam computed tomographic coronary angiography for segmental analysis of coronary artery
A Schmermund1, B J Rensing, P F Sheedy
1Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota, USA. tka0i0@sp2.power.uni-essen.de
Insights
Electron-beam computed tomography (EBCT) coronary angiography accurately identifies significant coronary stenoses, especially in major arteries. Substantial calcification can lead to false negatives, while small vessel size may cause false positives.
Area of Science:
- Cardiovascular Imaging
- Radiology
- Medical Diagnostics
Background:
- Clinical utility of intravenous EBCT coronary angiography remains undefined.
- Limitations of EBCT for coronary artery assessment require clarification.
Purpose of the Study:
- To identify and localize significant coronary stenoses segmentally using EBCT.
- To evaluate the accuracy of EBCT coronary angiography compared to selective coronary angiography (SCA).
Main Methods:
- EBCT performed within 24 hours of SCA in 28 patients.
- Overlapping 1mm slices with 0.34-0.41mm in-plane resolution used for EBCT.
- Quantitative analysis of 8 or 12 coronary artery segments based on SCA findings (> or = 50% diameter narrowing).
Main Results:
- EBCT visualized 72% of assessable segments, achieving 87% overall accuracy.
- Sensitivity for significant stenoses was 82%, specificity 88%.
- False negatives were linked to severe calcification (p=0.02); false positives to small vessel size (p<0.001).
Conclusions:
- Intravenous EBCT coronary angiography provides accurate segmental evaluation of significant coronary artery disease.
- EBCT may be valuable for excluding significant coronary artery disease.
- Calcification and small vessel size are key factors affecting EBCT accuracy.
Objectives:
We sought to identify and localize significant coronary stenoses on a segmental basis by electron-beam computed tomography (EBCT) and intravenous administration of a contrast agent.
Background:
The clinical applicability and limitations of intravenous EBCT coronary angiography have not been defined.
Methods:
EBCT was performed within 24 h of selective coronary angiography (SCA) in 28 patients (19 men and 9 women, mean [+/-SD] age 60 +/- 10 years). After examination for coronary calcium, EBCT coronary angiography was performed using overlapping slices (in-plane resolution 0.34 to 0.41 mm) with a nominal slice thickness of 1 mm. Based on quantitative analysis of SCA, lumen diameter narrowing > or = 50% (i.e., significant stenoses) was evaluated in 8 (major) or 12 (including side branches) coronary artery segments, using both two-dimensional (tomographic) and three-dimensional (volume) data sets.
Results:
Of the 330 segments assessable by SCA, 237 (72%) were visualized by EBCT. The sensitivity (+/-SE) for detection of significant stenoses was 82 +/- 6%; specificity was 88 +/- 2%; positive and negative predictive values were 57 +/- 7% and 96 +/- 2%, respectively; and overall accuracy was 87 +/- 2%. If only eight (major) coronary artery segments were considered, 194 (88%) of 221 segments were visualized, and the overall accuracy was 90 +/- 2%. Seven (18%) of 38 significantly stenotic segments were classified as having < 50% stenoses by EBCT. Six of these segments (86%), but only 9 (29%) of the 31 correctly classified stenotic segments, were severely calcified (area > 20 mm2, p = 0.02). In 23 (12%) of 199 nonstenotic segments falsely classified as having > or = 50% stenosis by EBCT, the lumen diameter was significantly smaller than that of the segments correctly classified as negative (mean [+/-SD] 1.5 +/- 0.8 vs. 2.9 +/- 1.1 mm, p < 0.001).
Conclusions:
Intravenous EBCT coronary angiography allows for accurate segmental evaluation of significant disease in the major coronary arteries and may be of value for ruling out significant disease. The main determinant of false negative results is substantial segmental calcification, whereas the main determinant of false positive results is small vessel size.