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Application of intravascular ultrasound for detection and quantitation of coronary atherosclerosis
1University of Kentucky Medical Center, Lexington.
Insights
Coronary intravascular ultrasound offers detailed views of coronary artery disease (CAD) beyond angiography. This imaging technique reveals vessel wall structure and motion, aiding in CAD detection and quantification.
Area of Science:
- Cardiovascular Imaging
- Medical Ultrasound
- Interventional Cardiology
Background:
- Angiography provides lumen silhouette but limited vessel wall detail for coronary artery disease (CAD).
- Coronary intravascular ultrasound (IVUS) offers tomographic imaging of lumen geometry and vessel wall structure.
- IVUS probes are small, flexible, and capable of navigating tortuous coronary arteries.
Purpose of the Study:
- To evaluate the utility of coronary intravascular ultrasound (IVUS) in assessing coronary artery disease (CAD).
- To compare IVUS measurements with traditional angiography for lumen dimensions and vessel wall characteristics.
- To assess coronary artery wall motion and structural differences between normal and atherosclerotic vessels.
Main Methods:
- Performed in vivo coronary ultrasound in over 100 patients, including normal subjects.
- Correlated lumen dimension measurements between angiography and IVUS.
- Measured coronary artery wall motion and analyzed vessel wall structure using IVUS.
Main Results:
- Close correlation between IVUS and angiography for normal (r=0.92) and concentric atherosclerotic vessels (r=0.90).
- Fair to poor correlation for eccentric (r=0.79) and post-angioplasty vessels (r=0.30).
- IVUS revealed significant differences in wall motion and structure, identifying atherosclerotic plaques and abnormalities at angiographically normal sites.
Conclusions:
- Coronary intravascular ultrasound (IVUS) provides valuable tomographic information on lumen and vessel wall not seen with angiography.
- IVUS demonstrates distinct structural and functional differences in atherosclerotic versus normal coronary arteries.
- Despite limitations like echo dropout, IVUS shows promise for CAD detection and quantification.
Abstract:
Although angiography is widely utilized to assess the extent and severity of coronary artery disease (CAD), arteriography yields only a silhouette of the vessel lumen. Coronary intravascular ultrasound supplements angiography by providing a tomographic perspective of lumen geometry and vessel wall structure. Intracoronary ultrasound can now be performed in vivo utilizing small, flexible probes capable of negotiating tortuous vessels. We have performed coronary ultrasound in more than 100 patients, including a group of normal subjects, with no serious complications. Measurements of coronary lumen dimensions by angiography and ultrasound correlated closely for normal vessels (r = 0.92) and for concentrically narrowed atherosclerotic vessels (r = 0.90). However, the correlation between angiography and ultrasound was only fair for eccentrically narrowed arteries (r = 0.79) and was poor following angioplasty (r = 0.30). Coronary artery wall motion was measured by intravascular ultrasound and demonstrated significant differences between normal arteries (18% lumen area change) and atherosclerotic vessels (11% change). Coronary ultrasound demonstrated important differences in the structure of normal and atherosclerotic vessel walls. Arteries in normal subjects exhibited a thin intimal leading-edge echo (mean 0.20 mm) and subadjacent sonolucent zone (mean 0.12 mm). Atherosclerotic vessels typically demonstrated increased thickness of both structures and often exhibited dense fibrocalcific plaques that shadowed underlying anatomy. These ultrasound abnormalities were often present at angiographically normal sites. Several limitations of coronary intravascular ultrasound were apparent, including echo 'dropout', distortions produced by non-coaxial imaging, and inability to image small or severely narrowed vessels. Coronary intravascular ultrasound holds great promise for the detection and quantification of CAD in the clinical setting.