therosclerosis consists of 2 pathological processes: atherosis characterized by morphologic atheromatous lesions in the intima, and sclerosis characterized by an increase in the stiffness of the vessel walls. Whereas in the past, computed tomography (CT) of the coronary arteries could detect only calcifications, multislice CT (MSCT) can now achieve sufficiently high spatial and temporal resolutions to allow visualization of stenoses 1 and plaques in the coronary arteries. 2,3 Aortic stiffness has not been readily taken into account for the evaluation of coronary artery disease (CAD), although both in vitro and in vivo studies have shown that MSCT provides a sufficiently accurate determination of aortic luminal dimension, cross-sectional area, and wall thickness to measure the distensibility and stiffness of the aorta. 4,5 Aortic stiffness is known to increase with age, 6 but it also correlates with various diseases such as CAD 7 and hyperCirculation Journal Vol.72, December 2008 tension, 8 or hypercholesterolemia. 6 So far, atherosis and sclerosis of the descending thoracic aorta (DTA) have been observed and analyzed during transesophageal echocardiography (TEE) performed for indications other than CAD. 6,9 Sclerosis could also be estimated by the brachial-ankle pulse wave velocity (baPWV), which has the disadvantage of giving only an average estimation over a large vascular bed.In contrast, for patients who already have an indication for coronary angiography (CAG) by MSCT, which is noninvasive, it would be a clinically important advantage if the same MSCT data could be used to gain additional information about CAD through analysis of the aorta at multiple locations. A time-resolved, ECG-gated CT technique to derive aortic distensibility from cyclic cross-sectional area changes has already been validated in a phantom set-up with porcine aortic specimens. 4 Ganten et al reported a negative correlation between abdominal aortic distensibility and aging with the use of this method, albeit using 4-or 16-slice CT. 5 Distensibility, however, depends on blood pressure, whereas stiffness is considered to be independent of blood pressure. 10,11 The diagnostic accuracy of MSCT for detecting coronary artery stenoses has been reported by many investigators, with very high specificity and very high negative predictive values. However, the positive predictive values have been relatively low. Most previous studies did not consist of consecutive patients and most studies excluded images that were unsatisfactory for interpretation. It should also be noted that patients with high heart rates or severe coronary calcification were excluded from the analyses. MSCT scans Background With multislice computed tomography (MSCT) it is possible to visualize the coronary arteries, as well as the aorta, in a single computed tomography scan. Using MSCT, atherosis and sclerosis of the descending thoracic aorta (DTA) were quantified and differences between patients with and without coronary artery disease (CAD) were analyzed.
Methods and Resu...