Prevalence of aortic root dilation in patients with CT angiography of the aorta.

272 T horacic aortic aneurysm (TAA) is a potentially life-threatening disorder if not diagnosed before the development of dissection and rupture. TAA is defined as a localized dilation of the aorta to more than 50% of baseline. The incidence of TAA is estimated at 6 people per 100,000 per year, and the mean age at diagnosis is 60–70 years. (1). Of all patients presenting with TAA, 60% involve the aortic root and/or ascending aorta (2). The aortic root is described as the part of the aorta that supports the aortic valve leaflets, delineated superiorly by the sinotubular junction (STJ) and inferiorly by the annulus (3). Determination of the segment, or segments involved in the dilation has clinical and surgical significance. Multi–detector row computed tomography (MDCT) is an emerging noninvasive tool for the accurate detection and segmentation of TAA. The current generations of 64-slice scanners, with submillimeter slice collimation and high temporal resolution, have improved our ability to identify and localize TAA. Retrospective electrocardiographically (ECG)gated MDCT has enabled high quality multiplanar reformation (MPR) and volume-rendered (VR) images. Thus, visualization of the extension of the aneurysm as well as estimation of diameter of the aortic annulus, sinuses of valsalva and sinotubular junction are possible. Although there have been extensive studies on measurements of the aortic valve with MDCT, little imaging information is available on the rate of dilation of the different aortic segments and aortic root structures (4, 5). Recently, Lu et al. (6) reported normal measurements of the ascending aorta (the mean diameters of the coronary sinus, sinotubular junction and ascending aorta were 34.2 mm, 29.7 mm and 32.7 mm, respectively) in 78 patients with MDCT. Accordingly, the present study was undertaken to explore the physical dimensions of the aortic root and its structures at the level of the sinuses of valsalva, annulus, sinotubular junction, and AAo with MPR in a patient population scanned for CTA of the aorta.