Figure 4b. Preoperative assessment of the thoracic aorta in a 57-year-old man with a history of aortic stenosis. (a) Oblique axial MPR view of the aortic valve shows a bicuspid aortic valve (arrow), with mild thickening of the aortic leaflets and calcification within the aortic sinuses. (b) Virtual endoscopic image of the thoracic aorta shows the bicuspid aortic valve (arrow) and valvular calcification. Note the origin of the left coronary artery within the sinus of Valsalva (L), whereas the origin of the right coronary artery (R) is above the sinotubular junction. Because the ostia of the coronary arteries are less than 180o apart, a stentless aortic valve can be safely placed within the aortic valve position.