Normal aortic arch diameter8/14/2023 ![]() ![]() However, measurement of the aortic annulus for preprocedural CT evaluation of aortic valve replacement is traditionally performed in the systolic phase, during which it manifests with its intrinsically largest diameter. However, whether the measurement of the aortic root should be performed during the systole or diastole phase has not yet been accurately assessed nevertheless, diastolic images have the best reproducibility. The dimension of the aortic root varies through the phases of the cardiac cycle. Electrocardiography (ECG)-gated acquisition protocols have recently been used to reduce motion artifacts, especially for the aortic root and ascending aorta. Recent prognostic data were derived from measurements that included the wall. No consensus has been reached on whether the aortic wall should be included or excluded in the aortic diameter measurements, even though the difference in diameter can be large, depending on the amount of intraluminal thrombus or atheromas on the arterial wall. In situations where 3D and MPR imaging are unavailable, the minor axis (smaller diameter) is generally closer to the true maximum diameter than is the major axis diameter on transaxial images Use of the minor axis diameter enables more accurate and reproducible measurements, particularly in tortuous aneurysms ( Fig. Measurement of aortic diameter by CTA is generally recommended with three-dimensional (3D) reconstructed images whenever possible the maximum diameter is measured perpendicular to the centerline of the vessels on the curved multiplanar reconstruction (MPR) images. RBCA: right brachiocephalic artery, LSCA: left subclavian artery, LCCA: left common carotid artery.Ĭlick for larger image Download as PowerPoint slide The aortic arch begins at the origin of the RBCA and ends at the origin of the LSCA and is subdivided into proximal (RBCA to LCCA) and distal segments. ![]() The aortic root includes the aortic annulus, sinus of Valsalva, and sinotubular junction. The thoracic aorta is grossly divided into four segments: aortic root, ascending aorta, aortic arch, and descending aorta. The distal arch is often narrower than the proximal descending aorta at the attachment site of the ligamentum arteriosum, called the “aortic isthmus.” The descending aorta begins at the ligamentum arteriosum and extends to the diaphragmatic hiatus its proximal dilated portion has been termed the “aortic spindle.” The aortic wall is histologically composed of three layers: the inner mostly “intima” layer lined with thin endothelium the “media” composed of smooth muscle cells, which are encased by concentric elastic and collagen fibers on the border zone in both the inner and outer layers and the “adventitia” layer containing mainly collagen, the vasa vasorum, and lymphatics. The aortic arch is subdivided into the proximal (RBCA to left common carotid artery) and distal segments. The aortic arch begins at the origin of the RBCA and ends at the origin of the left subclavian artery (LSCA). The ascending aorta extends from the sinotubular junction to the origin of the right brachiocephalic artery (RBCA). The aortic root is the first portion of the aorta, beginning just distal of the aortic valve, and consists of the aortic annulus, sinus of Valsalva, and sinotubular junction. The thoracic aorta is grossly divided into four segments: the aortic root, ascending aorta, aortic arch, and descending aorta ( Fig. ![]()
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