Muhs B E, Vincken K L, van Prehn J, Stone M K C, Bartels L W, Prokop M, Moll F L, Verhagen H J M
Department of Vascular Surgery, University Medical Center Utrecht, The Netherlands.
Eur J Vasc Endovasc Surg. 2006 Nov;32(5):532-6. doi: 10.1016/j.ejvs.2006.05.009. Epub 2006 Jun 22.
Thoracic aneurysm preoperative imaging is performed using static techniques without consideration of normal aortic dynamics. Improved understanding of the native aortic environment into which thoracic endografts are placed may aid in device selection. It is unclear what comprises normal thoracic aortic pulsatility. We studied these phenomena dynamically using ECG-gated 64-slice CTA.
Maximum diameter and area change per cardiac cycle was measured at surgically relevant anatomic thoracic landmarks in ten patients; 1.0 cm proximal and distal to the subclavian artery, 3.0 cm distal to the subclavian artery, and 3.0 cm proximal to the celiac trunk. Data was acquired using a novel ECG-gated dynamic 64-slice CT scanner during a single breath hold with a standard radiation dose and contrast load. Eight gated data sets, covering the cardiac cycle were reconstructed, perpendicular to the central lumen.
There is impressive change in both maximum diameter and area in the thoracic aorta during the cardiac cycle. Mean maximum diameter changes of greater than 10% are observed in the typical sealing zones of commercially available endografts corresponding to diameter increases of up to 5mm. Aortic area increases by over 5% per cardiac cycle.
ECG-gated dynamic CTA with standard radiation dose is feasible on a 64-slice scanner and provides insight into (patho) physiology of thoracic aortic conformational changes. Clinicians typically oversize thoracic endografts by 10%. With aortic pulsatility resulting in diameter changes of up to 17.8%, the potential exists for endograft undersizing, graft migration, intermittent type I endoleak, and poor patient outcome. Furthermore, aortic pulsatility is not evenly distributed, and non-circular stentgraft designs should be considered in the future since aortic distension in the aneurysm neck is not evenly distributed.
胸主动脉瘤术前成像采用静态技术，未考虑正常主动脉动力学。更好地了解胸主动脉内植入物所处的天然主动脉环境可能有助于器械选择。目前尚不清楚正常胸主动脉搏动的构成要素。我们使用心电图门控64层CT动态研究了这些现象。
在10例患者的手术相关胸段解剖标志处测量每个心动周期的最大直径和面积变化；锁骨下动脉近端和远端1.0 cm处、锁骨下动脉远端3.0 cm处以及腹腔干近端3.0 cm处。使用新型心电图门控动态64层CT扫描仪在单次屏气期间以标准辐射剂量和造影剂负荷采集数据。重建覆盖心动周期的8个门控数据集，垂直于中心管腔。
心动周期中胸主动脉的最大直径和面积均有显著变化。在市售腔内移植物的典型密封区域观察到平均最大直径变化大于10%，对应直径增加可达5mm。主动脉面积每个心动周期增加超过5%。
采用标准辐射剂量的心电图门控动态CTA在64层扫描仪上是可行的，并能深入了解胸主动脉形态变化的（病理）生理学。临床医生通常将胸段腔内移植物尺寸加大10%。由于主动脉搏动导致直径变化高达17.8%，存在腔内移植物尺寸过小、移植物移位、间歇性I型内漏以及患者预后不良的可能性。此外，主动脉搏动分布不均，未来应考虑非圆形支架型人工血管设计，因为动脉瘤颈部的主动脉扩张分布不均。
