Analysis of the aortic wall motion by SPAMM tagging method.

为了分析胸主动脉主动脉壁的血流动力学负荷，我们使用磁共振通过SPAMM标记方法评估局部主动脉壁运动。我们研究了四名健康志愿者，七名主动脉弓瘤患者和十名降主动脉夹层患者。纵向参数表示的弯曲指数（λ），这是计算使用切片标记parasagitally。环形参数用畸变指数（RST）表示，该指数是使用主动脉横截面的标记切片计算的。在4名正常主动脉的志愿者中，降主动脉近端的弯曲指数最大，降主动脉血管水平的弯曲指数最小。高扭曲指数，在正常志愿者中发现（1）前壁，（2）小弯壁。（3）主动脉水平前壁，提示主动脉壁血流动力学负荷高。有趣的是，这些高失真部位与真正动脉瘤患者的破裂部位吻合良好。主动脉瘤边缘的变形指数与瘤壁边缘的角度相关。边缘高角度的动脉瘤具有高的变形指数，这将表明动脉瘤扩张或破裂的风险较高。主动脉夹层假腔管壁的变形指数并不高于真腔管壁的变形指数，但假腔血栓管壁的变形指数明显小于真腔管壁。因此，畸变指数可作为主动脉夹层预后的指标。这对分析主动脉壁的血流动力学负荷是有用的。这种方法可以分析运动，它是有用的，了解血流动力学负荷的主动脉壁和主动脉瘤的表征。

To analyze hemodynamic load to the aortic wall of thoracic aorta, we evaluate local aortic wall motion by the SPAMM tagging method using magnetic resonance. We studied four healthy volunteers, seven patients with true aortic arch aneurysm, and ten patients with descending aortic dissection. The longitudinal parameters were expressed by the bending index(lambda), which was calculated using slices tagged parasagittally. Circular parameters were expressed by the distortion index(epsilon), which was calculated using tagged slices of aortic cross-section. In four volunteers with normal aorta, the bending index was greatest at the proximal descending aorta, and was smallest at the diaphragmatic level of the descending aorta. High distortion index, found in normal volunteers on (1)the anterior wall, (2)wall of lesser curvature. and (3)anterior wall of diaphragmatic level, may suggest high hemodynamic loads on the aortic wall. Interestingly, those high distortion sites confirm well to ruptured sites of patients with true aneurysm. Distortion index at the border of aortic aneurysm was well related to the angle of the aneurysmal border. Aneurysm with a high angle at its border had a high distortion index, which would indicate high risks of expansion or rupture of the aneutysm. Distortion index at the wall of pseudo-lumen of aortic dissection was not higher than that of the wall at the true lumen, but the distortion index at thrombosed wall of the pseudo-lumen was significantly smaller. Therefore, the distortion index may indicate the prognosis of aortic dissection. It is useful to analyze hemodynamic load to the aortic wall. This method can analyze the motion, and it is useful for understanding hemodynamic loading to the aortic wall and for characterization of the aortic aneurysm.