Fromageau Jérémie, Lerouge Sophie, Maurice Roch Listz, Soulez Gilles, Cloutier Guy
Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center (CRCHUM), Montréal, Québec, H2L 2W5, Canada.
Phys Med Biol. 2008 Nov 21;53(22):6475-90. doi: 10.1088/0031-9155/53/22/013. Epub 2008 Oct 31.
Experimental and simulation studies were conducted to noninvasively characterize abdominal aneurysms with ultrasound (US) elastography before and after endovascular treatment. Twenty three dogs having bilateral aneurysms surgically created on iliac arteries with venous patches were investigated. In a first set of experiments, the feasibility of elastography to differentiate vascular wall elastic properties between the aneurismal neck (healthy region) and the venous patch (pathological region) was evaluated on six dogs. Lower strain values were found in venous patches (p < 0.001). In a second set of experiments, 17 dogs having endovascular repair (EVAR) by stent graft (SG) insertion were examined three months after SG implantation. Angiography, color Doppler US, examination of macroscopic sections and US elastography were used. The value of elastography was validated with the following end points by considering a solid thrombus of a healed aneurysm as a structure with small deformations and a soft thrombus associated with endoleaks as a more deformable tissue: (1) the correlation between the size of healed organized thrombi estimated by elastography and by macroscopic examinations; (2) the correlation between the strain amplitude measured within vessel wall elastograms and the leak size; and (3) agreement on the presence and size of endoleaks as determined by elastography and by combined reference imaging modalities (angiography + Doppler US). Mean surfaces of solid thrombi estimated with elastography were found correlated with those measured on macroscopic sections (r = 0.88, p < 0.001). Quantitative strain values measured within the vessel wall were poorly linked with the leak size (r = 0.12, p = 0.5). However, the qualitative evaluation of leak size in the aneurismal sac was very good, with a Kappa agreement coefficient of 0.79 between elastography and combined reference imaging modalities. In summary, complementing B-scan and color Doppler, noninvasive US elastography was found to be potentially a relevant tool for aneurismal follow-up after EVAR, provided it allows geometrical and mechanical characterizations of the solid thrombus within the aneurismal sac. This elasticity imaging technique might help detecting potential complications during follows-up subsequent to EVAR.
开展了实验和模拟研究，以利用超声（US）弹性成像技术在血管内治疗前后对腹主动脉瘤进行无创性特征描述。对23只通过静脉补片在髂动脉上手术制造双侧动脉瘤的犬进行了研究。在第一组实验中，对6只犬评估了弹性成像技术区分动脉瘤颈部（健康区域）和静脉补片（病变区域）血管壁弹性特性的可行性。在静脉补片中发现较低的应变值（p < 0.001）。在第二组实验中，对17只通过植入支架移植物（SG）进行血管内修复（EVAR）的犬在SG植入三个月后进行了检查。使用了血管造影、彩色多普勒超声、宏观切片检查和超声弹性成像。通过将愈合动脉瘤的实性血栓视为变形小的结构，将与内漏相关的软血栓视为更易变形的组织，以以下终点验证弹性成像的价值：（1）弹性成像估计的愈合有组织血栓大小与宏观检查结果之间的相关性；（2）血管壁弹性图内测量的应变幅度与漏口大小之间的相关性；（3）弹性成像与联合参考成像方式（血管造影 + 多普勒超声）确定的内漏存在情况和大小的一致性。发现弹性成像估计的实性血栓平均表面积与宏观切片测量的结果相关（r = 0.88，p < 0.001）。血管壁内测量的定量应变值与漏口大小的关联性较差（r = 0.12，p = 0.5）。然而，对动脉瘤腔内漏口大小的定性评估非常好，弹性成像与联合参考成像方式之间的Kappa一致性系数为0.79。总之，补充B超和彩色多普勒后，发现无创性超声弹性成像技术可能是EVAR后动脉瘤随访的相关工具，前提是它能够对动脉瘤腔内的实性血栓进行几何和力学特征描述。这种弹性成像技术可能有助于在EVAR后的随访期间检测潜在并发症。
