Sensitive detection of abnormal aortic architecture in Marfan syndrome with high-frequency ultrasonic tissue characterization.
Sensitive detection of abnormal aortic architecture in Marfan syndrome with high-frequency ultrasonic tissue characterization.
复制标题
利用高频超声组织表征灵敏检测马凡综合征中的异常主动脉结构。
DOI：
10.1161/01.cir.91.4.1036
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发表时间：
1995
期刊：
影响因子：
37.8
通讯作者：
Wickline,SA
中科院分区：
文献类型：
--
作者：
Recchia,D;Sharkey,AM;Bosner,MS;Kouchoukos,NT;Wickline,SA
背景：马凡氏综合征患者常发生主动脉血管扩张并随之破裂或剥离，这是发病的主要原因。这些并发症与主动脉中膜成分改变和结构紊乱有关。我们的目的是使用高频超声组织表征来识别马凡氏综合征患者异常主动脉的这些结构变化。我们测量了马凡氏综合征患者行主动脉根置换术的主动脉标本的超声后向散射积分和各向异性，并将这些值与无临床主动脉病理的患者的主动脉标本进行了比较。方法与结果从11例马凡氏综合征患者行主动脉瘤修复或夹层手术时获得主动脉组织。在尸检时从8例无主动脉疾病证据的患者中获得正常组织。在50 MHz的声学显微镜下测量每个样品的综合后向散射。每个组织类型的超声后向散射各向异性的大小被确定为血管基质三维（3D）组织的指标。每个标本的胶原含量用羟基脯氨酸测定法测定。马凡氏综合征患者和健康人的后向散射比正常主动脉小（分别为- 40.9±2.9 dB和- 32.6±2.2 dB，P< 0.0001）。尽管后向散射差异很大，但正常主动脉和马凡氏主动脉的胶原浓度差异无统计学意义（分别为262.7±52.7和282.4±41.8 mg/g，P= 0.42）。组织学分析显示，与正常主动脉相比，马凡氏综合征患者主动脉瘤段弹性蛋白的数量和组织都有显著差异。正常主动脉的特点是弹性蛋白纤维呈板层状排列。马凡主动脉动脉瘤的基质弹性蛋白含量显著降低，这与高度排列有序的板层排列丧失有关。散射的方向依赖性或超声各向异性在两种组织类型之间也存在显著差异。与垂直于弹性蛋白纤维的主轴相比，当介质与弹性蛋白纤维的主轴平行时，正常主动脉的后向散射显著减少。马凡氏主动脉对散射的方向依赖性小得多。正常主动脉的超声各向异性比马凡氏主动脉高14倍（正常主动脉和马凡氏主动脉分别为24.1±3.7 dB和12.4±3.3 dB，P< 0.0001），这表明马凡氏综合征中基质紊乱程度严重。结论高频超声组织表征可灵敏地检测马凡氏综合征患者主动脉血管壁组成和组织的变化。与正常主动脉相比，这些患者的主动脉段的综合后向散射显著降低（约8db，或大于6倍的散射降低）。观察到马凡氏组织的超声各向异性降低了15倍，这表明这些主动脉的3D结构明显紊乱。这些数据支持了高频超声组织表征可能有助于识别血管壁组成、结构和材料特性异常的假设。
BackgroundAneurysmal dilation of the aorta with subsequent rupture or dissection occurs frequently in patients with Marfan syndrome and is the primary cause of morbidity. These complications are related to the altered composition and disorganized structure of the aortic media. Our goal was to use high-frequency ultrasonic tissue characterization to identify these structural changes in abnormal aorta from patients with Marfan syndrome. We measured integrated backscatter and anisotropy of backscatter of ultrasound from specimens of aorta from patients with Marfan syndrome undergoing aortic root replacement and compared these values with those from aortic specimens of patients without clinical aortic pathology.Methods and ResultsAortic tissue was obtained at the time of surgery from 11 patients with Marfan syndrome undergoing repair of an aortic aneurysm or dissection. Normal tissue was obtained at the time of autopsy from 8 patients without evidence of aortic disease. Acoustic microscopy at 50 MHz was performed to measure integrated backscatter from each specimen. The magnitude of ultrasonic anisotropy of backscatter for each tissue type was determined as an index of the three-dimensional (3D) organization of the vessel matrix. The collagen content of each specimen was determined with a hydroxyproline assay. Marfan aortas exhibited less backscatter than did normal aortas (−40.9±2.9 versus −32.6±2.2 dB for patients with Marfan syndrome and healthy subjects, respectively,P<.0001). No significant difference in collagen concentrations was observed between normal and Marfan aorta (262.7±52.7 versus 282.4±41.8 mg/g tissue for normal and Marfan aortas, respectively,P=.42), despite the large difference in backscatter. Histological analysis revealed striking differences in both the amount and organization of the elastin in the aortic aneurysm segments from patients with Marfan syndrome compared with normal aorta. Normal aorta was characterized by well-formed elastin fibers arranged in a lamellar pattern. The media from aneurysms in Marfan aorta exhibited a profound decrease in elastin content that was associated with loss of the highly aligned and ordered lamellar arrangement. The directional dependence of scattering, or ultrasonic anisotropy, also differed dramatically between the two tissue types. Backscatter from normal aorta decreased substantially when the media was insonified parallel compared with perpendicular to the principal axis of the elastin fibers. Marfan aorta exhibited a much smaller directional dependence of scattering. Normal aortas manifested a 14-fold greater ultrasonic anisotropy than did Marfan aortas (24.1±3.7 versus 12.4±3.3 dB for normal and Marfan aortas,P<.0001), which is indicative of the profound extent of matrix disorganization in Marfan syndrome.ConclusionsThese data show that high-frequency ultrasonic tissue characterization sensitively detects changes in vessel wall composition and organization that occur in the aorta of patients with Marfan syndrome. Aortic segments from these patients manifested a significant decrease in integrated backscatter compared with normal aorta (approximately 8 dB, or greater than a 6-fold decrease in scattering). A 15-fold reduction in the ultrasonic anisotropy of Marfan tissue was observed, which suggests a marked disorganization of the 3D architecture of these aortas. These data support the hypothesis that high-frequency ultrasonic tissue characterization may be useful for identifying abnormalities of vessel wall composition, architecture, and material properties.