1 Laboratory of Biorheology and Medical Ultrasonics, University of Montreal Hospital Research Center, 900 St Denis, Rm R11-464, Montreal, QC H2X 0A9, Canada.
2 Cardiovascular Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
AJR Am J Roentgenol. 2017 Jul;209(1):142-151. doi: 10.2214/AJR.16.17176.
Vulnerable and nonvulnerable carotid artery plaques have different tissue morphology and composition that may affect plaque biomechanics. The objective of this study is to evaluate plaque vulnerability with the use of ultrasound noninvasive vascular elastography (NIVE).
Thirty-one patients (mean [± SD] age, 69 ± 7 years) with stenosis of the internal carotid artery of 50% or greater were enrolled in this cross-sectional study. Elastography parameters quantifying axial strain, shear strain, and translation motion were used to characterize carotid artery plaques as nonvulnerable, neovascularized, and vulnerable. Maximum axial strain, cumulated axial strain, mean shear strain, cumulated shear strain, cumulated axial translation, and cumulated lateral translations were measured. Cumulated measurements were summed over a cardiac cycle. The ratio of cumulated axial strain to cumulated axial translation was also evaluated. The reference method used to characterize plaques was high-resolution MRI.
According to MRI, seven plaques were vulnerable, 12 were nonvulnerable without neovascularity, and 12 were nonvulnerable with neovascularity (a precursor of vulnerability). The two parameters cumulated axial translation and the ratio of cumulated axial strain to cumulated axial translation could discriminate between nonvulnerable plaques and vulnerable plaques or determine the presence of neovascularity in nonvulnerable plaques (which was also possible with the mean shear strain parameter). All parameters differed between the non-vulnerable plaque group and the group that combined vulnerable plaques and plaques with neovascularity. The most discriminating parameter for the detection of vulnerable neovascularized plaques was the ratio of cumulated axial strain to cumulated axial translation (expressed as percentage per millimeter) (mean ratio, 39.30%/mm ± 12.80%/mm for nonvulnerable plaques without neovascularity vs 63.79%/mm ± 17.59%/mm for vulnerable plaques and nonvulnerable plaques with neovascularity, p = 0.002), giving an AUC value of 0.886.
The imaging parameters cumulated axial translation and the ratio of cumulated axial strain to cumulated axial translation, as computed using NIVE, were able to discriminate vulnerable carotid artery plaques characterized by MRI from nonvulnerable carotid artery plaques. Consideration of neovascularized plaques improved the performance of NIVE. NIVE may be a valuable alternative to MRI for carotid artery plaque assessment.
易损和非易损颈动脉斑块具有不同的组织形态和组成，这可能影响斑块生物力学。本研究旨在使用超声无创血管弹性成像（NIVE）评估斑块易损性。
31 例（平均[±SD]年龄 69±7 岁）狭窄程度≥50%的颈内动脉患者纳入本横断面研究。弹性成像参数用于量化轴向应变、剪切应变和平移运动，以将颈动脉斑块分为非易损、新生血管化和易损。测量最大轴向应变、累积轴向应变、平均剪切应变、累积剪切应变、累积轴向平移和累积侧向平移。在心动周期中对累积测量值进行求和。还评估了累积轴向应变与累积轴向平移的比值。用于斑块特征描述的参考方法是高分辨率 MRI。
根据 MRI，7 个斑块为易损斑块，12 个斑块为非易损但无新生血管斑块，12 个斑块为非易损伴新生血管斑块（易损的前兆）。累积轴向平移和累积轴向应变与累积轴向平移的比值这两个参数可以区分非易损斑块和易损斑块，或者确定非易损斑块中新生血管的存在（平均剪切应变参数也可以）。所有参数在非易损斑块组和易损斑块和伴新生血管斑块组之间均有差异。用于检测易损新生血管斑块的最具鉴别力的参数是累积轴向应变与累积轴向平移的比值（表示为每毫米的百分比）（非易损无新生血管斑块的平均比值为 39.30%/mm±12.80%/mm，易损和非易损伴新生血管斑块的比值为 63.79%/mm±17.59%/mm，p=0.002），曲线下面积（AUC）值为 0.886。
使用 NIVE 计算的累积轴向平移和累积轴向应变与累积轴向平移的比值可以区分 MRI 特征为易损的颈动脉斑块和非易损的颈动脉斑块。考虑新生血管斑块可提高 NIVE 的性能。NIVE 可能是颈动脉斑块评估的 MRI 有价值的替代方法。
