Department of Radiology, 299, Tufts Medical Center, 800 Washington Street, Boston, MA 02111, USA.
Stroke. 2011 Jul;42(7):1912-6. doi: 10.1161/STROKEAHA.110.603449. Epub 2011 May 5.
Carotid intima-media thickness (IMT) is a marker of cardiovascular disease derived from ultrasound images of the carotid artery. In most outcome studies, human readers identify and trace the key IMT interfaces. We evaluate an alternate approach using automated edge detection.
We studied a subset of 5640 participants with an average age 61.7 years (48% men) of the Multi-Ethnic Study of Atherosclerosis composed of whites, Chinese, Hispanic, and blacks that are part of the Multi-Ethnic Study of Atherosclerosis IMT progression study. Manual tracing IMT (mt-IMT) and edge-detected IMT (ed-IMT) measurements of the far wall of the common carotid artery served as outcome variables for multivariable linear regression models using Framingham cardiovascular risk factors and ethnicity as independent predictors.
Measurements of mt-IMT were obtainable in 99.9% (5633/5640) and measurements of ed-IMT were obtainable in 98.9% (5579/5640) of individuals. Average ed-IMT was 0.19 mm larger than mt-IMT. Inter-reader systematic differences (bias) in IMT measurements were apparent for mt-IMT but not ed-IMT. Based on complete data for 5538 individuals, associations of IMT with risk factors were stronger (P<0.0001) for mt-IMT (model r2, 19.5%) than for ed-IMT (model r2, 18.5%).
We conclude that this edge-detection process generates IMT values equivalent to manually traced ones because it preserves key associations with cardiovascular risk factors. It also decreases inter-reader bias, potentially making it applicable for use in cardiovascular risk assessment.
颈动脉内膜中层厚度（IMT）是一种来源于颈动脉超声图像的心血管疾病标志物。在大多数结果研究中，人类读者会识别并追踪关键的 IMT 界面。我们评估了一种使用自动边缘检测的替代方法。
我们研究了动脉粥样硬化多民族研究（Multi-Ethnic Study of Atherosclerosis）中 5640 名参与者的一个子样本，这些参与者的平均年龄为 61.7 岁（48%为男性），包括白人、中国人、西班牙裔和黑人，他们是动脉粥样硬化 IMT 进展研究的一部分。使用Framingham 心血管危险因素和种族作为独立预测因子，对颈总动脉远侧壁的手动 IMT （mt-IMT）和边缘检测 IMT （ed-IMT）测量值进行多变量线性回归模型分析。
mt-IMT 的测量值在 99.9%（5633/5640）的个体中可获得，ed-IMT 的测量值在 98.9%（5579/5640）的个体中可获得。ed-IMT 的平均测量值比 mt-IMT 大 0.19 毫米。mt-IMT 的 IMT 测量值存在明显的读者间系统差异（偏倚），而 ed-IMT 则没有。基于 5538 名个体的完整数据，mt-IMT 与危险因素的关联更强（P<0.0001，模型 r2，19.5%），而 ed-IMT 的关联则较弱（模型 r2，18.5%）。
我们的结论是，这种边缘检测过程产生的 IMT 值与手动追踪的结果相当，因为它保留了与心血管危险因素的关键关联。它还降低了读者间的偏倚，可能使其适用于心血管风险评估。
