Biomedical Simulation Laboratory and Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
J Magn Reson Imaging. 2011 Feb;33(2):482-9. doi: 10.1002/jmri.22440.
To demonstrate the feasibility of rapid and reliable geometric characterization of normal carotid bifurcation geometry from routine 3D contrast-enhanced magnetic resonance (MR) angiograms.
Repeat scans of 61 participants, acquired as part of the Atherosclerosis Risk in Communities (ARIC) Carotid MRI substudy, were digitally segmented using automated 3D level set methods, relying on an operator only to select the branch endpoints and thresholds for the 3D lumen surface initialization. Geometric factors characterizing the 3D lumen geometry were then extracted automatically.
Of 122 scans, 117 could be segmented within 5 minutes each, with 40% being of sufficiently high quality to require less than 2 minutes each. Irrespective of scan quality, geometric factors were found to be highly reproducible, with intraclass correlation coefficients (ICCs) typically above 0.9. The reconstructed lumen surfaces were reproducible to <0.3 mm on average, comparable to previous MRI-based reproducibility studies. Owing to the automated nature of the analysis, operator reliability was near-perfect (ICC >0.99), with lumen surface differences <0.1 mm.
The 3D geometry of the carotid bifurcation can be characterized rapidly and with a high degree of consistency, even for suboptimal image qualities. This bodes well for large-scale retrospective or prospective studies aimed at teasing out the influence of local vs. systemic risk factors for early atherosclerosis.
从常规的三维对比增强磁共振（MR）血管造影中演示快速可靠的正常颈动脉分叉几何形状的几何特征的可行性。
重复扫描了 61 名参与者，这些参与者是作为社区动脉粥样硬化风险（ARIC）颈动脉 MRI 子研究的一部分进行采集的，使用自动的三维水平集方法进行数字化分割，仅依靠操作者选择分支端点和三维管腔表面初始化的阈值。然后自动提取了描述三维管腔几何形状的几何特征。
在 122 次扫描中，有 117 次可以在 5 分钟内完成分割，其中 40%的扫描质量足够高，每个扫描的分割时间不到 2 分钟。无论扫描质量如何，几何特征都具有高度的可重复性，组内相关系数（ICC）通常高于 0.9。重建的管腔表面平均重复性为<0.3mm，与以前基于 MRI 的重复性研究相当。由于分析的自动化性质，操作者的可靠性非常高（ICC>0.99），管腔表面差异<0.1mm。
即使对于次优的图像质量，也可以快速且高度一致地描述颈动脉分叉的三维几何形状。这对于旨在梳理早期动脉粥样硬化的局部与系统性风险因素的影响的大规模回顾性或前瞻性研究来说是个好兆头。
