Li Zhi-Yong, Howarth Simon, Tang Tjun, Graves Martin, U-King-Im Jean, Gillard Jonathan H
University Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
Cerebrovasc Dis. 2007;24(5):452-9. doi: 10.1159/000108436. Epub 2007 Sep 19.
Rupture of vulnerable atheromatous plaque in the carotid and coronary arteries often leads to stroke and heart attack respectively. The role of calcium deposition and its contribution to plaque stability is controversial. This study uses both an idealized and a patient-specific model to evaluate the effect of a calcium deposit on the stress distribution within an atheromatous plaque.
Using a finite-element method, structural analysis was performed on an idealized plaque model and the location of a calcium deposit within it was varied. In addition to the idealized model, in vivo high-resolution MR imaging was performed on 3 patients with carotid atheroma and stress distributions were generated. The individual plaques were chosen as they had calcium at varying locations with respect to the lumen and the fibrous cap.
The predicted maximum stress was increased by 47.5% when the calcium deposit was located in the thin fibrous cap in the model when compared with that in a model without a deposit. The result of adding a calcium deposit either to the lipid core or remote from the lumen resulted in almost no increase in maximal stress.
Calcification at the thin fibrous cap may result in high stress concentrations, ultimately increasing the risk of plaque rupture. Assessing the location of calcification may, in the future, aid in the risk stratification of patients with carotid stenosis.
颈动脉和冠状动脉中易损动脉粥样硬化斑块破裂通常分别导致中风和心脏病发作。钙沉积的作用及其对斑块稳定性的影响存在争议。本研究使用理想化模型和患者特异性模型来评估钙沉积物对动脉粥样硬化斑块内应力分布的影响。
使用有限元方法，对理想化斑块模型进行结构分析，并改变其中钙沉积物的位置。除了理想化模型外，对3例颈动脉粥样硬化患者进行了体内高分辨率磁共振成像，并生成了应力分布。选择这些个体斑块是因为它们在相对于管腔和纤维帽的不同位置有钙。
与无沉积物模型相比，当模型中钙沉积物位于薄纤维帽时，预测的最大应力增加了47.5%。在脂质核心添加钙沉积物或远离管腔添加钙沉积物的结果几乎不会使最大应力增加。
薄纤维帽处的钙化可能导致高应力集中，最终增加斑块破裂的风险。未来，评估钙化位置可能有助于对颈动脉狭窄患者进行风险分层。
