Lilledahl Magnus Borstad, Haugen Olav Anton, de Lange Davies Catharina, Svaasand Lars Othar
Norwegian University of Science and Technology, Department of Electronics and Telecommunications, O.S. Bragstads Plass 2A, 7491 Trondheim, Norway.
J Biomed Opt. 2007 Jul-Aug;12(4):044005. doi: 10.1117/1.2772652.
Cardiovascular disease is the primary cause of death in the United States; the majority of these deaths are caused by the rupture of vulnerable plaques. An important feature of vulnerable plaques is the thickness of the fibrous cap that covers the necrotic core. A thickness of less than 65 microm has been proposed as a value that renders the plaque prone to rupture. This work shows that multiphoton microscopy (MPM) can image the plaque with microm resolution to a depth deeper than 65 microm. The fibrous cap emits primarily second harmonic generation due to collagen, in contrast to the necrotic core and healthy artery, which emits primarily two-photon excited fluorescence from elastin. This gives a good demarcation of the fibrous cap from underlying layers, facilitating the measurement of the fibrous cap thickness. Based on a measure of the collagen/elastin ratio, plaques were detected with a sensitivity of 65% and specificity of 81%. Furthermore, the technique gives detailed information on the structure of the collagen network in the fibrous cap. This network ultimately determines the mechanical strength of the plaque. A mechanical model based on this information could yield a measure of the propensity of the plaque to rupture.
心血管疾病是美国的主要死因；这些死亡中的大多数是由易损斑块破裂引起的。易损斑块的一个重要特征是覆盖坏死核心的纤维帽厚度。已提出纤维帽厚度小于65微米是使斑块易于破裂的值。这项研究表明，多光子显微镜（MPM）可以以微米级分辨率对斑块进行成像，深度超过65微米。与坏死核心和健康动脉主要发射来自弹性蛋白的双光子激发荧光不同，纤维帽主要由于胶原蛋白而产生二次谐波产生。这使得纤维帽与下层有良好的分界，便于测量纤维帽厚度。基于胶原蛋白/弹性蛋白比率的测量，检测斑块的灵敏度为65%，特异性为81%。此外，该技术还提供了纤维帽中胶原网络结构的详细信息。这个网络最终决定了斑块的机械强度。基于这些信息的力学模型可以得出斑块破裂倾向的度量。
