Kato Koji, Yasutake Masahiro, Yonetsu Taishi, Kim Soo Joong, Xing Lei, Kratlian Christina M, Takano Masamichi, Mizuno Kyoichi, Jang Ik-Kyung
Cardiology Division, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
J Nippon Med Sch. 2011;78(6):340-51. doi: 10.1272/jnms.78.340.
The concept of vulnerable plaque (VP) has been widely accepted as the primary cause of acute coronary syndrome (ACS) and sudden cardiac death. ACS is thought to result from sudden disruption of a VP with subsequent occlusive thrombosis. VP typically consists of several components; a large necrotic core, thin fibrous cap, increase in macrophage activity, increase in vaso vasorum, and positive remodeling. In recent years, invasive or non-invasive diagnostic imaging modalities have been developed for indentifying VP. VP has been recognized in various modalities not only by visualization of cross sectional images by high-resolution imaging modalities, such as virtual histology intravascular ultrasound (VH-IVUS), integrated backscatter (IB) IVUS, and optical coherence tomography (OCT), but also by direct visualization by intracoronary angioscopy. VH-IVUS uses advanced radiofrequency signal analysis of ultrasound signals and allows detailed qualitative and quantitative assessment of plaque composition, while IB-IVUS analyzes the radiofrequency signal by applying a fast Fourier transformation of the component of the backscattered signals. Different tissue components reflect the radiofrequency signaling at different power levels, which could be used to differentiate various tissue components. Angioscopy allows direct visualization of internal surface of the lumen, providing the detailed information of characteristics of plaque and thrombus. Optical coherence tomography (OCT) is an analog of IVUS, but uses light instead of sound. OCT has a 10-fold higher image resolution (10-15 μm) compared to conventional IVUS, therefore it is able to provide superior image quality. The commercially available versions of the technology used time-domain (TD) OCT (M2, M3, Lightlab, Westford, MA, USA) and fourier-domain (FD) OCT (C7XR, Lightlab, Westford, MA, USA). OCT is the only imaging modality with high enough resolution to measure fibrous cap thickness and neovascularization. Moreover OCT has a unique ability of detecting macrophages. In this review, we attempted to summarize the advantages and limitations of the currently available intravascular modalities.
易损斑块（VP）的概念已被广泛认为是急性冠状动脉综合征（ACS）和心源性猝死的主要原因。ACS被认为是由VP突然破裂并随后发生闭塞性血栓形成所致。VP通常由几个成分组成；一个大的坏死核心、薄纤维帽、巨噬细胞活性增加、滋养血管增多和正性重塑。近年来，已开发出用于识别VP的有创或无创诊断成像方法。VP不仅通过高分辨率成像方法（如虚拟组织学血管内超声（VH-IVUS）、背向散射积分（IB）IVUS和光学相干断层扫描（OCT））可视化横截面图像来识别，还通过冠状动脉血管镜直接可视化来识别。VH-IVUS使用超声信号的先进射频信号分析，并允许对斑块成分进行详细的定性和定量评估，而IB-IVUS通过对背向散射信号的成分应用快速傅里叶变换来分析射频信号。不同的组织成分在不同的功率水平下反射射频信号，这可用于区分各种组织成分。血管镜可直接观察管腔的内表面，提供斑块和血栓特征的详细信息。光学相干断层扫描（OCT）是IVUS的类似物，但使用光而不是声音。与传统IVUS相比，OCT的图像分辨率高10倍（10-15μm），因此能够提供更高质量的图像。该技术的商业可用版本使用时域（TD）OCT（M2、M3，Lightlab，美国马萨诸塞州韦斯特福德）和频域（FD）OCT（C-7XR，Lightlab，美国马萨诸塞州韦斯特福德）。OCT是唯一具有足够高分辨率来测量纤维帽厚度和新生血管形成的成像方法。此外，OCT具有检测巨噬细胞的独特能力。在本综述中，我们试图总结当前可用的血管内成像方法的优点和局限性。
