Development of real-time color intravascular ultrasound using Wavelet Analysis

背景与目的：小波分析是一种新的用于评估时间序列信号几何轮廓局部变化的数学模型。我们以前报道过血管内超声（IVUS）视频图像的小波分析可能有助于检测体内动脉粥样硬化斑块的富脂区。本研究的目的是利用小波分析开发实时彩色血管内超声。方法：采用40 MHz血管内超声导管采集32例经福尔马林固定的非钙化动脉粥样硬化斑块的血管内超声信号。使用Daubechies-2小波对这些图像进行小波分析，以获得在小波尺度的x-y平面上重建的小波与IVUS导管距离的相关系数。结果：26例斑块组织学检查可见脂质段。当进行小波分析时，鸟瞰图显示了与其他类型的斑块相比，脂质斑块中明显不同的模式。应用该小波分析方法检测含脂斑块的敏感性为81%（26/32），特异性为80%。

Background and Objects : Wavelet analysis is a new mathematical model for assessing local changes in geometrical profile of time-series signals. We previously reported that Wavelet analysis of video-images of intravascular ultrasound (IVUS) might be useful for detecting lipid-rich area with atherosclerotic plaque in vivo. The purpose of this study is the development of real-time color intravascular ultrasound using Wavelet Analysis. Methods : IVUS signals were acquired from 32 formalin-fixed noncalcifled atherosclerotic plaques from human necropsy by a 40MHz IVUS catheter. Wavelet analysis of these images was performed with Daubechies-2 wavelet to obtain the correlation coefficient with the wavelet reconstructed over the x-y plane of the wavelet scale and the distance from IVUS catheter. Results : Histological examination revealed lipid-laden segment in 26 plaques. When performing a wavelet analysis, the bird eye view revealed an apparently different pattern in lipid-laden plaque compared to other types of plaque. Using this wavelet analysis, the lipid-laden plaque could be detected with sensitivity of 81% (26/32) and specificity of 80%.