Moore M P, Spencer T, Salter D M, Kearney P P, Shaw T R, Starkey I R, Fitzgerald P J, Erbel R, Lange A, McDicken N W, Sutherland G R, Fox K A
Department of Cardiology, University of Edinburgh, UK.
Heart. 1998 May;79(5):459-67. doi: 10.1136/hrt.79.5.459.
To determine whether spectral analysis of unprocessed radiofrequency (RF) signal offers advantages over standard videodensitometric analysis in identifying the morphology of coronary atherosclerotic plaques.
97 regions of interest (ROI) were imaged at 30 MHz from postmortem, pressure perfused (80 mm Hg) coronary arteries in saline baths. RF data were digitised at 250 MHz. Two different sizes of ROI were identified from scan converted images, and relative amplitudes of different frequency components were analysed from raw data. Normalised spectra was used to calculate spectral slope (dB/MHz), y-axis intercept (dB), mean power (dB), and maximum power (dB) over a given bandwidth (17-42 MHz). RF images were constructed and compared with comparative histology derived from microscopy and radiological techniques in three dimensions.
Mean power was similar from dense fibrotic tissue and heavy calcium, but spectral slope was steeper in heavy calcium (-0.45 (0.1)) than in dense fibrotic tissue (-0.31 (0.1)), and maximum power was higher for heavy calcium (-7.7 (2.0)) than for dense fibrotic tissue (-10.2 (3.9)). Maximum power was significantly higher in heavy calcium (-7.7 (2.0) dB) and dense fibrotic tissue (-10.2 (3.9) dB) than in microcalcification (-13.9 (3.8) dB). Y-axis intercept was higher in microcalcification (-5.8 (1.1) dB) than in moderately fibrotic tissue (-11.9 (2.0) dB). Moderate and dense fibrotic tissue were discriminated with mean power: moderate -20.2 (1.1) dB, dense -14.7 (3.7) dB; and y-axis intercept: moderate -11.9 (2.0) dB, dense -5.5 (5.4) dB. Different densities of fibrosis, loose, moderate, and dense, were discriminated with both y-axis intercept, spectral slope, and mean power. Lipid could be differentiated from other types of plaque tissue on the basis of spectral slope, lipid -0.17 (0.08). Also y-axis intercept from lipid (-17.6 (3.9)) differed significantly from moderately fibrotic tissue, dense fibrotic tissue, microcalcification, and heavy calcium. No significant differences in any of the measured parameters were seen between the results obtained from small and large ROIs.
Frequency based spectral analysis of unprocessed ultrasound signal may lead to accurate identification of atherosclerotic plaque morphology.
确定未处理的射频（RF）信号频谱分析在识别冠状动脉粥样硬化斑块形态方面是否优于标准视频密度测定分析。
在盐浴中对97个感兴趣区域（ROI）进行成像，这些区域取自死后经压力灌注（80毫米汞柱）的冠状动脉，频率为30兆赫。RF数据以250兆赫进行数字化处理。从扫描转换图像中识别出两种不同大小的ROI，并从原始数据中分析不同频率成分的相对振幅。使用归一化频谱计算给定带宽（17 - 42兆赫）内的频谱斜率（分贝/兆赫）、y轴截距（分贝）、平均功率（分贝）和最大功率（分贝）。构建RF图像，并与通过显微镜和放射技术在三维空间中获得的对比组织学结果进行比较。
致密纤维化组织和重度钙化组织的平均功率相似，但重度钙化组织（-0.45（0.1））的频谱斜率比致密纤维化组织（-0.31（0.1））更陡，重度钙化组织（-7.7（2.0））的最大功率高于致密纤维化组织（-10.2（3.9））。重度钙化组织（-7.7（2.0）分贝）和致密纤维化组织（-10.2（3.9）分贝）的最大功率显著高于微钙化（-13.9（3.8）分贝）。微钙化（-5.8（1.1）分贝）的y轴截距高于中度纤维化组织（-11.9（2.0）分贝）。中度和致密纤维化组织可通过平均功率进行区分：中度为-20.2（1.1）分贝，致密为-14.7（3.7）分贝；以及y轴截距：中度为-
