New Developments in Ultrasonic Tissue Characterization
Ultrasonic tissue characterization (UTC) encompasses a broad range of signal processing techniques applied to video or radio-frequency (rf) echo signals.1 In our laboratories, we have investigated several rf-signal analysis techniques that are based on calibrated power spectra.2 To obtain summary spectral parameters, we have used linear regression analysis to determine spectral slopes, spectral intercepts, and residual intercept uncertainties (measures of the goodness-of-fit to the spectrum). In ophthalmology, we have employed these features in more than 2,000 examinations, and we have established clinical data-bases to diagnose and monitor ocular tumors.3,4 As part of these studies, discriminant analysis has been used to classify and sub-classify malignant melanomas, metastatic carcinomas, and choroidal hemangiomas. For abdominal 5 and vascular 6 examinations, we have developed means for using these spectral parameters to compute additional UTC features (e.g., attenuation and heterogeneity indices) that are not affected by attenuation in intervening tissues. We have also developed a mathematical framework 7 that relates spectral parameters to physical scatterer properties.
KeywordsSpectral Parameter Spectral Slope Heterogeneity Index Acoustic Concentration Tissue Microstructure
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