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Signal processors in duplex sonography: in vitro comparison between analog and digital methods
W G Zoller1, C Wierscher, D R Wagner
1Medizinische Poliklinik, Universität München, Germany.
Research in Experimental Medicine. Zeitschrift Fur Die Gesamte Experimentelle Medizin Einschliesslich Experimenteller Chirurgie
|January 1, 1993
Summary
Duplex sonography accurately measures blood flow, though it tends to overestimate real flow. A digital signal processor showed less overestimation than an analog one, but offered no advantage for stenosis studies.
Area of Science:
- Medical Imaging
- Biomedical Engineering
- Cardiovascular Diagnostics
Background:
- Accurate blood flow measurement is crucial for diagnosing vascular diseases.
- Duplex sonography is a common non-invasive imaging technique for assessing blood flow.
- Evaluating the performance of signal processing techniques is essential for improving diagnostic accuracy.
Purpose of the Study:
- To assess the performance of analog and digital (Fast Fourier Transform) duplex sonography signal processors in blood flow measurements.
- To compare the accuracy of these processors under various physiological and mechanical conditions.
- To evaluate their efficacy in studying asymmetric stenoses.
Main Methods:
- Development and utilization of a novel flow-test phantom simulating blood's acoustic properties and circulatory impedances.
- Testing of analog and dynamic (FFT) signal processors with the phantom under steady and pulsatile flow conditions.
- Varying parameters such as heart rate, blood pressure, and hematocrit in silicon tubes and animal vessels.
Main Results:
- High correlation (0.96-0.99) was observed between duplex sonography and quantitative flow measurements across diverse conditions.
- Duplex sonography consistently overestimated real blood flow.
- The digital processor exhibited less overestimation (1.22-1.64) compared to the analog processor (1.87-4.20) (P < 0.05).
- The digital processor did not outperform analog methods in evaluating asymmetric stenoses.
Conclusions:
- Duplex sonography, with both analog and digital processing, demonstrates high correlation with quantitative flow measurements.
- Digital signal processing offers improved accuracy by reducing blood flow overestimation compared to analog methods.
- Current digital processors do not provide superior performance over established analog techniques for assessing arterial stenoses.