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Further studies on ultrasonic properties of blood clots
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Ultrasonic tissue characterization improves intracardiac thrombi diagnosis. Aged thrombi exhibit significantly higher ultrasonic backscatter than fresh ones, aiding differentiation from other masses.
Area of Science:
- Biomedical Ultrasound
- Medical Imaging
- Cardiovascular Diagnostics
Background:
- Two-dimensional echocardiography is crucial for diagnosing intracardiac thrombi.
- Differentiating thrombi from other intracavitary masses based solely on echographic appearance remains challenging, leading to potential misdiagnosis.
- Ultrasonic tissue characterization offers a method to reduce diagnostic uncertainty.
Purpose of the Study:
- To investigate the changes in ultrasonic attenuation and backscatter of thrombi over time after clotting.
- To assess the frequency-dependent ultrasonic properties of thrombi.
- To compare the echogenicity of thrombi with myocardial tissue.
Main Methods:
- Measurements of ultrasonic attenuation and backscatter were performed on thrombi at various times post-clotting.
- The frequency range studied was from 3 MHz to 8 MHz.
- Integrated backscatter measurements were also conducted.
Main Results:
- Ultrasonic backscatter from thrombi 12 hours old was at least 18 dB higher than that of unclotted blood across the 3-8 MHz frequency range.
- The slope of the attenuation coefficient increased to 0.43 dB/cm-MHz for aged thrombi.
- Bovine myocardium was more echogenic than fresh thrombi but less echogenic than thrombi aged 12-24 hours.
Conclusions:
- Time-dependent changes in ultrasonic backscatter and attenuation can help differentiate intracardiac thrombi from other masses.
- Ultrasonic tissue characterization provides valuable quantitative data for improved thrombi diagnosis.
- The distinct echogenic properties of aged thrombi compared to myocardium are significant for diagnostic accuracy.
Abstract:
Two-dimensional echocardiography has been found to be an effective clinical tool in diagnosing intracardiac thrombi. Misdiagnosis may, however, still frequently occur because of the difficulty in differentiating the thrombi from other intracavitary masses based only on the echographic appearance of these structures. Ultrasonic tissue characterization techniques have been used in attempts to minimize this diagnostic uncertainty. Previously, we have shown that all ultrasonic parameters of blood, including ultrasonic backscatter, a quantitative measure of echogenicity, at 7.5 MHz increase rapidly following clotting. In this article, we report recent results on the measurements of attenuation and backscatter of thrombi as a function of time following clotting over the frequency range of 3 MHz to 8 MHz. These results indicate that ultrasonic backscatter from thrombi 12 h old is at least 18 dB higher than that of unclotted blood over the frequency range of 3 MHz to 8 MHz, and the slope of the attenuation coefficient is increased to 0.43 dB/cm-MHz. Comparison with the backscatter of bovine myocardium shows that the myocardium is more echogenic than fresh thrombi and is less echogenic than thrombi 12 to 24 h old. Similar results were also obtained for integrated backscatter measurements over the same frequency range.