Measurement of the Doppler Power of Flowing Blood Using Ultrasound Doppler Devices |
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| Institution: | 1. Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan;2. Department of Electrical Engineering, Fu Jen Catholic University, New Taipei City, Taiwan;1. Division of Cardiology, Seattle Adult Congenital Heart Service, Seattle Children’s Hospital, University of Washington Medical Center, University of Washington School of Medicine, 1959 Northeast Pacific Street, Seattle, WA 98109, USA;2. Adult Congenital Heart Program at Stanford, Lucile Packard Children’s Hospital, Stanford Hospital and Clinics, Stanford University School of Medicine, 750 Welch Road, Suite 321, Palo Alto, CA 94304, USA;1. Knight Cardiovascular Institute, Oregon Health & Science University, Portland, Oregon;2. Division of Cardiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea;1. University of Alexandria, Department of Obstetrics and Gynecology, El Shatby Maternity University Hospital, Port-Said Street, 21526 El-Shatby, Alexandria, Egypt;2. Carl von Ossietzky University Oldenburg, Department of Obstetrics and Gynecology, Oldenburg University Women''s Hospital, Rahel-Straus-Straße 10, 26133 Oldenburg, Germany;1. Joint Department of Biomedical Engineering, University of North Carolina Chapel Hill and North Carolina State University, Chapel Hill, NC, USA;2. Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA;3. UNC Kidney Center and Division of Nephrology & Hypertension, University of North Carolina Chapel Hill, Chapel Hill, NC, USA |
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| Abstract: | Measurement of the Doppler power of signals backscattered from flowing blood (henceforth referred to as the Doppler power of flowing blood) and the echogenicity of flowing blood have been used widely to assess the degree of red blood cell (RBC) aggregation for more than 20 y. Many studies have used Doppler flowmeters based on an analogue circuit design to obtain the Doppler shifts in the signals backscattered from flowing blood; however, some recent studies have mentioned that the analogue Doppler flowmeter exhibits a frequency-response problem whereby the backscattered energy is lost at higher Doppler shift frequencies. Therefore, the measured Doppler power of flowing blood and evaluations of RBC aggregation obtained using an analogue Doppler device may be inaccurate. To overcome this problem, the present study implemented a field-programmable gate array-based digital pulsed-wave Doppler flowmeter to measure the Doppler power of flowing blood, in the aim of providing more accurate assessments of RBC aggregation. A clinical duplex ultrasound imaging system that can acquire pulsed-wave Doppler spectrograms is now available, but its usefulness for estimating the ultrasound scattering properties of blood is still in doubt. Therefore, the echogenicity and Doppler power of flowing blood under the same flow conditions were measured using a laboratory pulser–receiver system and a clinical ultrasound system, respectively, for comparisons. The experiments were carried out using porcine blood under steady laminar flow with both RBC suspensions and whole blood. The experimental results indicated that a clinical ultrasound system used to measure the Doppler spectrograms is not suitable for quantifying Doppler power. However, the Doppler power measured using a digital Doppler flowmeter can reveal the relationship between backscattering signals and the properties of blood cells because the effects of frequency response are eliminated. The measurements of the Doppler power and echogenicity of flowing blood were compared with those obtained in several previous studies. |
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| Keywords: | Red blood cell aggregation Hematocrit Doppler power Laminar flow Digital Doppler flowmeter |
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