1,721,150 research outputs found
Un nuovo strumento diagnostico ad ultrasuoni per la misura dei profili di flusso nei vasi umani
No full textprogramma su videocassetta a cura del Centro Didattico Televisivo dell’Università di Firenze, n. 401/a, 199
Improved blood velocity estimation using the maximum Doppler frequency, , Vol. 21, No. 4, pp.
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Invariance of the Doppler bandwidth with range cell size above a critical beam-to-flow angle
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Clinical validation of common carotid artery wall distension assessment based on multigate doppler processing
No full textMechanical properties of human large arteries result from the interaction between blood pressure, wall distensibility and shear stress. Both the arterial diameter changes through the cardiac cycle (distension) and blood flow velocities can be noninvasively investigated through Doppler ultrasound approaches. Recently, an integrated system processing in real-time all the echo signals produced along an M-line has been developed. This system has been so far demonstrated to be suitable for accurate hemodynamic studies through the detection of blood velocity profiles. This paper reports on the extension of its processing capabilities to the real-time measurement of arterial distension. Tissue motion estimation is based on a modified 2-D autocorrelation algorithm. A novel adaptive approach to track wall position over time using the sum of the high-pass filtered displacement waveform and the low-pass filtered wall position is described. By observing the blood velocity profile, a rapid and accurate positioning of the ultrasound probe and an inherent check on perpendicular observation are provided. First clinical results obtained by measuring the distension of common carotid arteries in a group of 41 volunteers are reported and measurements are validated against those provided by a dedicated wall-track reference system. Average measured distension and diameter were 499 ± 188 μm and 6.90 ± 0.66 mm and intraobserver intrasession reproducibility tests showed coefficients of variability of 8.5% and 5.9%, respectively. The agreement between the proposed system and the reference system, expressed as bias ± 2 SD of the differences, was −34 ± 141 μm for distension and 0.05 ± 1.07 mm for diameter
Analysis of vascular flow dynamics through open Doppler flowmeters
No full textCardiovascular fluid dynamics seminar, IMechE Headquarters, 1 Birdcage Walk SW1H 9JJ Londra, 7 December 1999. Relazione su invito
Applicazione del computer alle tecniche: il problema dell'aliasing
No full text2° Workshop Internazionale di Emodinamica Vascolare su: “Il laboratorio vascolare: tecniche di indagine ed organizzazione”, Bologna 16-18 Ottobre 1989
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