Real-time digital processing of Doppler ultrasound signals and calculation of flow parameters.
Vascular diseases and their complications are responsible for around 27% of deaths in Brazil. Doppler ultrasound is a non-invasive technique that has been used to study blood flow in intact blood vessels since Satomura first reported the potential of the technique in 1959. Because it is non-invasive it makes sequential studies and those in normals feasible. Whereas in contrast angiography only vessel anatomy is displayed, Doppler ultrasound produces dynamic information on blood-flow. It may be used to estimate flow-rates, to image regions of blood flow (colour Doppler), and to help in locating sites of arterial disease, thus complementing X-ray examinations. This paper describes a system based on a Digital Signal Processor for real-time spectrum analysis of Doppler ultrasound signals, real-time display of sonograms, and calculation and analysis of three parameters of clinical interest derived from the Doppler signal. The system comprises a TMS320C25 development board, which acquires the signal and performs spectrum analysis, and a microcomputer, which reads the spectral estimates, displays them as a sonogram in real-time and calculates a set of spectral parameters proposed in the literature. The system permits a maximum sampling frequency of 40.96 kHz, and in the sonogram, 80 power spectra per second (each with 128 frequency bins) are displayed. In a preliminary study, the stability of the haemodynamic parameters and their dependence on a user-defined threshold value is investigated.
Universidade Federal do Rio de Janeiro, Brazil.
F S
FS
Schlindwein
M H
MH
Vieira
C F
CF
Vasconcelos
D M
DM
Simpson
D000465:Algorithms; D001783:Blood Flow Velocity; D006801:Humans; D008838:Microcomputers; D008954:Models, Biological; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013018:Sound Spectrography; D014465:Ultrasonics; D014463:Ultrasonography / Q000379:methods*