Quantificação semiautomática da velocidade do sangue em imagens de ultrassonografia Doppler

Blood velocity vs. time graphic images acquired by ultrasound Doppler technique can be used to reveal relationships between data within those graphics and the presence of cardiovascular diseases, among other applications. To facilitate this kind of study in clinical protocols involving hundreds of patients, a computational tool was developed to extract quantitative data from the graphics. After calibration and selection of the region of interest defined by the user, the algorithm automatically detects the baseline and the curve envelope to calculate the peak velocities and the velocity-time integral (VTI). Image processing techniques, such as Connected Components, Gaussian and Median filters were applied to improve the robustness of the envelope detection. A comparative analysis between measurements obtained with commercial ultrasound systems operated by specialists (named as 'A') and by the present methodology (named as 'B') included systolic peak velocities and VTIs of common carotid and brachial arteries under basal condition, brachial arteries in the reactive hyperemic response and echocardiographic exams. The results showed a small mean difference, calculated as d = A - B, in the Bland-Altman analysis and a high correlation for both: peak velocity (d = 0.02 m/s; r > 0.99; p 0.99; p < 0.01; 75 samples). These findings indicate the reliability of this methodology which, in addition to the user friendly graphical interface of this new tool, can be easily used by the clinicians for their large-scale studies based on Doppler ultrasound images.