Speckle decorrelation due to two-dimensional flow gradients

The performance of ultrasonic velocity estimation methods is degraded by speckle decorrelation, the change in received echoes over time. Because ultrasonic speckle is formed by the complex sum of echoes from subresolution scatterers, it is sensitive to the relative motion of those scatterers. Velocity gradients in flowing blood result in relative scatterer motion and can be a significant source of speckle decorrelation. Computer simulations were performed to evaluate speckle decorrelation due to two-dimensional flow gradients. Results indicate that decorrelation due to flow gradients is sensitive to the angle of flow and has a maximum at a beam-vessel angle of 0/spl deg/, i.e., purely axial flow. A quantitative summary of the major factors causing speckle decorrelation indicates that flow gradients are the most significant contributors under the conditions modeled.

[1]  K. W. Cattermole.  The Fourier Transform and its Applications , 1965 .

[2]  C. H. Edwards,et al.  Calculus and Analytic Geometry , 1982 .

[3]  R. F. Wagner,et al.  Statistics of Speckle in Ultrasound B-Scans , 1983, IEEE Transactions on Sonics and Ultrasonics.

[4]  L. Hatle,et al.  Doppler ultrasound in cardiology , 1985 .

[5]  R. F. Wagner,et al.  Fundamental correlation lengths of coherent speckle in medical ultrasonic images , 1988, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[6]  D. Evans.  Doppler Ultrasound: Physics Instrumentation and Clinical Applications , 1989 .

[7]  W. O’Brien,et al.  Flow velocity profile via time-domain correlation: error analysis and computer simulation , 1990, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[8]  E. Ritenour.  Doppler Ultrasound: Physics, Instrumentation and Clinical Applications , 1990 .

[9]  J. Jensen,et al.  Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[10]  G E Trahey,et al.  A real time system for quantifying and displaying two-dimensional velocities using ultrasound. , 1993, Ultrasound in medicine & biology.

[11]  V. Algazi,et al.  A statistical analysis of the received signal from blood during laminar flow , 1994, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[12]  F. Kallel,et al.  Speckle motion artifact under tissue rotation , 1994, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  K.W. Ferrara.  Effect of the beam-vessel angle on the received acoustic signal from blood , 1995, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[14]  B. Friemel,et al.  Experimental velocity profiles and volumetric flow via two-dimensional speckle tracking. , 1995, Ultrasound in medicine & biology.