Tendon displacement assessment by pulsed Doppler tissue imaging: Validation with a reciprocating string test target

After hand trauma and surgery, assessment of tendon excursion is important in reconstructive surgery and rehabilitation. Aimed as a more reliable alte rnative to traditional noninvasive methods, a colour Doppler imaging scanne r was adapted to measure longitudinal tendon displacement, Displacement was quantified by integrating the velocity estimated from the zero-crossing ra te of the Doppler signal. The system was tested by measuring displaced dist ances of a rubber string that was moved back and forth. At a determined opt imal receiver gain, 1.5-cm string displacements were measured with less tha n +/- 0.05-cm bias throughout an echo-signal dynamic range of 22 dB; standa rd deviations were around 0.05 cm, Regression analysis between measured and true displacements in the range 0.5-2.5 cm resulted in a best fit straight line with slope 0.927, intercept 0.041 cm and residual standard error of 0 .06 cm, A transfer technique was conceived to ensure accuracy when measurin g tendons in the body. This CDI-based pulsed Doppler system merits verifica tion for measurement of tendon excursion in patients. (C) 1999 World Federa tion for Ultrasound in Medicine & Biology.