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

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Orthopedic Surgery

Background:

• Accurate assessment of tendon excursion is crucial for post-hand trauma and surgery reconstructive procedures and rehabilitation.
• Traditional noninvasive methods for measuring tendon excursion often lack sufficient reliability.
• A need exists for improved, accurate, and noninvasive techniques to quantify tendon displacement.

Purpose of the Study:

• To adapt a colour Doppler imaging (CDI) scanner as a reliable noninvasive tool for measuring longitudinal tendon displacement.
• To quantify tendon excursion by integrating velocity data derived from the Doppler signal's zero-crossing rate.
• To validate the accuracy and reliability of the CDI system for tendon displacement measurements.

Main Methods:

• A colour Doppler imaging scanner was modified to measure longitudinal tendon displacement.
• Displacement was quantified using the zero-crossing rate of the Doppler signal to estimate velocity.
• The system's accuracy was tested using a moving rubber string, with regression analysis performed on measured displacements.

Main Results:

• The CDI system measured 1.5-cm string displacements with a bias of less than +/- 0.05 cm across a 22 dB dynamic range.
• Standard deviations for measurements were approximately 0.05 cm, indicating high precision.
• Regression analysis showed a strong correlation between measured and true displacements (slope 0.927, intercept 0.041 cm, RSE 0.06 cm) for displacements between 0.5-2.5 cm.

Conclusions:

• The developed CDI-based pulsed Doppler system shows significant promise for accurate and reliable measurement of tendon excursion.
• A transfer technique was developed to enhance measurement accuracy in vivo.
• Further verification in patients is recommended to confirm the clinical utility of this CDI system for tendon excursion assessment.