Tendon-motion tracking in an ultrasound image sequence using optical-flow-based block matching

Area of Science:

• Medical imaging
• Biomechanics
• Orthopedics

Background:

• Tendon motion analysis via ultrasound is crucial for tendinopathy diagnosis.
• Speckle noise and out-of-plane artifacts complicate ultrasound-based tendon tracking.
• Manual tracking is time-consuming and lacks inter-observer consistency.

Purpose of the Study:

• To develop an automated method for accurate tendon motion tracking in ultrasound images.
• To address limitations of manual tracking and image artifacts in tendinopathy diagnosis.

Main Methods:

• A novel hybrid approach combining optical flow and multi-kernel block matching was developed.
• Adaptive frame interval selection based on estimated displacement using optical flow.
• Interpolation of detailed displacements using optical flow to minimize tracking errors.

Main Results:

• The method achieved a mean absolute error of less than 0.05 mm on cadaver data.
• Successful tracking of in vivo tendon motion was demonstrated.
• The proposed method showed significantly higher accuracy compared to existing techniques.

Conclusions:

• The developed method offers an accurate and automated solution for tendon motion tracking.
• Adaptive frame interval determination provides a novel index for improved tracking.
• The findings support enhanced clinical diagnosis of tendinopathy using ultrasound.