Background and purpose: B-mode measurement of the sagital diameter of the Achilles Tendon (AT) based on manual tracing (MT) procedures is partly dependent on the subjectivity of the reader. The aim of this study is to establish a standardised automatic procedure to differentiate between normal and chronic degenerated tendons. For this compare the tracing results of the AT boundaries of an automatic identification (AI) process, already established the detection of the Intima-Media-Thickness, are compared with computer-assisted MT.
Methods and Results: The detection of the AT boundaries was performed in 115 Ultrasound images of the AT including the cranial border of the calcaneal tuberosity. The measured section (starting point 4cm away from the anterior boundary of the calcaneal tuberosity) amounted 3 cm and was divided in 3 sub segments (1 cm each). Intra- and inter-reader/observer variability for mean and maximum AT Thickness (ATT) with AI and MT were evaluated. A normal group and a group with clinical diagnosed chronic AT degeneration were compared concerning mean ATT and maximum ATT. Using MT the intra- and inter-reader variability amounted 3.0 % and 6.8 %, respectively, using the AI 1.6 % and 3.9 % mm. Mean and maximum ATT were measured systematically lower by AI compared with MT in all regions by 0,4 mm. The AI procedure was most suitable in the 2nd segment. The mean ATT and maximum ATT were correctly detected in 93.9 % and 96.6 % of the images.
Conclusion: The AI procedure detects the ATT with a high precision in all three segments. The most robust measurement was reached in the 2nd segment. It eliminates most of inter-/intra-reader variability of the ATT measurement using MT. We suggest using the new method for new gold-standard for quantification of chronic disorder in AT.
- Achilles tendon
- automatic analysis
- pattern recognition