Textural correlation is novel approach for the measurement of displacement and strain patterns within connective orthopaedic soft tissue. Magnetic resonance images of an equine suspensory ligament in loaded and unloaded states have been compared by creating virtual markers to determine displacements and measure local axial relative displacements. The advantages of texture correlation over traditional surface marker measurements include a non-invasive in-situ method of strain measurement, real time rapid strain measurement, measurement of intra-tissue strain, and allowance for strain measurement over potentially very small regions of interest that is limited only by the resolution of the medical image.
Validation of this technique is confirmed by comparison of strain measurements from texture correlation and surface markers of a soft-tissue specimen. It was determined that texture correlation was accurate to 7.4% absolute error when 2.5% grip strain was applied; however, the accuracy was significantly diminished at 5.0% grip strain. Further refinements are suggested to improve the accuracy; however, currently validation is required with all reports of non-invasive strain measurements using digital image analysis.