Contrast-enhanced Sonography for the Evaluation of Neovascularization in Tendinopathic Tissues

ObjectiveThe purpose of this study was to evaluate the usefulness of contrast-enhanced ultrasound for detecting neovascularization in tendinopathic tissues using an animal model.MethodsDoses of 100 μL and 50 μL collagenase were injected into the left and right Achilles tendons of six rabbits. Power Doppler ultrasonography was used before and after the administration of a contrast agent to evaluate tendon perfusion on Day 0 and Day 14 after the collagenase injections. The number of color pixels within the region of interest represented the amount of vascularity.ResultsThe tendon cross-sectional area was similar between Day 0 and Day 14, and comparisons between both tendons also appeared to be insignificantly different between these two times. Noncontrast power Doppler ultrasonography failed to detect more color pixels in the tendons after collagenase injections in comparison with baseline, whereas a higher peak signal intensity was identified using contrast enhancement in the collagenase-treated tendons. In addition, differences in vascularity between the tendons that received different amounts of collagenase were clearly revealed after the administration of the contrast agents.ConclusionThe present study demonstrates that contrast-enhanced ultrasound is superior to the noncontrast ultrasound for measuring hypervascularity in Achilles tendinopathy in a rabbit model.