endinopathy, a common soft tissue disorder in tendons and their insertions, features hypercellularity, a disoriented fiber arrangement, and neovascularization on histologic examinations. 1,2 Healthy tendons are hypovascular in architecture, receiving a blood supply from the extrinsic system through the paratendon or synovial sheath and the intrinsic system at the myotendinous or osteotendinous junction. 3 Although temporary hyperemia is a normal response after exercise or a healing process on injury, 4,5 persistent hypervascularity elicits unresolved pain and possibly alters the mechanical properties of tendons. 6 Sclerosing Ke-Vin Chang, MD, Chueh-Hung Wu, MD, Yu-Hui Ding, BD, Hsiu-Yu Shen, MD, Tyng-Guey Wang, MD, Wen-Shiang Chen, MD, PhD Received September 30, 2011,
ORIGINAL RESEARCHObjectives-The purpose of this study was to investigate the ability of contrastenhanced sonography in staging and grading hypervascularity in tendinopathic tissues by using a rabbit model.Methods-Fourteen rabbits were injected with 100 and 50 μL of collagenase in their left and right Achilles tendons, respectively. The vascularity was assessed by non-contrastenhanced and contrast-enhanced power Doppler sonography on day 0 (baseline) and days 1, 7, and 14 after collagenase injections. Color pixels within targeted areas were plotted according to time and analyzed by a curve-fitting method.Results-Non-contrast-enhanced power Doppler sonography failed to differentiate vascularity at various stages or between bilateral tendons, whereas contrast-enhanced sonography showed that the peak color pixel amount reached its maximum on day 1 and declined over time in tendons treated with 100 μL of collagenase. A similar trend was observed in tendons receiving 50 μL of collagenase. For comparisons between bilateral tendons, higher vascularity was detected in those treated with more collagenase on day 1 or 7. Time-intensity curve analysis revealed rapid microbubble replenishment in both tendons during their initial phase after collagenase injections.Conclusions-Contrast-enhanced sonography discriminated the vascularity of various injury grades at different time points after collagenase injections. Time-intensity curve analysis detailed the hemodynamics in tendinopathic tissues, which helped differentiate vascularity in acute inflammatory from later degenerative phases.