Application of Contrast-Enhanced Sonography With Time-Intensity Curve Analysis to Explore Hypervascularity in Achilles Tendinopathy by Using a Rabbit Model

Abstract

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.

Mechanisms of tendon injury and repair

“…Still others have used full-thickness, partial-width, laceration of the infraspinatus tendon in sheep to induce overstressed and stress-deprived portions of the tendon 13 . Finally, collagenase injection has been used to induce chronic tendon injury in the rat 14 rabbit 15 and sheep 16 models. While all of these models capture important aspects of tendon degeneration and injury, it is important to keep in mind that none captures the complete etiology of the chronic tendon injuries seen in human patients.…”

Chronic Nicotine Exposure Alters Uninjured Tendon Vascularity and Viscoelasticity

“…AT vascularity was assessed with adaptations to previously described methods. 3,11 Briefly, the signal of a 21-MHz ultrasound transducer (MS250, VisualSonics, Toronto, ON), with an axial resolution of 75 mM, was attached to a mount to image AT from the myotendinous junction to calcaneus. Video was recorded at 1 frame per second and contrast gain of 35 dB along the sagittal plane of the entire AT for 10 minutes following a bolus injection of 100 mL of microbubble contrast agent through the tail vein (Definity; Lantheus Medical Imaging, Billerica, MA) to capture the full wash-in and wash-out of the contrast in the tissue.…”

“…Perfusion parameters were then derived from this model, including peak enhancement, rise time, time to peak, wash-in rate, wash-in area under the curve, and wash-in perfusion index as previously described. 3,11…”

Orthopedic Models and Imaging Techniques in Preclinical Researchs

“…Sonoelastografi yöntemi, tendon elastikiyetini izleyebilme yeteneği kanıtlanan ultrason temelli bir tekniktir. Kronik lokal hipervaskülarite, tendinopatiye bağlı ağrıyla ilişkilendirilmiş olup indüklenmiş tendinopatiden sonra gelişen vaskülariteyi derecelendirmede kontrastı artırılmış sonografinin etkili olduğu kanıtlanmıştır (65,66).…”