title: Application of contrast-enhanced sonography with time-intensity curve analysis to explore hypervascularity in Achilles tendinopathy by using a rabbit model.
abstract: OBJECTIVE
  The purpose of this study was to investigate the ability of contrast-enhanced 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-contrast-enhanced 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.
authors.affiliation: Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Ke-Vin
authors.initials: KV
authors.lastname: Chang
authors.forename: Chueh-Hung
authors.initials: CH
authors.lastname: Wu
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Ding
authors.forename: Hsiu-Yu
authors.initials: HY
authors.lastname: Shen
authors.forename: Tyng-Guey
authors.initials: TG
authors.lastname: Wang
authors.forename: Wen-Shiang
authors.initials: WS
authors.lastname: Chen
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging*; D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging*; D010743:Phospholipids; D010865:Pilot Projects; D011817:Rabbits; D012044:Regression Analysis; D013459:Sulfur Hexafluoride; D052256:Tendinopathy / Q000000981:diagnostic imaging*; D013997:Time Factors; D018608:Ultrasonography, Doppler
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride