Power Doppler assessment of vascular changes during fracture treatment with low-intensity ultrasound

Objective. To study the use of power Doppler sonography for assessing changes in vascularity during treatment of fracture sites with low-intensity ultrasound. Methods. In 6 dogs (3 pairs), subcutaneous dissection of the midshaft of the ulna allowed symmetrical osteotomies to be made with a reciprocation saw. Three dogs were treated and 3 were used as controls. The fracture site was subjected to 1.5-MHz low-intensity ultrasound (30 mW/cm(2)) for 20 minutes daily from a therapeutic ultrasonic device. Gray scale sonography was performed to evaluate the fracture site. Power Doppler sonography was used to assess flow patterns at the fracture site and surrounding soft tissue. A sonographic contrast agent was administered intravenously. The dose was 0.2 mL/kg. Results. Power Doppler sonography showed an increase in flow around the fracture site in the treated dogs compared with that in control dogs. Color pixel values on day 7 were 3-fold higher in treated legs than control legs and on day 11 were 33% higher in treated legs than control legs. Enhancement after contrast agent administration was consistently higher in treated legs than control legs. Conclusions. Power Doppler sonography showed increased vascularity around the fracture sites in treated dogs with and without contrast agent administration.