Measurement of healing area using planimetry after applying low intensity ultrasound to the skin of rats

Background: Planimetry is a method used to evaluate the progression of skin wound healing. Computerized planimetry is still an experimental method, but its advantages have been demonstrated in several investigations. Objective: To evaluate the effects of lowintensity pulsed ultrasound on the healing of a skin lesion produced on the dorsal region of rats, by means of computerized planimetry. Methods: Sixty male Wistar rats of mean weight 300g were used. They were divided into two groups according to the treatment applied: 1) simulated irradiation (control); 2) effective irradiation (fundamental frequency 1.5MHz, pulse repetition frequency 1KHz, pulse width 200μs, SATA intensity 30mW/cm2 and application for ten minutes on alternate days). Each group was divided into three subgroups according to the length of time for which ultrasound irradiation was applied of three, seven and 14 days, respectively, and healing was evaluated by means of planimetry; a tracing of the wound was obtained on special paper and this was digitized and measured by means of a graphing software. Statistical analysis was performed using the Mann-Whitney non-parametric method. Results: The healed area was signifi cantly greater (p<0.05) in group 2 (141.88±18.50mm2) than in group 1 (117.38±15.14mm2) on the 14th day. There were no signifi cant differences between the subgroups for the other experimental periods. Conclusions: Low-intensity pulsed ultrasound irradiation stimulated secondary skin healing under these experimental conditions. Computerized planimetry was shown to be a low cost method that was easy to use and present clinical applicability.