The Intra-rater reliability and validity of ultrasonography in the evaluation of hypertrophic scars caused by burns.

PURPOSE

Hypertrophic scars that occur after burns are less flexible and less elastic than normal skin. Objective measurement tools are required to assess hypertrophic scars after thermal injury. Cutometer® MPA 580 has been widely used for evaluating the properties of hypertrophic scars. Ultrasonography can evaluate elasticity, stiffness, and structure of tissues simultaneously using elastography and B-mode. This study aimed to investigate the intra-rater reliability and validity of elastography to visualize hypertrophic scars.

METHODS

Sixteen participants with a total of 96 scars were evaluated. The measurement sequence was elastography, Cutometer®, and elastography every 10 min. We then analyzed the intra-rater reliability using intraclass correlation coefficients (ICC). The results measured using elastography on the hypertrophic scars and surrounding normal skin were compared. The relationships between the elastographic and Cutometer® measurements using the 2-and 8-mm probes were compared.

RESULTS

The intra-rater reliability of elastographic measurements was acceptable for clinical use in terms of strain ratio (SR), shear-wave elastography (SWE), shear-wave speed (SWS), and SWE ratio ( ICC = 0.913, ICC=0.933, ICC = 0.842, and ICC = 0.921). The average SWS and SWE in hypertrophic scars were significantly greater than that for normal skin ( p < 0.001 and p < 0.001). SWE showed correlations with the R0 (r = -0.32, p = 0.002) and R8 (r = -0.30, p = 0.003) measured with the 8-mm probe. The SWE ratio was correlated with the R7 (r = -0.34, p = 0.001) measured with the 2-mm probe. The thickness of hypertrophic scars showed correlations with the R5 (r = 0.33, p < 0.001), R6 (r = 0.44, p < 0.001) and R8 (r = -0.35, p < 0.001) measured with the 8-mm probe. R0-R9 measured with 2-mm Cutometer® probes were not correlated with scar thickness ( r < 0.30, P > 0.05). The total scores of mVSS showed correlations with the R0 (r = 0.35, p < 0.001), R1(r = 0.32., p = 0.001), R3 (r = 0.38, p < 0.001), R4 (r = 0.38, p < 0.001), R8 (r = 0.34, p = 0.001), and R9 (r = 0.34, p = 0.001) measured with the 2-mm probe. R0-R9 measured with 8-mm Cutometer® probes were not correlated with mVSS ( r < 0.30, P > 0.05). The thickness of hypertrophic scars showed correlations with the SWE (r = 0.38, p < 0.001) and SWE ratio (r = 0.35, p < 0.001). Elastographic findings were not correlated with mVSS ( r < 0.30, P > 0.05).

CONCLUSION

In this study, together with the Cutometer®, ultrasound was confirmed as an evaluation tool that can objectively compare and analyze the difference between normal skin and hypertrophic scars.