Standardized measurement of auricle: A method of high-precision and reliability based on 3D scanning and Mimics software

Objective measurement is important for diagnosing congenital or acquired auricular abnormalities and the evaluation of therapeutic efficacy. However, methods applied in the past were mostly inaccurate and unreliable. The present study aimed to introduce five standardized indices for auricle measurement and present a highly precise and reliable methodology combining three-dimensional (3D) scanning techniques and the Materialise Mimics software for the evaluation of auricle sizes. A total of 20 normal ears were measured independently by four surgeons using the standardized digital method with 3D scanning technique and the traditional manual method. Parameters of the auricle, including the length and width, arc length, cranioauricular height and angle were measured using the Mimics software. Paired t-test, Wilcoxon signed rank test and intra-class correlation coefficients (ICC) were performed on the data to assess the precision, uniformity and observer independence of the method. Pearson's product moment correlation was calculated to assess the correlation between auricle length and width in addition to the correlation between cranioauricular height and angle. No significant differences were indicated between measurements of five auricular parameters made by two surgeons using the digital method. However, significant differences were found using the manual method (P<0.01). ICC values derived from digital measurements ranged from 0.901 to 0.987, whereas those derived from manual measurements ranged from 0.526 to 0.807. These results suggested that the standardized digital method was replicable and reliable compared with the traditional manual method. Pearson's coefficient analysis showed that there was a significant correlation between cranioauricular height and angle (P<0.05), but no correlations were found between the height and width of the auricle (P>0.05). Taken together, data from the present study suggested that measurements of the length and width, arch length, and cranioauricular height and angle of auricles using the standardized digital method combining 3D scanning with the Mimics software were comprehensive, precise, convenient, repeatable and reliable.