Auricular dimensions in computed-tomography: Unveiling the relationship between ear dimensions, age, and sex using three-dimensional volume rendering reconstructions.

Background: The auricle, or auricula, defines the visible boundaries of the external ear and is essential in forensic investigations, including facial reconstruction and human remains identification. Beyond its forensic significance, auricular morphology attracts interest from various fields, such as medicine and industry. The size of the ears is culturally associated with health and longevity, while surgical techniques for ear reconstruction address both congenital and aesthetic concerns.

Aim: To determine whether known correlations with various measurements and observations regarding sex and age could also be established through computed tomography (CT).

Methods: Computed tomography scans of the head from 342 females and 329 males aged 18 to 97 years (mean = 60 ± 19 years) were included in this study. Different auricular lengths, widths and perimeters were measured for both sides. Additionally, the preauricular area was assessed using three-dimensional volume rendering technique images.

Results: The measured auricular dimensions in centimeters are presented as mean values (right/left) for males (length 1 6.91 ± 0.51/6.93 ± 0.52; length 2 2.83 ± 0.35/2.84 ± 0.34; width 1 3.94 ± 0.32/4.01 ± 0.36; width 2 3.51 ± 0.34/3.46 ± 0.31; perimeter 17.66 ± 1.25/17.71 ± 1.28) and females (length 1 6.44 ± 0.5/6.48 ± 0.51; length 2 2.7 ± 0.32/2.71 ± 0.33; width 1 3.6 ± 0.32/3.68 ± 0.31; width 2 3.3 ± 0.3/3.26 ± 0.27; perimeter 16.36 ± 1.2/16.46 ± 1.2). A positive correlation with age was shown in all measurements, with the highest value for perimeter in both, males (-value: right/left: 0.49/0.47) and females (-value: right/left: 0.53/0.53). After confounding factors were excluded, the preauricular vertical line was first seen at 45 years. The mean age for males with preauricular vertical lines was 66.65 ± 10.92 years (95%CI: 63.99-69.3), while without vertical lines, it was 44.48 ± 16.15 years (95%CI: 41.21-47.74); for females, it was 70.18 ± 12.44 years (95%CI: 68.9-71.46) with and 47.87 ± 17.09 years (95%CI: 45.96-49.78) without vertical lines.

Conclusion: In this study, we pioneered the use of CT volumetric data to examine human auricle morphology and we achieved a precise 3D (pre-) auricular assessment. Sex-specific positive correlations between ear dimensions and age, as well as the mean age for the appearance of preauricular lines, were identified, providing valuable insights into the capabilities of modern CT devices.