Bone Abstracts

Background: Skeletal maturation is the most reliable indicator of biological age in children and adolescents. The evaluation of hand and wrist X-Ray according to Tanner-Whitehouse (TW3) or Greulich-Pyle (GP) are the most commonly used methods for biological age assessment. Automated bone age assessment has recently become increasingly popular, however a large independent study comparing automated and manual evaluation of bone age is still missing. The aim of this study was to assess the differences between automated and manual evaluation of bone age using TW3 and GP method.

Methods: In this cross-sectional study we evaluated bone age scans using TW3 and GP methods in 1285 children and adolescents (659 boys, range 5.0–15.9 years, median 10.3, IQR 4.9 years) with various endocrine conditions in parallel manually and using BoneXpert software (version 2.4.5.1). Root mean square errors (RMSE) were calculated for the whole group and for sex-specific one-year age categories (girls 5–15 years, boys 5–16 years, over 50 children in each category).

Results: In total RMSE were 0.61 years and 0.58 years in boys and 0.79 years and 0.60 years in girls, respectively for TW3 and GP. Sex- and age-specific analysis showed the greatest differences between manual and automated TW3 evaluation in girls between 6–7, 12–13 and 13–14 years with RMSE 0.90, 0.90 and 1.05 years, respectively. Manual and automated evaluation differed by more than 1 year in 9.7% and 7.0% boys and 18.2% and 8.6% girls, respectively for TW3 and GP. In more detailed analysis of the TW3 method RMSE showed improvement (RMSE for boys 0.54; for girls 0.71), after the exclusion of X-Rays where stages for radius and ulna assigned by BoneXpert significantly differed from the definition set by Tanner and Whitehouse.

Conclusion: Automated bone age assessment provides sufficient agreement with manual evaluation in most scans of children with common endocrine disorders. Bone age assessment provided by BoneXpert tends to be underestimated, especially in girls during puberty using TW3 method. The greatest emphasis in the TW3 method is put on the radius and ulna evaluation, differences in assigned stages can therefore be a source of discrepancies between manual and automated rating.

Disclosure: The authors declared no competing interests.