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Thodberg H.H.,Visiana | Tanaka T.,National Center for Child Health and Development | Martin D.D.,University of Tubingen | Kreiborg S.,Copenhagen University
Osteoporosis International | Year: 2010

Hand radiographs are obtained routinely to determine bone age of children. This paper presents a method that determines a Paediatric Bone Index automatically from such radiographs. The Paediatric Bone Index is designed to have minimal relative standard deviation (7.5%), and the precision is determined to be 1.42%. Introduction: We present a computerised method to determine bone mass of children based on hand radiographs, including a reference database for normal Caucasian children. Methods: Normal Danish subjects (1,867), of ages 7-17, and 531 normal Dutch subjects of ages 5-19 were included. Historically, three different indices of bone mass have been used in radiogrammetry all based on A = πTW(1- T/W), where T is the cortical thickness and W the bone width. The indices are the metacarpal index A/W 2, DXR-BMD=A/W, and Exton-Smith's index A/(WL), where L is the length of the bone. These indices are compared with new indices of the form A/(W a L b ), and it is argued that the preferred index has minimal SD relative to the mean value at each bone age and sex. Finally, longitudinal series of X-rays of 20 Japanese children are used to derive the precision of the measurements. Results: The preferred index is A/(W 1.33 L 0.33), which is named the Paediatric Bone Index, PBI. It has mean relative SD 7.5% and precision 1.42%. Conclusions: As part of the BoneXpert method for automated bone age determination, our method facilitates retrospective research studies involving validation of the proposed index against fracture incidence and adult bone mineral density. © 2009 International Osteoporosis Foundation and National Osteoporosis Foundation.

Thodberg H.H.,Visiana | Neuhof J.,University of Tubingen | Ranke M.B.,University of Tubingen | Jenni O.G.,University of Zurich | Martin D.D.,University of Tubingen
Hormone Research in Paediatrics | Year: 2010

Aim: Several bone age (BA) methods are in use today. The aim of this study was to introduce a framework for assessing the validity of a BA method by its ability to predict adult height (H) and to apply it to manual ratings based on Greulich-Pyle (GP) and Tanner-Whitehouse 3 (TW) and to the fully automated BoneXpert method. Material: The study used X-rays of 232 children from the First Zurich Longitudinal Study recorded close to each anniversary. Method: For each height measurement (h), we calculated the growth potential (gp), defined as gp = (H - h)/H. The standard deviation of the gp prediction error for children of the same age was taken as a measure of the validity of the BA method and averaged over the age range 10-18 years for boys and 8-16 years for girls to obtain the overall gp prediction error (GPPE). Results: Manual TW yielded GPPE = 1.32% [95% CI 1.28-1.36], and was significantly outperformed by manual GP with GPPE = 1.26% [1.22-1.30]. The automated rating obtained GPPE = 1.23%, and omitting radius and ulna yielded GPPE = 1.22%. Conclusion: Manual GP rating is better than manual TW rating in predicting adult height, and the fully automated method works as well as manual GP rating. © 2010 S. Karger AG.

Martin D.D.,University of Tubingen | Neuhof J.,University of Tubingen | Jenni O.G.,University of Zurich | Ranke M.B.,University of Tubingen | Thodberg H.H.,Visiana
Hormone Research in Paediatrics | Year: 2010

Background/Aims: A more advanced bone age (BA) has been reported for the left hand relative to the right hand, while another study has found no such effect. The aim was to study the average difference of automated BoneXpert BA determination (left- vs. right-hand) for normal children, examine the precision of automatic BA and provide a BA reference for normal Caucasian children. Methods: Radiographs of both hands (age range: 2-20 years) were digitised and analysed automatically to determine Greulich-Pyle BA, producing analysis results for 3,374 left-hand and 2,752 right-hand images. Results: Comparison of left- and right-hand BA showed no average difference (<0.07 years, 95% confidence). The SD of the differences between left and right sides was 0.25 years for boys as well as girls, implying the precision of automated Greulich-Pyle BA determination was 0.18 years or better. Greulich-Pyle BA for boys and girls were on average 0.10 and 0.21 years below the chronological age. Conclusion: The left and right hand give the same BA on average and the SD between the sides is 0.25 years, indicating an excellent precision of the automated method. © 2010 S. Karger AG.

Martin D.D.,University of Tubingen | Schittenhelm J.,University of Tubingen | Thodberg H.H.,Visiana
Pediatric Radiology | Year: 2016

Background: An adult height prediction model based on automated determination of bone age was developed and validated in two studies from Zurich, Switzerland. Varied living conditions and genetic backgrounds might make the model less accurate. Objective: To validate the adult height prediction model on children from another geographical location. Materials and methods: We included 51 boys and 58 girls from the Paris Longitudinal Study of children born 1953 to 1958. Radiographs were obtained once or twice a year in these children from birth to age 18. Bone age was determined using the BoneXpert method. Radiographs in children with bone age greater than 6 years were considered, in total 1,124 images. Results: The root mean square deviation between the predicted and the observed adult height was 2.8 cm for boys in the bone age range 6–15 years and 3.1 cm for girls in the bone age range 6–13 years. The bias (the average signed difference) was zero, except for girls below bone age 12, where the predictions were 0.8 cm too low. Conclusion: The accuracy of the BoneXpert method in terms of root mean square error was as predicted by the model, i.e. in line with what was observed in the Zurich studies. © 2015, Springer-Verlag Berlin Heidelberg.

Thodberg H.H.,Visiana | Jenni O.G.,University Childrens Hospital Zrich | Ranke M.B.,University of Tubingen | Martin D.D.,University of Tubingen
Annals of Human Biology | Year: 2012

Background/aims: The Tanner-Whitehouse (TW) method for bone age determination has been the basis for many population studies and it is used in many clinics. However, TW bone age raters can differ systematically from each other. The aim of the study was to present a new standard version of TW bone age rating implemented by the automated BoneXpert method and calibrated on the manual TW stage ratings of the First Zurich Longitudinal Study.Subjects: Hand radiographs of 231 children born in 19541956 were recorded annually from an average age of 520 years. For validation, 76 X-rays of Tanner's original Gold Series from eight boys were used.Results: The root mean square deviation between manual and automated TW ratings in the Zurich data was 0.67 years for boys in the TW bone age range 515 years and 0.63 years for girls, 514 years. The new standard TW rating differs systematically from two previous TW versions of the automated method, based on different raters.Conclusion: The new automated TW ratings show good accuracy relative to the manual ratings of the Zurich data and the Gold Series. There are significant differences between manual TW raters, an effect which is eliminated with the automated method. © 2012 Informa UK, Ltd.

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