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Thodberg H.H.,Visiana | Jenni O.G.,University of Zürich | Martin D.D.,University of Tübingen
International Journal of Legal Medicine | Year: 2016

The BoneXpert method for automated determination of bone age from hand X-rays was introduced in 2009, covering the Greulich–Pyle bone age ranges up to 17 years for boys and 15 years for girls. This paper presents an extension of the method up to bone age 19 years for boys and 18 years for girls. The extension was developed based on images from the First Zurich Longitudinal Study of 231 healthy children born in 1954–1956 and followed with annual X-rays of both hands until adulthood. The method was validated on two cross-sectional studies of healthy children from Rotterdam and Los Angeles. We found root mean square deviations from manual rating of 0.69 and 0.45 years in these two studies for boys in the bone age range 17–19 years. For girls, the deviations were 0.75 and 0.59 years, respectively, in the bone age range 15–18 years. It is shown how the automated bone age method can be applied to infer the age probability distribution for healthy Caucasian European males. Considering a population with age 15.0–21.0 years, the method can be used to decide whether the subject is above 18 years with a false positive rate (children classified as adults) of 10 % (95% confidence interval = 7–13%) and a false negative rate of 30 % (adults classified as children). To apply this method in other ethnicities will require a study of the average of “bone age − age” at the end of puberty, i.e. how much this population is shifted relative to the Greulich–Pyle standard. © 2016 Springer-Verlag Berlin Heidelberg


PubMed | Visiana, Institute of Diagnostic and Interventional Radiology and Friedrich - Schiller University of Jena
Type: Journal Article | Journal: BMC musculoskeletal disorders | Year: 2017

The Digital X-ray Radiogrammetry (DXR) method measures the cortical bone thickness in the shafts of the metacarpals and has demonstrated its relevance in the assessment of hand bone loss caused by rheumatoid arthritis (RA). The aim of this study was to validate a novel approach of the DXR method in comparison with the original version considering patients with RA.The study includes 49 patients with verified RA. The new version is an extension of the BoneXpert method commonly used in pediatrics which has these characteristics: (1) It introduces a new technique to analyze the images which automatically validates the results for most images, and (2) it defines the measurement region relative to the ends of the metacarpals. The BoneXpert method measures the Metacarpal Index (MCI) at the metacarpal bone (II to IV). Additionally, the MCI is quantified by the DXR X-posure System.The new version correctly analyzed all 49 images, and 45 were automatically validated. The standard deviation between the MCI results of the two versions was 2.9% of the mean MCI. The average Larsen score was 2.6 with a standard deviation of 1.3. The correlation of MCI to Larsen score was -0.81 in both versions, and there was no significant difference in their ability to detect erosions.The new DXR version (BoneXpert) validated 92% of the cases automatically, while the same good correlation to RA severity could be presented compared to the old version.


PubMed | Visiana, Friedrich - Schiller University of Jena and Copenhagen University
Type: | Journal: Archives of osteoporosis | Year: 2016

Digital X-ray radiogrammetry performs measurements on a hand radiograph in digital form. We present an improved implementation of the method and provide reference curves for four indices for the amount of bone. We collected 1662 hand radiographs of healthy subjects of age 9-100years.The digital X-ray radiogrammetry (DXR) method has been shown to be efficient for diagnosis of osteoporosis and for assessment of progression of rheumatoid arthritis. The aim of this work is to present a new DXR implementation and reference curves of four indices of cortical bone and to compare their relative SDs in healthy subjects at fixed age and gender.A total of 1662 hand radiographs of healthy subjects of age 9-100years were collected in Jena in 2001-2005. We also used a longitudinal study of 116 Danish children born in 1952 with on average 11 images taken over the age range 7 to 40years. The new DXR method reconstructs the whole metacarpal contour so that the metacarpal lengths can be measured and used in two of the indices. The new DXR method automatically validates 97% of the images and is implemented as a local server for PACS users.The Danish bone health index (BHI) data are consistent with the Jena data and also with the published BHI reference for healthy children. BHI is found to have smaller relative SD than the other three indices in the Jena cohort over the age range 20-80years.The new DXR method is an extension of the existing BoneXpert method for children, which allows patients to be followed from childhood into adulthood with the same method. By making all four indices of cortical bone available within the same medical device, it becomes possible to decide which index has the best relation to fracture risk in future studies.


Thodberg H.H.,Visiana | Savendahl L.,Karolinska Institutet
Academic Radiology | Year: 2010

Rationale and Objectives: Bone age (BA) rating is associated with a considerable rater variability, which would be eliminated with an automated computerized method. The aim of the study was to validate the BoneXpert method, an automated determination of BA, in American children of four ethnicities. Materials and Methods: The study is based on a publicly available database of hand x-rays of healthy children, established in a previous, National Institutes of Health-funded study. Radiographs of the left hand were recorded between 1993 and 2006 in Los Angeles, including 1100 images with two independent manual BA ratings and 280 additional images for which the manual ratings were not used. Images were evenly split between Caucasian, African American, Hispanic, and Asian children, and the age range was 0-18.99 years. Results: The automated method analyzed all images with BA >2.5 years for boys and >2 years for girls. The root-mean-square (RMS) error between the two manual ratings was 0.63 years, whereas the RMS deviation between the automated BA and the average of the two manual ratings was 0.61 years. The mean BA minus age was computed versus age for each sex and ethnicity. The largest deviation from zero was seen for Hispanic and Asian children older than 12 years, who were about 1 year advanced relative to the Greulich and Pyle standard. Conclusion: The automated method can analyze images of all ethnicities within a BA range of 2.5-17 years for boys and 2-15 years for girls, and can therefore eliminate the problem with rater variability in BA rating. © 2010 AUR.


Thodberg H.H.,Visiana | Neuhof J.,University of Tübingen | Ranke M.B.,University of Tübingen | Jenni O.G.,University of Zürich | Martin D.D.,University of Tübingen
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 Tübingen | Neuhof J.,University of Tübingen | Jenni O.G.,University of Zürich | Ranke M.B.,University of Tübingen | 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.


Thodberg H.H.,Visiana | Van Rijn R.R.,Emma Childrens Hospital | Tanaka T.,National Center for Child Health and Development | Martin D.D.,University of Tübingen | 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.


Martin D.D.,University of Tübingen | Schittenhelm J.,University of Tübingen | 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.


Unrath M.,University of Tübingen | Thodberg H.H.,Visiana | Schweizer R.,University of Tübingen | Ranke M.B.,University of Tübingen | And 2 more authors.
Hormone Research in Paediatrics | Year: 2012

Aim: A new method (BX AHP) for adult height prediction (AHP), based on automated bone age (BoneXpert®, here called autBA) assessment, has been developed and validated. The aim of this study was to evaluate the performance of autBA and BX AHP in comparison with manual Greulich-Pyle bone age (manBA) and Bayley-Pinneau AHP (BP AHP) in children with untreated idiopathic short stature (ISS; including familial short stature and constitutional delay of growth and puberty). Materials and Methods: We acquired the adult height of 190 patients (123 boys and 67 girls) with ISS and 448 (303 male and 135 female) X-rays of their left hand. Results: Mean adult height was 168 ± 6 cm for boys and 155 ± 7 cm for girls. The root mean square error of AHP using BP AHP was 6.35 cm for boys and 4.55 cm for girls. BX AHP using autBA achieved 4.71 cm for boys (p = 0.0013) and 3.72 cm for girls (0.04); including parent's height improved its root mean square error to 4.46 cm (0.0001) for boys and 3.35 cm (0.02) for girls. Conclusion: The new AHP model performed significantly better than the BP AHP model. Including parental height further improved the performance of AHP. Copyright © 2013 S. Karger AG, Basel.


PubMed | University of Tübingen and Visiana
Type: Evaluation Studies | Journal: Pediatric radiology | Year: 2016

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.To validate the adult height prediction model on children from another geographical location.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 6years were considered, in total 1,124 images.The root mean square deviation between the predicted and the observed adult height was 2.8cm for boys in the bone age range 6-15years and 3.1cm for girls in the bone age range 6-13years. The bias (the average signed difference) was zero, except for girls below bone age 12, where the predictions were 0.8cm too low.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.

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