Evaluation of the possibility to assess bone age on the basis of DXA derived hand scans-preliminary results.

The classical method of skeletal age assessment is based on the recognition of changes in the radiographic appearance of the maturity indicators in hand-wrist radiographs by comparison with a reference atlas. The purpose of this study was the evaluation of the possibility to assess bone age using a less invasive method such as dual-energy X-ray absorptiometry (DXA). Bone ages of 50 children free of any chronic diseases (5-18 years old) and ten with multihormonal pituitary deficiency (MPD) (8-20 years old) were assessed using an Expert-XL densitometer. Hand scans and classical hand-wrist radiographs were evaluated by two independent observers for bone age by visual comparison with reference standards of skeletal development published in the atlas. The precision errors of duplicate bone age ratings were low both for radiographs (<1%) and DXA hand scans (<0.9%). A high degree of agreement between bone age ratings done by two observers was assessed by intraclass correlation coefficients. The same bone age based on radiographs and DXA hand scans was assessed in 44 of 60 cases (73.3%); in 16 cases the differences between bone age were no higher than 0.5 year. No significant difference between mean bone age based on radiographs and DXA hand scans was observed ( P>0.05). Moreover, there was a very strong correlation between bone age results ( r=0.998; r(2)=0.996; P<0.0001), indicating agreement of bone age assessments based on DXA and radiographic images. Remarkable differences (up to 3 years) between bone age and chronological age were observed in healthy subjects, probably reflecting the effect of the secular trend towards earlier maturation or alterations in pubertal development. The study indicates that evaluation of skeletal maturity using DXA images is less invasive (up to 8 micro Sv) than radiography, giving results comparable to the classical method.