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A paediatric bone index derived by automated radiogrammetry
H H Thodberg1, R R van Rijn, T Tanaka
1Visiana, Søllerødvej 57 C, 2840, Holte, Denmark. thodberg@gmail.com
Insights
A new automated method determines the Paediatric Bone Index (PBI) from hand radiographs for children's bone age assessment. This PBI offers high precision (1.42%) and minimal standard deviation (7.5%) for reliable bone mass measurement.
Area of Science:
- Radiology
- Pediatrics
- Biomedical Engineering
Background:
- Routine hand radiographs are used for assessing children's bone age.
- Existing radiogrammetry indices for bone mass have limitations.
- A computerized method for bone mass determination in children is presented.
Purpose of the Study:
- To develop an automated method for determining a Paediatric Bone Index (PBI) from hand radiographs.
- To establish a precise and reliable index for pediatric bone mass assessment.
- To facilitate retrospective research on bone health in children.
Main Methods:
- Inclusion of 1,867 Danish and 531 Dutch children aged 5-19.
- Comparison of historical bone mass indices (metacarpal index, DXR-BMD, Exton-Smith) with novel indices.
- Derivation and validation of the preferred index using longitudinal X-rays from 20 Japanese children.
Main Results:
- The Paediatric Bone Index (PBI), defined as A/(W(1.33) L(0.33)), was identified as the preferred index.
- The PBI demonstrated a minimal relative standard deviation of 7.5%.
- The precision of the PBI measurements was determined to be 1.42%.
Conclusions:
- The automated PBI determination method enhances pediatric bone age assessment.
- The PBI facilitates retrospective studies correlating bone mass with fracture incidence and adult bone density.
- This method supports the BoneXpert system for automated bone age determination.
Summary:
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 = piTW(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.
