Feasibility of bone density evaluation using plain digital radiography

Area of Science:

• Radiology
• Osteoarthritis Research
• Biomedical Imaging

Background:

• Subchondral bone changes, specifically sclerosis, are key indicators in osteoarthritis (OA) radiographic evaluation.
• Current bone density (BD) assessment in OA often relies on subjective interpretation of plain digital radiographs.
• Acquisition and post-processing (PP) settings can influence the accuracy of BD measurements from digital radiographs.

Purpose of the Study:

• To investigate the impact of digital radiography acquisition and post-processing settings on bone density (BD) measurement.
• To determine if accurate BD measurements are achievable for evaluating subchondral bone changes in osteoarthritis (OA).

Main Methods:

• A hydroxyapatite bone density standard (BDS) simulating BD range of 1.0-5.75 g/cm² was used.
• Digital radiographs were acquired with varied settings and subjected to clinical and minimal post-processing (PP).
• An aluminum step wedge normalized gray values to mm aluminum equivalents (mmAl) for BD assessment.

Main Results:

• Minimal PP improved the correlation between actual BD and normalized BD (R²=0.98) compared to clinical PP (R²=0.96).
• Increased kilovoltage (kV) further enhanced the correlation.
• Despite clinical PP, the average standard deviation (SD) was 0.97 mmAl, smaller than the clinically observed change in early OA (2.51 mmAl), indicating feasibility.

Conclusions:

• Post-processing and acquisition settings critically affect radiographic bone density measurement outcomes.
• Accurate bone density measurement using plain digital radiography is feasible when settings are carefully controlled.