Quantification of bone volume on radiographs using NIH Image.

Area of Science:

• Radiology
• Orthopedics
• Rheumatology

Background:

• Rheumatoid arthritis (RA) is a chronic inflammatory disease that can lead to bone loss.
• Quantifying periarticular bone atrophy in RA patients is crucial for monitoring disease progression and treatment efficacy.
• Existing methods for assessing bone atrophy may lack precision or accessibility.

Purpose of the Study:

• To quantify periarticular bone atrophy in the proximal phalanx of rheumatoid arthritis (RA) patients.
• To evaluate the utility of the National Institutes of Health (NIH) Image computer program for this quantification.
• To establish a reliable index for bone volume assessment in RA.

Main Methods:

• Utilized the NIH Image computer program to analyze radiographs of the proximal phalanx.
• Measured the brightness/darkness index (BDI) in 20x20 pixel squares within the bone.
• Defined BDI as a measure of bone volume, with 0 representing complete darkness and 255 maximum brightness.

Main Results:

• The mean BDI was significantly lower in RA patients (100 at diaphysis midpoint, 75 at proximal end) compared to normal volunteers (176 and 145, respectively).
• The difference in BDI was most pronounced in younger individuals.
• Low BDI values at the proximal end clearly indicated periarticular bone atrophy in some young RA patients.

Conclusions:

• Periarticular bone atrophy in RA patients can be reliably quantified using the NIH Image computer program.
• The brightness/darkness index (BDI) serves as an effective measure of bone volume in RA.
• This quantitative approach offers a valuable tool for assessing bone changes in rheumatoid arthritis.