Precision of dual X-ray absorptiometry and peripheral computed tomography using mobile densitometry units

Area of Science:

• Medical Imaging
• Bone Densitometry
• Epidemiology

Background:

• Comparing bone mass data across different centers is challenging due to significant interunit variation in noninvasive measurement methods.
• Standardization of bone densitometry is crucial for large-scale epidemiologic studies and clinical trials.

Purpose of the Study:

• To evaluate the effectiveness of mobile densitometry units in reducing interunit variability for bone mass determination.
• To assess the precision and stability of mobile dual X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) scanners.

Main Methods:

• Two mobile densitometry units were deployed across Germany, one equipped with DXA (QDR 1000 Hologic) and the other with pQCT (XCT 900 Stratec).
• In vitro precision was assessed using hydroxyapatite phantoms.
• In vivo reproducibility was evaluated through duplicate measurements on 48 patients at the lumbar spine and hip.

Main Results:

• Long-term in vitro precision for DXA instruments was 0.41% and 0.59% for bone mineral density (BMD), with minimal machine drift.
• Short-term in vivo reproducibility showed coefficients of variation of 1.02% for spinal BMD and 1.72% for femoral neck BMD.
• Long-term in vitro precision for the pQCT scanner was 0.9%.

Conclusions:

• Mobile densitometry units achieve precision and stability comparable to stationary equipment.
• Mobile densitometry is a viable tool for epidemiologic surveys, clinical trials, and routine bone mass evaluation in remote areas.