What is the accuracy of Radiographic (REM) (Radiographic Evaluation of Bone Mineralization) bone densitometry?

Accuracy of REMS Bone Densitometry

REMS (Radiofrequency Echographic Multi Spectrometry) bone densitometry demonstrates high diagnostic accuracy comparable to DXA, with sensitivity of 90-91% and specificity of 95% for detecting osteoporosis, but is not yet recognized as the gold standard in clinical guidelines. 1, 2

Comparison with Gold Standard DXA

DXA (Dual-Energy X-ray Absorptiometry) remains the established gold standard for bone mineral density (BMD) measurement and osteoporosis diagnosis according to multiple guidelines 3, 4:

• DXA has been clinically validated to accurately predict fracture risk
• DXA measurements are the basis for WHO diagnostic criteria for osteoporosis (T-scores)
• DXA is recommended as the first-line screening and follow-up test for bone density

REMS Technology Performance

Recent multicenter European studies show REMS technology compares favorably to DXA:

• Diagnostic agreement between REMS and DXA shows sensitivity of 90.4-90.9% and specificity of 95.1-95.5% 2
• Average difference in BMD measurements between REMS and DXA:
  • Lumbar spine: -0.026±0.179 g/cm²
  • Femoral neck: -0.027±0.156 g/cm² 5
• REMS precision (coefficient of variation):
  • Intra-operator: 0.51% (lumbar spine), 1.08% (femoral neck)
  • Inter-operator: 1.43% (lumbar spine), 1.93% (femoral neck) 5

Advantages of REMS Technology

REMS offers several potential benefits over traditional densitometry methods:

• Non-ionizing technology (ultrasound-based) making it suitable for:
  • Children
  • Women of childbearing age
  • Pregnant women
  • Patients requiring frequent monitoring 1
• Potentially better fracture discrimination ability:
  • ROC curve analysis for identifying patients with previous fractures showed AUC of 0.683 for REMS vs. 0.631 for DXA at femoral neck 2
• Transportable equipment increasing accessibility 1
• Potential for qualitative bone assessment beyond just density measurements 1

Clinical Implementation Considerations

Despite promising accuracy data, several important considerations apply when evaluating REMS for clinical use:

1. Precision assessment is critical: Like DXA, REMS requires facility-specific precision studies to determine the least significant change (LSC) for monitoring 3, 6

2. Quality control matters: Both DXA and REMS require proper quality control procedures to ensure accurate results 3

3. Diagnostic criteria standardization: WHO diagnostic criteria (T-scores) were developed specifically for DXA, and their direct application to REMS requires further validation 3

4. Current guideline status: Major guidelines from organizations like the American College of Radiology still recommend DXA as the primary method for BMD assessment 3, 4

Practical Implications

For clinicians considering REMS technology:

• REMS appears to be a promising alternative for populations without access to DXA 5
• REMS may be particularly valuable for monitoring patients who cannot or should not undergo repeated radiation exposure 1
• When implementing REMS, facilities should establish their own precision values rather than relying on manufacturer specifications 3, 6
• For diagnostic purposes, the high concordance with DXA suggests REMS could be used in settings where DXA is unavailable, but diagnostic thresholds may need adjustment

In summary, while REMS shows excellent diagnostic agreement with DXA and offers radiation-free advantages, current clinical guidelines still position DXA as the reference standard for bone densitometry. REMS represents an emerging technology with promising accuracy that may become increasingly important in specific clinical scenarios.