Quantitative Ultrasound for Bedside Fracture Risk Assessment
Part II
Clinical Evidence, Appropriate Use, and Implementation in Mobility-Limited Populations
Access to bone health assessment has become increasingly limited for frail, non‑ambulatory, and institutionalized patients. While DXA remains the reference standard for bone mineral density measurement, the absence of commercially available portable DXA systems has created a significant care gap.
Quantitative Ultrasound (QUS) provides a validated, non‑ionizing method for fracture‑risk assessment that can be performed at the bedside. Multiple large studies demonstrate that QUS predicts fracture risk independently of DXA BMD and established clinical risk factors, indicating that it captures aspects of skeletal integrity not fully reflected by mineral density alone.
This paper outlines the scientific basis, clinical role, limitations, and operational implementation of AIS’s bedside QUS program.
1. Clinical Background
Osteoporosis management has historically centered on DXA‑derived BMD thresholds. While BMD is an important risk factor, it is now well established that:
A substantial proportion of fragility fractures occur in individuals with osteopenia or even normal BMD
Fracture risk reflects cumulative skeletal and non‑skeletal factors
This recognition has driven interest in technologies that provide fracture‑risk information beyond mineral density alone.
2. Technology Overview
2.1 DXA
DXA measures areal BMD at axial sites (hip and spine) using ionizing radiation. It remains the reference for formal osteoporosis diagnosis and many treatment algorithms.
2.2 Quantitative Ultrasound
QUS evaluates bone by measuring ultrasound propagation through peripheral skeletal sites. Reported parameters (e.g., SOS) relate to bone density, structure, and elasticity.
Key attributes:
Non‑ionizing
Portable
Peripheral site assessment
3. Evidence Review
3.1 Fracture Prediction
Prospective studies demonstrate that QUS measurements predict incident fractures independently of DXA BMD and clinical risk factors. This independence suggests QUS captures skeletal properties distinct from mineral density.
3.2 Discriminatory Performance
Peripheral QUS measurements (e.g., distal radius SOS) have shown good discriminatory ability between fracture and non‑fracture populations, with reported AUC values approaching 0.8 in some studies.
3.3 Correlation With DXA
QUS and DXA measurements are correlated but not interchangeable. This is expected given the different physical properties assessed. QUS is best interpreted as complementary, not equivalent, to DXA.
3.4 Longitudinal Considerations
Longitudinal data show that QUS metrics can change over time and may reflect clinically relevant trends, including differences observed in patients receiving anti‑resorptive therapy. While not a universal monitoring standard, QUS may support longitudinal assessment in defined clinical protocols.
4. AIS Bedside QUS Program
AIS performs peripheral QUS measurements at the distal radius using a standardized acquisition protocol. Each study includes:
Quality‑controlled acquisition
Comparison to validated normative databases
Radiologist interpretation
Structured report delivery
Sample reports demonstrate how results are communicated in a clinically interpretable format.
5. Appropriate Use and Limitations
Appropriate Uses
Fracture‑risk stratification when DXA is unavailable
Screening in mobility‑limited populations
Informing care planning, fall‑risk mitigation, and referral decisions
Limitations
Peripheral measurement (not axial hip/spine)
Not a substitute for DXA‑based diagnosis in all clinical scenarios
Results must be interpreted in clinical context
6. Coverage and Policy Context
Medicare covers bone mass measurement services for qualifying beneficiaries. CMS guidance recognizes ultrasound bone density as part of this category.
Coverage and Access
Medicare covers bone mass measurements for qualifying patients. CMS guidance includes ultrasound bone density and QUS within the broader category of bone mass measurement services.
However, coverage does not always equal payment.
For Medicare Advantage plans, on-site services may be available subject to payer‑specific rules, plan design, supplier enrollment, and documentation requirements to include preauthorization.
For Medicare enrollees, Medicare does not provide a pathway to gain access for Portable Diagnostic Providers to transport or bill the QUS bone density exam at this time.
When a service is ordered that is not covered by Original Medicare, the patient must sign the Advance Beneficiary Notice of Noncoverage (ABN), Form CMS-R-131.
AIS works with ordering providers and patients to determine the most appropriate and compliant pathway for each situation.
7. Conclusion
QUS is not new technology, but its relevance has increased as bedside DXA access has disappeared. For patients who cannot safely travel, QUS offers a clinically supported, operationally feasible method to assess fracture risk and skeletal health.
When used appropriately and interpreted within its known limitations, bedside QUS represents a responsible, evidence‑based extension of bone health assessment into populations that would otherwise go unserved.
Prepared by Advanced Imaging Services (AIS). This document is educational in nature and does not constitute medical advice or billing guidance.
