(545 days)
The CTXA Hip Bone Mineral Densitometer is intended to estimate bone mineral content (BMC) and bone mineral density (BMD) in the proximal femur. The BMD estimates can be compared with CTXA Hip-derived reference data. T-scores are calculated with respect to CTXA Hip young normal female reference data, and the T-scores can be used by the physician as an aid in determining fracture risk.
The CTXA Hip Bone Mineral Densitometer (CTXA Hip) is a software package intended for estimation of bone mineral content (BMC), in grams, and bone mineral density (BMD), in glem', of the proximal femur. The CTXA Hip uses quantitative computed tomography (QCT) methods to derive bone mass and bone density estimates from 3D CT image data sets. The CTXA Hip is intended to be used with compatible, whole-body CT scanners and with compatible CT calibration phantoms. BMD estimates are derived in units of g/cm2 equivalent K2HPO4 density.
Here's a breakdown of the acceptance criteria and study details for the CTXA Hip Bone Mineral Densitometer, based on the provided 510(k) summary:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| In vitro precision | Not explicitly stated, but expected to be low for accuracy | Approximately 0.007 g/cm² |
| In vitro bias | Unbiased when expressed as equivalent K2HPO4 density | Unbiased |
| In vivo precision (Total Hip) | Not explicitly stated, but expected to be low for clinical reliability | 0.011 g/cm² |
| In vivo precision (Femoral Neck) | Not explicitly stated, but expected to be low for clinical reliability | 0.012 g/cm² |
| Correlation with predicate DXA devices (Total Hip) | Not explicitly stated, but expected to demonstrate strong correlation (e.g., R > 0.85-0.90) | 0.90-0.97 (Pearson's R) |
| Correlation with predicate DXA devices (Femoral Neck) | Not explicitly stated, but expected to demonstrate strong correlation (e.g., R > 0.85-0.90) | 0.88-0.95 (Pearson's R) |
Note: The 510(k) summary does not explicitly state numerical acceptance criteria for many of these metrics. Instead, it reports the device performance and implicitly suggests these values are acceptable by concluding substantial equivalence to predicate devices.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set: Not explicitly stated. The summary mentions "clinical studies" for both in vivo precision and correlation with predicate devices, and "a clinical study" for collecting reference data. No specific numbers are provided for patient cohorts in these studies.
- Data Provenance:
- In vitro phantom studies: Location not specified, but likely laboratory-based.
- Clinical studies (in vivo precision & correlation): Not explicitly stated, but the reference data collection mentions "young normal US Caucasian females," implying US origin for at least that part of the clinical data.
- Retrospective or Prospective: Not explicitly stated for any of the clinical studies.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications of Those Experts
This information is not provided in the summary. The studies described are focused on device precision and correlation with other devices, not on diagnostic accuracy against a human-established ground truth in a direct sense.
4. Adjudication Method for the Test Set
This information is not provided in the summary. Given the nature of the device (automated bone mineral density estimation), direct human adjudication of results in the traditional sense (e.g., consensus on image interpretation) is not applicable in the same way it would be for a diagnostic AI device. The comparison is against established device outputs (DXA) or precision metrics.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not reported. The device is a "standalone" algorithm for quantitative measurement, not an AI-assisted diagnostic tool for human readers.
- Effect size of human readers improve with AI vs without AI assistance: Not applicable, as no MRMC study was performed with human readers.
6. If a Standalone Study Was Done
Yes, standalone performance was assessed. The entire submission describes the performance of the CTXA Hip software itself (an algorithm) in various scenarios:
- In vitro phantom studies: Assessed precision and bias independently.
- Clinical studies for in vivo precision: Assessed the device's consistency over time when applied to human subjects.
- Clinical studies comparing BMD results with predicate DXA devices: Evaluated the device's output against established measurement systems.
7. The Type of Ground Truth Used
- For in vitro phantom studies: The ground truth was based on the known physical properties and densities of the phantoms used, expressed as equivalent K2HPO4 mineral density.
- For in vivo precision studies: The "ground truth" was the device's own consistent measurement of BMD in the same individuals over time, aiming for low variability.
- For correlation studies with predicate devices: The "ground truth" was the BMD measurements obtained from the predicate DXA devices (Hologic QDR 1000 and QDR 4500), which are established methods for bone densitometry.
8. The Sample Size for the Training Set
This information is not provided in the summary. The CTXA Hip is described as a software package using QCT methods to derive estimates, but the details of any machine learning or specific algorithm training are not discussed. It's likely based on established QCT principles rather than a distinct "training set" in the modern AI sense.
9. How the Ground Truth for the Training Set Was Established
Since a "training set" in the typical machine learning sense is not explicitly mentioned and the device appears to be based on established QCT principles rather than being a trained AI model, the method for establishing "ground truth for the training set" is not applicable/provided. The summary focuses on validation of the methodology and its output against existing standards.
§ 892.1170 Bone densitometer.
(a)
Identification. A bone densitometer is a device intended for medical purposes to measure bone density and mineral content by x-ray or gamma ray transmission measurements through the bone and adjacent tissues. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories.(b)
Classification. Class II.