(140 days)
The intended use of the CTXA Hip Extence Data accessory for the CTXA Hip Bone Mineral Densitometry module is to provide a context for the clinical interpretation of a patient's proximal femur BMD estimates. T-scores are calculated relative to a US normal female Caucasian reference population age 20-39 years, and Z-scores are calculated relative to a US normal female Caucasian reference population age 20-79 years. The use of a reference data set and the interpretation of parameters derived by the CTXA Hip module when comparing patient-specific BMD estimates to the installed and selected reference data set is at the discretion of the physician.
The CTXA Hip Extenced Reference Data is an accessory to the CTXA Hip Bone Mineral Densitometer. The CTXA Hip Extended Reference Data is used within the CTXA Hip module to calculate T-scores and percent young normal for any patient, and Z-scores for patients age 20-80 for BMD estimates made using the CTXA Hip module.
The provided text describes a 510(k) premarket notification for the "CTXA Hip Extended Reference Data" device, which is an accessory to the CTXA Hip Bone Mineral Densitometer. The purpose of this accessory is to provide a broader reference dataset for calculating T-scores and Z-scores for Bone Mineral Density (BMD) estimates from the CTXA Hip module.
1. A table of acceptance criteria and the reported device performance:
| Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|
| Premarket Equivalence to Predicate Device: The device must demonstrate substantial equivalence to the legally marketed predicate device (K002113: CTXA Hip Bone Mineral Densitometer) in terms of safety and effectiveness, despite the expanded reference data. | The CTXA Hip Extended Reference Data is intended to be an accessory to the CTXA Hip Bone Mineral Densitometer. The submission explicitly states: "The CTXA Hip Extended Reference Data is substantially equivalent to the listed predicate device." |
| Accuracy of BMD Estimates: BMD estimates obtained with the accessory should be consistent with those from the predicate device. | "BMD estimates obtained with CTXA Hip with Extended Reference Data accessory are identical to BMD estimates obtained with the predicate CTXA Hip." |
| Clinical Significance of T-score Differences: Any differences in calculated T-scores due to the expanded reference data should not be clinically significant. | "T-scores calculated with CTXA Hip with Extended Reference Data accessory are slightly less negative than those calculated with CTXA Hip, approximately 0.1-0.2 Tscore units. This difference is not significant clinically." |
| Clinical Interpretation: The clinical interpretation of BMD estimates made with the accessory should be comparable to that of the predicate device. | "The clinical interpretation of BMD estimates made with CTXA Hip Extence Data is comparable to that associated with the predicate device." |
| Expanded Z-score Range: The device must successfully calculate Z-scores for a broader age range (20-80 years) compared to the predicate (20-39 years). | The device description and intended use clearly indicate this expanded capability: "The current CTXA Hip Extence Data is an accessory to CTXA Hip that also is used to calculate T-scores and percent young normal, and also is used to calculate Z-scores for ages 20-80." And in Indications for Use: "Z-scores are calculated relative to a US normal female Caucasian reference population age 20-79 years." |
2. Sample size used for the test set and the data provenance:
The document does not explicitly state a specific sample size used for a test set in the context of a validation study for the "CTXA Hip Extended Reference Data" accessory itself.
Instead, the substantiation for substantial equivalence appears to rely on:
- Logical deduction: BMD estimates are "identical" to the predicate, implying the core measurement accuracy is unchanged.
- Quantification of T-score differences: A "0.1-0.2 T-score unit" difference, which is then deemed "not significant clinically."
- Reference Population: The reference data set used for T-scores and Z-scores is described as a "US normal female Caucasian reference population." The specific size, collection methodology (retrospective/prospective), or exact provenance (e.g., specific study) of this reference population is not detailed in the provided text.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
The document does not mention the use of experts to establish ground truth for a test set in the context of the device's performance evaluation. The device's function is a calculation based on predefined reference data, not a diagnostic interpretation that typically requires expert consensus for ground truth.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set:
Not applicable. The document does not describe an adjudication method for a test set, as its evaluation focuses on the consistency of calculations and the clinical insignificance of minor differences, rather than a diagnostic accuracy study where adjudication is common.
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
Not applicable. The device, "CTXA Hip Extended Reference Data," is an accessory for a bone densitometer providing reference data for score calculation. It does not involve AI assistance to human readers or a multi-reader multi-case study. It simply provides a new reference population for existing BMD measurements.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
The device's core function is standalone in the sense that it provides a calculation of T-scores and Z-scores based on a reference database. The "algorithm" (i.e., the method of calculating these scores against the reference data) is performed without human intervention in the calculation itself. However, the interpretation of these scores "is at the discretion of the physician," meaning the overall diagnostic process remains human-in-the-loop. The document focuses on the accuracy and clinical insignificance of differences in these calculated scores.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
The "ground truth" in this context refers to the reference population data against which patient BMD estimates are compared to calculate T and Z scores. The document describes this as a "US normal female Caucasian reference population age 20-39 years" for T-scores and "US normal female Caucasian reference population age 20-79 years" for Z-scores. The specific methodology for establishing this "normal" reference population (e.g., how subjects were selected, what criteria defined "normal," how BMD was measured for this database) is not detailed in the provided text.
8. The sample size for the training set:
The document does not mention a training set in the context of machine learning or AI. The "reference data" would be analogous to a training set here, but its sample size is not specified.
9. How the ground truth for the training set was established:
The document does not detail how the "US normal female Caucasian reference population" (which serves as the "ground truth" or reference for the device's calculations) was established. It is simply referred to as a "reference population."
§ 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.