(199 days)
The QCT Pro Asynchronous Calibration Module is intended to provide an alternative method for calibrating QCT data sets that are intended for analysis with QCT Pro Spine and Hip application modules. Installation of the QCT Pro Asynchronous Calibration Module does not alter the clinical indications for use of the QCT Pro Spine and Hip application modules. It does, however, provide an additional means of obtaining calibration data that does not require the simultaneous scanning of a patient with a CT calibration standard as is required when using the QCT Pro Spine and Hip application modules without the installation of the QCT Pro Asynchronous Calibration Module. Thus the QCT Pro Asynchronous Calibration Module facilitates: (1) retrospective assessment of bone density from CT scans acquired for other purposes, (2) assessment of bone density in conjunction with another medically appropriate procedure involving CT scans of the anatomical regions where estimating bone density is prescribed, and (3) assessment of bone density without a phantom as an independent measurement procedure.
The QCT Pro Asynchronous Calibration Module is intended to extend the capabilities of QCT Pro bone mineral densitometer products (K894854. K002113. K030330) currently marketed by Mindways to the measurement of bone mineral content (BMC) and bone mineral density (BMD) from patient-specific CT images acquired without the simultaneous use of a CT calibration phantom. The QCT Pro bone mineral densitometer products distributed with or supplemented with the QCT Pro Asynchronous Calibration Module will be marketed under the name QCT Pro CliniQCT or more simply CliniQCT. Mineral calibration with the asynchronous calibration method is obtained from phantom measurements acquired on the same CT scanner, operated in a substantially similar mode used to acquire a patient CT scan. The phantom measurements used for calibration purposes may be acquired before or after a patient CT scan to which they are to be applied. The asynchronous calibration mode facilitates: (1) retrospective assessment of bone density from CT scans acquired for other purposes, (2) assessment of bone density in conjunction with another medically appropriate procedure involving CT scans of the anatomical regions where estimating bone density is prescribed, and (3) assessment of bone density without a phantom as an independent measurement procedure. Retrospective bone density analysis provides bone density information without exposing a patient to additional ionizing radiation while combining CT studies results in an overall reduction in patient exposure to ionizing radiation relative to the expected radiation dose associated with performing the studies separately.
Here's an analysis of the acceptance criteria and study detailed in the provided document, restructured to address your specific points:
The document describes the QCT Pro Asynchronous Calibration Module (marketed as CliniQCT), which provides an alternative calibration method for QCT data sets without requiring a simultaneous CT calibration phantom scan with the patient.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Specific Metric | Acceptance Criteria (CliniQCT) | Reported Device Performance (CliniQCT) | Predicate Device Performance (QCT Pro) |
|---|---|---|---|---|
| Performance | In vitro Precision (relative to calibration reference standard) | Non-inferior to QCT Pro | Non-inferior to QCT Pro (Implied to meet or exceed predicate precision) | Volume Density: 1.4 mg/cm³ (0.7% at a nominal volume density of 200 mg/cm³) |
| Area Density: 0.007 g/cm² (0.7% at a nominal area density of 1.0 g/cm²) | ||||
| In vivo Precision (patient) | Non-inferior to QCT Pro | Non-inferior to QCT Pro (Implied to meet or exceed predicate precision) | Spine: Up to 1% | |
| Total Hip ROI: 0.011 g/cm² (1.1% at 1.0 g/cm²) | ||||
| Femoral Neck: 0.012 g/cm² (1.2% at 1.0 g/cm²) | ||||
| Accuracy (relative to calibration reference standard) | Unbiased | Unbiased | Unbiased | |
| Equivalence of BMC/BMD estimates | Similar to those obtained from predicate QCT Pro devices for spine and proximal femur. | CliniQCT provides estimates of bone mineral content (BMC) and bone mineral density (BMD) values similar to those obtained from the predicate QCT Pro bone densitometer devices. | Yes | |
| Safety/Usability | Radiation dose with examination | Within currently accepted guidelines and equivalent to predicate use cases. | Facilitates retrospective assessment without additional radiation exposure beyond the initial scan. | Radiation dose associated with examination is within currently accepted guidelines regarding radiation health risks associated with common radiologic diagnostic procedures. (Note: QCT Pro does not directly control radiation delivery). |
| Ability to provide retrospective measurements from CT scans acquired for other purposes. | Yes (primary benefit of asynchronous calibration) | Yes, without exposing the patient to additional ionizing radiation. | No (Predicate QCT Pro requires simultaneous phantom scanning, limiting retrospective analysis without re-scanning). | |
| Ability to provide dual-use BMD/BMC measurements from CT scans for multiple purposes. | Yes (primary benefit of asynchronous calibration) | Yes, without exposing the patient to additional ionizing radiation beyond the other, non-QCT, purpose(s). | No (Predicate QCT Pro requires simultaneous phantom scanning, making dual-use for unrelated CT scans challenging without additional radiation for QCT-specific phantom scan). |
Note: The document states that the new device has "the same technological characteristics as its predicate QCT Pro devices" with the exception of the asynchronous calibration method, and that "BMD estimates derived with the asynchronous calibration method are suitable for comparison to the same reference data sets as are used with the QCT Pro predicate devices." This implies that the performance metrics (precision, accuracy) of CliniQCT are expected to be on par with the predicate devices.
2. Sample Size Used for the Test Set and Data Provenance
The document states that the testing involved:
- Retrospective data analysis
- Phantom testing
- Prospective patient studies
However, specific sample sizes for the test set (number of images, patients, or phantoms) are not explicitly provided in the excerpt. The data provenance (e.g., country of origin, retrospective or prospective) is partially indicated by "retrospective data analysis" and "prospective patient studies," but further details (like country/institution) are missing.
3. Number of Experts Used to Establish Ground Truth and Their Qualifications
The document does not provide information regarding the number of experts used to establish ground truth or their qualifications. The device appears to be for quantitative measurements (BMC/BMD) rather than diagnostic image interpretation requiring expert consensus.
4. Adjudication Method for the Test Set
The document does not specify an adjudication method. Since the device provides quantitative measurements (BMC/BMD) rather than classification/diagnosis for which human readers would typically adjudicate, an adjudication method for a "test set" in the traditional sense of diagnostic image review is not applicable here. Performance is evaluated against objective reference standards and comparison to predicate devices.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
An MRMC comparative effectiveness study was not conducted, or at least not described in this document. The device is a quantitative measurement tool (densitometer) and not designed for human-in-the-loop diagnostic image interpretation where AI assistance to human readers would be evaluated. The focus is on the accuracy and precision of the quantitative measurements produced by the device itself, compared to existing, validated methods.
6. Standalone Performance (Algorithm Only Without Human-in-the-Loop Performance)
Yes, the study primarily describes the standalone performance of the CliniQCT device. The "non-inferiority" and "unbiased" claims for precision and accuracy directly reflect the algorithm's performance in generating BMC and BMD values. It is a tool that provides quantitative data, and its performance evaluation is centered on the accuracy and reliability of these quantitative outputs.
7. The Type of Ground Truth Used
The ground truth used for evaluating the device appears to be:
- Calibration Reference Standard: For in vitro precision and accuracy, the device's output is compared against established calibration reference standards (e.g., aqueous K2HPO4 bone density standard).
- Predicate QCT Pro device outputs: For in vivo precision and similarity of BMC/BMD estimates, the device's performance is compared against the performance characteristics of its predicate QCT Pro devices, which are already legally marketed and established.
8. The Sample Size for the Training Set
The document does not specify a separate training set sample size. The testing described ("retrospective data analysis, phantom testing and prospective patient studies") appears to be for evaluating the device's performance (validation), not for initial model training data, as the device's underlying principles are based on Quantitative Computed Tomography (QCT) and existing predicate technology.
9. How the Ground Truth for the Training Set Was Established
Since a separate "training set" is not explicitly mentioned for a machine learning model, the concept of ground truth establishment for a training set in that context is not directly applicable here. The device's calibration and underlying algorithms would be based on established QCT principles and phantom measurement protocols. The phrase "calibration data necessary for use with the QCT Pro Asynchronous Calibration Module is obtained from a standard QCT Pro QA phantom CT scan performed on the same CT scanner" suggests calibration is done using physical phantoms with known density values.
§ 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.