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UltraScan 650 can be used to determine BMDus Index in adult men and women and to assess appendicular fracture risk in postmenopausal women.

The BMDus Index is a clinical measure based on ultrasound variables of the forearm which is highly correlated with the value of BMD of the 1/3 radius as provided by DXA, with a standard error of the estimate of 0.041 grams/cm2.

BMDus Index is expressed in grams/cm² and as a T- and z-score, derived from comparison to a normative x-ray absorptiometry reference database.

BMD 15 Index has a precision comparable to that of x-ray absorptiometry, which makes it suitable for monitoring bone changes in postmenopausal women.

The UltraScan 650 is an ultrasound device that is designed to non-invasively and quantitatively assess the amount of bone at the 1/3 location of the radius in the forearm of an individual.

The UltraScan 650, with a user-supplied laptop, is designed for the estimation of bone mineral density (BMD in g/cm²) of the radius at the 1/3 location. The UltraScan 650 outputs a BMD is Index an estimate of the BMD that would be measured by dual-energy X-ray absorptiometry (DXA) at the same anatomical location, that is, an estimate of BMDDXA, at the 1/3 radius. The UltraScan 650 also outputs the T-score in standard deviations (SD) and Z-score in SD as well. The precision of the measurement is 2.1%, when expressed as a coefficient of variation. The range of the output of the UltraScan 650, depends on the subjects that are measured. However, based on the normative (reference) data, we can calculate the range that will include 99.85% of all subjects.

Here's an analysis of the acceptance criteria and study information for the UltraScan 650, based on the provided document.

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a formal, quantifiable list. However, based on the performance comparisons made to establish substantial equivalence, we can infer the key performance metrics and the reported results for the UltraScan 650. The primary goal is to correlate with DXA measurements and demonstrate comparable precision.

2. Sample Size Used for the Test Set and Data Provenance

The document provides limited detail on specific sample sizes for each clinical test. It mentions a "broader population" for patient population discussions and multiple "data sets."

• Sample Size for Test Set: Not explicitly stated as a single number.
• Data Provenance: The document generally refers to "Clinical Data" without specifying country of origin or whether it's retrospective or prospective. Given the FDA submission, it's likely the data were gathered for this submission. The reference database used is "Hologic 1/3 radius adult white females and males, K023398 / K103265," which suggests a US-centric or internationally recognized normative database.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

This information is not provided in the document. The ground truth relies on DXA measurements, which are considered the "gold standard," but no details are given about the experts who performed or interpreted these DXA scans or established the ground truth.

4. Adjudication Method for the Test Set

This information is not provided in the document.

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

This device, the UltraScan 650, is a bone sonometer and not an AI-assisted diagnostic imaging interpretation tool for human readers. Therefore, an MRMC comparative effectiveness study involving human reader improvement with or without AI assistance is not applicable and was not performed. The device provides a direct measurement (BMDus Index) rather than assisting human interpretation of complex images.

6. If a Standalone (i.e., Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes, the very nature of the UltraScan 650 is a standalone device. It's an "ultrasound device that is designed to non-invasively and quantitatively assess the amount of bone at the 1/3 location of the radius." It outputs a BMDus Index, T-score, and Z-score directly. There is no mention of a human-in-the-loop component for its primary function of generating these measurements.

7. The Type of Ground Truth Used (Expert Consensus, Pathology, Outcomes Data, etc.)

The primary ground truth used for comparison and validation of the UltraScan 650 is Dual-energy X-ray Absorptiometry (DXA) measurements of BMD, specifically at the 1/3 radius. DXA is referred to as the "gold standard" for measuring BMD. The device's "BMD us Index" is described as an "estimate of the BMD that would be measured by DXA."

8. The Sample Size for the Training Set

The document does not explicitly state the sample size for a "training set." This type of device relies on a "normative x-ray absorptiometry reference database" (Hologic 1/3 radius adult white females and males, K023398 / K103265) for T- and z-score derivations. The "clinical data" mentioned are for "Estimation of BMD," "Reproducibility," "Fracture Risk," "Reference Data Base," and "Dominant vs Non-Dominant Arm," but specific sample sizes for these studies are not detailed.

9. How the Ground Truth for the Training Set Was Established

Since an explicit "training set" for an AI algorithm isn't detailed for this device, the concept of "ground truth for the training set" doesn't directly apply in the same way it would for AI-based image classification.

However, the device's T- and z-scores are "derived from comparison to a normative x-ray absorptiometry reference database." This means the ground truth for establishing these normative values would have been a large dataset of DXA measurements from a reference population (in this case, "Hologic 1/3 radius adult white females and males"). The establishment of this normative database itself would have involved numerous DXA scans performed according to established medical protocols to define normal bone density ranges across different age groups and genders.

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