(154 days)
The Norland Body Composition Option (body composition) assesses the non-bone tissue determined during the bone density scans performed by Norland DEXA bone densitometers, and estimates soft tissue mass, fat mass, lean mass, total soft tissue mass, % fat, TBMC/LBM (Total Bone Mineral Content / Lean Body Mass), and Siri and Brozek equation equivalent values.
These body composition estimates are useful to health care professionals in their management of diseases/conditions where the disease/condition itself, or its treatment, can affect the relative amounts of patient fat and lean tissue. The Norland Body Composition Option does not diagnose disease, or recommend treatment regimens, or quantify treatment effectiveness. Only the health care professional can make these judgments. Some of the diseases/conditions for which lean and fat tissue estimates are useful are chronic renal failure, Anorexia Nervosa, excessive obesity, AIDS/HIV, and Cystic Fibrosis. Body composition is also a convenient alternative to hydrostatic weighing and skin fold measurements.
The Norland Body Composition Option (body composition) is used with Norland DEXA bone densitometers to estimate the relative amounts of lean and fat tissue in the scan area. Body composition does not require any changes to the bone densitometer nor does it require additional scanning or radiation exposure beyond the bone density scans. In most cases, existing scans can be re-analyzed to provide the body composition values. Although body composition is most useful for whole body scans, it is compatible with all scan modes for Norland DEXA bone densitometers. Body composition values for whole body scans were compared to underwater weighing (UWW) values in clinical studies involving hundreds of subjects. The UWW values were determined using both the Siri and Brozek equations. Based on this study, the Norland body composition provides the Siri and Brozek equivalent values for the Whole Body scans.
The provided text describes the Norland Body Composition Option, a software addition to DEXA bone densitometers. The information available focuses on the device's intended use, safety, and regulatory clearance via 510(k) summary, rather than a detailed scientific study with explicit acceptance criteria.
However, based on the text, we can infer some details about the study and acceptance criteria related to its substantial equivalence claim.
1. Table of Acceptance Criteria and Reported Device Performance
The document states: "Body composition values for whole body scans were compared to underwater weighing (UWW) values in clinical studies involving hundreds of subjects. The UWW values were determined using both the Siri and Brozek equations. Based on this study, the Norland body composition provides the Siri and Brozek equivalent values for the Whole Body scans."
While specific numerical acceptance criteria (e.g., a specific correlation coefficient or percentage agreement) are not provided, the implicit acceptance criterion is that the Norland Body Composition Option's values "provide the Siri and Brozek equivalent values." This suggests that the device's output was considered sufficiently close to the UWW measurements (calculated via Siri and Brozek equations) to be deemed equivalent and acceptable.
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Device provides "Siri and Brozek equivalent values" for Whole Body scans compared to Underwater Weighing (UWW) measurements. | The Norland body composition provides the Siri and Brozek equivalent values for the Whole Body scans. |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: "clinical studies involving hundreds of subjects."
- Data Provenance: The document does not specify the country of origin. It does not explicitly state whether the data was retrospective or prospective, but "clinical studies" typically imply prospective data collection for such comparisons.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
This information is not provided in the document. Underwater weighing (UWW) is a direct measurement method for body density, from which body composition is calculated using established equations (Siri and Brozek). Therefore, human expert "ground truthing" in the sense of image interpretation is not directly applicable to the UWW measurements themselves. The expertise would lie in correctly performing UWW and applying the equations, which is assumed.
4. Adjudication Method for the Test Set
Not applicable, as the ground truth (UWW) is a direct measurement, not an expert-driven assessment requiring adjudication.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done
No, an MRMC study was not done. The study described compares the device's output to a physical measurement (UWW), not to human readers' interpretations with and without AI assistance.
6. If a Standalone Study (i.e., algorithm only without human-in-the-loop performance) was done
Yes, the study described is a standalone performance assessment. The Norland Body Composition Option, a software feature, generates body composition values, which were then directly compared to UWW values. There's no mention of a human-in-the-loop component in this comparison.
7. The Type of Ground Truth Used
The ground truth used was outcomes data / physical measurement, specifically Underwater Weighing (UWW), from which body composition values were derived using the Siri and Brozek equations. This is considered a gold standard for body composition assessment.
8. The Sample Size for the Training Set
The document does not specify a separate training set or its sample size. The description of the clinical study appears to refer to the validation of the device's output against UWW. Given the nature of this 510(k) summary for a software option, it's possible the core algorithms for converting DEXA data to body composition were developed and validated independently prior to this specific submission, or the "clinical studies involving hundreds of subjects" served as the primary validation set for the software's performance against a gold standard.
9. How the Ground Truth for the Training Set was Established
This information is not provided, as a distinct training set and its ground truth establishment are not discussed in the document. If the "clinical studies involving hundreds of subjects" served as the primary validation, then the ground truth for this validation was established via Underwater Weighing (UWW) as described in point 7.
§ 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.