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.

Device Description

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.

AI/ML Overview

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.

Summary

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K002113

510(k) SUMMARY OF SAFETY AND EFFECTIVENESS

This summary of safety and effectiveness information is submitted in accordance with the requirements of 21 CFR 807.92(c).

Contact Information:	Christopher E. Cann, Ph.D.CEO and Director of Research and DevelopmentMindways Software, Inc282 Second St., 4th FloorSan Francisco, CA 94105Phone: 415-247-9930Fax: 415-247-9931Email: chris@qct.com
Date:	September 28, 2001
Device/Trade Name:	CTXA Hip
Common/Usual Name:	Bone Mineral Densitometer
Classification Name:	Bone Densitometer, 21 CFR 892.1170, Class II
Predicate Devices:	K894854: QCT Bone Mineral Density Analysis SoftwareIntended Use: Estimate bone mineral density within the spine.
	K883280: Hologic QDR 1000 X-Ray Bone DensitometerIntended Use: Estimate bone mineral density and bone mineralcontent at various anatomical sites, including the proximalfemur.
	K943505: Hologic QDR 3000 X-Ray Bone DensitometerIntended Use: Estimate bone mineral density and bone mineralcontent at various anatomical sites, including the proximalfemur.
	Preamendment: Norland Model 178 Bone DensitometerIntended Use: An aid to the physician in determining fracturerisk.

Device Description

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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.

Intended Use

Summary of Technological Characteristics and Comparison with Predicate Devices

The CTXA Hip Bone Mineral Densitometer Module (CTXA Hip) provides estimates of bone mineral content (BMC) and bone mineral density (BMD) values smilar to those obtained from the predicate DXA devices (K883280: Hologic QDR 1000 X-Ray Bone Densitometer, K943505: Hologic ODR 3000 X-Ray Bone Densitometer) for regions of interest in the proximal femur. CTXA Hip uses the same technical procedures to acquire and calibrate CT image data as are used for the predicate device K894854: QCT Bone Mineral Density Analysis Software. CTXA Hip reference data for young normal US Caucasian females were acquired in a clinical study so that patient results obtained using CTXA Hip can be compared to this normal reference population. The CTXA Hip BMD estimates compared to the CTXA Hip reference population are used as an aid to the physician in identifying patients with low bone mineral density. Additionally, normal data comparisons provide a basis for estimating fracture risk, as is done with the predicate preamendment device Norland Model 178 Bone Densitometer.

BMC and BMD estimates are returned by the CTXA Hip for the following proximal femur regions-of-interest (ROIs): (1) femoral neck, (2) trochanter, (3) intertrochanter, (4) Ward's Triangle, and (5) total hip (i.e., superposition of ROIs 1-3).

Summary of Non-Clinical Performance Data

In vitro phantom studies with the CTXA Hip indicate a device precision of approximately 0.007 g/cm2 across a variety of CT scanners. These tests also indicate that in vitro CTXA Hip BMD estimates are unbiased when expressed as equivalent K2HPO4 mineral density.

Summary of Clinical Performance Data

CTXA Hip clinical studies indicate a long term in vivo device precision of 0.011 g/cm2 for total hip and 0.012 g/cm2 for femoral neck regions of interest. Clinical studies were done comparing BMD results from CTXA Hip with results from Hologic QDR 1000 and QDR4500 bone densitometers. BMD correlations (Pearson's R) were 0.90-0.97 for the Total Hip region of interest and 0.88-0.95 for the Femoral Neck region of interest. A clinical study was done to collect a set of young normal female reference data for calculation of T-scores for CTXA Hip results.

Conclusions

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The CTXA Hip Bone Mineral Densitometer is substantially equivalent to the listed predicate devices. The CTXA Hip in vitro and in vivo performance is comparable to that associated with the predicate devices. The radiation dose associated with the CT study that provides the data set to be analyzed by the CTXA Hip is well within accepted patient dose guidelines.

lyzed by the CTAA trip is well wi

Signature

Christopher Cann Printed Name

CEO and Director of Research and Development Title

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Image /page/3/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo is circular, with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" arranged around the top half of the circle. Inside the circle is a stylized symbol that resembles a bird or an abstract human figure, composed of three curved lines.

Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850

DEC 0 4 2001

Christopher E. Cann. Ph.D. CEO and Director of Research Mindways Software, Inc. 282 Second St., 4th Floor SAN FRANCISCO CA 94105 Re: K002113

Trade/Device Name: CTXA HIP, CTXA; QCT PRO CTXA HIP Regulation Number: 21 CFR 892.1170 Regulation Name: Bone densitometer Regulatory Class: II Product Code: 90 KGI Dated: September 28, 2001 Received: October 2, 2001

Dear Dr. Cann:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (sections 531-542 of the Act); 21 CFR 1000-1050.

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This letter will allow you to begin marketing your device as described in your 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Office of Compliance at one of the following numbers, based on the regulation number at the top of this letter:

8xx.1xxx	(301) 594-4591
876.2xxx, 3xxx, 4xxx, 5xxx	(301) 594-4616
884.2xxx, 3xxx, 4xxx, 5xxx, 6xxx	(301) 594-4616
892.2xxx, 3xxx, 4xxx, 5xxx	(301) 594-4654
Other	(301) 594-4692

Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its Internet address http://www.fda.gov/cdrh/dsma/dsmamain.html.

Sincerely yours,

Nancy C. Brogdin

Nancy C. Brogdon Director, Division of Reproductive, Abdominal, and Radiological Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Page _ of _

510(k) Number (if known): K002113/S002
Device Name: CTXA Hip Bone ellineral Densitometer

Indications For Use:

Intended Use

The CTXA Hip Bone Mineral Densitometer is intended to estimate bone mineral content (BMC) The CTAA Hip Bone Mineral Dalishour. 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.

(PLEASE DO NOT WRITE BELOW THIS LINE - CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of Device Evaluation (ODE)

Prescription Use(Per 21 CFR 801.109)	✓
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Over-The-Counter Use
	(Optional Format 1-2-96)

(Division Sign-Off)	Nancy C Brogdon
Division of Reproductive, Abdominal,and Radiological Devices
510(k) Number	K02113

Regulation Number and Section

§ 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.