(126 days)
The O-arm™ O2 Imaging System is a mobile x-ray system, designed for 2D and 3D imaging for adult and pediatric patients weighing 60 lbs or greater and having an abdominal thickness greater than 16 cm, and is intended to be used where a physician benefits from 2D and 3D information of anatomic structures and objects with high x-ray attenuation such as bony anatomy and metallic objects. The O-arm™ O2 Imaging System is compatible with certain image guided surgery systems.
The O-arm™ O2 Imaging System is a mobile x-ray system that provides 3D and 2D imaging. The O-arm™ O2 Imaging System consists of two main assemblies that are used together: The Image Acquisition System (IAS) and The Mobile View Station (MVS). The two units are interconnected by a single cable that provides power and signal data. The IAS has an internal battery pack that provides power for motorized transportation and gantry positioning. In addition, the battery pack is used to power the X-ray tank. The MVS has an internal UPS to support its function when mains power is disconnected. The O-arm™ O2 Imaging System operates off standard line voltage within the following voltages: VAC 100, 120 or 240, Frequency 60Hz or 50Hz, Power Requirements 1440 VA.
The Medtronic O-arm™ O2 Imaging System with 4.3.0 software introduces three new features: Medtronic Implant Resolution (MIR) (referred to as KCMAR in the document), 3D Long Scan (3DLS), and Spine Smart Dose (SSD). The device's performance was evaluated through various studies to ensure substantial equivalence to the predicate device (O-arm™ O2 Imaging System 4.2.0 software) and to verify that the new features function as intended without raising new safety or effectiveness concerns.
Here's a breakdown of the requested information:
1. Table of Acceptance Criteria and Reported Device Performance
| Feature/Metric | Acceptance Criteria (Implicit from Study Design/Results) | Reported Device Performance |
|---|---|---|
| Spine Smart Dose (SSD) | Clinical equivalence to predicate 3D acquisition modes (Standard and HD) by board-certified neuroradiologists. | Deemed clinically equivalent to O-arm™ O2 Imaging System 4.2.x Standard and Predicate High-Definition modes by board-certified neuroradiologists in a blinded review of 100 clinical image pairs. |
| SSD Image Quality (Bench Testing) | Meet system-level requirements for 3D Line pair, Contrast, MTF, Uniformity, and Geometric accuracy. | Met all system-level requirements. |
| SSD Navigational Accuracy (Bench Testing) | Meet system-level requirements in terms of millimeters. | Met all system-level requirements. |
| Medtronic Implant Resolution (KCMAR) | Clinical utility of KCMAR images to be statistically better than corresponding non-KCMAR images from the predicate device by board-certified radiologists. | Statistically better clinical value when compared to corresponding images from the Predicate Device (O-arm O2 Imaging System version 4.2.0) under specified indications. |
| KCMAR Metal Artifact Reduction (Bench Testing) | Qualitative comparison to demonstrate metal artifact reduction between non-KCMAR and KCMAR processed images. | Demonstrated metal artifact reduction. |
| KCMAR Implant Location Accuracy (Bench Testing) | Quantitative assessment of implant location accuracy in millimeters and degrees to meet system requirements. | Met all system-level requirements. |
| 3D Long Scan (3DLS) Clinical Utility | Clinical utility of Standard 3DLS and SSD 3DLS to be statistically equivalent to the corresponding Standard acquisition mode available in the predicate system by board-certified radiologists. | Statistically equivalent clinical utility when compared to the corresponding Standard acquisition mode available in the predicate system (version 4.2.0). |
| 3DLS Image Quality (Bench Testing) | Meet system-level requirements for 3D Line pair, Contrast, MTF, and Geometric accuracy. | Met all system-level requirements. |
| 3DLS Navigational Accuracy (Bench Testing) | Meet system-level requirements in terms of millimeters. | Met all system-level requirements. |
| Usability (3DLS, SSD, KCMAR) | Pass summative validation with critical tasks and new workflows for intended users in simulated use environments. | Passed summative validation, providing objective evidence of safety and effectiveness for intended users, uses, and environments. |
| Dosimetry (SSD, 3DLS) | Confirm dose accuracy (kV, mA, CTDI, DLP) meets system-level requirements for new acquisition features. | All dosimetry testing passed system-level requirements. |
2. Sample Size for the Test Set and Data Provenance
- Spine Smart Dose (SSD) Clinical Equivalence:
- Sample Size: 100 clinical image pairs.
- Data Provenance: "Clinical" images, suggesting retrospective or prospective clinical data. No specific country of origin is mentioned.
- KCMAR Clinical Equivalence:
- Sample Size:
- Initial study: 40 image pairs from four cadavers (small, medium, large, and extra-large habitus).
- Subsequent study: 33 image pairs from two cadavers (small and extra-large habitus).
- Data Provenance: Cadavers (ex-vivo data). No country of origin specified.
- Sample Size:
- 3D Long Scan (3DLS) Clinical Utility:
- Sample Size: 45 paired samples from acquisitions of three cadavers (small, medium, and extra-large habitus). Two cadavers were instrumented with pedicle screw hardware.
- Data Provenance: Cadavers (ex-vivo data). No country of origin specified.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- Spine Smart Dose (SSD) Clinical Equivalence: "board-certified neuroradiologist" (singular, implied one, but could be more based on typical study designs not explicitly stated as count of 1). The document mentions "board-certified neuroradiologist involving 100 clinical image pairs".
- KCMAR Clinical Equivalence: "Board-certified radiologists" (plural).
- 3D Long Scan (3DLS) Clinical Utility: "Board-certified radiologists" (plural).
4. Adjudication Method for the Test Set
The document does not explicitly state an adjudication method (e.g., 2+1, 3+1). It describes a "blinded review" for SSD and "clinical utility scores (1-5 scale)" for KCMAR and 3DLS, implying individual assessments that were then potentially aggregated or statistically compared.
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
The studies for SSD, KCMAR, and 3DLS involved multiple readers (board-certified radiologists/neuroradiologists) evaluating images.
- SSD: Compared "O-arm™ O2 Imaging System 4.3.0 SSD images" to "O-arm™ O2 Imaging System 4.2.x Standard and Predicate High-Definition modes." The outcome was clinical equivalence, not an improvement in human reader performance with AI assistance. It states the SSD leverages Machine Learning technology to reduce noise.
- KCMAR: Compared images reconstructed "without KCMAR feature" to images "with KCMAR feature." The outcome was "statistically better" clinical value for KCMAR. This indicates that the feature itself (which uses an algorithm for metal artifact reduction) resulted in better images, which would indirectly benefit the reader, but it doesn't quantify an improvement in human reader performance directly.
- 3DLS: Compared "Standard 3DLS and SSD 3DLS" to "corresponding Standard acquisition mode." The outcome was "statistically equivalent clinical utility." This specifically relates to the utility of the scan modes, not an AI-assisted interpretation by readers.
Therefore, while MRMC-like studies were conducted to assess the performance of the features, the focus was on the characteristics of the images produced by the device (clinical equivalence/utility/better value) rather than quantifying an effect size of how much human readers improve with AI versus without AI assistance in their diagnostic accuracy or efficiency.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
Yes, aspects of standalone performance were evaluated through bench testing.
- SSD Bench Testing: Evaluated image quality parameters (3D Line pair, Contrast, MTF, Uniformity, Geometric accuracy) and navigational accuracy.
- KCMAR Bench Testing: Qualitatively compared metal artifact reduction and quantitatively assessed implant location accuracy.
- 3DLS Bench Testing: Verified system-level requirements for image quality (3D Line pair, Contrast, MTF, Geometric accuracy) and navigational accuracy.
These bench tests assess the algorithmic output directly against defined performance metrics, independent of human interpretation.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Clinical Equivalence/Utility for SSD, KCMAR, 3DLS: Ground truth was established by expert assessment/consensus from board-certified neuroradiologists/radiologists providing clinical utility scores and making equivalence/superiority judgments.
- Bench Testing: Ground truth was based on phantom measurements and objective system-level requirements for image quality, geometric accuracy, and navigational accuracy.
8. The Sample Size for the Training Set
The document states that the Spine Smart Dose (SSD) feature "leverages Machine Learning technology with existing O-arm™ images to achieve reduction in dose..." However, it does not specify the sample size of the training set used for this Machine Learning model.
9. How the Ground Truth for the Training Set was Established
For the Spine Smart Dose (SSD) feature, which uses Machine Learning, the document mentions "existing O-arm™ images." It does not explicitly state how the ground truth for these training images was established. Typically, for such denoising or image enhancement tasks, the "ground truth" might be considered the higher-dose, higher-quality images, with the ML model learning to reconstruct a similar quality image from lower-dose acquisitions. The document implies that the model's output (low-dose reconstruction) was then validated against expert opinion for clinical equivalence.
§ 892.1650 Image-intensified fluoroscopic x-ray system.
(a)
Identification. An image-intensified fluoroscopic x-ray system is a device intended to visualize anatomical structures by converting a pattern of x-radiation into a visible image through electronic amplification. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories.(b)
Classification. Class II (special controls). An anthrogram tray or radiology dental tray intended for use with an image-intensified fluoroscopic x-ray system only is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9. In addition, when intended as an accessory to the device described in paragraph (a) of this section, the fluoroscopic compression device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9.