(85 days)
The Computed Tomography X-ray system is intended to produce cross-sectional images of the body by computer reconstruction of X-ray transmission data taken at different angles and planes, including Axial, Cine, Helical (Volumetric), Cardiac, Spectral, and Gated acquisitions for all ages. These images may be obtained either with or without contrast. This device may include signal analysis and display equipment, patient and equipment supports, components and accessories.
This device may include data and image processing to produce images in a variety of trans-axial and reformatted planes. Further the images can be post processed to produce additional imaging planes or analysis results.
The system is indicated for head, whole body, cardiac and vascular X-ray Computed Tomography applications for both single kV acquisitions and with the fast KV switching spectral imaging option (GSI).
The device output is a valuable medical tool for the diagnosis of disease, trauma, or abnormality and for planning, guiding, and monitoring therapy.
If the spectral imaging option is included on the system, the system can acquire CT images using different kV levels of the same anatomical region of a patient in a single rotation from a single source. The differences in the energy dependence of the attenuation coefficient of the different materials provide information about the chemical composition of body materials. This approach enables images to be generated at energies selected from the available spectrum to visualize and analyze information about anatomical and pathological structures.
GSI provides information of the chemical composition of renal calculi by calculation and graphical display of the spectrum of effective atomic number. GSI Kidney stone characterization provides additional information to aid in the characterization of uric acid versus non-uric acid stones. It is intended to be used as an adjunct to current standard methods for evaluating stone etiology and composition.
The Discovery CT750 HD CT Scanner System with GSI Cardiac Option is composed of a gantry, patient table, operator console, computer, and PDU and includes image acquisition hardware, image acquisition and reconstruction software, associated accessories and connections/interfaces to accessories.
The Discovery CT750 HD CT Scanner System with GSI Cardiac Option is intended to be a head and whole body CT system incorporating the same basic fundamental operating principles and the same indications for use as the predicate device. Materials and construction are equivalent to our existing marketed products, which are compliant with UL 60601-1, IEC 60601-1 and associated collateral and particular standards, 21CFR Subchapter J, and NEMA XR-25. It has been developed under the same GE quality system and has successfully completed all design controls, including risk management, verification, and validation.
The provided text describes the GE Medical Systems Discovery CT750 HD with GSI Cardiac Option and outlines its safety and effectiveness documentation for 510(k) submission. Here's a breakdown of the acceptance criteria and the study details:
Acceptance Criteria and Reported Device Performance
The document doesn't explicitly list "acceptance criteria" in a quantitative, pass/fail format for clinical performance. Instead, it demonstrates the device's capabilities and effectiveness through clinical studies, focusing on diagnostic quality and the ability to provide additional information through GSI. The overall "acceptance criterion" appears to be demonstrating substantial equivalence to the predicate device and the utility of the GSI features.
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Diagnostic quality of images and additional information from GSI cardiac output (monochromatic + material density images). | Demonstrated that the output of GSI cardiac feature (monochromatic + material density images) provides diagnostic images and includes additional information related to material composition. |
| Ability to characterize uric acid vs. non-uric acid kidney stones using GSI. | For characterizing UA versus non-UA stones: material density (MD) images demonstrated 100% sensitivity and accuracy. In patients, Effective Z identified 83% of calcium stones and accurately identified dominant composition in mixed-type stones. HU measurements alone were 71% sensitive and 69% accurate. |
| Enhanced assessment capabilities for coronary lumen and plaque visualization using GSI. | Engineering testing with a custom phantom demonstrated enhanced assessment capabilities when using GSI cardiac, including its material separation capability. |
| Ability of GSI acquisition to reduce beam hardening artifact in a simulated cardiac environment and improve CT number accuracy. | Testing with a custom cardiac phantom demonstrated the ability for GSI acquisition to reduce beam hardening artifact and improve CT number accuracy, important for perfusion calculations. |
Study Details
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Sample Size Used for the Test Set and Data Provenance:
- Cardiac Study: 29 subjects from 3 sites.
- Kidney Stone Study:
- Phantom: 20 stones of pure crystalline composition.
- In-vivo: 11 patients with urinary tract stones (resulting in 39 verified patient stones).
- Data Provenance: The document does not explicitly state the country of origin for the clinical studies, but given it's a 510(k) submission for a US market, it's highly likely to be US-based or multi-national with significant US involvement. Both clinical studies were prospective, as they involved "obtaining images from subjects" and "evaluating patients."
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Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications:
- Cardiac Study: Two radiologists at each of the 3 sites independently assessed images. Their specific qualifications (e.g., years of experience, subspecialty) are not provided, only that they were "radiologists."
- Kidney Stone Study: The "gold standard" for ex-vivo analysis of the stones was "polarized microscopy with infrared spectrophotometry," which would be performed by laboratory experts, likely pathologists or specialized lab technicians. The experts for reviewing the in-vivo images and correlating them are not explicitly stated, but would typically be radiologists or urologists.
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Adjudication Method for the Test Set:
- Cardiac Study: "Two radiologists at each site independently assessed..." The document does not specify if or how disagreements were resolved (e.g., 2+1, 3+1, or simple consensus if agreement was assumed). It implies independent assessment rather than a structured adjudication process.
- Kidney Stone Study: The ground truth for stone composition was established by ex-vivo analysis, which is an objective method for the stones analyzed outside the body. For in-vivo patient stone characterization, it's not explicitly detailed how "truth" was adjudicated without ex-vivo confirmation for all stones, but the "gold standard" mentioned was for the ex-vivo analysis.
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Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- No MRMC comparative effectiveness study is explicitly described where human readers' performance with and without AI assistance is compared. The cardiac study involved radiologists assessing diagnostic quality and additional information from the GSI cardiac feature, but it doesn't compare their performance with GSI assistance versus without it in a structured MRMC design.
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Standalone (Algorithm Only) Performance Study:
- For the kidney stone characterization, the MD images were evaluated for sensitivity and accuracy in characterizing UA versus non-UA stones, which can be interpreted as a standalone performance measure for the algorithm's output. The "Effective Z" and "HU measurements" were also studied for their performance in predicting composition.
- For cardiac, the "output of the GSI cardiac feature" was assessed, implying evaluation of the algorithm's processed images and material density maps. This can be seen as an evaluation of the standalone output, which is then interpreted by radiologists.
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Type of Ground Truth Used:
- Cardiac Study: Expert consensus (implied agreement, or independent assessment by radiologists) on diagnostic quality and additional information related to material composition based on images and GSI output. There is no mention of a "true" physical ground truth (e.g., pathology) for the cardiac cases described.
- Kidney Stone Study: Pathology/laboratory analysis ("polarized microscopy with infrared spectrophotometry") served as the gold standard for ex-vivo stone composition. This gold standard was then applied to verified phantom stones and patient stones.
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Sample Size for the Training Set:
- The document does not explicitly state the sample size for a training set. The descriptions relate to verification and validation testing of the existing system and its features, rather than a new AI/algorithm separate from the CT system itself. If any machine learning was used implicitly within the GSI algorithms, the training data details are not provided.
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How Ground Truth for the Training Set Was Established:
- As no explicit training set is mentioned in the context of a machine learning algorithm, the method for establishing its ground truth is not provided. The development process mentions "system verification and validation," "design controls," and "risk management," which would include internal testing and validation against defined specifications and possibly some 'ground truth' for those engineering tests (e.g., with phantoms of known composition).
§ 892.1750 Computed tomography x-ray system.
(a)
Identification. A computed tomography x-ray system is a diagnostic x-ray system intended to produce cross-sectional images of the body by computer reconstruction of x-ray transmission data from the same axial plane taken at different angles. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories.(b)
Classification. Class II.