(90 days)
The Cardius 3 X-ACT Imaging System is a gamma camera for Single Photon Emission Computed Tomography (SPECT) integrated with an attenuation device consisting of an x-ray generator. The Cardius 3 X-ACT Imaging System is intended for use in the generation of cardiac studies, including planar and SPBCT studies, in nuclear medicine applications. Cardius 3 X-ACT produces non-attenuation corrected SPECT Images and attenuation corrected SPECT images with x-ray transmission data that may also be corrected for scatter.
The Cardius® 3 X-ACT Imaging system is a gamma camera for the acquisition and processing of Single Photon Emission Computed Tomography (SPECT) as well as correcting attenuation artifacts associated with these Emission studies. The device consists of an x-ray generator integrated with the previously cleared Cardius 3 XPO triple head SPECT system to provide attenuation correction functionality. The attenuation correction functionality will be included with the Cardius 3 X-ACT imaging system, or offered as an accessory for previously purchased Cardius 3 XPO systems that are configured to accept the attenuation correction functionality.
The Cardius 3 X-ACT Imaging system is designed to provide extended imaging functionality relative to the current Cardius XPO series imagers. A typical patient study comprises an emission (SPECT) study followed by a transmission study. The SPECT study is acquired using the similar system hardware and software technology as a Cardius-3 XPO imaging system. For the transmission study, the low dose x-ray generator is used to produce an attenuation map that is used for attenuation correction (AC) of the emission data. An iterative reconstruction technique then uses the attenuation map and the SPECT data as input, and the AC and non-AC reconstructed volumes are saved in the database for physician review. The attenuation correction data provided is additional information that may be reviewed by the interpreter. The original SPECT data remains available to the interpreter.
The provided text describes the Digirad Cardius 3 X-ACT Imaging System, a gamma camera for SPECT imaging with integrated X-ray-based attenuation correction. The document focuses on its substantial equivalence to predicate devices and does not contain a detailed study with specific acceptance criteria, reported performance metrics, or information on ground truth establishment and expert adjudication typical for a clinical study comparing AI performance against established criteria.
Therefore, many of the requested fields cannot be directly extracted from the provided text. The device received 510(k) clearance based on demonstrating substantial equivalence to existing predicate devices, rather than meeting specific quantitative performance acceptance criteria in a clinical study that would involve expert readers assessing AI output.
Here's a breakdown of what can and cannot be answered based on the provided input:
1. A table of acceptance criteria and the reported device performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| (Not explicitly stated as quantitative acceptance criteria in the provided text) | The testing shows Cardius 3 X-ACT meets the design specifications, which are similar to the predicate device functional specifications. Digirad internal testing and clinical images obtained with the Cardius 3 X-ACT imaging system have demonstrated equivalent efficacy to the predicate devices, and did not raise new questions regarding safety and effectiveness. |
| Demonstrates substantial equivalence to predicate devices based on intended use and technology | The FDA issued a substantial equivalence determination. |
| Functions as per its specifications (bench testing) | All tests passed with the actual results substantially matching the expected results. |
2. Sample size used for the test set and the data provenance
- Sample Size: Not specified. The document mentions "clinical images obtained with the Cardius 3 X-ACT imaging system" but does not quantify the number of images or patients.
- Data Provenance: Not specified (e.g., country of origin, retrospective or prospective).
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
- Number of Experts: Not specified.
- Qualifications of Experts: Not specified. The document mentions "physician review" but no details on expert qualifications for establishing ground truth are provided.
4. Adjudication method (e.g., 2+1, 3+1, none) for the test set
- Adjudication Method: Not specified. Given that the clearance is based on substantial equivalence and "equivalent efficacy," a formal adjudication process for a test set is not explicitly described.
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
- MRMC Study Done: No. The device itself is an imaging system providing attenuation corrected images, not an AI assistance tool for human readers.
- Effect Size of Human Readers Improvement with AI: Not applicable, as this is not an AI-assisted diagnostic device. The attenuation correction data is described as "additional information that may be reviewed by the interpreter."
6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done
- Standalone Performance: Not explicitly evaluated in the context of an "algorithm only" performance against a ground truth in the way modern AI devices are. The device "produces non-attenuation corrected SPECT Images and attenuation corrected SPECT images with x-ray transmission data," implying the output is for physician review. The device's performance is implicit in its ability to produce these corrected images and its "equivalent efficacy" to predicate devices.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Type of Ground Truth: Not specified. The basis for "equivalent efficacy" is not detailed, but it would likely be based on expert interpretation of images for relevant clinical findings (e.g., myocardial perfusion defects) compared to predicate devices. It is not stated if this involved pathology or outcomes data.
8. The sample size for the training set
- Sample Size for Training Set: Not applicable. The device uses "Digirad's internally developed proprietary algorithms" (for reconstruction and attenuation correction) but does not describe these as "trained" in the typical machine learning sense with a distinct training set. The algorithms are part of the system's design and function.
9. How the ground truth for the training set was established
- Ground Truth for Training Set Establishment: Not applicable for the reasons stated above.
Summary of what the document provides for regulatory clearance:
The device received 510(k) clearance by demonstrating substantial equivalence to existing predicate devices (Philips Medical Systems BrightView VCT Imaging System and Digirad's Cardius 3 XPO Imaging System). The equivalence was based on:
- Similar intended use: Gamma camera for SPECT imaging, generating cardiac studies, and providing attenuation-corrected images.
- Similar technology: Gamma camera for SPECT imaging and X-ray based attenuation correction.
- Design Specifications: Bench testing confirmed the device met its design specifications, which were similar to the predicate device's functional specifications.
- Equivalent Efficacy: Internal testing and clinical images demonstrated "equivalent efficacy" and did not raise new safety or effectiveness concerns compared to predicate devices.
The document does not detail a clinical study with quantitative performance metrics for the device against specific acceptance criteria, nor does it describe a ground truth process involving expert readers in the context of an AI device. Instead, it focuses on the engineering and functional demonstration of equivalence.
§ 892.1200 Emission computed tomography system.
(a)
Identification. An emission computed tomography system is a device intended to detect the location and distribution of gamma ray- and positron-emitting radionuclides in the body and produce cross-sectional images through computer reconstruction of the data. This generic type of device may include signal analysis and display equipment, patient and equipment supports, radionuclide anatomical markers, component parts, and accessories.(b)
Classification. Class II.