(71 days)
The MR system is an imaging device, and is intended to provide the physician with physiological and clinical information, obtained non-invasively and without the use of ionizing radiation. The MR system produces transverse, coronal, sagittal, and curved cross-sectional images that display the internal structure of the head, body, or extremities. The images produced by the MR system reflect the spatial distribution of protons (hydrogen nuclei) exhibiting magnetic resonance. The NMR properties that determine the image appearance are proton density, spin-lattice relaxation time (T1), spin-spin relaxation time (T2), and flow. When interpreted by a trained physician, these images provide information that can be useful in diagnosis determination, surgery planning, or therapy monitoring.
In order to ensure the availability for evaluating the accuracy of MRI results, intended patients are those subjects for whom it is anticipated that adequate. independent confirmation of any lesion apparently detected with the MR system can be obtained. With the exception of normal volunteers, eligible patients must have suspected or documented neoplastic, degenerative, infectious, or developmental disease process strongly suspected or established by physical exam, history, or conventional histologic, biochemical, bacteriological, or imaging techniques, or have surgical or aspiration biopsy pending that will be used to establish a diagnosis. The intended patients are primarily drawn from a pool of those subjects undergoing diagnostic evaluation by physicians who are skilled in diagnosis and treatment of the disease process(es) under consideration.
The AIRIS RF Transmit Coil offers improved RF Field Uniformity at the edge of the Imaging Volume to accommodate larger patients. MR images are obtained by placing the patient or area of interest within a powerful, highly uniform, static magnetic field. A portion of the protons (hydrogen nuclei) within the patient align with this main magnetic field, similar to small bar magnets. These protons precess, or rotate about the axis of the main magnetic field, much like a spinning child's top. The frequency of rotation is directly proportional to the strength of the main magnetic field, and is given by the Larmor equation, w = 2n y Bo, where w is the frequency of rotation, y is the gyromagnetic ratio, and Bo is the strength of the main magnetic field. In the case of Hydrogen protons, the precessional frequency is 4.26MHz for a magnetic field strength of 0.1Tesla. This precessional frequency of rotation is the resonant frequency of the protons. A resistive, permanent, or cryostat magnet provides the strong, homogeneous static magnetic field.
Here's an analysis of the provided text, focusing on the acceptance criteria and study information:
Key Takeaway: The provided document (K961876) describes a "Revised RF Transmit Coil" for an MRI system. This is a 510(k) submission, which typically focuses on demonstrating substantial equivalence to a predicate device rather than presenting a de novo study with acceptance criteria and performance data like one would find for a novel AI/software medical device.
Therefore, much of the requested information regarding acceptance criteria, specific performance metrics, sample sizes for test/training sets, expert adjudication, MRMC studies, or standalone performance studies is not present in this document. The submission is primarily a descriptive summary of the device's function, scientific concepts, physical/performance characteristics, and intended use, asserting its technological characteristics are "Identical to the Predicate Device."
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Table of Acceptance Criteria and Reported Device Performance
Acceptance Criteria Reported Device Performance Not explicitly stated in the document. For a 510(k) submission, acceptance criteria are generally implied by demonstrating substantial equivalence to a predicate device. This often involves showing that the new device does not raise new questions of safety or effectiveness, and performs as intended. Specific quantitative metrics for sensitivity, specificity, accuracy, or other clinical performance are typically not part of this type of submission for a hardware component unless it fundamentally changes the diagnostic imaging capabilities in a way that is not comparable to the predicate. Instead, the focus is on physical and performance characteristics being equivalent or improved without adverse impact. The core acceptance criterion seems to be "improved RF Field Uniformity" and "technological characteristics identical to predicate." The document states: "The AIRIS RF Transmit Coil offers improved RF Field Uniformity at the edge of the Imaging Volume to accommodate larger patients." Beyond this qualitative statement, no specific quantitative performance metrics or a direct comparison against concrete acceptance criteria are provided.
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Sample sizes used for the test set and the data provenance
- Test Set Sample Size: Not applicable / Not provided. This document describes a hardware component (RF transmit coil) for an MRI machine, not a software algorithm that would typically use a "test set" in the context of AI or diagnostic performance studies. The evaluation implicitly refers to the performance of the MRI system with the new coil.
- Data Provenance: Not applicable. There is no mention of data-driven experiments with human subjects or retrospective/prospective data collection for performance evaluation in the way an AI algorithm would be evaluated. The "performance" assessment appears to be based on engineering design and bench testing demonstrating improved RF field uniformity.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts
- Not applicable. Ground truth, in the context of diagnostic accuracy, is not established for this type of hardware submission. The document discusses "diagnostic determination" by a "trained physician" for the overall MR system, but this is the general clinical use case, not a specific ground truth establishment for a study of the coil itself.
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Adjudication method for the test set
- Not applicable. There is no test set or adjudication process described.
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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
- Not applicable. This document pertains to an MRI hardware component, not an AI or software algorithm. Therefore, an MRMC study related to AI assistance would not be relevant here.
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If a standalone (i.e., algorithm only without human-in-the-loop performance) was done
- Not applicable. This is not an algorithm.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Not applicable. For a hardware device like an RF coil, "ground truth" would typically relate to its physical properties and RF field characteristics (e.g., measured uniformity, power output) rather than diagnostic accuracy against pathology. These technical specifications are implicitly evaluated against engineering standards and the performance of the predicate device.
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The sample size for the training set
- Not applicable. There is no software algorithm being trained; therefore, no training set is mentioned or implied.
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How the ground truth for the training set was established
- Not applicable. As there is no training set, no ground truth for a training set was established.
§ 892.1000 Magnetic resonance diagnostic device.
(a)
Identification. A magnetic resonance diagnostic device is intended for general diagnostic use to present images which reflect the spatial distribution and/or magnetic resonance spectra which reflect frequency and distribution of nuclei exhibiting nuclear magnetic resonance. Other physical parameters derived from the images and/or spectra may also be produced. The device includes hydrogen-1 (proton) imaging, sodium-23 imaging, hydrogen-1 spectroscopy, phosphorus-31 spectroscopy, and chemical shift imaging (preserving simultaneous frequency and spatial information).(b)
Classification. Class II (special controls). A magnetic resonance imaging disposable kit intended for use with a magnetic resonance diagnostic device only is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9.