(75 days)
The Medrad Quad T/L Spine Coil is a receive only coil intended to be used in MRI Scanner Systems for imaging of the thoracic and lumbar regions of the spine anatomy.
The Medrad Quad T/L Spine Coil is intended for use only under the supervision of a physician who is trained in the field of Diagnostic Magnetic Resonance Imaging.
The Medrad Quad T/L Spine Coil is a receive only coil designed to enhance the MR Imaging of the thoracic and lumbar regions of the spine anatomy.
The provided text describes the 510(k) premarket notification for the Medrad Quad T/L Spine Coil. It focuses on demonstrating substantial equivalence to a predicate device, as the proposed device is essentially identical to the predicate with a change in branding (from GE to Medrad).
Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Signal-to-Noise Ratio (SNR) | A Signal to Noise Ratio (SNR) study was conducted to generate a comparison between the proposed Medrad Quad T/L Spine coil and the predicate GE Quad T/L Spine Coil. The document implies that the comparison showed sufficient equivalence, though specific numerical results are not provided. The conclusion states that based on SNR results, the .5T and 1.0T coils "will produce similar clinical image results." |
| Image Uniformity | The Medrad Quad T/L Spine Coil was evaluated using NEMA Standards to characterize the non-uniformity of the proposed coil. Contours of the images obtained with the coil were constructed for the axial image, sagittal image. The implication is that the uniformity met acceptable standards, likely similar to the predicate. |
| Geometric Distortion | None. The device contains slightly magnetic materials, but they are positioned to ensure "no observable distortion of the static magnetic field is present." This implies the device meets the criterion of not introducing geometric distortion. |
| Transmit RF Field [B1] Distortion | Analysis of the electrical design and blocking network demonstrates that "no significant currents are induced." "No artifacts of any type were observed during imaging." This indicates the device meets the criterion of not introducing B1 distortion. |
| Resolution, Slice Thickness, and Contrast | These parameters "are not affected by the use of a surface coil and were not separately tested." The acceptance criterion here is that the coil should not negatively impact these inherent MRI system parameters. The assumption is that because the coil is "receive only" and mechanically/electrically identical to the predicate, these parameters remain unaffected. |
| Clinical Effectiveness | Clinical images for the proposed 1.5T Quad T/L Spine Coil were provided to "demonstrate the clinical effectiveness." Based on these results and the SNR results for the .5T and 1.0T coils, Medrad concludes that all proposed coils "will produce similar clinical image results." This surrogate endpoint of "similar clinical image results" combined with direct clinical images for one model serves as the criterion for clinical effectiveness. |
| Patient Contacting Materials | All materials used are the same as the GE Quad T/L Spine coil (Predicate device). Medrad, Inc. certifies that the patient contacting materials and formulations for the proposed Medrad Quad T/L Spine Coils are unchanged. This implies the biocompatibility and safety of materials are maintained, relying on the predicate's established safety profile. |
| Mechanical and Electrical Identity | The proposed device and the predicate device are stated to be "Mechanically and electrically identical." This is a fundamental acceptance criterion for demonstrating substantial equivalence based on the nature of the change (labeling/branding only). |
| Overall Substantial Equivalence | The ultimate acceptance criterion is that the device is substantially equivalent to a legally marketed predicate device. The conclusion explicitly states: "The proposed device is deemed by Medrad to be substantially equivalent." The FDA letter confirms the finding of substantial equivalence. |
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly state the numerical "sample size" for the performance tests in terms of number of patients or scans.
- SNR Study: "A Signal to Noise Ratio(SNR) study was conducted..." No specific number of acquisitions or phantoms is mentioned.
- Image Uniformity: "The Medrad Quad T/L Spine Coil was evaluated using NEMA Standards..." No specific number of images or phantoms.
- Clinical Evaluation: "Clinical images for the proposed 1.5T Quad T/L Spine Coil have been provided with this submission..." It does not specify how many images or from how many patients.
Data Provenance: The document does not explicitly state the country of origin or whether the data was retrospective or prospective. Given the nature of a 510(k) for a branding change, it's highly probable many of these tests were conducted internally by Medrad on phantoms and potentially healthy volunteers, rather than a large-scale clinical trial. The "clinical images" for the 1.5T are likely from a limited number of cases.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
The document does not mention the use of experts to establish ground truth in the context of radiologists or similar clinical reviewers for image quality. The assessment of image quality (SNR, uniformity, distortion) appears to be based on engineering and NEMA standards rather than expert consensus on clinical findings. The "clinical images" were simply used to "demonstrate clinical effectiveness," implying they were reviewed, but not by a panel establishing ground truth in a diagnostic sense for a new algorithm.
4. Adjudication Method for the Test Set
No adjudication method is described. This is expected given that the studies primarily focus on physical and electrical device performance (SNR, uniformity, distortion) and a direct comparison to a known predicate which is mechanically and electrically identical. The "clinical images" are for demonstration, not for a diagnostic performance study requiring adjudication of expert readings.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No MRMC comparative effectiveness study was done or mentioned. This is a device modification submission (branding change for an existing device), not a new diagnostic algorithm requiring an MRMC study to compare human performance with and without AI assistance.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Not applicable. This device is a passive, receive-only MR coil. It is a hardware component, not an algorithm, and therefore does not have a "standalone" or "human-in-the-loop" performance in the context of an AI/software device.
7. Type of Ground Truth Used
The "ground truth" for this device's performance is primarily based on:
- Physical and Electrical Measurements against Engineering Standards: For SNR, Image Uniformity (NEMA Standards), Geometric Distortion, and RF Field Distortion, the "ground truth" is adherence to established engineering principles and measurement techniques to ensure the coil performs as expected and identically to the predicate.
- Identity to Predicate Device: The core "ground truth" establishing substantial equivalence is the mechanical and electrical identity of the proposed device to the already-cleared predicate device.
- Clinical Images: For clinical effectiveness, the "ground truth" is implied by the satisfactory appearance and interpretability of the "clinical images," demonstrating that the coil functions appropriately in a clinical setting to acquire images of the spine.
8. Sample Size for the Training Set
Not applicable. This is a hardware device (MR coil), not a machine learning model. Therefore, there is no "training set."
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no training set for a hardware device.
§ 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.