(83 days)
mDIXON is a software option intended for use on Intera 1.5T, Achieva 1.5T and Achieva 3T. MR Systems. It is indicated for magnetic resonance imaging of the chest, abdomen and pelvis. mDIXON is a multipoint (echo) method for 3D clinical imaging with the possibility to reformat into multiple planes (axial, sagittal and coronal). mDIXON provides improved fat suppression, increased scan speed in addition and/or an improved signal-to-noise relative to other current 3D volumetric fat suppressed imaging methods
The modified-DIXON (mDIXON) sequence is a novel two and multi-point method for 2D and 3D water-fat magnetic resonance imaging. mDIXON is a modification of previous DIXON implementations due to the unrestricted echo-time (TE) approach. This allows more freedom in protocol optimization resulting in more efficient (faster) scanning and an increase in signal to noise (SNR). Additionally, it provides a technique for improved fat suppression (in comparison to other current 3D volumetric fat suppressed imaging methods.) While the primary use is for torso imaging, it may also be applicable to other anatomies requiring in- and opposed-phase, water-only, and/or fatonly imaging. While the current 3D volumetric fat suppressed technique (e-THRIVE) is an imaging method, mDIXON is a multi echo sequence with multiple gradient echo readouts. Phase and amplitude of complex data acquired at different echo times are used to separate the water and fat signals. The separation is made possible by the chemical shift difference between water and fat. The resultant images can be reconstructed to produce "water-only" images, "fat-only" images and in-phase/opposed-phase images (synthesized from the acquired multiecho images). The fat suppression is enhanced especially at the edges of larger fields of view due to the mDIXON reconstruction algorithm and its use of the chemical shift difference between water and fat.
Acceptance Criteria and Study for Philips mDIXON Software Option (K102344)
The provided document describes the Philips mDIXON software option for MR systems. It highlights the device's improvements over existing 3D volumetric fat-suppressed imaging methods, specifically regarding fat suppression, scan speed, and signal-to-noise ratio (SNR). However, it does not explicitly state specific numerical acceptance criteria or detail a formal clinical study to prove these criteria.
Instead, the documentation focuses on:
- Verification and Validation (V&V) Testing: Stating that "mDIXON verification and validation tests were performed on the complete system relative to the requirement specification and risk management results. Corresponding test results are included in this submission." This implies that internal tests were conducted against pre-defined requirements, but the specifics of these requirements and their quantitative thresholds are not provided in this summary.
- Substantial Equivalence: The primary strategy for regulatory clearance (510(k)) relies on demonstrating substantial equivalence to predicate devices (INTERA 1.5T, ACHIEVA 1.5T, ACHIEVA 3.0T MR systems Release 2.5-series and the IDEAL software option). The core argument is that the mDIXON option does not introduce new risks and maintains the safety and effectiveness profile of these predicate devices, while offering improved performance.
Given the information, a table of explicit acceptance criteria and corresponding performance cannot be created directly as they are not explicitly mentioned in this summary. The assessment revolves around the general claims of improvement and the maintenance of safety and effectiveness as per predicate devices.
Based on the provided text, here's an analysis of the requested information:
1. Table of Acceptance Criteria and Reported Device Performance
Note: The document does not explicitly list quantitative acceptance criteria for mDIXON. The performance claims are qualitative improvements over current 3D volumetric fat-suppressed imaging methods. The "acceptance" is implied by the successful completion of V&V testing and the FDA's determination of substantial equivalence.
| Acceptance Criteria Category | Specific Acceptance Criteria (as implied) | Reported Device Performance (as stated) |
|---|---|---|
| Fat Suppression | Improved fat suppression compared to other current 3D volumetric fat-suppressed imaging methods. | "mDIXON provides improved fat suppression...especially at the edges of larger fields of view" |
| Scan Speed | Increased scan speed compared to other current 3D volumetric fat-suppressed imaging methods. | "increased scan speed" |
| Signal-to-Noise Ratio (SNR) | Improved SNR relative to other current 3D volumetric fat-suppressed imaging methods. | "and/or an improved signal-to-noise" |
| Safety & Effectiveness | No new risks introduced compared to predicate devices; maintain overall safety and effectiveness. | "mDIXON software option does not induce any other risks than already indicated for their predicate devices with the same safety and effectiveness." |
| Compliance | Systems comply with international and relevant FDA standards. | "The INTERA 1.5T, ACHIEVA 1.5T and ACHIEVA 3.0T systems comply with the international IEC and ISO standards identified in the submission." |
2. Sample size used for the test set and the data provenance
- Sample Size: Not specified. The document only mentions "mDIXON verification and validation tests were performed," but no details on the number of cases, subjects, or data points in the test set.
- Data Provenance: Not specified (e.g., country of origin, retrospective/prospective).
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
- Not specified. The document does not describe the involvement of human experts or ground truth establishment for specific test cases. The V&V process likely involved technical assessments rather than clinical evaluations by experts described here.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set
- Not specified. There is no mention of an adjudication process for a test set in the summary provided.
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
- No, a MRMC comparative effectiveness study is not mentioned. This document pertains to a software option for an MR system, enhancing image acquisition and reconstruction, not a diagnostic AI tool for interpretation. Therefore, a study comparing human reader performance with and without AI assistance is not described or relevant for this type of device based on the provided information.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
- The mDIXON is itself an "algorithm only" (software option) that generates images. The "standalone" performance
is assessed by its ability to produce images with improved characteristics (fat suppression, scan speed, SNR) compared to existing methods. The validation of these characteristics is stated to have been performed through V&V tests, but no specific study details are given beyond this general statement. Essentially, the device is the algorithm, and its performance is evaluated on the quality of the output images.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Not explicitly stated. Given the nature of the device (image acquisition/reconstruction), the "ground truth" for the V&V tests would likely be related to objective measures of image quality (e.g., quantitative fat suppression metrics, SNR measurements, acquisition time) compared against a reference standard or expected performance, rather than clinical ground truth like pathology or expert consensus on disease presence.
8. The sample size for the training set
- Not applicable/Not specified. The mDIXON sequence is a physics-based magnetic resonance imaging technique, not a machine learning model that requires a "training set" in the conventional sense. Its development would involve engineering and physics principles rather than data-driven training.
9. How the ground truth for the training set was established
- Not applicable. See point 8.
§ 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.