(81 days)
Anatomical Region: Head, body, extremity, spine, neck, TMJ, Knee
Nuclei excited: Hydrogen
Diagnostic Use: 2D and 3D imaging, Contrast Media, MR Vascular Imaging
The 8.5CD Upgrade for MRT-35A adds a new sequence and software enhancements to the existing MRT-35A software version.
The provided document describes an upgrade to an existing Magnetic Resonance Imaging (MRI) device, the MRT-35A, with the new version 8.5CD. This upgrade primarily introduces a new 2D Time-Of-Flight (TOF) sequence and software enhancements for improved image reconstruction in Fast Spin Echo (FSE) sequences.
Here's an analysis of the acceptance criteria and the study information based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state formal "acceptance criteria" for the device performance in terms of diagnostic accuracy or clinical utility. Instead, it details the device specifications and highlights the enhancements introduced by the 8.5CD upgrade compared to the previous 8.0CD version. The "reported device performance" refers to the capabilities and specifications of the upgraded system.
| Acceptance Criteria (Implied/Specified) | Reported Device Performance (8.5CD Upgrade) |
|---|---|
| Magnetic Field Strength | 0.35 Tesla (Static Field) |
| RF Power Deposition | 0.34 W/kg |
| Rate of Change of Magnetic Field | 6.83 Tesla/sec Axial, 6.69 Tesla/sec Transverse |
| Acoustic Noise Levels | L-peak: 101.6 db (peak impulse sound pressure) |
| L-eq: 86.5 db (time integral of a-weighted sound pressure) | |
| New 2DTOF Sequence Availability | Provided as "2D ANGIO TOF" (Seq #27) with Min Thick 2.0mm and Flow Comp (FC), and optional walking presat (superior or inferior). |
| Image Reconstruction (FSE) | Improved image reconstruction to reduce subtle acquisition artifacts previously found in TE=20 FSE sequences. |
| Clinical Benefit (2DTOF) | Allows image acquisitions of vascular structures with reduced motion artifacts. |
| Clinical Benefit (FSE) | Image quality is improved for Fast Spin Echo TE=20 (4 and 7 echo). |
| Signal-to-Noise (SNR) | Sample phantom images and clinical images were presented for all new sequences. SNR for each phantom image was given. Clinical studies were presented for all new sequences. (No specific SNR value stated as a criterion). |
| Slice Thickness | 0.8 mm to limits of FOV and sequence. |
| Interslice Spacing | 0 mm minimum. |
| Acquisition Matrix | 256x32 to 256x256 in steps of 1. |
| Display Matrix | 512x512. |
| Image Acquisition Time | 3 seconds for fluoro acquisitions typical, 6 minutes for 4 NEX FSE typical. |
| Hardware Configuration Changes | Version 8.5CD does not change the configuration of hardware for the MRT-35A. |
| Software Feature Changes | Version 8.5CD does not introduce new software features to the MRT-35A. |
2. Sample Size for Test Set and Data Provenance
The document states: "Sample phantom images and clinical images were presented for all new sequences. Signal-to-noise ratios for each phantom image was given. Clinical studies were presented for all new sequences."
- Sample Size for Test Set: Not specified, other than "sample phantom images and clinical images." The exact number of patients or images used in these "clinical studies" is not provided.
- Data Provenance: Not explicitly stated. Given that the manufacturer is "TOSHIBA AMERICA MRI, INC." located in California, USA, the clinical data would likely be from the USA or collaborating sites. Whether the data was retrospective or prospective is also not mentioned.
3. Number of Experts Used to Establish Ground Truth and Qualifications
The document does not provide any information regarding the number or qualifications of experts used to establish ground truth for the test set. It mentions "clinical studies were presented," implying expert review and interpretation, but details are absent.
4. Adjudication Method
The document does not describe any adjudication method (e.g., 2+1, 3+1, none) for the test set.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No information about an MRMC comparative effectiveness study is mentioned. The document focuses on the technical specifications and general improvements of the device rather than a study comparing human reader performance with and without AI assistance. The described enhancements are for the imaging device itself, not an AI-powered diagnostic aide.
6. Standalone (Algorithm Only) Performance
The device is an MRI machine with software upgrades, not an AI algorithm performing standalone diagnostic tasks. Therefore, a standalone performance study in the context of an AI algorithm is not applicable here. The "performance" refers to the image quality and sequence capabilities of the MRI system.
7. Type of Ground Truth Used
The concept of "ground truth" as typically defined for diagnostic AI (e.g., pathology, outcomes data) is not directly applicable to this document. The "ground truth" in this context would likely refer to:
- Physical Phantom Measurements: For parameters like SNR, slice thickness, uniformity, etc., using known physical standards.
- Qualitative Assessment by Clinicians: For "image quality" improvements and "reduced motion artifacts" in clinical images. This would be based on expert consensus, though the details of how this consensus was achieved are not provided.
8. Sample Size for Training Set
This information is not provided. As this is an upgrade to an MRI device and not an AI model requiring a separate "training set" in the machine learning sense, this question is not directly applicable. The software enhancements would have been developed and refined using internal R&D data and potentially prior versions' clinical data.
9. How Ground Truth for Training Set Was Established
Not applicable as this is an MRI device upgrade, not an AI model with a distinct training set. The development of the sequence and reconstruction algorithms would involve engineering specifications, phantom studies, and possibly iterative clinical feedback, but not a formally established "ground truth" for a training set in the AI paradigm.
§ 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.