(70 days)
Cirrus Open is an open, 0.2 Tesla MR imaging device intended to provide a physician with physiological and clinical information obtained non-invasively using magnetic resonance imaging (MRI) without the use of ionizing radiation. Cirrus Open is indicated for use as a diagnostic imaging device to produce images in the transverse, sagittal, coronal and oblique scan planes of a patient's head. The images produced by Cirrus Open reflect the spatial distribution of protons (hydrogen nuclei). The magnetic properties that determine the appearance of images are proton density, spin-lattice relaxation time (T1), spinspin relaxation time (T2) and T2* relaxation time. Additional contrasts that can be used include magnetization transfer and diffusion. When interpreted by a trained physician, these images provide information that can be useful in diagnosis.
Cirrus Open is a Magnetic Resonance Imaging (MRI) System that utilizes a 0.2 Tesla permanent magnet to acquire 2D single and multi slice, and 3D volume images of a patient's head in the transverse, sagittal, coronal and oblique scan planes using pulse sequences such as spin echo, gradient echo, inversion recovery, driven equilibrium and free procession acquisitions. The open, fourpost magnet system helps maintain a patient's connection to the external environment and offers MR personnel convenient access to the patient from all four directions. The patient bed system is manually operated by a push or pull from the hand of the MR personnel. The bed top has six, numbered discreet locating positions for placement of the radio frequency (RF) coil. By inserting the bed into the magnet to one of its six, numbered snap-in (detent) locations, that matches the numbered position of the RF coil placement, the patient region of interest is conveniently placed at magnet iso-centre. The MR console station allows the operator to enter patient registration information, and to select, edit and execute the required scan protocols. The MR console operator can also store, review and print image data.
The provided text describes MRI-TECH's Cirrus Open device, which is a Magnetic Resonance Imaging (MRI) System that utilizes a 0.2 Tesla permanent magnet to acquire 2D single and multi-slice, and 3D volume images of a patient's head. The document is a 510(k) Summary for regulatory submission.
Here's an analysis of the acceptance criteria and study information provided:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Specific Criteria/Standard | Reported Device Performance | Comments |
|---|---|---|---|
| Safety | SAR (Specific Absorption Rate) limits | SAR levels are below the limits for normal MRI operation | Testing performed in accordance with IEC 60601-2-33 |
| Safety | dB/dt (Rate of change of magnetic field) limits | dB/dt levels are below the limits for normal MRI operation | Testing performed in accordance with IEC 60601-2-33; higher gradient slew rate than predicates but still within limits. |
| Safety | Acoustic Noise levels | Acoustic noise levels are below the limits for normal MRI operation | Testing performed in accordance with IEC 60601-2-33 |
| Performance | NEMA MRI performance test standards (general) | Performance test results are similar to those for the predicate devices | Supports claim of substantial equivalence. |
| Performance | Image Quality | Produces images reflecting spatial distribution of protons, T1, T2, T2* relaxation times, and additional contrasts like magnetization transfer and diffusion. | System is capable of acquiring multi-slice 2D and 3D volume images of the head in various planes (transverse, sagittal, coronal, oblique) using various pulse sequences. |
| Performance | Functionality | Device performs tasks of generating and processing NMR signals to create images of anatomical structure. | Console allows operator to enter patient registration, select/edit/execute scan protocols, store/review/print image data. |
| Substantial Equivalence | To predicate devices (GE SIGNA PROFILE 0.2 T, HITACHI AIRIS MATE) | Indications for use are the same as predicate devices, with the exception of being limited to head imaging. Technological characteristics (magnet strength, gradient system, RF coil, console) are similar or improved while remaining within safety and performance limits. | Differences in magnet design, gradient slew rate, and RF coil configuration were evaluated and deemed not to negatively impact safety or effectiveness. |
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly state the sample size used for a clinical test set involving patients or data. The testing primarily refers to "NEMA MRI performance test standards" and "IEC 60601-2-33 Particular requirements for the safety of magnetic resonance equipment for medical diagnosis." These standards typically involve phantom testing and engineering evaluations rather than clinical patient studies for initial device clearance.
Therefore:
- Sample size for the test set: Not explicitly stated as human patient data. Performance testing appears to be based on physical measurements and phantoms.
- Data provenance: Not explicitly stated. The context suggests engineering and phantom-based testing rather than patient data from a specific country or retrospective/prospective study.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
This information is not provided in the document. Since the testing primarily focuses on technical safety and performance standards (NEMA, IEC), the "ground truth" would be defined by the specifications of these standards and the accuracy of the measurement equipment, rather than expert consensus on clinical images in a testing set.
4. Adjudication Method for the Test Set
This information is not provided. As noted above, the testing described is primarily technical compliance to standards, not a clinical image review study requiring adjudication.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done based on the provided text. The document describes technical performance testing against standards and comparison to predicate devices, not an evaluation of human reader performance with or without AI assistance.
6. If a Standalone Study (Algorithm Only Without Human-in-the-Loop Performance) Was Done
The device itself is a Magnetic Resonance Diagnostic Device, not an AI algorithm. Therefore, the concept of a "standalone (i.e., algorithm only without human-in-the-loop performance)" study does not directly apply in the context of this device's regulatory submission. The performance assessment is of the imaging system itself.
7. The Type of Ground Truth Used
The ground truth used for the reported studies is primarily the technical specifications and limits defined by NEMA MRI performance test standards and IEC 60601-2-33.
- For safety aspects (SAR, dB/dt, acoustic noise), the ground truth is the maximum permissible limits set by IEC 60601-2-33.
- For performance aspects, the ground truth is the expected measurements for various parameters (e.g., spatial resolution, signal-to-noise ratio) as defined by NEMA standards, and comparison to the performance of predicate devices.
8. The Sample Size for the Training Set
This information is not applicable/not provided. The Cirrus Open is a hardware MRI device, not a machine learning or AI algorithm that requires a "training set" in the conventional sense. Its functionality is based on established physics principles of MRI.
9. How the Ground Truth for the Training Set Was Established
This information is not applicable/not provided for the reasons stated above.
§ 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.