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MR Elastography is an optional package for Canon Medical Systems magnetic resonance imaging (MRI) systems. This option allows the user to obtain an image that reflects the stiffness, in kPa, of body tissue such as liver and muscle.

MR Elastography is an optional package for Canon Medical Systems magnetic resonance imaging (MRI) system. This option allows the user to obtain an image that reflects the stiffness of body tissue.

MR Elastography consists of Acoustic Driver System including Active Driver, Passive Driver, QA Phantom and Other parts, TTL trigger converter includes AC adaptor, Manuals and Software (License).

By MRI scanning while applying vibration from the Acoustic Driver System, it is possible to obtain an image that reflects the stiffness of the body tissue in kPa. The sequence to be used with Acoustic Driver System is FE2D or SE-EPI2D. The MRI scanner outputs the following images from the acquired phase image and magnitude image.

• · Wave image
• · Stiffness image (capable of registration and display in color image format)
• · Confidence image (capable of superimposing confidence image on the stiffness image)

The provided text describes the 510(k) submission for Canon Medical Systems' MR Elastography (MZEK-001A) device. Here's an analysis of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample Size Used for the Test Set and Data Provenance

The text states: "The phantoms were scanned 5 times per day, multiple days per scanner, on 2 different 1.5T and 2 different 3T scanners by FE2D and SE-EPI2D techniques."

• Test Set Sample Size: While an exact number of "scans" isn't explicitly given beyond "5 times per day, multiple days per scanner," it indicates a sufficient number of measurements across different scanner types (2x 1.5T, 2x 3T) and scanning techniques (FE2D, SE-EPI2D). The total number of individual phantom measurements would be 5 (scans/day) * X (days) * 4 (scanners) * 2 (techniques). The document implies a robust bench testing setup rather than patient data.
• Data Provenance: The data appears to be from prospective bench testing conducted by Canon Medical Systems, likely in a controlled laboratory environment. The country of origin of the data is not specified, but given the manufacturer is Japan and the US agent is in the US, the testing could have occurred in either location or a combination. The data is synthetic (phantom-based) rather than clinical patient data.

3. Number of Experts Used to Establish Ground Truth and Qualifications

• Number of Experts: Not applicable/not mentioned. The ground truth was established using "Resoundant-provided calibration phantoms having known stiffness values." This indicates a physical phantom with pre-calibrated, known stiffness properties, rather than expert interpretation of images.
• Qualifications of Experts: Not applicable, as expert interpretation was not used for ground truth.

4. Adjudication Method for the Test Set

• Adjudication Method: Not applicable/not mentioned. Since the ground truth was based on physical phantoms with known stiffness values, there was no need for expert adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

• MRMC Study: No, a multi-reader multi-case (MRMC) comparative effectiveness study was not reported. The study focused on the device's ability to accurately measure stiffness against known phantom values, not on human reader performance or improvement with AI assistance.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

• Standalone Performance: Yes, the described testing is akin to a standalone (algorithm only) performance evaluation. The device (hardware and software) outputs stiffness values based on the acquired data, and these values are compared directly against the known stiffness of the phantoms. There is no mention of human interpretation being part of this core performance evaluation. The output stiffness image and confidence image are for user display, but the performance metrics are system-derived.

7. The Type of Ground Truth Used

• Ground Truth Type: The ground truth used was phantom-based with known stiffness values. Specifically, "three Resoundant-provided calibration phantoms having known stiffness values representing the expected clinical range."

8. The Sample Size for the Training Set

• Training Set Sample Size: The document does not provide details on the sample size of any training set. It describes the performance testing of the final device. The software was "based on an estimation algorithm provided by the Mayo Clinic and Resoundant, Inc." and "developed in conjunction with The Mayo Clinic and Resoundant, Inc.," suggesting external development and/or collaboration, but no specifics on training data are given.

9. How the Ground Truth for the Training Set Was Established

• Training Set Ground Truth Establishment: The document does not provide details on how the ground truth for any training set was established. Given the software's origin from Mayo Clinic and Resoundant, Inc., it's plausible they used a combination of phantom data and potentially de-identified clinical data with histopathological correlation for development and training, but this is speculative based on common practice for such devices and not explicitly stated in the provided text.

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MR Elastography is a software option intended for use on Achieva and Ingenia 1.5T and 3.0T MR Systems for producing images representing tissue stiffness of the abdomen area such as liver and muscle. MR Elastography applies an MR acquisition sequence synchronized with an external source of vibration to produce images representing tissue stiffness (in kiloPascals, kPa). The stiffness image production technique also creates an overlay representing the reliability of the stiffness image production algorithm.

The MR Elastography feature consists of a specialized acquisition: a source of acoustic frequency vibration and means to impart that vibration to the scan subject: an image processing step to produce stiffness maps, confidence maps, and wave images; and an analysis tool to evaluate the parametric images created.

The acquisition is based on the Phase Contrast FFE sequence acquired while imparting a known frequency of vibration into the patient. A set of images with controlled phase differences between the acquisition and the mechanical oscillation is created by synchronizing the mechanical driver with the acquisition at different time delays. The vibration source and connecting equipment are provided by Resoundant Inc. as a complete set. Elasticity images are created from the image data generated by this acquisition strategy using an algorithm developed by Resoundant Inc. and The Mayo Clinic. In addition, wave images and confidence overlays are also produced to provide data quality assurance.

The Philips MR Elastography software option is intended for use on Achieva and Ingenia 1.5T and 3.0T MR Systems to produce images representing tissue stiffness of the abdomen area (e.g., liver and muscle). It utilizes an MR acquisition sequence synchronized with an external vibration source to generate stiffness images (in kiloPascals, kPa) and an overlay indicating the reliability of the stiffness image production algorithm.

The acceptance criteria for the device are not explicitly quantified with specific performance metrics in the provided document. Instead, the document describes the successful completion of verification activities to demonstrate functionality and substantial equivalence to predicate devices.

Here's an analysis of the provided information:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample Size Used for the Test Set and Data Provenance

The document does not specify the sample size used for the test set. It mentions "sample images" and "confidence studies" but does not provide details on the number of subjects or images included in these tests. The data provenance is also not explicitly stated in terms of country of origin or whether the studies were retrospective or prospective.

3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications of Experts

This information is not provided in the document. The document mentions an "algorithm developed by Resoundant Inc. and The Mayo Clinic" and that the "MR Elastography software post-processing package was based on an estimation algorithm provided by The Mayo Clinic and Resoundant, Inc." but does not detail the specific involvement of experts in establishing ground truth for testing, nor their qualifications.

4. Adjudication Method for the Test Set

The adjudication method used for the test set is not described in the provided document.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No MRMC comparative effectiveness study is mentioned or referenced in the provided text. The document focuses on demonstrating substantial equivalence to predicate devices and fulfilling functionality and safety requirements.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

The document describes the "MR Elastography" feature as consisting of hardware and software elements, including an "image processing step to produce stiffness maps, confidence maps, and wave images" and an "analysis tool." The "confidence studies" seem to be related to the algorithm's performance in producing repeatable results and differentiating tissue stiffness, which implies a standalone evaluation of the algorithm's output. However, it's not explicitly stated as a formal "standalone" study to evaluate algorithmic performance against a definitive ground truth in a clinical context.

7. The Type of Ground Truth Used

The type of ground truth used is not explicitly specified. The document states that "confidence studies prove that MR Elastography produces repeatable results and can reliably differentiate between tissues of different stiffness," suggesting that some form of reference independent of the device was used to confirm stiffness differentiation, potentially phantoms with known stiffness or other established methods. However, the specific type (e.g., pathology, outcomes data) is not detailed.

8. The Sample Size for the Training Set

The document does not provide any information regarding the sample size used for the training set. It mentions that the algorithm was "developed by Resoundant Inc. and The Mayo Clinic" and that the software was developed "in conjunction with The Mayo Clinic and Resoundant, Inc.," but does not elaborate on the data used during development.

9. How the Ground Truth for the Training Set Was Established

This information is not provided in the document.

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