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Use of the Magnes 2500 WH is indicated for the patient whose physician believes that information about the magnetic fields produced by that patient's brain and information about the location of the sources of those magnetic fields could contribute to diagnosis or therapy planning.

The Magnes 2500 WH biomagnetometer (hereafter "Magnes 2500 WH") comprises a magnetic sensor for detecting and measuring the magnetic fields produced by the human brain, along with the auxiliary equipment required to perform the measurements in a conventional medical facility environment and to display the results of the measurements to physicians in a variety of ways. The sensor utilizes an array of superconducting magnetic field pickup coils arranged in such a manner as to sense the magnetic fields over the portion of the skull enclosing the brain. For each such coil, a superconducting quantum interference device (SQUID) is used to detect the current induced in that coil by the brain magnetic field and produce a voltage proportional to the magnetic flux change. Conventional electronic and computer circuitry is used to amplify, filter, digitize, store and display the result of the measurement. The sensor includes an insulated reservoir of liquid helium as a refrigerant for cooling the superconducting components - pickup coils, SQUIDs, and interconnecting leads - to temperatures below their superconducting transition temperature. Heat is conducted from these superconducting elements along thermally conductive pathways into the helium reservoir. Provided as part of the Magnes 2500 WH biomagnetometer are the following ancillary items: Magnetically shielded room, comprised primarily of nickel-rich alloy and aluminum sheeting, to provide shielding from environmental sources of magnetic or ff noise. Manually operated non-magnetic gantry to place the sensor over the head of the patient in either a seated or supine position. Non-magnetic patient table with hydraulic elevation, to support the patient securely in either seated or supine position. Non-magnetic patient monitoring and communication devices, including video monitor, intercom, and head motion detector. Head shape and head position measurement system, to provide head shape and location relative to the sensor for data modeling and display. Computer workstation, operator console, and software to control system operation, data acquisition and storage, and data analysis and display. Sensory stimulus systems, to provide stimulation of the patient's somatosensory, auditory, y sumulus systems, to pro for magnetic measurement of evoked response.

The acceptance criteria and study proving the device meets them are described below. However, it's important to note that this 510(k) summary focuses on demonstrating substantial equivalence to a predicate device rather than presenting a performance study against predefined acceptance criteria for a novel device. The "acceptance criteria" here are implicitly linked to the performance of the predicate device.

1. Table of Acceptance Criteria and Reported Device Performance

performance in detecting brain magnetic fields with magnetometer coils as the predicate's gradiometer coils. | -   **Bench Test 1 (Dipolar Source in Head Phantom):** Waveforms measured with Magnes 2500 WH (magnetometer coils) and Magnes II (gradiometer coils) showed no significant difference for both normal alignment and presence of artificial magnetic noise conditions. 

• Bench Test 2 (Dipole Localization in Head Phantom): No significant difference in localized dipole parameters (physical location, strength, or orientation) between Magnes 2500 WH and Magnes II in multiple trials. |
  | - Refrigeration Method: No material difference in
  sensitivity. | - Fixed Source Sensitivity Test: Sensitivity of various channels in Magnes 2500 WH (solid thermal conduction) showed no material difference when the helium reservoir was full versus nearly empty. This was compared to a similar test on a Magnes II (direct immersion). |
  | - Head Position Measurement: No significant difference
  in relative location of reference points. | - Head Position Measurement Test: Repetitive measurements of reference points on a head phantom using the Magnes 2500 WH's new positioning system and the Magnes II's system showed no significant difference in the relative locations of the reference points. |

Study Details:

Since this is a 510(k) for substantial equivalence, the "study" described is a series of non-clinical comparative tests.

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

• Sample Size: Not explicitly stated in terms of number of patients or distinct head phantom configurations. The tests involved:
  • A head phantom with a dipolar source.
  • A fixed magnetic source.
  • A head phantom for position measurement.
• Data Provenance: The tests were non-clinical bench tests conducted by the manufacturer, Biomagnetic Technologies, Inc. This implies a controlled laboratory environment. The country of origin of the data is therefore the USA (where the company is based). The data is prospective in the sense that these tests were performed specifically for this 510(k) submission.

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

• Not applicable (N/A). For these non-clinical bench tests demonstrating substantial equivalence, the "ground truth" was established by the physical setup of the experiments (e.g., a known dipolar source in a head phantom, a fixed magnetic source, reference points on a head phantom). The comparison was against the performance of a predicate device, not against expert interpretation of a complex clinical scenario.

4. Adjudication Method for the Test Set

• Not applicable (N/A). There was no human interpretation or adjudication required for the output of these technical performance tests. The comparison was based on quantitative measurements and waveform analysis.

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, an MRMC comparative effectiveness study was not done. This 510(k) pertains to a non-AI medical device (a biomagnetometer) and focuses on substantial equivalence based on technological characteristics, not on the impact of AI assistance on human reader performance.

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

• Yes, in essence, standalone performance was assessed. The tests directly evaluated the physical performance of the Magnes 2500 WH hardware and its signal processing against the Magnes II. This is a "device-only" evaluation in a controlled setting, which can be considered analogous to standalone performance for a software algorithm, though it's for hardware.

7. The Type of Ground Truth Used

• The "ground truth" in these comparative non-clinical tests was established by:
  • Known physical parameters: The characteristics of the dipolar source in the head phantom (strength, location, orientation).
  • Known physical configuration: The fixed magnetic source and reference points on the head phantom.
  • Comparative measurement: The performance of the predicate device (Magnes II) served as the benchmark for "truthfulness" in some comparisons.

8. The Sample Size for the Training Set

• Not applicable (N/A). This device is not an AI/ML algorithm that requires a training set. It is a measurement device where its operation is based on fundamental physics and engineering principles, not learned patterns from data.

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

• Not applicable (N/A). As stated above, there is no training set for this type of device.

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