(193 days)
The X-trodes System M is intended for prescription use only in the home or healthcare facility to acquire, record, transmit and display physiological signals from adult patients. The X-trodes System M acquires, records, transmits, and displays electroencephalogram (EEG), electrooculogram (EOG), electrocardiogram (ECG), and/or electromyogram (EMG), and accelerometer and gyroscope signals. The X-trodes System M only acquires and displays physiological signals, no claims are being made for analysis of the acquired signals with respect to the accuracy, precision, and reliability.
The X-trodes System M combines hardware, firmware, and software to acquire the following physiological signals: physiologic signal amplifier (EEG), electrooculography (EOG), surface electromyography (sEMG), electrocardiography (ECG), and accelerometer and gyroscope signals. It acquires physiological data through a data acquisition unit connected to electrode arrays patches, applied by a technician or patient to the patient. The data is recorded and transmitted to a cloud where it is converted to an EDF (European Data Format) format, suitable for analysis by third party software.
Here's a detailed breakdown of the acceptance criteria and the study that proves the X-trodes System M meets them, based on the provided FDA 510(k) summary:
Acceptance Criteria and Device Performance
The provided document focuses on demonstrating substantial equivalence to predicate devices rather than establishing specific, quantified clinical acceptance criteria for standalone diagnostic accuracy or effectiveness against a clinical gold standard. The "acceptance criteria" can be inferred from the "comparison of technological features" table (Table 1) and the discussion items (Sections 9.1-9.7), where the X-trodes System M's performance characteristics are compared to those of the predicate devices and relevant IEC standards.
The closest thing to a directly stated performance acceptance criterion, beyond comparisons to predicates and standards, is for the clinical study's primary endpoint:
- Primary Study Endpoint (Infered Acceptance Criterion): A high proportion of interpretable readings of each ExG signal (ECG, EEG, EMG, EOG) by the X-trodes System M that are equivalent to those of the reference device, with lower 98.75% confidence intervals higher than 60%.
| Feature/Metric | Acceptance Criteria (from Predicate comparison/Standards) | Reported Device Performance (X-trodes System M) | Comments/Reference |
|---|---|---|---|
| Full Scale Input Range | Sufficient for EEG (10-100 µV), ECG (10 µV-5 mV), and EMG (0-10 mV) | ± 12.5 mV | Well within required range for all modalities (Sec. 9.1) |
| A/D Conversion | Sufficient resolution to capture physiological signals (e.g., 16 bits for ECG for many cleared devices, 24 bits for predicates) | 16 bits | Adequate resolution, especially for AC-coupled signals (Sec. 9.2) |
| Sampling Frequency (Rate) | At least 220% of max sampled frequency (Nyquist) | 4000 Hz/Channel | Exceeds required sampling rate for its broader frequency range (Sec. 9.3) |
| Frequency Response | Linear between 0.1 and 100 Hz (EEG/EOG Predicate), 0.01 Hz ~ 350 Hz (-3 dB) (ECG Predicate) | 0.35 Hz ~ 700 Hz (-3 dB) | Supersedes predicates' ranges (Table 1) |
| Input Impedance | ≥10 MΩ (EEG Predicate), ≥100 MΩ (ECG/EMG Predicate), ≥2.5 MΩ (IEC60601-2-25) | ≥10 MΩ | Complies with IEC standard and comparable to predicate (Sec. 9.4) |
| DC Offset Voltage | Tolerant to DC offset (e.g., ±960mV for ECG predicate) | +3000mV, -1000mV ±5% | Broader range, more tolerant to DC offset (Sec. 9.5) |
| Noise | 90 dB (EEG Predicate), ≥140 dB (ECG Predicate), >100 dB (EMG Predicate) | >95 dB at 60 Hz/50Hz | Complies with IEC60601-2-26 EEG and IEC60601-2-25 ECG standards (>90dB) (Sec. 9.7) |
| Primary Clinical Endpoint | Agreement proportion for each ExG signal with reference device, with lower 98.75% CI > 60% | ECG: 89.36%, EEG: 97.37%, EMG: 96.15%, EOG: 95.24%. All lower 98.75% CIs > 60%. | Primary endpoint successfully met (Sec. 11) |
| Secondary Clinical Endpoint | Consistency and reliability of RMS values | RMS values obtained and compared | Demonstrates consistency and reliability (Sec. 11) |
Study Details
The document describes a clinical study to demonstrate the X-trodes System M's performance compared to an FDA-cleared clinical electrophysiology device.
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Sample Size used for the test set and the data provenance:
- Sample Size: 55 subjects.
- Data Provenance: The study was a "case-controlled study" conducted in a "clinic environment." The subjects were "adults who had been referred by either a neurologist for an electrophysiology test in the last 5 years." This suggests the data is prospective, collected specifically for this study, and likely from a single or limited number of clinical sites. The country of origin is not explicitly stated, but the applicant's address is Herzliya, Israel, which might imply the study was conducted there or in the US.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The study design describes a comparison against an "FDA-cleared clinical electrophysiology device" (referred to as X8). The "interpretability" and "equivalency" of XTR signals to the reference device were assessed.
- The document does not explicitly state the number or qualifications of experts used to establish the ground truth or determine the "interpretable readings" and "equivalency" for the test set. It implies the reference device (X8) provided the comparison standard, and then the XTR signals were evaluated against that. It's unclear if independent human experts adjudicated the signals from both devices or if a software-based comparison was used for "equivalency."
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Adjudication method for the test set:
- The document states "The primary study endpoint was the proportion of interpretable readings of each ExG signal by the XTR that are equivalent to those of the reference device."
- The specific adjudication method (e.g., 2+1, 3+1, none) is not detailed in the provided text. It's unclear how "interpretability" and "equivalency" were precisely determined.
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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 multi-reader multi-case (MRMC) comparative effectiveness study was not done. The study was a comparison of the X-trodes System M (the subject device) against another predicate device (X8) and focused on signal acquisition and display, not on the impact of an AI algorithm on human reader performance. The device "only acquires and displays physiological signals, no claims are being made for analysis of the acquired signals with respect to the accuracy, precision, and reliability." Therefore, there is no AI assistance component to measure the effect size for human readers.
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If a standalone (i.e. algorithm only without human-in-the loop performance) was done:
- Yes, in spirit, a standalone performance assessment was conducted for the device's signal acquisition capabilities. The study directly compared the signals acquired by the X-trodes System M to a reference device. It's "algorithm only" in the sense that the device itself acquires and processes the signals for display, and its performance (interpretable readings, RMS values) was directly evaluated without a human-in-the-loop task for diagnosis. However, it's crucial to note that the device does not perform analysis or provide diagnostic output; it just collects and displays signals.
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The type of ground truth used:
- The "ground truth" was established by an FDA-cleared clinical electrophysiology device (X8). The X-trodes System M's acquired physiological signals (EEG, EOG, ECG, EMG) were compared for "interpretable readings" and "equivalency" against the signals simultaneously acquired by the X8 device. This is a comparative ground truth against an established device, rather than a clinical outcome or pathology report.
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The sample size for the training set:
- The document does not provide information on a training set sample size. This makes sense as the device is stated to "only acquires and displays physiological signals, no claims are being made for analysis of the acquired signals," implying it's not an AI/ML-driven device that typically requires a dedicated training set for diagnostic or analytical tasks. The performance evaluation focused on the device's ability to accurately capture and display raw physiological signals.
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How the ground truth for the training set was established:
- As no information on an AI/ML training set is provided (and the device is described as not performing analysis), there is no mention of how ground truth for a training set was established.
§ 882.1835 Physiological signal amplifier.
(a)
Identification. A physiological signal amplifier is a general purpose device used to electrically amplify signals derived from various physiological sources (e.g., the electroencephalogram).(b)
Classification. Class II (performance standards).