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The Nexstim Navigated Brain Therapy (NBT®) System 2 is indicated for the treatment of Major Depressive Disorder in adult patients who have failed to achieve satisfactory improvement from prior antidepressant medication in the current episode.

The Nexstim Navigated Brain Therapy (NBT®) System is a non-invasive, repetitive transcranial magnetic stimulation (rTMS) system that delivers repetitive pulsed magnetic fields of sufficient magnitude to induce neural action potentials in the prefrontal cortex to treat the symptoms of major depressive disorder (MDD) without inducing seizure in patients who have failed one (1) antidepressant medication.

The Nexstim NBT System 2 is used for patient treatment by prescription only and must be operated by a trained medical professional. It can be used in both inpatient and outpatient settings including physician's offices and clinics, psychiatric hospitals, and general medical/surgical hospitals with psychiatric units.

The Nexstim NBT System 2 consists of a group of devices designed to localize the stimulation site in the brain and deliver rTMS stimulation using controlling and interpretive software. Operational control of the Nexstim NBT System 2 is provided by the software.

The Nexstim NBT System 2 combines magnetic resonance imaging-based (MRI-based), three dimensional (3D) localization of cortical motor areas of the brain with non-invasive TMS and simultaneous electromyography (EMG) measurement to locate areas of the brain that are capable of evoking muscle responses when stimulated, and to locate the target area for depression therapy.

The Nexstim NBT System 2 software is used to import a patient's MR image slices to generate an accurate 3D model of the patient's head which can be electronically peeled back to reveal the anatomical structures of the brain.

The provided text is a 510(k) Premarket Notification from the FDA for the Nexstim Navigated Brain Therapy (NBT) System 2. This document is primarily focused on demonstrating substantial equivalence to a previously cleared predicate device, rather than providing a detailed clinical study demonstrating the device's efficacy against specific, quantitative acceptance criteria in the manner one might see for a diagnostic AI.

The "acceptance criteria" discussed in this document are primarily related to technical specifications and regulatory compliance for a neurostimulation device, and the "study" proving it meets them refers to verification and validation activities against these technical standards, and a direct comparison to a predicate device.

Therefore, many of the requested sections (e.g., sample size for test set, number of experts for ground truth, MRMC study, training set details) are not applicable or not explicitly detailed within this type of regulatory submission because the approval is based on demonstrating equivalence in technical characteristics and safety/performance, not on a novel clinical efficacy trial with specific, quantitatively defined "acceptance criteria" for a diagnostic algorithm's performance on a test set.

However, I can extract and present the information that is available and relevant to your request based on the provided document.

Acceptance Criteria and Device Performance (Based on Technical Equivalence)

The acceptance criteria here are implicitly met by demonstrating that the proposed device (Nexstim NBT® System 2 (Proposed Device)) is substantially equivalent to the predicate device (Tonica Electronik A/S Mag Vita TMS Therapy System w/ Theta Burst Stimulation ([K173620](https://510k.innolitics.com/search/K173620))) and the previously cleared version of its own device (Nexstim Navigated Brain Therapy (NBT®) System 2 ([K171902](https://510k.innolitics.com/search/K171902))), particularly for the new Intermittent Theta Burst (iTBS) Protocol. The "performance" is demonstrated by showing that the key technical characteristics are the same or comparable, and that compliance with relevant standards has been achieved.

Note: The performance here is primarily about technical specifications rather than statistical performance metrics (like sensitivity, specificity, AUC) for a diagnostic output, as this is a therapeutic rather than a diagnostic device, and the submission is focused on substantial equivalence.

Study Details:

1. Sample Size used for the Test Set and Data Provenance:

   • This submission is a 510(k) premarket notification primarily demonstrating substantial equivalence for a therapeutic device (rTMS system for MDD), specifically adding a new treatment protocol (iTBS).
   • The document does not describe a specific clinical "test set" or study in the sense of an independent data set used to evaluate a diagnostic algorithm's performance. Instead, it relies on:
     • Bench testing and verification/validation activities against technical standards (listed in the table above).
     • Comparison to a legally marketed predicate device (Tonica Electronik A/S / Mag Vita TMS Therapy System w/ Theta Burst Stimulation, K173620), which already had the iTBS protocol cleared.
     • Comparison to its own previously cleared device version (K171902) to show that existing features remain unchanged or are consistent.
   • Therefore, there's no "sample size" for patients/cases in a typical AI/diagnostic study sense within this document for a "test set." The document focuses on technical and safety equivalence.

2. Number of Experts used to establish the Ground Truth for the Test Set and Qualifications of those Experts:

   • Not applicable in the context of this 510(k) submission. This is not a study assessing the diagnostic performance of an AI against expert ground truth. The "ground truth" for this device's function is its ability to deliver the specified magnetic stimulation parameters accurately and safely, and for the clinical efficacy of this type of therapy for MDD, which is established by larger clinical trials for the class of devices and specific protocols (e.g., those reviewed for the predicate device).

3. Adjudication Method for the Test Set:

   • Not applicable. No external "test set" requiring expert adjudication is described.

4. 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:

   • Not applicable. This device is a therapeutic rTMS system, not a diagnostic AI system intended to assist human readers. Therefore, an MRMC study is not relevant to this submission.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • Not applicable in the traditional sense of a diagnostic algorithm. The device itself (the Nexstim NBT System 2) operates based on software control and delivered TMS pulses. Its "standalone performance" is implicitly demonstrated through the various verification and validation activities (software, electrical safety, EMC, bench testing), which confirm it functions according to its predetermined specifications, independently of a human operator, in terms of delivering the therapy. The clinical use always involves a trained medical professional.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

   • The "ground truth" for this submission is multi-faceted, aligning with the nature of a therapeutic device and a substantial equivalence review:
     • Technical Specifications: The core "ground truth" for the device itself is its adherence to specified physical parameters (magnetic field intensity, frequency, pulse length, etc.) and compliance with recognized industry standards (IEC, ISO, FDA guidance) for safety and performance. This is verified through bench testing and engineering evaluations.
     • Predicate Device Performance: The "ground truth" for clinical effectiveness of the iTBS protocol is based on the established performance of the predicate device (K173620) which already had clearance for this protocol. The submission argues that since the proposed device's technical characteristics for delivering iTBS are equivalent, its clinical effect would also be equivalent.
     • Clinical Effectiveness of rTMS for MDD: The broader "ground truth" for the treatment of Major Depressive Disorder with rTMS is established by clinical outcomes data from pivotal studies that led to the approval of the predicate device and other similar rTMS systems for MDD. This document refers to the established indication for use for rTMS in MDD, rather than presenting new clinical trial data for this specific device's efficacy beyond the established equivalence.

7. The sample size for the training set:

   • Not applicable. This document describes a medical device seeking 510(k) clearance, not an AI/machine learning algorithm undergoing training with a specific dataset. The software is developed and verified via traditional software engineering processes, not "trained."

8. How the ground truth for the training set was established:

   • Not applicable. As there is no "training set" for an AI/ML algorithm, no ground truth needed to be established in that context.

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Nexstim Navigated Brain Therapy (NBT®) System 2 is indicated for the treatment of Major Depressive Disorder in adult patients who have failed to achieve satisfactory improvement from prior antidepressant medication in the current episode.

The Nexstim NBT® System 2 is a repetitive transcranial magnetic stimulation (rTMS) system that delivers repetitive pulsed magnetic fields of sufficient magnitude to induce neural action potentials in the prefrontal cortex to treat the symptoms of major depressive disorder (MDD) without inducing seizure in patients who have failed one antidepressant medication.

The Nexstim NBT System 2 is used for patient treatment by prescription only and must be operated by a trained medical professional. It can be used in both inpatient and outpatient settings including physician's offices and clinics, psychiatric hospitals, and general medical/surgical hospitals with psychiatric units.

The Nexstim NBT System 2 consists of a group of devices designed to localize the stimulation site in the brain and deliver rTMS stimulation using controlling and interpretive software. Operational control of the Nexstim NBT System 2 is provided by the software.

The Nexstim NBT System 2 combines magnetic resonance imaging-based (MRI-based), three-dimensional (3-D) localization of cortical motor areas of the brain with non-invasive TMS and simultaneous electromyography (EMG) measurement to locate areas of the brain that are capable of evoking muscle responses when stimulated, and to locate the target area for depression therapy.

The Nexstim NBT System 2 software is used to import a patient's MR image slices through standard DICOM communication protocols, and generates an accurate 3-D model of the patient's head which can be "peeled back" to reveal the anatomical structures of the brain.

The provided text describes the Nexstim Navigated Brain Therapy (NBT) System 2, a repetitive transcranial magnetic stimulation (rTMS) system for treating Major Depressive Disorder. However, it does not contain specific acceptance criteria, reported device performance metrics in a table, or details of a study directly proving the device meets acceptance criteria in the format requested for AI/ML devices.

The document is a 510(k) summary, which focuses on demonstrating substantial equivalence to predicate devices rather than providing detailed clinical trial results or performance metrics against pre-defined acceptance criteria typical for novel AI/ML device evaluations.

It primarily details:

• Device Description and Intended Use
• Technology Comparison with predicate devices (showing similar technical characteristics)
• Summary of Performance Testing related to general medical device standards (sterilization, biocompatibility, software verification, electrical safety, EMC, and usability).

There are two studies mentioned under "Performance Testing – Bench Verification," which relate to the device's methods for determining motor threshold (MT) and coil localization, comparing them to manually-determined methods. However, these are not presented as a "study that proves the device meets the acceptance criteria" in the context of clinical effectiveness or diagnostic accuracy, which is often what is implied by "acceptance criteria" and "reported device performance" for AI/ML enabled devices.

Given the information provided, here's what can be extracted and what is missing:

Acceptance Criteria and Study Details (Based on provided text)

1. A table of acceptance criteria and the reported device performance

The document does not explicitly state acceptance criteria or device performance in the context of clinical efficacy or diagnostic accuracy in a table format. Instead, it refers to compliance with various medical device standards and internal specifications. The "Performance Testing - Bench Verification" section mentions two studies that compare specific aspects of the device's function (MT determination and coil localization) to other methods, suggesting "no significant statistical difference" or "substantially equivalent results" as outcomes for these functional aspects, which could be interpreted as meeting an implicit acceptance criterion of equivalence for these specific functions.

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

The document lists "Study Comparing Nexstim's Electromyography-Determined Motor Threshold (MT) Method to the Manually-Determined MT Method (O'Reardon, 2007; Pridmore, 1998)" and "Study Comparing Nexstim's Navigated Coil Localization Method to Manually-Determined Method (Ahdab, 2010)".

• Sample Size: Not specified in the provided text for either study.
• Data Provenance: Not specified in the provided text for either study (e.g., country of origin, retrospective or prospective). The studies are referenced by author and year, suggesting they are published literature or internal studies referring to published methods.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

Not specified in the provided text. For the MT and coil localization comparison studies, "manually-determined methods" serve as a reference, implying human expertise, but details are not given.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

Not specified in the provided text.

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

Not applicable. The Nexstim NBT System 2 is not an AI-assisted diagnostic device where "human readers" would be involved in interpreting data with or without AI. It is a therapeutic device (rTMS system). The listed comparative studies focus on functional aspects of the device (MT determination and coil localization) rather than comparative effectiveness studies in the context of improving human reader performance.

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

Not applicable in the typical sense of standalone AI performance. The device is a system operated by a trained medical professional. The functional comparisons (MT determination, coil localization) are aspects of the system's operation that are being compared to manual methods.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)

• For the Motor Threshold (MT) determination, the ground truth appears to be established by a "manually-determined MT method" (implied expert determination, likely involving visual and/or manual assessment of muscle twitch).
• For the Navigated Coil Localization, the ground truth is a "manually-determined method (moving the coil 5.5 cm anteriorly from the motor cortex)," which is a standard anatomical targeting approach.

8. The sample size for the training set

Not applicable/specified. The document does not describe the device as an AI/ML system that undergoes "training." The software development process is mentioned, but without details on a training set for model development.

9. How the ground truth for the training set was established

Not applicable/specified, as there is no mention of an AI/ML "training set."

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