SubtleHD (1.x)
K243250Subtle Medical, Inc. · cleared 2025-02-12 · product code QIH · Radiology
Premarket evidence — what FDA accepted
source quote (p.6)
“SubtleHD is Software as a Medical Device (SaMD) consisting of a software algorithm that enhances images taken by MRI scanners.”
source quote (p.6)
“SubtleHD software implements an image enhancement algorithm using a convolutional neural network based filtering. Original images are enhanced by running through a cascade of filter banks, where thresholding and scaling operations are applied. A single neural network is trained for adaptive noise reduction and sharpness increase. The parameters within the neural network were obtained through an image-guided optimization process. Additional nonlocal mean based denoising and unsharp masking based sharpening filters are applied to the deep learning processed image.”
source quote (p.9)
“The algorithm will be locked with fixed model parameters prior to release.”
source quote (p.9)
“SubtleHD has a Predetermined Change Control Plan (PCCP), which details planned device modifications, the associated methodology to develop, validate, and implement those modifications, and an assessment of the impact of those modifications.”
Validation studies (4)
Bench
sample size not stated
Bench
n=471 cases
endpoints: L1 loss; SSIM; PSNR
Retrospective clinical
sample size not stated
endpoints: Denoising (SNR); Sharpness (Image Intensity Change); Sharpness (Image Intensity Change for Brains); Sharpness and Over Smoothing (Gradient Entropy)
Reader study (MRMC)
n=410 images
endpoints: Signal-to-Noise Ratio; Overall Image Quality / Diagnostic Confidence; Visibility of Small Structures; Artifact Introduction
Reported performance (0 observations)
FDA source did not state a quantitative performance metric — non-reporting is itself the signal.
Each value carries its own analysis unit and task — never compare or pool across devices. Source: 510(k) summary PDF.
Predicate network
Postmarket — what happened after clearance
Recall and MAUDE counts are product-code-level (reports aren't reliably attributable to one device); a recall is shown as device-attributed only when the recall record itself lists this clearance number. Signals are descriptive observables with sources — never a judgment that the device is unsafe or drifting. Snapshot 2026-07-08.
Reimbursement — how devices like this got paid
Not yet tracked — no payment pathway indexed for this clearance (the reimbursement corpus is a growing seed set).
Applicable FDA guidance — what the submission is measured against
FDA guidance documents and guiding principles applicable to 510(k) AI/ML devices in the Radiology panel. A curated reference index, not legal or regulatory advice — each item states its own status, and a draft is never binding.
- Final guidanceRadiology-specific2022-09Computer-Assisted Detection Devices Applied to Radiology Images and Radiology Device Data - Premarket Notification [510(k)] Submissions
Radiology CADe/CADx · Software premarket content
Original July 2012; current database date reflects a Sept 2022 reissue. Governs CADe device 510(k) content.
- Final guidanceRadiology-specific2022-09Clinical Performance Assessment: Considerations for Computer-Assisted Detection Devices Applied to Radiology Images and Radiology Device Data in Premarket Notification (510(k)) Submissions
Radiology CADe/CADx
Original July 2012, revised 2020; current database date Sept 2022. Covers standalone and reader-study performance assessment for CADe.
- Final guidanceRadiology-specific2022-06Technical Performance Assessment of Quantitative Imaging in Radiological Device Premarket Submissions
Quantitative imaging · Radiology CADe/CADx
Final (June 2022). Relevant to devices outputting quantitative imaging measurements.
- Final guidance2026-01Clinical Decision Support Software
Clinical decision support · SaMD (general)
New final guidance issued Jan 2026, superseding the Sept 2022 version; narrows the device-CDS scope. Applies to software that informs clinical management.
- Final guidance2026-01General Wellness: Policy for Low Risk Devices
SaMD (general) · Clinical decision support
Revised final (Jan 2026); now addresses noninvasive products estimating physiologic parameters (SpO2, BP, glucose). Reshapes the device / non-device line for AI wellness features.
- Final guidance2025-09Computer Software Assurance for Production and Quality Management System Software
SaMD (general) · Postmarket
Final (Sept 2025). Covers software used in production/QMS (incl. ML development-pipeline tooling), superseding Section 6 of the 2002 GPSV — not device software functions themselves.
- Final guidance2025-06Cybersecurity in Medical Devices: Quality Management System Considerations and Content of Premarket Submissions
Cybersecurity · Software premarket content
Reissued June 2025 (retitled 'Quality Management System', was Sept 2023 'Quality System'); adds coverage of FD&C Act §524B cyber devices.
- Final guidance2024-12Marketing Submission Recommendations for a Predetermined Change Control Plan for Artificial Intelligence-Enabled Device Software Functions
Predetermined Change Control Plan · AI/ML lifecycle · Software premarket content
Final (Dec 2024). Supersedes the April 2023 AI/ML PCCP draft.
- Final guidance2023-10Electronic Submission Template for Medical Device 510(k) Submissions
Software premarket content
eSTAR has been mandatory for 510(k)s since Oct 2023 — operationally unavoidable, though not AI-specific.
- Final guidance2023-08Off-The-Shelf Software Use in Medical Devices
Software premarket content · SaMD (general)
Final (Aug 2023). Applies when a device incorporates off-the-shelf software components (common in ML stacks).
- Final guidance2023-06Content of Premarket Submissions for Device Software Functions
Software premarket content · SaMD (general)
Final (June 2023); replaced the May 2005 'Software Contained in Medical Devices' guidance. Documentation level drives the software content of the submission.
- Final guidance2022-09Policy for Device Software Functions and Mobile Medical Applications
SaMD (general) · Clinical decision support
Current version Sept 2022. Frames which software functions FDA regulates as devices.
- Final guidance2021-10De Novo Classification Process (Evaluation of Automatic Class III Designation)
De Novo pathway
Final (Oct 2021), issued with the De Novo final rule. Most relevant to first-of-a-kind devices without a predicate (DEN-numbered clearances).
- Final guidance2016-12Postmarket Management of Cybersecurity in Medical Devices
Cybersecurity · Postmarket
- Final guidance2002-01General Principles of Software Validation
SaMD (general) · Software premarket content
Still active except Section 6 (superseded Sept 2025 by the Computer Software Assurance final guidance).
- Draft guidance2025-01Artificial Intelligence-Enabled Device Software Functions: Lifecycle Management and Marketing Submission Recommendations
AI/ML lifecycle · Software premarket content · Transparency
Draft as of July 2026 (published Jan 2025); finalization is on CDRH's FY2026 agenda but not yet published. Treat as FDA's stated direction, not a binding expectation.
- Draft guidance2024-08Predetermined Change Control Plans for Medical Devices
Predetermined Change Control Plan · Postmarket
Draft (Aug 2024) extending PCCPs beyond AI to all devices under FD&C §515C; not final as of July 2026.
- Guiding principles2024-06Transparency for Machine Learning-Enabled Medical Devices: Guiding Principles
Transparency · AI/ML lifecycle
- Guiding principles2023-10Predetermined Change Control Plans for Machine Learning-Enabled Medical Devices: Guiding Principles
Predetermined Change Control Plan · AI/ML lifecycle
FDA/Health Canada/MHRA joint principles (Oct 2023); companion to the GMLP and Transparency principles.
- Guiding principles2021-10Good Machine Learning Practice for Medical Device Development: Guiding Principles
AI/ML lifecycle · SaMD (general)
FDA/Health Canada/MHRA joint principles (Oct 2021). Foundational, not a binding guidance; IMDRF issued a related GMLP document Jan 2025.
Applicability is derived from the device's FDA advisory panel and pathway — cross-cutting guidances apply to every AI/ML device; panel-specific ones are flagged. Titles, dates, and links verified against fda.gov as of July 2026.