FDA 510(k) Premarket Notification
The FDA pathway for medical devices substantially equivalent to predicates already legally marketed. The dominant clearance route for medical-imaging capital equipment in the United States — most CT, MRI, ultrasound, X-ray, mammography (FFDM era), and nuclear-medicine systems clear via 510(k), not full PMA. Cleared devices receive a "K-number" (e.g., K243017) used as the canonical regulatory identifier.
How it works
- Manufacturer submits documentation showing substantial equivalence to a legally marketed predicate device — same intended use, same or substantially equivalent technological characteristics, no new questions of safety or effectiveness.
- FDA reviews with a target review time of 90 days; complex submissions take longer in practice.
- If cleared, the device can be marketed. The legal language is "cleared", not "approved" — the distinction matters in due diligence and marketing claims.
- Predicates can be daisy-chained — a device cleared in 2024 might cite a predicate cleared in 2018 that itself cited a 2012 predicate. The chain matters for understanding lineage.
Subtypes
- Traditional 510(k) — full submission with comprehensive comparative documentation.
- Special 510(k) — for modifications to the manufacturer's own previously cleared device; faster review.
- Abbreviated 510(k) — references FDA-recognized consensus standards or guidance documents.
Software changes
Imaging-equipment software upgrades commonly clear via follow-on 510(k)s. A scanner purchased in 2018 with K-number 18xxxxx may have a 2024 software upgrade cleared under K-number 24xxxxx. Both K-numbers are part of the device's regulatory footprint.
Why it matters to buyers
- Every system has one or more K-numbers in its regulatory history. The K-number identifies the cleared configuration — a refurb sold as "current FDA-cleared" must reference a current K-number, not an obsolete predicate.
- Software-license tier changes sometimes correspond to follow-on 510(k)s; configuration claims should match cleared use.
- AI / SaMD components (e.g., recon software like TrueFidelity / AiCE / ADMIRE, CAD applications, AI-triage tools) frequently have their own K-numbers separate from the imaging hardware.
- Reverse-due-diligence — search the FDA 510(k) database (free at FDA.gov) by manufacturer and device to understand the regulatory footprint of a candidate purchase.
- K-number for cited predicates is a red flag if expired / withdrawn. Verify the chain.
- NEVER use fabricated K-numbers — the database is authoritative; imprecise citation is worse than no citation.
What 510(k) doesn't do
- Doesn't establish efficacy data the way a PMA does.
- Doesn't cover post-market real-world performance — that's the job of MAUDE adverse-event reporting and FDA recalls.
- Doesn't replace state-level radiation registration (state X-ray-machine registration) or accreditation (ACR).