FDA warning letter: retraining an AI model or moving it to the cloud needs a new 510(k)
FDA's device center sent a warning letter, dated September 1, 2026, to O.N. Diagnostics after a March 2026 inspection found the company distributed version 3.0.0 of its VirtuOst VFA software — which reads spine CT scans to grade vertebral fractures for osteoporosis management — without a new 510(k) clearance. FDA said the update introduced a new machine-learning model for vertebral landmarking and moved the product from a desktop application to a web-based architecture, and that either change alone could affect how the device performs across different patients and imaging equipment. The agency deemed the device adulterated and misbranded and told the company to stop distributing version 3.0.0 until it submits a new clearance.
Why it's notable: It's one of FDA's clearest public statements that retraining an AI algorithm or re-architecting a cleared device for the cloud is a regulatory event requiring fresh premarket review, not a routine update — a precedent that bears on any practice or health system relying on continuously updated AI diagnostic software.