Filing activity in this dataset is concentrated among a handful of large medical imaging manufacturers whose portfolios include long-running RF coil, gradient coil and reconstruction filings. Corporate structures matter here: several of the top holders operate through linked entities, such as the Toshiba and Toshiba Medical Systems pairing that shares 575 families. Rather than a single dominant assignee, the picture is a concentrated top group followed by a long tail of smaller filers, so checking both a parent company and its medical-systems subsidiary is necessary for a complete picture.

No. Filings peaked at 670 in 2019, sat at 623 in 2017, and had fallen to 492 by the 2022 midpoint before dropping further toward 26 in 2026. That trajectory is flat to declining rather than growing, though the most recent one to two years will always look artificially low because publication typically lags filing by about 18 months. The honest read is a mature filing base rather than an expanding one.

G01R (electric and magnetic measurement) and A61B (diagnosis and surgery) carry the bulk of the record volume, at 10,752 and 7,403 respectively, and between them define the core claim space for scanner hardware and diagnostic system integration. G06T (image data processing) is a smaller but distinct layer covering reconstruction and acceleration software. Smaller subclasses like A61N, H01F, G06N and G01N mark adjacent or emerging areas rather than core territory.

US10921401B2, granted 2021-02-16 to GE Precision Healthcare LLC, covers a flexible, lightweight anterior RF coil array for MRI systems built from coil loops with integrated capacitors, per-loop coupling electronics, and a shared interface board, described as a high-density or high-definition anterior array. It is a hardware-level coil claim rather than a broad system claim, so its blocking effect is specific to that coil architecture rather than to RF coil arrays in general. Anyone designing a competing anterior array should check this claim combination specifically rather than assuming general freedom to operate in coil design.

The thinnest filed categories relative to the core G01R and A61B volumes are material analysis integration (G01N, 321 records), magnet and inductor hardware (H01F, 404 records) and electrotherapy-linked MRI (A61N, 472 records). These are areas where claim density is low rather than technically impossible, which is a meaningfully different signal than a crowded field. Recent-year momentum also shows several established filers, including Philips, pulling back sharply, which can create room for new claims even in adjacent core areas.