Patent activity in this field is concentrated at the top: the leading assignee holds 1,140 of the 15,101 records in scope, and the five largest assignees together account for 17.1% of all records. That concentration extends through the ten largest holders, who together hold 23.1% of records, before dropping off sharply into a long tail of smaller filers. This pattern typically means the core compound chemistry and delivery formats are already well defended by a small group, while device and diagnostic-adjacent claims remain more open.

Filings peaked at 623 records in 2020 and had fallen to 348 by 2024, a 39% decline from the 567 filed in 2021. That is a genuine pullback over a three-year span, not a data artefact. However, counts for 2025 and 2026 are still incomplete because publication typically lags actual filing by around 18 months, so it would be premature to describe the field as still declining based on the most recent one or two years alone.

The large majority of records, 61.6% of the 15,101 in scope, carry A61K medicinal preparation classifications, reflecting the field’s roots in contrast compound formulation. Diagnostic and surgical claims (A61B, 18.6%) and therapeutic activity claims (A61P, 18.2%) form a second tier, with delivery devices (A61M, 11.1%) and material testing (G01N, 10.6%) further behind. Because a single patent record can carry several of these classifications at once, the shares add up to more than 100% and describe claim density per class rather than a strict breakdown of the field.