United States Patent 5,558,094: Scope, Claims, and US Patent Landscape for Perfluorocarbon Microbubble Ultrasound Imaging

United States Patent 5,558,094 covers a US method of ultrasound imaging that uses “free gas microbubbles” or dispersed microbubble formulations made from specific fluorine-containing/perfluorocarbon gases with a defined “Q coefficient” threshold (Q > 30, comparing persistence versus air), followed by ultrasound scanning of an organism (animal or human). The claim set is narrow in the chemistry-to-Q requirement and broad in the imaging step, since it does not limit transducer type, scan modality, imaging target, or specific microbubble size distribution.

What is the core claim construction?

The patent’s claim language centers on four building blocks:

Ultrasound imaging method: includes “performing an ultrasound scan.”
Microbubbles as the contrast mechanism: “introducing a collection of free gas microbubbles” or “preparing a dispersion” and “infusing free gas microbubbles.”
Chemistry with persistence metric: the microbubble gas (a “biocompatible chemical”) must have Q > 30 where Q compares microbubble persistence in water relative to air.
Enumerated gas list: multiple claims specify exact perfluorocarbon gases (and one claim recites “perfluorocarbon” or “fluorine containing”).

Defined term that drives infringement risk: Q coefficient

The claims define:

Q = (persistence of microbubbles of said gas in an aqueous solution) / (persistence of microbubbles of air in said solution)
The claimed gases must satisfy Q > 30.

This Q requirement functions as a functional chemistry gate: even if a later formulation uses the “right” gas, it still must meet the persistence criterion as defined by the patent.

What do independent claims cover, and what do they not cover?

Claim 1 (independent)

Scope

Method of ultrasound imaging
Introduces a collection of free gas microbubbles of a biocompatible chemical
The chemical must have Q > 30
Performs an ultrasound scan

Not covered

No requirement for targeting a specific organ or lesion.
No requirement for ultrasound mode (contrast mode, harmonic imaging) or machine parameters.
No requirement for formulation details beyond “free gas microbubbles” and Q.

Practical read Claim 1 can be asserted against any use of the claimed microbubble gases that meet the Q persistence threshold, regardless of imaging protocol, so long as the accused product/practice uses microbubbles that fall within the patent’s “Q > 30” definition.

Claim 14 (independent-like, but method with dispersion + human scan)

Scope

Prepares a dispersion of the biocompatible chemical in aqueous solution
Infuses “free gas microbubbles” of that chemical into an organism
Performs a human ultrasound scan
Requires Q > 30 by the same definition

Not covered

No required administration route, dosing amount, or bubble size distribution.
No specific scanning technique beyond “human ultrasound scan.”

Practical read Claim 14 is tighter than claim 1 because it requires:

a dispersion-preparation step, and
a human imaging context.

Claim 15 and Claim 16 (dependent but operationally distinct)

Claim 15: providing a contrast agent comprising dodecafluoropentane to an organism; ultrasound scanning
Claim 16: providing dodecafluoropentane to a human; ultrasound scanning

These claims shift from “Q>30 and free gas microbubble introduction” into a “contrast agent comprising [specific gas]” framing. However, because the patent’s specification (as reflected in claim phrasing) ties these gases to the Q>30 microbubble persistence concept, enforcement still tends to require that the supplied agent actually behaves as the claimed ultrasound contrast agent using the defined bubble persistence.

Claim 17

Provides an agent where the chemical is from a specified member group:
- hexafluoropropylene
- octafluoropropane
- octofluoro-2-butene
- hexafluoro-2-butyne
- hexafluorobuta-1,3-diene
- octafluorocyclobutane
- decafluorobutane
To an animal, then ultrasound scan

Claim 17 is the broadest animal-side enumerated set.

What is the enumerated gas coverage (claims 2-10 and 13)?

The claims list perfluorocarbon and fluorinated gases that are intended to form microbubbles with Q > 30 persistence in aqueous solution.

Claim-by-claim gas list

Claim	Coverage type	Chemical specificity
2	Dependent on Claim 1	Hexafluoropropylene
3	Dependent on Claim 1	Octafluoropropane
4	Dependent on Claim 1	Hexafluoroethane
5	Dependent on Claim 1	Octafluoro-2-butene
6	Dependent on Claim 1	Hexafluoro-2-butyne
7	Dependent on Claim 1	Hexafluorobuta-1,3-diene
8	Dependent on Claim 1	Octafluorocyclobutane
9	Dependent on Claim 1	Decafluorobutane
10	Dependent on Claim 1	Dodecafluoropentane
11	Dependent on Claim 1	“Fluorine containing” (generic)
12	Dependent on Claim 1	“Perfluorocarbon” (generic)
13	Independent-like, but enumerated	Selected from: hexafluoropropylene, octafluoropropane, octafluoro-2-butene, hexafluoro-2-butyne, hexafluorobuta-1,3-diene, octafluorocyclobutane, decafluorobutane, dodecafluoropentane

Notes on the list

Claims 2-10 explicitly call out specific molecules.
Claims 11-12 broaden chemical class language but remain constrained by Claim 1’s Q > 30 requirement (because they are dependent on Claim 1).

How does the patent treat “microbubbles” and “biocompatible chemical”?

The claims use two distinct microbubble concepts:

“Free gas microbubbles of a biocompatible chemical”
- Claims 1 and 14 use the “free gas microbubbles” construct.
- Claim 14 adds the step of preparing an aqueous dispersion, then infusing free gas microbubbles into the organism.
“Ultrasound contrast agent comprising [gas]”
- Claims 15-17 frame the invention as providing a contrast agent with specified gases to an organism (or human/animal), followed by ultrasound scanning.

The “biocompatible” qualifier is present in Claim 1 and in the dispersion claim. The gas enumerations in later dependent claims are consistent with that biocompatibility requirement but do not add new functional constraints beyond what is inherited from Claim 1 and claim 14.

What is the actionable infringement surface?

Likely infringement theories

Direct performance: A provider administers the gas microbubble contrast agent (with Q > 30 microbubble persistence in aqueous solution) and then performs ultrasound imaging.
Product use infringement: The relevant “use” is the method of ultrasound imaging; companies selling such agents into clinical practice can be exposed if the method steps are performed.

How competitors can avoid this patent (scope-limiting reading)

Given the claim text provided, avoidance routes would need to attack at least one of:

the Q > 30 persistence definition (chemistry performance),
the use of the specific enumerated fluorinated gases, or
the presence of “free gas microbubbles” rather than a different bubble-generation mechanism not matching the claim phrasing.

The claims do not appear to require bubble shells, surfactants, targeting ligands, or ultrasound hardware details, so those are unlikely to be effective “design-around” levers on their own.

What does the “US drug patent” label imply for the landscape?

Despite the user prompt calling it a “drug patent,” the asserted claim set is a method of ultrasound imaging using microbubble gas contrast agents. In a US landscape sense, this places the patent in a common cluster with:

microbubble ultrasound contrast formulations,
gas selection and microbubble persistence performance,
clinical imaging methods for ultrasound contrast.

This claim set competes most directly against patents that claim:

perfluorocarbon gas microbubbles for ultrasound contrast,
microbubble longevity/persistence metrics,
methods of ultrasound contrast imaging in animals/humans.

US patent landscape: where 5,558,094 fits and what it blocks

A full landscape analysis requires precise bibliographic details, prosecution history, and citation networks for US 5,558,094 and related families. Those details are not included in the prompt. Under the constraints here, the analysis below stays strictly on claim-level scope and its implications for competitive patent positioning, without inventing citation relationships.

Claim-based “blocking” categories

The patent blocks at least three categories of later filings/practices:

Gas selection with a persistence threshold
- Any ultrasound microbubble contrast method that uses fluorinated gases whose persistence in aqueous solution yields Q > 30, risks overlapping Claim 1 and Claim 14.
Enumerated gas microbubble contrast
- Enumerated agents (e.g., dodecafluoropentane) are specifically claimed as contrast agents provided to humans/animals (Claims 15-17 and Claim 10 and Claim 13).
Human imaging methods
- Claim 14 and Claim 16 expressly cover human scan settings. Even if an agent is used outside the US or in research, performance in human ultrasound imaging triggers risk.

Competitive product designs likely to be evaluated against these claims

Perfluorocarbon microbubble gas formulations with evidence of improved aqueous persistence.
Any ultrasound contrast agent marketed or used with the fluorinated gases enumerated.
Clinical protocols that administer those agents and then perform ultrasound imaging.

Claim-to-portfolio mapping for diligence

For licensing, clearance, or freedom-to-operate screening, the key is to map an accused practice into the claim elements:

Element checklist derived from Claims 1 and 14

Element	Present in claim text	What diligence must confirm
Ultrasound imaging method	“performing an ultrasound scan”	Imaging performed after administration
Animal/human scope	“animal” (Claim 1) and “human” (Claim 14)	Intended subject
Biocompatible chemical	“biocompatible chemical”	Gas and formulation plausibly biocompatible
Free gas microbubbles	“introducing a collection of free gas microbubbles”	Administration results in free gas microbubbles (not a different mechanism)
Q > 30 metric	Q coefficient defined and threshold	Persistence ratio vs air in aqueous solution
Enumerated gases	Dependent/enumerated claims	Whether gas is one of the claimed fluorinated/perfluorocarbon molecules

Element checklist derived from Claims 15-17

Element	Present in claim text	What diligence must confirm
Contrast agent provided	“providing a biocompatible ultrasound contrast agent comprising…”	Agent composition includes the specific gas
Specific gas	dodecafluoropentane (Claims 15-16) or listed gases (Claim 17)	Chemical identity
Scan performed	“subjecting…to an ultrasound scan”	Ultrasound imaging follows administration
Human/animal	human in Claims 16 and 14; animal in Claims 1 and 17	Intended patient/subject class

Key takeaways on scope breadth and risk

Claim breadth is driven by the Q threshold (Q > 30), not by imaging technique or target anatomy.
Enumerated perfluorocarbon gases are repeatedly singled out, especially dodecafluoropentane, which appears in two “providing contrast agent comprising…” claims (Claims 15 and 16).
Human use exposure is direct via Claim 14 (human scan after dispersion and infusion) and Claim 16 (dodecafluoropentane provided to human; scan).
Animal use exposure is direct via Claim 1 (Q>30 and free gas microbubbles; ultrasound scan) and Claim 17 (specific gas list to animal).

Key Takeaways

US 5,558,094 claims ultrasound imaging methods that rely on free gas microbubbles from fluorine-containing/perfluorocarbon gases with Q > 30 aqueous persistence versus air.
The enforceable scope is strongest where the accused practice uses the enumerated gases, especially dodecafluoropentane, in human or animal ultrasound contrast workflows.
Imaging mechanics, transducer type, and target anatomy are not claim-limiting in the provided claim text, which concentrates risk analysis on gas identity and microbubble persistence (Q).
Freedom-to-operate clearance should treat the Q coefficient as the central claim element for Claim 1 and Claim 14.

FAQs

1) What does “Q coefficient greater than 30” mean in practice?

It is defined in the claims as the ratio of microbubble persistence in aqueous solution for the claimed gas to the persistence of air microbubbles in the same medium, and the method requires Q > 30.

2) Does the patent require a specific ultrasound imaging mode?

The provided claims require “performing an ultrasound scan” but do not specify imaging mode or hardware parameters, so those details are not claim-limiting based on the claim text provided.

3) Which gas appears most prominently in the claim set?

Dodecafluoropentane appears in dependent gas claims (Claim 10), the enumerated selection list (Claim 13), and contrast-agent providing claims for both animals/organisms (Claim 15) and humans (Claim 16).

4) Is the patent limited to animal models or does it cover human use?

It covers both. Claim 1 is written for “animal.” Claim 14 and Claim 16 explicitly cover “human ultrasound scan.”

5) Are “perfluorocarbon” and “fluorine containing” generic enough to cover any fluorinated gas?

They broaden beyond the enumerated list, but in the provided claims they are dependent on Claim 1, so they still incorporate the Q > 30 requirement and “biocompatible chemical” limitation.

References

[1] United States Patent 5,558,094 (claims provided in prompt): “A method of ultrasound imaging” using microbubbles of biocompatible fluorine-containing/perfluorocarbon gases with Q > 30 persistence, including specific gas embodiments and human/animal imaging steps.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	191346	⤷ Start Trial
Australia	2550392	⤷ Start Trial
Australia	3995997	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,558,094

Summary for Patent: 5,558,094