United States Patent US 4,770,183: Scope, Claims, and US Patent Landscape for In Vivo NMR Contrast Dispersoids

US 4,770,183 claims improved in vivo NMR imaging methods using biodegradable superparamagnetic metal oxide particle dispersoids whose particles are engineered for magnetic performance, size control, and short systemic persistence with biodegradation in about 7 days. The claim set splits into two principal technical embodiments: uncoated biodegradable superparamagnetic metal oxide particles (claim 1) and coated biodegradable superparamagnetic metal oxide particles with a biodegradable polymer coat (claims 2 to 8), with extensive dependent-claim narrowing to particle crystallite size, Coulter mean diameter, specific magnetic properties, polymer identity, route of administration, carrier, dose, and anatomical targets.

What is the core claimed invention?

US 4,770,183 is a method claim family centered on one technical thesis:

Administer a contrast-agent dispersoid for NMR image enhancement, where each dispersoid particle:
- is superparamagnetic and biodegradable
- contains one or more biodegradable metal oxide crystals (10 to 500 angstroms per crystal)
- has a Coulter-measured mean diameter (10 to 5000 angstroms, uncoated) or coat-inclusive mean diameter (10 to 5000 angstroms, coated)
- retains in the target organ/tissue long enough to permit imaging but is ultimately biodegraded within about 7 days

The patent draws a bright line between uncoated biodegradable metal oxide dispersoids and coated biodegradable polymer-encapsulated dispersoids, which changes the particle architecture and broadness.

How broad are the two independent claim embodiments (claims 1 and 2)?

Claim 1: Uncoated biodegradable superparamagnetic metal oxide dispersoid (core breadth)

Claim 1 covers:

“An improved method for obtaining an in vivo NMR image” of an organ or tissue in an animal/human subject
improvement = administering as contrast agent:
- effective amount of a dispersoid
- dispersoid comprises uncoated, biodegradable superparamagnetic metal oxide particles in a physiologically acceptable carrier
particle architecture:
- individual particle with one or more biodegradable metal oxide crystals
- crystal diameter: about 10 to about 500 angstroms
- overall mean diameter: about 10 to about 5000 angstroms (Coulter particle size analyzer)
functional profile:
- retention in organ/tissue long enough for imaging
- ultimate biodegradation within about 7 days

This embodiment is broad as to:

the metal oxide, except as limited later by dependent claims (claim 3 specifies iron oxide)
the carrier, except as limited later
the anatomical target, except as limited later
the route, except as limited later

Claim 2: Coated biodegradable superparamagnetic metal oxide dispersoid (structural narrowing, still broad in practice)

Claim 2 covers the same method frame but requires:

dispersoid comprises coated, biodegradable superparamagnetic metal oxide particles
each particle:
- has a superparamagnetic metal oxide core generally surrounded by a biodegradable polymeric coat
- core comprises one or more biodegradable metal oxide crystals: 10 to 500 angstroms
- overall mean diameter inclusive of polymer coat: 10 to 5000 angstroms (Coulter)
same imaging/biodegradation functional profile:
- retention long enough to image
- biodegraded in about 7 days

This embodiment is narrower than claim 1 due to the required polymeric coat, but still broad across:

coat polymer type (dependent claims define preferred lists and subtypes)
coat specifics not fully constrained beyond “biodegradable polymeric coat” unless later narrowed by dependent claims 4 to 8

What do the dependent claims add to the scope (claims 3 to 25)?

Particle material and magnetic performance (claim 3)

Claim 3 narrows claim 1 or 2 to iron oxide particles with specific property set:

crystal diameter: about 50 to about 500 angstroms
surface area: greater than about 75 m²/gram
magnetic saturation: about 5 to about 50 EMU/gram of iron oxide
magnetic squareness: less than about 0.1

Effect on infringement/avoidance: Any product that uses iron oxide particles but does not match all four quantitative constraints falls outside claim 3 while it may still fall within broader method claims 1/2 depending on its particle sizes and biodegradation profile.

Polymer coat selection (claims 4 to 8)

Claim 4 selects coat classes:

polymeric coat is selected from:
- carbohydrates
- proteins
- composites

Claim 5 narrows further:

coat consists of albumin

Claim 6 narrows albumin source:

human serum albumin or bovine serum albumin

Claim 7 narrows to dextran:

coat consists of dextran, molecular weight between 5,000 and 250,000 daltons

Claim 8 narrows dextran MW exemplars:

dextran of 9,000 MW
17,900 MW
35,600 MW
71,000 MW
249,000 MW

Effect on scope: Claims 5 through 8 create multiple “islands” of explicit polymer coat coverage that are more enforceable than a generic “coated with biodegradable polymer” reading.

Administration route and formulation carrier (claims 9 to 12)

Claim 9:

dispersoid administered by intravascular injection

Claim 10:

dispersoid administered by method selected from:
- oral administration
- intubation
- enema

Claim 11:

physiologically acceptable carrier selected from:
- normal saline
- distilled water

Claim 12:

carrier is distilled water

Effect on landscape: Many competing MRI contrast platforms concentrate on IV injection; this patent also claims non-IV routes (oral/intubation/enema), which can matter for GI target imaging.

Dosage cap (claim 13)

Claim 13:

particles administered at dosage of up to about 250 mg/kg body weight

Effect on scope: Provides a numeric ceiling for claim 13 only; it does not necessarily exclude use at higher doses from claims 1/2 unless those independent claims implicitly require “effective amount” that could include higher doses.

Anatomical targeting (claims 14 to 25)

Claim 14 anchors imaging target:

part of reticuloendothelial system

Claims 15 to 18 specify:

organ: liver (15)
organ: spleen (16)
tissue: bone marrow (17)
organ/tissue: lymph or lymph nodes (18)

Claims 19 to 25 cover additional targets:

tissue: neural tissue (19)
organ: lung (20)
part of gastrointestinal tract (21)
- organ: esophagus (22)
- organ: stomach (23)
- organ: small intestine (24)
- organ: large intestine (25)

Effect on enforcement: Dependent claim coverage is target-specific; broader method claims 1/2 could still be asserted for other tissues if biodegradation within 7 days and retention/image requirements are met, but dependent claims provide cleaner, narrower hooks.

What is the claim architecture for scope mapping?

A. Independent-method skeleton

Method of obtaining in vivo NMR images
Administer effective amount of contrast-agent dispersoid
Particles are:
- superparamagnetic
- biodegradable
- meet size specs:
  - crystal diameter: 10 to 500 Å
  - mean diameter: 10 to 5000 Å (uncoated) or coat-inclusive 10 to 5000 Å (coated)
Functional biodegradation: ultimately biodegraded within about 7 days
Retention long enough to permit imaging

B. Dependent “filters” that narrow products/uses

Material and properties (iron oxide; surface area, saturation, squareness)
Coat chemistry (albumin; dextran MW ranges)
Administration route (IV injection; oral/intubation/enema)
Carrier (saline; distilled water)
Dose ceiling (≤250 mg/kg)
Target tissue (RES; liver; spleen; bone marrow; lymph; neural tissue; lung; GI segments)

Where are the likely infringement hotspots? (Most claim-sensitive technical elements)

The most technically discriminating elements in this claim set are:

Biodegradable superparamagnetic metal oxide particle dispersoid
- Whether competitor uses a superparamagnetic metal oxide is central.
Crystal diameter (10 to 500 Å; claim 3: 50 to 500 Å for iron oxide)
Coulter mean diameter range (10 to 5000 Å)
Retention and biodegradation profile
- explicit “ultimately biodegraded within about 7 days”
- this is a functional limitation tied to in vivo fate, and is typically the hardest element to design around without data.
Coating vs uncoated architecture
- claim 1 requires uncoated; claim 2 requires coated.
Quantitative iron-oxide magnetic property set (claim 3)
- surface area, magnetic saturation, magnetic squareness each narrows.
Coat identity and molecular weights (claims 5 to 8)
Non-IV administration routes (claims 10 and 12)
- oral/intubation/enema plus distilled water carrier.

How does claim scope likely compare to typical MRI contrast-agent designs?

This patent’s particle system aligns with “biodegradable iron oxide-like” concepts, but its enforceable scope is defined by three simultaneous constraints:

Size at nanoscale in both crystal and mean diameter terms (angstrom-level crystallites; 10 to 5000 angstrom mean diameter)
Superparamagnetism with optionally iron-oxide property constraints
In vivo biodegradation in about 7 days (and retention sufficient to image)

Many MRI contrast agents (including certain clinically used iron oxide and gadolinium platforms) may fail at least one of:

the biodegradation time window
the specific crystallite and mean diameter ranges
the iron-oxide property constraints (if asserting claim 3)
the required coated/uncoated dispersoid architecture and/or polymer identities (if asserting claims 2, 4 to 8)

What is the US patent landscape around US 4,770,183 (scope and claim overlap map)?

What can be stated from the provided claim text

Based strictly on the claim content supplied, US 4,770,183 positions a landscape around:

biodegradable superparamagnetic metal oxide nanoparticles used as NMR/MRI contrast agents
particle size and crystallite size distribution constraints (angstrom-level)
biodegradation kinetics (about 7 days)
coating polymers (carbohydrates and proteins, especially albumin and dextran with stated MW ranges)
use with routes beyond IV injection (oral/intubation/enema)
target organs with strong emphasis on RES/liver/spleen/lymph plus expanded tissue targets (bone marrow, neural tissue, lung, GI segments)

What cannot be reliably produced without external bibliographic/patent-source data

A complete “US patent landscape” typically requires:

the patent’s assignee, filing/grant dates, prosecution history, and citation graph
identification of US continuations/divisionals and family members
the set of commonly cited patents and their claim coverage
terminal disclaimer or reissue history that affects enforceability
literal vs dependent-claim overlap across the competitive corpus

Those items are not present in your input, so the landscape below is limited to a claim-element overlap framework rather than a citation-verified list of US competitor patents.

Competitive overlap framework (how other US portfolios typically collide with this claim set)

1) Coated iron-oxide/polymer biodegradable nanoparticle MRI agents

Overlap is strongest when a competitor:

uses superparamagnetic metal oxide cores
uses biodegradable polymer coats (carbohydrates/proteins)
uses particle size and crystallite sizes within the stated angstrom and Coulter ranges
shows in vivo clearance/biodegradation consistent with about 7 days

Claim collision points:

claim 2 for coated architecture + size + biodegradation
claims 4 to 8 if the polymer is albumin or dextran with MW in range

2) Uncoated biodegradable metal oxide dispersoids

Overlap is strongest when a competitor:

uses uncoated biodegradable superparamagnetic metal oxide particles
matches uncoated mean diameter and crystallite ranges
biodegrades within about 7 days

Claim collision points:

claim 1 primarily
claim 3 if iron oxide property set matches (surface area, saturation, squareness)

3) Iron oxide agents with different biodegradation time profiles

If competitors biodegrade slower than the “about 7 days” limitation or do not biodegrade in the claimed timeframe, they are more likely to fall outside the independent claims because biodegradation kinetics is an express limitation.

4) Non-IV administration strategies

If a competitor limits claims to IV-only use, it may avoid some dependent claim hooks:

claim 10 (oral/intubation/enema) and claim 11-12 (carrier selection tied to those embodiments)

However, independent claims 1/2 are not explicitly restricted to IV, so route avoidance is not a complete defense unless the competitor also deviates on particle architecture/biodegradation/size constraints.

Claim-by-claim scope table (what each claim constrains)

Claim	Added limitation over preceding claim(s)	Practical scope effect
1	Uncoated biodegradable superparamagnetic metal oxide particles; crystal 10-500 Å; mean 10-5000 Å (Coulter); biodegrade within ~7 days	Broadest core for uncoated architecture
2	Coated particles; superparamagnetic core + biodegradable polymer coat; crystal 10-500 Å; mean 10-5000 Å including coat; biodegrade within ~7 days	Core protection for coated architecture
3	Iron oxide; crystals 50-500 Å; surface area >75 m²/g; saturation 5-50 EMU/g; squareness <0.1	Narrows to a specific magnetic/physical profile
4	Polymer coat is carbohydrates/proteins/composites	Locks polymer class
5	Coat consists of albumin	Locks polymer to albumin
6	Albumin is human serum albumin or bovine serum albumin	Locks specific sources
7	Coat consists of dextran MW 5,000-250,000 Da	Locks polymer to dextran with MW range
8	Dextran MW exemplars (9,000; 17,900; 35,600; 71,000; 249,000 Da)	Locks to specific MWs within range
9	Administer by intravascular injection	Dependent route lock
10	Administer by oral, intubation, or enema	Dependent non-IV routes
11	Carrier is normal saline or distilled water	Dependent formulation lock
12	Carrier is distilled water	Dependent narrower formulation lock
13	Dose ≤250 mg/kg	Dependent numeric dose cap
14	Image target is part of reticuloendothelial system	Dependent tissue anchor
15	Liver	Dependent organ anchor
16	Spleen	Dependent organ anchor
17	Bone marrow	Dependent tissue anchor
18	Lymph or lymph nodes	Dependent organ/tissue anchor
19	Neural tissue	Dependent tissue anchor
20	Lung	Dependent organ anchor
21	Part of GI tract	Dependent organ system anchor
22-25	Esophagus, stomach, small intestine, large intestine	Dependent GI sub-site anchors

What is the practical “design-around” map implied by the claim language?

The claim language points to the strongest avoidance vectors:

Break the biodegradation timeline: do not biodegrade within about 7 days
Break the particle size limits:
- crystallite size (10-500 Å; iron oxide variant 50-500 Å)
- or Coulter mean diameter 10-5000 Å (coated vs uncoated depending on architecture)
Break the structural requirement:
- if claim 1 is uncoated, a coated particle may attempt to move into claim 2 territory (and vice versa)
Break specific dependent-claim subsets:
- use coat polymers not within claim 4-8 lists
- use iron oxide with property values outside claim 3 constraints
- use routes/doses not matching dependent-claim locks (while recognizing independent claims still cover “effective amount” without explicit route constraints)

Key Takeaways

US 4,770,183 protects method claims for in vivo NMR/MRI contrast using biodegradable superparamagnetic metal oxide dispersoids with explicit angstrom-level size parameters and an express biodegradation within about 7 days limitation.
The patent has two main independent embodiments: uncoated particles (claim 1) and coated polymer-encapsulated particles (claim 2).
Dependent claims add enforceable constraints around iron oxide magnetic properties (claim 3), polymer coat identity (albumin or dextran with specified MW ranges, claims 5-8), carrier and administration route (claims 9-12), dose cap (claim 13), and target tissues including RES and GI sub-sites (claims 14-25).
The most claim-sensitive technical elements for competitive assessment are particle size distributions, superparamagnetic iron oxide performance profile (if asserting claim 3), and in vivo biodegradation kinetics within about 7 days.

FAQs

1) Does US 4,770,183 require IV administration?

No. Claims 9 and 10 add route-specific limitations, but independent claims 1 and 2 cover “administering” without a route restriction. Claims 9 and 10 separately require intravascular injection or specific non-IV routes.

2) What is the biodegradation requirement?

The claims state that particles are “ultimately biodegraded in said organ or tissue within a period of about 7 days.”

3) What exact size ranges are claimed for the metal oxide crystals?

Claims 1 and 2 require biodegradable metal oxide crystals of about 10 to about 500 angstroms in diameter. Claim 3 narrows iron oxide crystals to about 50 to about 500 angstroms.

4) How is particle size measured?

The claims require mean diameter as measured on a Coulter particle size analyzer (overall mean diameter for uncoated; coat-inclusive mean diameter for coated particles).

5) Which polymer coats are explicitly claimed?

Coat polymers are constrained by dependent claims to carbohydrates and proteins (claim 4), with specific embodiments for albumin (claims 5-6) and dextran with 5,000 to 250,000 Da (claim 7) and listed MW exemplars (claim 8).

References

[1] United States Patent 4,770,183. Claims text provided in prompt.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
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Details for Patent: 4,770,183

Summary for Patent: 4,770,183