US5315997A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of magnetic resonance imaging using diamagnetic contrast
Assignee: Molecular Biosystems Inc
•
Filing: 1992-08-13
•
Granted: 1994-05-31
•
Expires: 2012-08-13
Abstract
Abstract A method of magnetic resonance imaging (MRI) is disclosed which employs a diamagnetic contrast agent comprising gas-carrying, microparticles, which are preferably microspheres consisting of minute gas bubbles encapsulated by stabilized biocompatible material. The MRI is carried out to produce a shortened T2* effect. The method is especially useful in imaging the vascular system as in angiography or venography.
Inventors
- 👤 Kenneth J. Widder
- 👤 James L. Barnhart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:29
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/5601; A; A61; A61K; A61K49/00; A61K49/06; A61K49/18; A61K49/1818; A61K49/1821
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
130 words
The method of magnetic resonance imaging (MRI), comprising the steps of: (a) introducing a bolus into a portion of the circulating blood of a mammal prior to or during an MRI examination, said bolus comprising an aqueous medium containing a dispersion of microspheres of diameters of less than 8 microns, said microspheres consisting of gas microbubbles encapsulated by stabilized biocompatible material, said bolus prior to administration having volume of 3.5 to 20 milliliters and a microsphere concentration of greater than 1×10 6 microspheres per milliliter; and (b) when the administered microspheres have reached the site to be imaged, carrying out magnetic resonance imaging by a fast imaging technique to produce a shortened T2* effect in which the portion of the blood containing the microspheres produces a decrease in signal intensity.
Claim 2
Independent Claim
130 words
The method of magnetic resonance imaging (MRI), comprising the steps of: (a) introducing a bolus into a portion of the circulating blood of a mammal prior to or during an MRI examination, said bolus comprising an aqueous medium containing a dispersion of microspheres of diameters of less than 8 microns, said microspheres consisting of gas microbubbles encapsulated by stabilized biocompatible material, said bolus prior to administration having volume of 3.5 to 20 milliliters and a microsphere concentration of greater than 1×10 6 microspheres per milliliter; and (b) when the administered microspheres have reached the site to be imaged, carrying out magnetic resonance imaging by a fast imaging technique to produce a shortened T2* effect in which the portion of the blood containing the microspheres produces a decrease in signal intensity.
Claim 3
Dependent Claim
17 words
The method of claim 1 in which the imaging is carried out by an echo planar technique.
Claim 4
Dependent Claim
25 words
The method of claim 1 in which the imaging is carried out by a fast MRI technique using a series of radio frequency excitation pulses.
Claim 5
Dependent Claim
21 words
The method of claim 1 in which the imaging is carried out with a time-to-repeat (TR) of less than 100 milliseconds.
Claim 6
Dependent Claim
24 words
The method of claim 4 in which the imaging is carried out by a technique in which the coherence of transverse magnetization is spoiled.
Claim 7
Independent Claim
23 words
The method of claims 1, 2, 3, 4, or 5 in which the microspheres consist of air microbubbles encapsulated by human serum albumin.
References Cited (Backward Citations)
US4657756A
Cited
US4775522A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-05-30 | 1997-11-29 | 1998-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-30 | 2001-11-29 | 2002-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-30 | 2005-11-29 | 2006-05-31 | $7700.00 | Window Closed / Lapsed |