Method of electron spin resonance enhanced MRI

• US 5,289,125 A
• Filed: 11/08/1991
• Issued: 02/22/1994
• Est. Priority Date: 11/12/1990
• Status: Expired due to Fees

• Current Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Original Assignee: Instrumentarium Dental Incorporated (Envista Holdings Corporation)
• Inventors: Ehnholm, Gosta J.
• Primary Examiner(s): Tokar, Michael J.
• Assistant Examiner(s): MAH, RAYMOND
• Application Number:
  US07/790,209
• Time in Patent Office: 837 Days
• Field of Search: 324/316, 324/309, 324/307, 324/318, 324/300
• US Class Current: 324/309
• CPC Class Codes: A61K 49/06 Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
• CPC Class Codes: G01R 33/281 Means for the use of in vitro contrast agents G01R33/282 takes precedence; involving use of a contrast agent in MR imaging G01R33/5601; in vivo contrast agents A61K49/0002
• CPC Class Codes: G01R 33/563 of moving material, e.g. flow contrast angiography
• CPC Class Codes: G01R 33/62 using double resonance G01R33/24 takes precedence

Abstract

A method of electron spin resonance enhanced magnetic resonance imaging of a paramagnetic substance-containing sample wherein an image of at least part of the sample is generated from a data set produced by manipulation of enhanced free induction decay signals detected under at least two different sets of operational parameters. The operating parameters which are varied to produce the different sets include the timing of the exposure of the sample to magnetic field gradients and spin resonance stimulating radiations and, optionally, also the amplitude and frequency distribution of the electron spin resonance stimulating radiations. The manipulation of the detected signals produces, for individual image elements, a normalized signal representative of the difference between signals for that element under the different sets of operational parameters.

Claims

1. A method of electron spin resonance enhanced magnetic resonance imaging of a paramagnetic substance-containing sample, said method comprising:

(i) detecting enhanced magnetic resonance signals from said sample under at least two different sets of operational parameters, said operational parameters including the timing of the exposure of said sample to magnetic field gradients and spin resonance stimulating radiations and the amplitude and frequency distribution of the electron spin resonance stimulating radiations;

(ii) manipulating the detected signals to provide, for individual image elements, a normalized difference signal having a value proportional to the ratio between the difference between signal amplitude for said element under two different sets of said operational parameters and a mean signal amplitude for said element; and

(iii) generating an image of at least part of said sample from said normalized difference signals.

3. A method as claimed in claim 1 wherein the operational parameters which are varied to obtain said at least two sets of operational parameters include at least one of the amplitude and frequency of the electron spin resonance stimulating radiation.

4. A method as claimed in claim 1 wherein generation of the normalized difference signal is effected by proton polarization averaging.

5. A method as claimed in claim 1 wherein generation of the normalized difference signal is effected by echo subtraction.

2. A method of electron spin resonance enhanced magnetic resonance imaging of a paramagnetic substance-containing sample, said method comprising:

(i) in repeated first pulse sequences, sequentially exposing said sample to a first radiation of at least two frequencies selected to stimulate electron spin resonance transitions in said sample and therebetween to 180°

pulses of a second radiation of a frequency selected to stimulate coupled nuclear spin resonance transitions in said sample and subsequently further exposing said sample to at least one pulse of a second radiation whereby to cause the sample to emit magnetic resonance signals from which a difference signal (Δ

A) image of said sample may be generated;

(ii) in repeated second pulse sequences interleaved with said first pulse sequences, exposing said sample to said first and second radiations as in said first pulse sequences but with the omission of said 180°

second radiation pulses whereby to cause said sample to emit magnetic resonance signals from which a normalizing (A) image of said sample may be generated;

(iii) detecting magnetic resonance signals emitted from said sample in said first and second pulse sequences; and

(iv) generating a normalized difference (Δ

A/A) image from the detected magnetic resonance signals.