Physiological corrections in functional magnetic resonance imaging

• US 6,073,041 A
• Filed: 05/11/1998
• Issued: 06/06/2000
• Est. Priority Date: 07/18/1996
• Status: Expired due to Term

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Hu, Xiaoping, Erhard, Peter W., Parrish, Todd B., Le, Tuong Huu
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US09/000,169
• Time in Patent Office: 757 Days
• Field of Search: 600/410, 600/413, 600/411, 600/419, 600/508, 600/509, 600/529, 600/534, 324/306, 324/307, 324/309
• US Class Current: 600/410
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/7289 Retrospective gating, i.e. associating measured signals or images with a physiological event after the actual measurement or image acquisition, e.g. by simultaneously recording an additional physiological signal during the measurement or image acquisition
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: G01R 33/4806 Functional imaging of brain activation
• CPC Class Codes: G01R 33/5613 Generating steady state signals, e.g. low flip angle sequences [FLASH]
• CPC Class Codes: G01R 33/5616 using gradient refocusing, e.g. EPI
• CPC Class Codes: G01R 33/567 gated by physiological signals , i.e. synchronization of acquired MR data with periodical motion of an object of interest, e.g. monitoring or triggering system for cardiac or respiratory gating
• CPC Class Codes: G01R 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

A functional magnetic resonance imaging method comprises the steps of:

(a) detecting a physiological timing profile;

(b) measuring cerebral k-space data to provide cerebral k-space data;

(c) ordering the measured cerebral k-space data into a unit cycle based on the detected physiological timing profile;

(d) estimating effects on individual k-space points resulting from physiological effects by non-linear least-square fitting to provide estimated physiological effects; and

(e) removing the estimated physiological effects from the cerebral k-space data by substraction of the estimated physiological effects from said k-space data.

Claims

1. A functional magnetic resonance imaging method comprising the steps of:

(a) detecting a physiological timing profile;

(b) measuring cerebral k-space data;

(c) ordering the measured cerebral k-space data into a unit cycle based on the detected physiological timing profile;

(d) estimating corresponding physiological effects for individual k-space data points by non-linear least-square fitting of cerebral k-space data;

(e) removing the estimated physiological effects from the cerebral k-space data by subtraction, providing cerebral k-space data from which the estimated physical effects have been removed; and

(f) providing an image from said cerebral k-space data from which the estimated physical effects have been removed.

2. A method of claim 1 in which the physiological timing profile of step (a) is based on respiration.

3. The method of claim 1 in which the physiological timing profile of step (a) is based on cardiac activity.

4. The method of claim 1 in which the physiological timing profile of step (a) is obtained from the phase of the center of a navigator echo in rapid, low flip angle pulsed NMR imaging (FLASH).

5. The method of claim 1 in which the physiological timing profile of step (a) is obtained from the phase of the center k-space point in echo-planar imaging (EPI).

6. The method of claim 1 in which step (a) comprises extracting the physiological timing profile directly from magnetic resonance data.

7. The method of claim 1 in which the non-linear least squares fitting of step (d) is performed as a finite order Fourier series.

9. The method of claim 1 wherein said physiological timing profile of step (a) is based upon effects selected from the group consisting of respiration and cardiac activity.

10. The method of claim 9 wherein step (a) comprises extracting the physiological timing profile directly from magnetic resonance data.

8. A functional magnetic resonance imaging method of comprising the steps of:

(a) detecting a physiological timing profile;

(b) measuring cerebral k-space data to provide cerebral k-space data;

(c) ordering the measured cerebral k-space data into a unit cycle based on the detected physiological timing profile;

(d) estimating effects on individual k-space points resulting from physiological effects by non-linear fitting of cerebral k-space data to provide estimated physiological effects;

(e) removing the estimated physiological effects from the cerebral k-space data by subtraction of the estimated physiological effects from said k-space data to form image data; and

(f) forming an image from said image data.