Determining velocity of cerebrospinal fluid by magnetic resonance imaging

• US 8,903,470 B2
• Filed: 08/09/2012
• Issued: 12/02/2014
• Est. Priority Date: 10/03/2008
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Tokai University Educational System
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Tokai University Educational System
• Inventors: Yamada, Shinya, Kanazawa, Hitoshi
• Primary Examiner(s): KISH, JAMES M
• Application Number:
  US13/570,569
• Publication Number:
  US 20120302871A1
• Time in Patent Office: 845 Days
• Field of Search: 600/407, 600410-423
• 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 5/7257 using Fourier transforms
• CPC Class Codes: G01R 33/5602 by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse
• CPC Class Codes: G01R 33/5608 Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels image data processing or generation, in general G06T
• CPC Class Codes: G01R 33/5616 using gradient refocusing, e.g. EPI
• CPC Class Codes: G01R 33/5617 using RF refocusing, e.g. RARE
• CPC Class Codes: G01R 33/56316 involving phase contrast techniques
• CPC Class Codes: G06T 2207/10088 Magnetic resonance imaging [MRI]
• CPC Class Codes: G06T 2207/20221 Image fusion; Image merging
• CPC Class Codes: G06T 2207/30016 Brain
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 7/277 involving stochastic approaches, e.g. using Kalman filters

Abstract

A velocity-image creating unit creates a velocity image that indicates a distribution of velocity components with respect to each of a plurality of images obtained by repeating a plurality of number of times Echo Planar Imaging (EPI) that is capable of obtaining velocity components of a Cerebrospinal Fluid (CSF) flowing inside a subject. A velocity-variance image creating unit calculates variance of velocity components along the time sequence by same position on velocity images by using a plurality of created velocity images. A superimposed-image processing unit then superimposes the distribution of the variance of the velocity components according to the velocity-variance image on an average absolute-value image, and an image display unit displays a superimposed image.

Claims

1. A magnetic resonance (MR) imaging apparatus comprising:

an MRI system having components including static and gradient magnetic field generators, at least one radio frequency (RF) coil coupled to an imaging volume, at least one RF transmitter, at least one RF receiver and at least one control computer having a processor and memory configured to control said system components so as to effect;

repeated acquisition of MR image data in a synchronized manner with a trigger signal using a phase-shift imaging process, the phase-shift imaging method including (a) application of an excitation pulse to an imaging region including a Cerebrospinal Fluid (CSF), (b) reconstructing one image based on a group of echo signals collected by applying one excitation pulse, and (c) applying a flow encode gradient magnetic field to give a phase shift proportional to a velocity onto the reconstructed image, thereby obtaining velocity components of the CSF;

creation of corresponding plural velocity images, a velocity image being created for each repeated trigger signal and indicating a distribution of velocity components;

creation of an average velocity image based on the plurality of reconstructed images; and

calculation of variances of the velocity components, with respect to each of same positions on the plurality of reconstructed images, based on the plurality of reconstructed velocity images and the average velocity image.

2. The apparatus according to claim 1, wherein the plurality of the reconstructed images are obtained by repeating the imaging with a fixed delay time from a triggering event to applying the excitation pulse.

3. The apparatus according to claim 2, wherein the variance of the velocity components is calculated along a time sequence.

4. The apparatus according to claim 2, wherein the trigger signal is a biological signal of the subject.

5. The apparatus according to claim 2, wherein the trigger signal is a signal generated in a fixed cycle.

6. The apparatus according to claim 1, wherein the variance of the velocity components is calculated along a time sequence.

7. The apparatus according to claim 1, wherein the trigger signal is a biological signal of the subject.

8. The apparatus according to claim 1, wherein the trigger signal is a signal generated in a fixed cycle.

9. The apparatus according to claim 1, further comprising a display configured to display a distribution of the variances.

10. The apparatus according to claim 9, wherein the display displays the distribution of the variances by superimposing on a certain calculation image.

11. The apparatus according to claim 9, wherein the display changes a display mode of the distribution of the variances in accordance with a value of the variances.

12. The apparatus according to claim 9, wherein the display changes a display mode of the distribution of the variances in accordance with a flowing direction of the CSF.

13. A magnetic resonance (MR) image processing apparatus comprising:

an MRI system having components including static and gradient magnetic field generators, at least one radio frequency (RF) coil coupled to an imaging volume, at least one RF transmitter, at least one RF receiver and at least one control computer having a processor and memory configured to control said system components so as to effect;

creation of plural velocity images indicating a distribution of velocity components, each velocity image corresponding to one of a plurality of reconstructed images acquired by repeated acquisition of an MR image using an imaging method synchronized manner with a trigger signal, the imaging method including (a) applying an excitation pulse to an imaging region including a Cerebrospinal Fluid CSF, (b) reconstructing one image based on a group of echo signals collected by applying one excitation pulse, and (c) applying a flow encode gradient magnetic field to give a phase shift proportional to velocity onto the reconstructed image, thereby obtaining velocity components of the CSF;

creation of an average velocity image based on the plurality of reconstructed images; and

calculation of variances of the velocity components with respect to each of same positions on the plurality of reconstructed images based on the plurality of reconstructed images and the average velocity image.

14. An image processing method comprising:

creating a velocity image indicating a distribution of the velocity components of a plurality of reconstructed images an imaging method synchronized with a trigger signal, the imaging method including applying an excitation pulse to an imaging region including a Cerebrospinal Fluid (CSF), reconstructing one image based on a group of echo signals collected by applying one excitation pulse, applying a flow encode gradient magnetic field to give a phase shift proportional to a velocity onto the reconstructed image, and thereby obtaining velocity components of the CSF;

creating an average velocity image based on the plurality of reconstructed images; and

calculating variances of the velocity components with respect to each of same positions on the plurality of reconstructed images based on the plurality of reconstructed images and the average velocity image.