Method for Correcting Motion-Induced Phase Errors In Magnetic Resonance Imaging

• US 20130181712A1
• Filed: 01/13/2012
• Published: 07/18/2013
• Est. Priority Date: 01/13/2012
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Hernando, Diego, Sutton, Bradley, Van, Anh
• Granted Patent: US 8,975,895 B2
• Time in Patent Office: Days
• US Class Current: 324/314
• CPC Class Codes: G01R 33/56341 Diffusion imaging
• CPC Class Codes: G01R 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• 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 method for correcting motion-induced phase errors in diffusion-weighted k-space data acquired with a magnetic resonance imaging (MRI) system is provided. The MRI system is directed to acquire the following data from an imaging volume: three-dimensional diffusion-weighted k-space data, three-dimensional diffusion-weighted navigator data, three-dimensional non-diffusion-weighted k-space data, and three-dimensional non-diffusion-weighted navigator data. Initial estimates of k-space shift values and a constant phase offset value are calculated using the three-dimensional diffusion-weighted navigator data and the three-dimensional non-diffusion-weighted navigator data. These initial k-space shift values and constant phase offset value are then updated by iteratively minimizing a cost function that relates the phase of the diffusion-weighted k-space data to the phase of the non-diffusion-weighted k-space data, as shifted by the initial k-space shift values and constant phase offset value. The diffusion-weighted k-space data is then corrected for motion-induced phase errors using the updated k-space shift values and constant phase offset value.

Claims

1. A method for correcting motion-induced phase errors in diffusion-weighted k-space data acquired with a magnetic resonance imaging (MRI) system, the steps of the method comprising:

a) directing the MRI system to;

i) acquire three-dimensional diffusion-weighted k-space data from an imaging volume;

ii) acquire three-dimensional diffusion-weighted navigator data from the imaging volume;

iii) acquire three-dimensional non-diffusion-weighted k-space data from the imaging volume;

iv) acquire three-dimensional non-diffusion-weighted navigator data from the imaging volume;

b) calculating k-space shift values and a constant phase offset value using the three-dimensional diffusion-weighted navigator data acquired in step a)ii) and the three-dimensional non-diffusion-weighted navigator data acquired in step a)iv);

c) updating the k-space shift values and the constant phase offset value calculated in step b) by iteratively minimizing a cost function that relates a phase of the diffusion-weighted k-space data acquired in step a)i) to a phase of the non-diffusion-weighted k-space data acquired in step a)iii) as shifted by the k-space shift values and constant phase offset value calculated in step b); and

d) correcting the diffusion-weighted k-space data acquired in step a)i) for motion-induced phase errors using the k-space shift values and constant phase offset value updated in step c).

2. The method as recited in claim 1 in which step b) includes calculating initial k-space shift values by calculating a difference between a k-space location associated with a maximum magnitude of the three-dimensional diffusion-weighted navigator data acquired in step a)ii) and a k-space location associated with a maximum magnitude of the three-dimensional non-diffusion-weighted navigator data acquired in step a)iv).

3. The method as recited in claim 1 in which step b) includes calculating the constant phase offset value by calculating a difference between a phase of k-space location associated with a maximum value of the three-dimensional diffusion-weighted navigator data acquired in step a)ii) and a phase of a k-space location associated with a maximum value of the three-dimensional non-diffusion-weighted navigator data acquired in step a)iv).

4. The method as recited in claim 1 in which step a) includes acquiring the three-dimensional diffusion-weighted k-space data, the three-dimensional diffusion-weighted navigator data, the three-dimensional non-diffusion-weighted k-space data, and the three-dimensional non-diffusion-weighted navigator data using a parallel imaging technique and an array of radio frequency (RF) receiver coils.

5. The method as recited in claim 4 in which step b) includes calculating initial k-space shift values by:

i) calculating, for each receiver coil in the array of RF receiver coils, a difference between a k-space location associated with a maximum magnitude of the three-dimensional diffusion-weighted navigator data acquired in step a)ii) with a given receiver coil and a k-space location associated with a maximum magnitude of the three-dimensional non-diffusion-weighted navigator data acquired in step a)iv) with the given receiver coil; and

ii) calculating a sum of the differences calculated in step b)i).

6. The method as recited in claim 1 in which step b) includes calculating the constant phase offset value by:

i) calculating, for each receiver coil in the array of RF receiver coils, a difference between a phase of a k-space location associated with a maximum value of the three-dimensional diffusion-weighted navigator data acquired in step a)ii) with a given receiver coil and a phase of a k-space location associated with a maximum value of the three-dimensional non-diffusion-weighted navigator data acquired in step a)iv) with the given receiver coil; and

ii) calculating a sum of the differences calculated in step b)i).

7. The method as recited in claim 1 in which step a) includes acquiring the three-dimensional diffusion-weighted k-space data, the three-dimensional diffusion-weighted navigator data, the three-dimensional non-diffusion-weighted k-space data, and the three-dimensional non-diffusion-weighted navigator data using cardiac gating to mitigate nonlinear motion-induced phase errors.