Diffusion weighted preparatory sequence for magnetic resonance imaging pulse sequence

• US 20080275329A1
• Filed: 05/04/2007
• Published: 11/06/2008
• Est. Priority Date: 05/04/2007
• Status: Active Grant

• Current Assignee: General Electric Company, Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Reeder, Scott B., Brittain, Jean H., Busse, Reed
• Granted Patent: US 7,804,299 B2
• Time in Patent Office: Days
• US Class Current: 600/410
• CPC Class Codes: G01R 33/56341 Diffusion imaging

Abstract

A preparatory pulse sequence is applied prior to an imaging pulse sequence during a diffusion-weighted MRI scan. The preparatory pulse sequence diffusion weights the longitudinal magnetization using a gradient waveform that is first moment nulled to reduce image artifacts caused by patient motion.

Claims

1. A method for producing a diffusion-weighted image with a magnetic resonance imaging (MRI) system, the steps comprising:

a) performing a preparation pulse sequence with the MRI system that diffusion weights longitudinal magnetization in a subject, the preparation pulse sequence including;

a)i) applying an rf excitation pulse to produce transverse spin magnetization;

a)ii) applying a first moment nulled diffusion weighting gradient waveform to diffusion weight the transverse spin magnetization; and

aiii) applying an rf excitation pulse to produce diffusion-weighted longitudinal spin magnetization from the diffusion weighted transverse magnetization;

b) performing an imaging pulse sequence following step a);

c) repeating steps a) and b) as necessary to acquire a set of data from which an image can be reconstructed; and

d) reconstructing a diffusion-weighted image from the acquired set of data.

2. The method as recited in claim 1 in which the diffusion-weighted gradient waveform is also second moment nulled.

3. The method as recited in claim 1 in which an rf refocusing pulse is applied in step a) such that the diffusion weighted transverse magnetization is refocused at the moment the rf excitation pulse is produced in step a)iii).

4. The method as recited in claim 1 in which a pair of rf refocusing pulses are applied during step a).