Time-resolved digital subtraction magnetic resonance angiography using echo-planar imaging

• US 6,044,290 A
• Filed: 04/06/1998
• Issued: 03/28/2000
• Est. Priority Date: 04/11/1997
• Status: Expired due to Term

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Grist, Thomas M, Mistretta, Charles A, Vigen, Karl K, Korosec, Frank R, Frayne, Richard
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US09/055,503
• Time in Patent Office: 722 Days
• Field of Search: 600/410, 600/419, 600/420, 324/306, 324/307, 324/309
• US Class Current: 600/419
• CPC Class Codes: G01R 33/4822 in three dimensions
• CPC Class Codes: G01R 33/5615 Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
• CPC Class Codes: G01R 33/5616 using gradient refocusing, e.g. EPI
• CPC Class Codes: G01R 33/563 of moving material, e.g. flow contrast angiography

Abstract

A dynamic MRA study of a subject is performed using a 3D echo-planar imaging pulse sequence. Four phase encoding views are acquired for each pulse repetition period (TR) and this enables higher resolution images to be acquired without a reduction of temporal frame rate or a loss of image CNR.

Claims

1. A method for acquiring contrast enhanced NMR data from a subject to produce a series of frame images by repeatedly acquiring samples from a selected k-space during a dynamic study of the subject, the steps comprising:

administering a contrast agent to the subject which enhances NMR signals;

performing a series of NMR data acquisitions using an echo-planar pulse sequence to sample a central region of the selected k-space at a temporal rate; and

to sample peripheral regions of the selected k-space at a lower temporal rate, each echo-planar pulse sequence acquiring a plurality of NMR signals which each sample a portion of k-space and the number of NMR signals acquired during each echo-planar pulse sequence being limited such that the contrast between contrast enhanced tissues and other tissues is not substantially diminished;

forming a data set for each set of central region k-space samples, which includes said central region k-space samples and samples derived from the most temporally adjacent samplings of the peripheral k-space regions; and

reconstructing a frame image from each data set.

2. The method as recited in claim 1 in which the NMR data is acquired from a three-dimensional region of the subject.

3. The method as recited in claim 1 in which there are two different peripheral k-space regions and the k-space is repeatedly sampled during the dynamic study by alternately sampling the central k-space region and one of the two different peripheral k-space regions.

4. The method as recited in claim 1 in which a portion of the central k-space region is sampled by each echo-planar pulse sequence.

7. The method as recited in claim 1 in which the number of NMR signals acquired during each echo-planar pulse sequence is substantially four.

8. The method as recited in claim 7 in which two of the NMR signals sample a portion of the central region of k-space.

9. The method as recited in claim 8 in which the remaining NMR signals in each echo-planar pulse sequence sample a portion of a peripheral region of k-space.

5. The method as recited in claim 5 in which a portion of only one of said peripheral regions is sampled by each echo-planar pulse sequence.

6. The method as recited in claim 5 in which each echo-planar pulse sequence samples the central k-space region a plurality of times.

10. A method for producing a contrast enhanced NMR image of a subject, the steps comprising:

a) administering a contrast agent to the subject which enhances NMR signals;

b) performing an echo-planar pulse sequence to acquire substantially four NMR signals which each sample different portions of k-space;

c) acquiring a k-space data set from which an image can be reconstructed by repeating step b) a plurality of times; and

d) reconstructing an image from the acquired k-space data set.

11. The method as recited in claim 10 in which one of the NMR signals in each echo-planar pulse sequence samples a central region of k-space.