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US 2006/0066306 A1Published application
Magnetic resonance imaging with dual velocity encoded projection reconstruction acquisition
AssigneeWisconsin Alumni Research Foundation
InventorsCharles Mistretta, Kevin Johnson, Tianliang Gu
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Abstract
A phase contrast image is produced using a 3D projection reconstruction pulse sequence. A high velocity-to-noise image is produced by using a LOW VENC motion encoding gradient. Phase wrap errors caused by high velocity flow is corrected using phase information in a HIGH VENC image produced from highly undersampled data acquired during the same scan.
Claims9
A method for producing an image with a magnetic resonance imaging (MRI) system, the steps comprising:
- a) acquiring a LOW VENC series of NMR signals using a pulse sequence having a first motion encoding gradient field with a first moment that imparts a phase shift in the NMR signals indicative of spin motion, the pulse sequence having a readout gradient that is rotated from one pulse sequence to the next such that the LOW VENC series of NMR signals sample k-space at a corresponding first series of different projection angles;
- b) acquiring a HIGH VENC series of NMR signals using a pulse sequence having a second motion encoding gradient field with a first moment that is substantially less than the first moment in step a) and that imparts a phase shift in the NMR signals indicative of spin motion, the pulse sequence having a readout gradient that is rotated from one pulse sequence to the next such that the HIGH VENC series of NMR signal sample k-space at a corresponding second series of different projection angles;
- c) reconstructing a LOW VENC image from the series of NMR signals acquired in step a);
- d) producing a LOW VENC phase image from the LOW VENC image reconstructed in step c);
- e) reconstructing a HIGH VENC image from the series of NMR signals acquired in step b);
- f) producing a HIGH VENC phase image from the HIGH VENC image reconstruction in step e);
- and
- g) correcting the LOW VENC phase image using phase information in the HIGH VENC phase image.
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