Back to results
US 8,077,955 B2Granted
B1 mapping in MRI system using k-space spatial frequency domain filtering
AssigneesKabushiki Kaisha Toshiba, Toshiba Medical Systems Corporation
InventorsWayne R. Dannels, Andrew J. Wheaton
Life of this patent
Estimating the term…
Abstract
Frequency filtering of spatially modulated or “tagged” MRI data in the spatial frequency k-space domain with subsequent 2DFT to the spatial domain and pixel-by-pixel arithmetic calculations provide robust ratio values that can be subjected to inverse trigonometric functions to derive B1 maps for an MRI system.
Claims25
A method for generating a B1 map in an MRI system, said method comprising using an MRI system to:
- (a) acquire at least one set of B1 amplitude tagged MRI data signals in spatial frequency domain k-space from MR nuclei within an imaged volume of the MRI system;
- (b) process said k-space data to produce at least two sub-sets of frequency-filtered k-space data:
- (i) a baseline low-frequency sub-set, and (ii) at least one of a positive higher frequency sub-set including a harmonic version of said baseline sub-set and a negative higher frequency sub-set including a harmonic version of said baseline sub-set;
- (c) separately transform each of said sub-sets to respectively corresponding spatial domain data sets:
- (i) a baseline magnitude set, and (ii) at least one of a positive harmonic magnitude set and a negative harmonic magnitude set;
- (d) arithmetically combine said baseline magnitude set with said at least one of the harmonic magnitude sets on a pixel-by-pixel basis to provide upper and lower magnitude data sets;
- (e) process said upper and lower magnitude data set values on a pixel-by-pixel basis to generate a B1 map value based on value related to a ratio of said upper and lower pixel data values at a given pixel location in the spatial domain;
- and
- (f) store said B1 map of values in a computer accessible and readable memory device for subsequent use by said MRI system.
6 more elements
An MRI system comprising:
- (a) an MRI scanner configured to acquire at least one set of B1 amplitude tagged MRI data signals in spatial frequency domain k-space from MR nuclei within an imaged volume of the MRI system;
- at least one processor configured to:
- (b) process said k-space data to produce at least two sub-sets of frequency-filtered k-space data:
- (i) a baseline low-frequency sub-set, and (ii) at least one of a positive higher frequency sub-set including a harmonic version of said baseline sub-set and a negative higher frequency sub-set including a harmonic version of said baseline sub-set;
- separately transform each of said sub-sets to respectively corresponding spatial domain data sets:
- (i) a baseline magnitude set, and (ii) at least one of a positive harmonic magnitude set and a negative harmonic magnitude set;
- arithmetically combine said baseline magnitude set with said at least one of the harmonic magnitude sets on a pixel-by-pixel basis to provide upper and lower magnitude data sets;
- process said upper and lower magnitude data set values on a pixel-by-pixel basis to generate a B1 map value based on a value related to a ratio of said upper and lower pixel data values at a given pixel location in the spatial domain;
- and
- (c) a data memory configured to store said B1 map of values in a computer accessible and readable memory device for subsequent use by said MRI system.
7 more elements
Dependencies are inferred from the claim text.