US 5,311,133 A · Concurrent generation of multiple images in fast (TR<T2) scanning sequences

Abstract

In a fast scanning technique in which the repeat time TR is less than the T2 relaxation time, a first generation component (34), a second generation component (52), and a third generation component (62) are each phase encoded by a phase encode gradient (36). The persisting second and third generation components are encoded with the sum of the phases with which they have been encoded in the present and prior repetitions. A composite data line is sampled during each echo and includes a first component (44), a second component (54), and a third component (64), each component having an independent phase encoding. The data lines are each stored in a first data set memory (80) in accordance with the phase encoding of the first generation component, in a second data set memory (82) in accordance with the phase encoding of the second component and in a third data set memory means (84) in accordance with the phase encoding of the third generation component. Each of these data sets is filtered (110), transformed (112) into a magnitude image (114) and phase image (116). The magnitude and phase images are filtered (120, 122) and reverse transformed (126) back into a filtered data set (128) and weighted (130) to form an estimate of one component of the other data sets. The estimate is subtracted (138, 140) from the other data sets. This process is iteratively repeated until each data set contains substantially only the data of one component. Each data set is then reconstructed (98) into a separate image representation.

Claims22

Dependent claims

A method of generating at least one image representation from first and prior generation magnetic resonance data, the method comprising:

a) in the presence of a phase encoded, prior generation magnetic resonance component from a preceding repetition, exciting a first generation magnetic resonance component;
b) applying a phase encoding gradient to phase encode the first generation magnetic resonance component and modify the phase encoding of the prior generation magnetic resonance component;
c) sampling a composite magnetic resonance signal which is a superimposition of at least the first and prior generation magnetic resonance components;
d) allowing at least the phase encoded first generation component to persist into a subsequent repetition as a phase encoded prior generation magnetic resonance component;
e) repeating steps (a)-(d) with each of a plurality of phase encode gradients;
f) assembling the sampled composite data lines into a first generation data set in which the composite data lines are organized in accordance with the phase encoding of the first generation magnetic resonance component;
g) assembling the sampled composite data lines into a prior generation magnetic resonance data set in which the composite data lines are organized in accordance with the phase encoding of the prior generation magnetic resonance component;
h) from the prior generation magnetic resonance data set, estimating a contribution of the prior generation magnetic resonance components to the first generation data set and correcting the first generation data set with the estimated contribution;
i) reconstructing a first generation image representation from the corrected first generation data set.

6 more elements

An apparatus for generating at least one image representation from first and prior generation magnetic resonance data, the apparatus comprising:

a resonance excitation means for repeatedly exciting a first generation magnetic resonance component in the presence of a previously phase encoded prior generation magnetic resonance component from a preceding repetition;
a phase encoding means for applying a phase encoding gradient to phase encode the first generation component and to modify the phase encoding of the prior generation component;
a sampling means for sampling a composite resonance signal which is superimposition of at least the first and prior generation components;
a first generation data set memory means for storing the sampled composite magnetic resonance signals;
a prior generation data set memory means for storing the sampled composite magnetic resonance signals;
a distributing means for distributing the sampled composite magnetic resonance signals for storage in the first generation data set memory means in accordance with the phase encoding of the first generation component and for storage in the prior generation data set memory means in accordance with the phase encoding of the prior generation component;
a correcting means for correcting the composite magnetic resonance signals stored in one of the first and prior generation data set memory means in accordance with the composite magnetic resonance signals stored in the other;
a reconstructing means for reconstructing the corrected magnetic resonance signals into an image representation.

5 more elements

A magnetic resonance image apparatus comprising:

a magnetic resonance scanner for generating a plurality of data lines, each data line including a first component with a first phase encoding and a second component with a second phase encoding, the second phase encoding being different from the first phase encoding;
a first data set memory means for storing the data lines;
a second data set memory means for storing the data lines;
a distributing means for causing the first data set memory means to store the data lines in an order in accordance with the phase encoding of the first component and for causing the second data set memory means to store each data line in accordance with the phase encoding of the second component;
a correcting means for correcting the data lines in at least one of the first and second data set memory means in accordance with the data lines in the other data set memory means;
a reconstructing means for reconstructing the corrected data lines of at least one of the data set memory means into an image representation for storage in an image memory.

3 more elements

Dependencies are inferred from the claim text.

Concurrent generation of multiple images in fast (TR<T2) scanning sequences

Life of this patent

Concurrent generation of multiple images in fast (TR<T2) scanning sequences

Life of this patent

Abstract

Claims22