Systems and methods for correcting phase errors
First Claim
1. A phase correction method comprising:
- repeating by N shots a pulse sequence in which when a k space is divided from a first line to an N×
Mth line in the phase encode axis direction, data collecting read gradients are applied while inverting so as to focus M-piece imaging echoes per inverting RF pulse and to focus one or more navigation echoes as an echo train continuous to the M-piece imaging echoes before the M-piece imaging echoes and an MPG pulse is applied before and after the inverting pulse;
collecting diffusion enhancement imaging data for filling the k-space from the imaging echoes;
collecting correcting data from the navigation echo; and
phase correcting the imaging data based on the correcting data, wherein the phase correcting includes smoothly changing phase errors of the imaging data in a phase encode axis direction from the first line to the N×
Mth line.
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Accused Products
Abstract
To correct motion and magnetic field inhomogeneity phase errors, inverting data collecting read gradients Nr1 and Nr2 are applied to collect correcting data H (n, 1) and H (n, 2) corresponding to focused navigation echoes Ne1 and Ne2, data collecting read gradients r1, . . . , rM which are inverted alternately are applied, and phase encode gradients pdn, p2, . . . , pM are applied at inverting, thereby collecting imaging data F (n, 1), . . . , F (n, M) corresponding to the focused imaging echoes e1, . . . , eM. This sequence is repeated for n=1, . . . , N while changing the magnitude of the phase encode gradient pdn, whereby data F (1, 1) to F (N, M) for filling a k space are collected. Based on the correcting data H (n, 1) and H (n, 2), the imaging data F (n, 1), . . . , F (n, M) are phase corrected.
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Citations
25 Claims
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1. A phase correction method comprising:
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repeating by N shots a pulse sequence in which when a k space is divided from a first line to an N×
Mth line in the phase encode axis direction, data collecting read gradients are applied while inverting so as to focus M-piece imaging echoes per inverting RF pulse and to focus one or more navigation echoes as an echo train continuous to the M-piece imaging echoes before the M-piece imaging echoes and an MPG pulse is applied before and after the inverting pulse;
collecting diffusion enhancement imaging data for filling the k-space from the imaging echoes;
collecting correcting data from the navigation echo; and
phase correcting the imaging data based on the correcting data, wherein the phase correcting includes smoothly changing phase errors of the imaging data in a phase encode axis direction from the first line to the N×
Mth line.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 11)
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10. A phase correction method comprising:
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repeating by N shots a pulse sequence in which when a k space is divided from a first line to an N×
Mth line in the phase encode axis direction, data collecting read gradients are applied while inverting so as to focus M-piece imaging echoes per inverting RF pulse and to focus one or more navigation echoes as an echo train continuous to the M-piece imaging echoes before the M-piece imaging echoes and an MPG pulse is applied before and after the inverting pulse;
collecting diffusion enhancement imaging data for filling the k space from the imaging echo;
collecting correcting data from the navigation echo;
collecting referring data corresponding to the imaging data and correcting data from a referring echo focused by executing a referring pulse sequence omitting the phase encode gradient and MPG pulse from the pulse sequence;
phase correcting the imaging data based on the corresponding referring data;
phase correcting the correcting data based on the corresponding referring data; and
phase correcting imaging data phase-corrected by the referring data based on correcting data phase-corrected by the referring data. - View Dependent Claims (12, 13)
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14. An MRI system comprising:
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an RE pulse transmitting device;
a gradient pulse application device;
an NMR signal receiving device;
a data collection control device for controlling the RE pulse-transmitting device, the gradient pulse application device, and the NMR signal receiving device, repeating by N shots a pulse sequence in which when a k space is divided in the phase encode axis direction from a first line to an N×
Mth line, data collecting read gradients are applied while inverting so as to focus M-piece imaging echoes per inverting RE pulse and to focus one or more navigation echoes as an echo train continuous to the M-piece imaging echoes before the M-piece imaging echoes and an MPG pulse is applied before and after the inverting pulse, collecting diffusion enhancement imaging data for filling the k space from the imaging echo, and collecting correcting data from the navigation echo;
a correction arithmetic operation device for phase correcting the imaging data based on the correcting data, wherein the correction arithmetic operation device phase corrects the imaging data to smoothly change phase errors of the imaging data in a phase encode axis direction from the first line to the N×
Mth line; and
a reconstruction arithmetic operating device for reconstructing an image from the imaging data after correction arithmetic operation. - View Dependent Claims (15, 16, 17, 18, 19, 21, 22)
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20. MRI system in accordance with claim wherein the correction amount of the magnetic field inhomogeneity phase error is determined to be an average of phase differences between the navigation echoes.
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23. An MRI system comprising:
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an RF pulse transmitting device;
a gradient pulse application device;
an NMR signal receiving device;
a data collection control device for controlling the RF pulse transmitting device, the gradient pulse application device, and the NMR signal receiving device, the data collection control device repeating by N shots a pulse sequence in which when a k space is divided in the phase encode axis direction from the first line to the N×
Mth line, data collecting read gradients are applied while inverting so as to focus M-piece imaging echoes per inverting RF pulse and to focus one or more navigation echoes as an echo train continuous to the M-piece imaging echoes before the M-piece imaging echoes and an MPG pulse is applied before and after the inverting pulse, collecting diffusion enhancement imaging data for filling the k space from the imaging echo, collecting correcting data from the navigation echo, and collecting referring data corresponding to the imaging data and correcting data from a referring echo focused by executing a referring pulse sequence omitting the phase encode gradient and MPG pulse from the pulse sequence;
a correction arithmetic operation device for phase correcting the imaging data based on the corresponding referring data, phase correcting the correcting data based on the corresponding referring data, and phase correcting imaging data phase-corrected by the referring data based on correcting data phase-corrected by the referring data; and
a reconstruction arithmetic operation device for reconstructing an image from the imaging data after correction arithmetic operation. - View Dependent Claims (24, 25)
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Specification