US2015212181A1PendingUtilityA1
Correction method and apparatus for magnetic resonance diffusion weighted imaging image
Est. expiryJan 27, 2034(~7.5 yrs left)· nominal 20-yr term from priority
A61B 5/7221A61B 5/055G01R 33/5659G01R 33/56341G06T 7/0012A61B 5/4875
48
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Claims
Abstract
In a correction method and apparatus for a magnetic resonance diffusion weighted imaging image, a diffusion weighted imaging image is corrected based on a launch site correction factor and/or a receiving field correction factor. The launch site correction factor is used for correcting inhomogeneity of a launch site, and the receiving field correction factor is used for correcting inhomogeneity of a receiving field. The imaging sequence of the diffusion weighted imaging image is thereby improved and the corresponding image reconstruction of the diffusion weighted imaging image, and the homogeneity of the diffusion weighted imaging image also can be improved, without measuring the intensity of the launch site, which significantly reduces the correction workload and is easy to automate.
Claims
exact text as granted — not AI-modifiedI claim as my invention:
1 . A correction method for a magnetic resonance diffusion weighted imaging image, comprising:
correcting a diffusion weighted imaging image based on a launch site correction factor and/or a receiving field correction factor, wherein the launch site correction factor is used for correcting inhomogeneity of a launch site, and the receiving field correction factor is used for correcting inhomogeneity of a receiving field.
2 . The correction method as claimed in claim 1 , comprising determining the launch site correction factor based on an excitation pulse flip angle actual value of the diffusion weighted imaging image and a refocusing pulse flip angle actual value corresponding thereto; and/or calculating the receiving field correction factor based on a pulse flip angle correction factor.
3 . The correction method as claimed in claim 2 , comprising calculating the receiving field correction factor based on a pulse flip angle correction factor by:
calculating a reciprocal of the pulse flip angle correction factor, and determining the reciprocal as the receiving field correction factor.
4 . The correction method as claimed in claim 2 , comprising:
calculating the excitation pulse flip angle actual value and the refocusing pulse flip angle actual value based on the pulse flip angle correction factor.
5 . The correction method as claimed in claim 2 , comprising:
calculating an excitation pulse flip angle actual value of a first diffusion weighted imaging image scanning according to an image signal intensity of the first and a second diffusion weighted imaging image scanning and a preset relationship between excitation pulse flip angle setting values of the first and second diffusion weighted imaging image scanning, and determining the pulse flip angle correction factor according to a ratio of the excitation pulse flip angle actual value of the first diffusion weighted imaging image scanning to the excitation pulse flip angle setting value of the first diffusion weighted imaging image scanning.
6 . The correction method as claimed in claim 5 , wherein in that the preset relationship is that, for the same diffusion sensitive factor, the excitation pulse flip angle setting value of the second diffusion weighted imaging image scanning is N times the excitation pulse flip angle setting value of the first diffusion weighted imaging image scanning, where N is a positive number, the excitation pulse flip angle actual value α actual of the first diffusion weighted imaging image scanning is determined according to a first general formula, and the first general formula is
Sin
(
N
*
α
actual
)
Sin
α
actual
=
S
2
,
measured
S
1
,
measured
,
wherein S 1,measured denotes the image signal intensity of the first diffusion weighted imaging image scanning, and S 2,measured denotes the image signal intensity of the second diffusion weighted imaging image scanning.
7 . The correction method as claimed in claim 6 , wherein N=2.
8 . The correction method as claimed in claim 7 , wherein the excitation pulse flip angle setting value of the first diffusion weighted imaging image scanning is 60 degrees.
9 . The correction method as claimed in claim 6 , wherein the diffusion sensitive factor is zero.
10 . The correction method as claimed in claim 2 , comprising determining the launch site correction factor, based on an excitation pulse flip angle actual value and a refocusing pulse flip angle actual value corresponding thereto, according to a second general formula, wherein the second general formula is
C
+
=
sin
θ
1
,
nominal
sin
2
(
θ
2
,
nominal
/
2
)
sin
θ
1
,
actual
sin
2
(
θ
2
,
actual
/
2
)
,
wherein C + denotes the launch site correction factor, α 1,actual denotes the excitation pulse flip angle actual value, θ 2,actual denotes the refocusing pulse flip angle actual value corresponding to θ 1,actual , θ 1,nominal denotes the excitation pulse flip angle setting value corresponding to θ 1,actual , and θ 2,nominal denotes the refocusing pulse flip angle actual value corresponding to θ 1,nominal .
11 . The correction method as claimed in claim 10 , wherein the diffusion sensitive factor is zero.
12 . A correction apparatus for a magnetic resonance diffusion weighted imaging image, comprising a correction factor acquisition unit and a correction unit, wherein:
the correction factor acquisition unit is configured to acquire a launch site correction factor and/or a receiving field correction factor, wherein the launch site correction factor is used for correcting inhomogeneity of a launch site, and the receiving field correction factor is used for correcting inhomogeneity of a receiving field; and the correction unit is configured to correct a diffusion weighted imaging image based on the launch site correction factor and/or the receiving field correction factor.
13 . The correction apparatus as claimed in claim 12 , wherein:
the correction factor acquisition unit is configured to calculate a reciprocal of the pulse flip angle correction factor, and to determine the reciprocal as the receiving field correction factor.
14 . The correction apparatus as claimed in claim 12 , wherein:
the correction factor acquisition unit is configured to determine the launch site correction factor based on an excitation pulse flip angle actual value of the diffusion weighted imaging image and a refocusing pulse flip angle actual value corresponding thereto; and/or calculate the receiving field correction factor based on a pulse flip angle correction factor.
15 . The correction apparatus as claimed in claim 14 , wherein the correction factor acquisition unit is configured to calculate the excitation pulse flip angle actual value and the refocusing pulse flip angle actual value based on the pulse flip angle correction factor.
16 . The correction apparatus as claimed in claim 14 , wherein the correction factor acquisition unit is configured to calculate an excitation pulse flip angle actual value of a first diffusion weighted imaging image scanning according to an image signal intensity of the first and a second diffusion weighted imaging image scanning and a preset relationship between excitation pulse flip angle setting values of the first and second diffusion weighted imaging image scanning, and determine the pulse flip angle correction factor according to a ratio of the excitation pulse flip angle actual value of the first diffusion weighted imaging image scanning to the excitation pulse flip angle setting value of the first diffusion weighted imaging image scanning.
17 . The correction apparatus as claimed in claim 16 , wherein the preset relationship is that, for the same diffusion sensitive factor, the excitation pulse flip angle setting value of the second diffusion weighted imaging image scanning is N times the excitation pulse flip angle setting value of the first diffusion weighted imaging image scanning, where N is a positive number, the excitation pulse flip angle actual value α actual of the first diffusion weighted imaging image scanning is determined according to a first general formula, and the first general formula is
Sin
(
N
*
α
actual
)
Sin
α
actual
=
S
2
,
measured
S
1
,
measured
;
wherein S 1,measured denotes the image signal intensity of the first diffusion weighted imaging image scanning, and S 2,measured denotes the image signal intensity of the second diffusion weighted imaging image scanning.
18 . The correction apparatus as claimed in claim 17 , wherein N=2.
19 . The correction apparatus as claimed in claim 18 , wherein the excitation pulse flip angle setting value of the first diffusion weighted imaging image scanning is 60 degrees.
20 . The correction apparatus as claimed in claim 19 , wherein the correction factor acquisition unit is configured to determine the launch site correction factor, based on an excitation pulse flip angle actual value and a refocusing pulse flip angle actual value corresponding thereto, according to a second general formula, wherein the second general formula is
C
+
=
sin
θ
1
,
nominal
sin
2
(
θ
2
,
nominal
/
2
)
sin
θ
1
,
actual
sin
2
(
θ
2
,
actual
/
2
)
,
wherein C + denotes the launch site correction factor, θ 1,actual denotes the excitation pulse flip angle actual value, θ 2,actual denotes the refocusing pulse flip angle actual value corresponding to θ 1,actual , θ 1,nominal denotes the excitation pulse flip angle setting value corresponding to θ 1,actual , and θ 2,nominal denotes the refocusing pulse flip angle actual value corresponding to θ 1,nominal .
21 . The correction apparatus as claimed in claim 17 , wherein the diffusion sensitive factor is zero.Join the waitlist — get patent alerts
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