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MRI method and MRI apparatus

A technology of magnetic resonance imaging and magnetic resonance image, which is applied in the direction of magnetic resonance measurement, measurement using nuclear magnetic resonance imaging system, and measurement equipment, can solve the problems of large influence, unavoidable influence of calculation error, and inaccurate calculation, etc., to achieve Effect of reducing signal strength, easy to calculate contrast

Inactive Publication Date: 2005-05-25
GE MEDICAL SYST GLOBAL TECH CO LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] However, if the image information in one pixel contains multiple tissue types, the technique faces the problem of not being able to accurately calculate
[0011] In addition, the technique is greatly affected by calculation errors caused by noise, and cannot avoid the influence of calculation errors

Method used

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  • MRI method and MRI apparatus
  • MRI method and MRI apparatus
  • MRI method and MRI apparatus

Examples

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no. 1 example

[0132] [First embodiment, T1 weighting]

[0133] Next, the T1 weighting as the first embodiment of the weighting process of the present invention will be explained.

[0134] For example, the following equation 1 gives the signal strength S of the MR signal in the SE technique or the FSE technique.

[0135] [Equation 1]

[0136] S=ρ{1-exp(-TR / T1)}exp(-TE / T2)...(1)

[0137] Where ρ is the concentration of hydrogen.

[0138] Thus, the following signal strengths S1 and S2 are applied to the MR signal (echo signal), which is used to assume that the echo time TE is the same but the repetition time TR is different (ie, the first and second repetition times TR1 and TR2, where TR1<TR2) the image generation process.

[0139] [Equation 2]

[0140] S1=ρ{1-exp(TR1 / T1)}exp(-TE / T2)

[0141] S2=ρ{1-exp(TR2 / T1)}exp(-TE / T2)...(2)

[0142]The following equation 3 gives the difference (S1-S2) between the signal intensities S1 and S2 of the two MR signals in the SE or FSE technique. The difference is ...

no. 2 example

[0169] [Second embodiment: T2 weighting]

[0170] Next, the T2 weighting as the second embodiment of the weighting process of the present invention will be explained.

[0171] The specific T2 value can be weighted in a method similar to the first embodiment.

[0172] In the case of performing two PSDs with the same repetition time TR and different echo times TE (that is, different first and second echo times TE1 and TE2, where TE1<TE2), the different echo times TE1 and TE2 are the same as The signal intensities Sa and Sb correspond to each other, and are expressed by Equation 5 below.

[0173] [Equation 5]

[0174] Sa=ρ{1-exp(-TR / T1)}exp(-TE1 / T2)

[0175] S2=ρ{1-exp(-TR / T1)}exp(-TE2 / T2)...(5)

[0176] The following equation 6 gives the difference (Sa-Sb) between the signal intensities Sa and Sb of the two MR signals. Taking (Sa-Sb) as an example (thus TE1

[0177] [Equation 6]

[0178] Sa-Sb=ρ(1-exp(-TR / T1))

[0179] x(exp(-TE1 / T2)-exp(-TE2 / T2))...(...

no. 3 example

[0184] [Third Embodiment: Normal Weighting]

[0185] The third embodiment of the weighting process according to the present invention preferably uses two types of contrasts to generate an image, and the weighting process only weights tissues with specific T1 and T2 values.

[0186] For example, the third embodiment uses PSD for SE technology or FSE technology.

[0187] In the third embodiment, images with different TR and TE are measured multiple times to generate an image with a specific contrast. These images are then combined to weight only tissues with specific T1 and T2 values.

[0188] For example, the contrast of SE technology is usually expressed by the following equation.

[0189] [Equation 8]

[0190] Σ n ρ n ( 1 - exp ( - TR m ...

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Abstract

It is an object of the present invention to simultaneously provide images with a desired new contrast, eg T1 weighted and T2 weighted images. (1) Provide 4 pulse sequence databases (PSD) (step 11). The provided PSD is: the first image PSD (TE, TR) = (TE1, TR1); the second image PSD (TE, TR) = (TE1, TR2); the third image PSD (TE, TR) = ( TE2, TR1); and the fourth image PSD(TE, TR)=(TE2, TR2), where TE1<TE2 and TR1<TR2. (2) Drive the magnet system of the MRI apparatus based on the 4 PSDs, and collect MR signals (steps 12 to 15). (3) Generate 4 MR images S1 to S4 from the MR signals collected from the PSD (step 16). (4) Calculate the difference (S3-S4)-(S1-S2) between the images to obtain T1-weighted and T2-weighted images based on the images corresponding to the calculated difference.

Description

Technical field [0001] The present invention relates to a magnetic resonance imaging (MRI) method and a magnetic resonance imaging device implementing the method. The method uses magnetic resonance (MR) signals to generate images, and the magnetic resonance signals are detected using magnetic resonance phenomena. [0002] More specifically, the present invention relates to an MRI method and an MRI apparatus that generate images with useful contrast from images with multiple different contrasts. Background technique [0003] The clinical examination using MR images enhances the contrast of the image in the area of ​​the object (human body) to be examined. The determinant of the basic contrast is the weighting of T1, T2, or proton concentration. T1 weighting enhances tissues with T1 values. T2 weighting enhances tissues with large T2 values. Proton concentration weighting strengthens tissues with high hydrogen concentration. [0004] There are various inspection techniques to enhan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B5/055G01R33/48G01R33/54
CPCG01R33/4828G01R33/54A61B5/055
Inventor 三好光晴
Owner GE MEDICAL SYST GLOBAL TECH CO LLC
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