Magnetic resonance imaging method for measuring R2, R2* and R2' parameter image of tissue in noninvasive and dynamic manner

A technology of magnetic resonance imaging and parametric image, which is applied in the direction of using nuclear magnetic resonance imaging system for measurement, magnetic resonance measurement, and magnetic variable measurement, etc., and can solve the problems of large estimation error, large estimation error, mismatch of image level contours, etc. Achieve the effect of reducing contribution and good flow velocity attenuation gradient

Inactive Publication Date: 2016-06-22
PEKING UNIV
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However, in this sequence, non-ideal slice-selection profiles caused by short radio frequency (RF) pulse times lead to a mismatch of image slice profiles acquired before and after the 180° refocusing pulse, which

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  • Magnetic resonance imaging method for measuring R2, R2* and R2' parameter image of tissue in noninvasive and dynamic manner
  • Magnetic resonance imaging method for measuring R2, R2* and R2' parameter image of tissue in noninvasive and dynamic manner
  • Magnetic resonance imaging method for measuring R2, R2* and R2' parameter image of tissue in noninvasive and dynamic manner

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[0025] The psMASE sequence scan should be performed after the routine positioning scan and reference image scan. During the use, the subject lies flat on the MR scan table. For example, imaging of lower extremity calf muscles, a suitable psMASE sequence parameter can be set as follows: fieldofview(FOV)=150×150mm 2 ,matrixsize=70×70,repetitiontime(TR)=2000ms,TE 1 / TE 2 / TE 3 / TE4 =60 / 80 / 100 / 120ms, echospace=20ms, τ=-10 / 0 / 10ms, slicethickness=6mm, SENSEfactor=2, NSA=1, echoshiftnumber=12. The above parameters can be adjusted according to different needs.

[0026] In order to reflect the characteristics of this method that can dynamically measure tissue R2, R2* and R2' parameter images, take a volunteer in a typical lower limb ischemia and recovery experiment as an example. The belt is tied to the thigh of the right leg and fixed with a nylon strap to prevent the blood pressure belt from loosening. During the scan, keep the subject's head, feet, and knees at the same level. ...

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Abstract

The invention discloses a magnetic resonance imaging method which utilizes the fact that a tissue with different deoxygenated hemoglobin content has magnetic sensitive chatacteristics of different degrees, uses an asymmetric spin echo magnetic resonance imaging sequence, adopts a strategy of moving a 180-degree echo refocusing RF pulse position periodically, allows 180-degree echo refocusing pulses to distribute on both sides of a TE/2 time position in each period, and obtains a high-time-resolution multiple-echo image. Further, aiming at acquired multiple-echo signals, the magnetic resonance imaging method performs mobile estimation by taking length of a corresponding 180-degree echo refocusing pulse mobile period as a window width, adopts least square estimation, and obtains dynamic parameter images of R2, R2* and R2' simultaneously according to a signal attenuation index model. By adopting the magnetic resonance imaging method, the high-time-resolution dynamic R2, R2* and R2' parameter images can be obtained, and a dynamic curves in an arbitrary region of interest can be displayed.

Description

technical field [0001] The invention belongs to the technical field of magnetic resonance imaging (MRI), in particular to a set of methods for dynamically and noninvasively and quantitatively measuring the intrinsic relaxation times R2, R2* and R2' of different tissues based on the magnetic resonance imaging technology. Background technique [0002] Susceptibility, as an important contrast mechanism, has a wide range of applications in magnetic resonance techniques. For example, blood oxygen level-dependent imaging (BOLD) is an imaging method developed based on the paramagnetic properties of deoxygenated hemoglobin. Blood) functional evaluation. [0003] In magnetic resonance imaging, susceptibility effects affect the R2* parameter, and R2* is the free decay rate of the tissue signal, usually fitted using a single-exponential decay model. And R2* contains two components: (1) one is the irreversible component R2, and (2) the other is the reversible R2', which reflects the d...

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Application Information

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IPC IPC(8): G01R33/50G01R33/54A61B5/055
Inventor 王成彦张锐王鹤金立新王霄英张珏方竞
Owner PEKING UNIV
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