A magnetic resonance imaging method for measuring sodium diffusion inside and outside cells

Abstract

This invention discloses a magnetic resonance imaging method for measuring sodium diffusion inside and outside cells, utilizing IR-DW-STRO sequences to acquire intracellular and systemic brain images. 23 Na images, intracellular brain images, and the brain as a whole. 23 Na diffusion-weighted images were finally fitted to obtain extracellular brain cells. 23 Apparent diffusion coefficient distribution of Na and extracellular matrix of brain cells 23 The signal intensity of Na; the IR-DW-STRO sequence of the present invention includes an IR sequence, a DW-STEAM sequence, and a Radial Osc UTE sampling sequence, which are used to sample intracellular signals via the IR sequence. 23 Na and the whole 23 Na signals are selectively acquired; the DW-STEAM sequence shortens the echo time (TE) and reduces [the signal density] by employing minimum-phase SLR pulses. 23 Na-level transverse relaxation signal loss; Radial Osc UTE sampling sequence improves k-space filling efficiency.

Description

Technical Field

[0001] This invention belongs to the field of magnetic resonance imaging technology, specifically relating to a magnetic resonance imaging method for measuring the diffusion of sodium elements inside and outside cells. It is applicable to the separation of intracellular and extracellular sodium elements based on sodium element magnetic resonance technology, and to obtain the diffusion coefficients of intracellular and extracellular sodium elements respectively. Background Technology

[0002] Magnetic resonance imaging (MRI) works by analyzing the concentration of water molecules in the human body. 1 H imaging can perform structural and functional imaging of most human tissues and organs non-invasively and without radiation. However, besides... 1 Besides H, there are many other atomic nuclei in the human body that can be detected using magnetic resonance imaging (MRI). 23 Na is present in the human body, except for... 1 Magnetic resonance imaging (MRI) of atoms other than hydrogen atoms can detect the most abundant endogenous atomic nuclei. These nuclei are indispensable elements for maintaining the homeostasis of the biological internal environment and the stability of cellular function and metabolism, and play a vital role in cellular osmotic regulation and physiological activities.

[0003] 23 Sodium (Na) is widely distributed throughout the brain, both inside and outside cell membranes, and participates in the transmission of nerve signals and the normal function of neurons. There is a significant difference in sodium concentration between intracellular and extracellular spaces. When brain tissue function is abnormal, changes in cell membrane permeability lead to an imbalance in sodium ion concentrations inside and outside the cell, potentially altering local sodium diffusion patterns. Measuring sodium in vivo... 23 Na diffusion is very difficult, mainly due to three challenges: 1) 23 Na compared to 1 H has a lower gyromagnetic ratio, requiring a stronger diffusion coding gradient; 2) Brain 23 The Na content is much lower than 1 H, low magnetic resonance signal; 3) 23 The short transverse relaxation time constant T2 of Na further increases the... 23The difficulty of Na signal acquisition. Van der Veen et al. acquired sodium diffusion in erythrocyte samples by diffusion-weighted spin echo [Magnetic Resonance in Medicine, 1993, 29(4): 571-574.], but this method has a long echo time (TE) and is not suitable for in vivo Na signal acquisition; Jonathan V. Sehy et al. obtained the apparent diffusion coefficient of intracellular sodium by injecting a displacement reagent into Xenopus oocytes to cause differences in the chemical displacement of sodium inside and outside the cells [Magnetic Resonance in Medicine, 2002, 48(1): 42-51.], but this method is invasive; James A. Goodman et al. measured the apparent diffusion coefficient of sodium in the whole brain of rats by adiabatic selective re-aggregation localization pulse sequence, but did not distinguish between intracellular and extracellular sodium [Magnetic Resonance in Medicine, 2005, 53(5): 1040-1045.]. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by providing a magnetic resonance imaging method for measuring the diffusion of sodium elements inside and outside cells.

[0005] The above-mentioned objectives of the present invention are achieved by the following technical means:

[0006] A magnetic resonance imaging method for measuring sodium diffusion inside and outside cells includes the following steps:

[0007] Step 1: Collect intracellular data from the subject's brain cells using IR-DW-STRO sequencing. 23 Na image Img IC IR-DW-STRO sequences include IR sequences, DW-STEAM sequences, and Radial Osc UTE sampling sequences;

[0008] Step 2: Collect whole brain images of the subject using IR-DW-STRO sequence. 23 Na image Img T Then, based on the brain cells 23 Na image Img IC and the brain as a whole 23 Na image Img T Calculations obtained intracellular and extracellular brain regions 23 Na content ratio diagram R map ;

[0009] Step 3: Use IR-DW-STRO sequence to collect intracellular data from the subject's brain cells.23 Na diffusion-weighted image Img IC-b Then, based on the brain cells 23 Na image Img IC and brain cells 23 Na diffusion-weighted image Img IC-b Calculation to obtain brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) IC ;

[0010] Step 4: Collect whole brain images of the subject using IR-DW-STRO sequence. 23 Na diffusion-weighted image Img T-b Then, based on the intracellular and extracellular spaces of the brain... 23 Na content ratio diagram R map Overall brain 23 Na image Img T and brain cells 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC Fitting to obtain extracellular brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) EC And extracellular brain cells when the strengths of diffusion bipolar gradient G1 and diffusion bipolar gradient G2 are 0. 23 The signal strength of Na, S EC .

[0011] As described above, step 1 includes the following steps:

[0012] Step 1.1: The subject lies flat on the MRI examination table and wears... 23 Na imaging coil;

[0013] Step 1.2: First, an IR sequence is applied to the subject. The IR sequence includes a radiofrequency pulse RF0 and an inversion recovery time TI. The radiofrequency pulse RF0 is a 180-degree radiofrequency pulse. The radiofrequency pulse RF0 affects the entire brain. 23 Na is used for excitation. After excitation by radio frequency pulse RF0, the inversion recovery time TI is waited for. After the inversion recovery time TI ends, the brain cells are excited. 23 The longitudinal magnetization vector of Na is restored, while extracellular brain cells... 23 The longitudinal magnetization vector of Na is suppressed;

[0014] Step 1.3: Apply the DW-STEAM sequence to the subject. The DW-STEAM sequence includes radio frequency pulses RF1, RF2, and RF3. Radio frequency pulses RF1, RF2, and RF3 are all 90-degree radio frequency pulses. Radio frequency pulses RF1 and RF3 both use minimum phase SLR pulses. The intensity of the diffused bipolar gradient G1 and diffused bipolar gradient G2 is set to 0.

[0015] Step 1.4: Apply a Radial Osc UTE sampling sequence to the subject to obtain data from one sampling spoke in k-space;

[0016] The readout gradients GEX and GEY in the Radial Osc UTE sampled sequence are calculated as follows:

[0017] First, the combined gradient vector of the read gradients GEX and GEY reaches the plateau intensity G0 according to the maximum gradient ascent rate.

[0018] Then, sine / cosine modulation is applied to the readout gradients GEX and GEY, and the readout gradients GEX and GEY after sine / cosine modulation are calculated based on the following formulas:

[0019]

[0020]

[0021] In the formula, G is the fundamental waveform of the readout gradient GEX and readout gradient GEY after time t0; θ is the angle between two adjacent sampling spokes in the Radial Osc UTE sequence; i = 0, 1, 2, ..., n-1, where n is the total number of sampling spokes; R is the acceleration factor; T osc It reads the gradient oscillation period; t G t0 is the total time from when the readout gradient GEX or GEY is turned on to when it is turned off, t0 is the time required for the readout gradient to reach the G0 intensity from 0 with the maximum gradient climb rate, and t is the time calculated from time t0.

[0022] Step 1.5: Repeat steps 1.2 to 1.4 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 in the nth repetition, thus completing the k-space data filling. Then, perform a non-uniform inverse Fourier transform on the k-space data to obtain the intracellular data of brain cells. 23 Na image Img IC .

[0023] As described above, step 2 includes the following steps:

[0024] Step 2.1: Repeat steps 1.3 to 1.4 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 on the nth repetition, thus completing the k-space data filling. Then, a non-uniform inverse Fourier transform is performed on the k-space data to obtain the overall brain data. 23 Na image Img T ;

[0025] Step 2.2: According to the following formula, extract the intracellular contents of the brain cells obtained in Step 1.5. 23 Na image Img IC Divide pixel by pixel by the total brain size obtained in step 2.1 23 Na image Img T Obtain intracellular brain cells 23 Na content distribution diagram C IC :

[0026] C IC =Img IC / Img T

[0027] Then obtain extracellular brain cells according to the following formula 23 Na content distribution diagram C EC :

[0028] C EC =1-C IC

[0029] Finally, the intracellular and extracellular spaces of the brain are calculated using the following formula. 23 Na content ratio diagram R map :

[0030]

[0031] As described above, step 3 includes the following steps:

[0032] Step 3.1: First, apply an IR sequence to the subject to induce extracellular irradiation of brain cells. 23 The longitudinal magnetization vector of Na is suppressed;

[0033] Step 3.2: Set the diffusion sensitivity factor b for the IR-DW-STRO sequence, apply the DW-STEAM sequence to the subject, and calculate the strengths of the diffusion bipolar gradient G1 and diffusion bipolar gradient G2 based on the following formula:

[0034]

[0035] In the formula, γ is 23 The gyromagnetic ratio of Na, δ and Δ are the diffusion gradient delay time and diffusion time of the IR-DW-STRO sequence, respectively;

[0036] Step 3.3: Apply a Radial Osc UTE sampling sequence to the subject to obtain data from one sampling spoke in k-space;

[0037] Step 3.4: Repeat steps 3.1 to 3.3 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 in the nth repetition, until the k-space data is filled. Then, perform a non-uniform inverse Fourier transform on the k-space data to obtain the brain cells with a diffusion sensitivity factor of b. 23 Na diffusion-weighted image Img IC-b ;

[0038] Step 3.5, based on the brain cells obtained in Step 1.5 23 Na image Img IC Compared with the brain cells obtained in step 3.4 23 Na diffusion-weighted image Img IC-b The following formula can be used to calculate the intracellular content of brain cells. 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC :

[0039]

[0040] In the formula, ln is the natural logarithm function.

[0041] As described above, step 4 includes the following steps:

[0042] Step 4.1: Repeat steps 3.2 to 3.3 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 in the nth repetition, thus completing the k-space data filling. After performing a non-uniform inverse Fourier transform on the k-space data, the whole brain with a diffusion sensitivity factor of b is obtained. 23 Na diffusion-weighted image Img T-b ;

[0043] Step 4.2: Combining the intracellular and extracellular brain data obtained in Step 2.2 23 Na content ratio diagram R map Step 2.1 Obtaining the overall brain 23 Na image Img T and the brain cells obtained in step 3.5 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC The extracellular matrix of brain cells was fitted using the following formula. 23 Apparent diffusion coefficient distribution of Na (ADC) EC And extracellular brain cells when the intensity of the diffusing bipolar gradients G1 and G2 is 0 23 The signal strength of Na, S EC:

[0044]

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] (1) This invention shortens the echo time (TE) of the IR-DW-STRO pulse sequence by using a minimum-phase SLR pulse, thereby enhancing the image signal-to-noise ratio and reducing noise. 23 In the case of loss of Na transverse relaxation signal, achieve the following 23 Measurement of long-term diffusion of Na.

[0047] (2) This invention effectively targets intracellular structures via IR sequences. 23 Na and the whole 23 Selective acquisition of Na signals can be performed, and extracellular signals can be further obtained based on these two factors. 23 The intensity of the magnetic resonance signal of Na.

[0048] (3) The Radial Osc UTE sampling sequence of the present invention improves the signal-to-noise ratio of image reconstruction and enhances the k-space filling efficiency. Attached Figure Description

[0049] Figure 1 This is a flowchart of the present invention;

[0050] Figure 2 This is a schematic diagram of the IR-DW-STRO pulse sequence used in steps 1 to 4 of Embodiment 1 of the present invention;

[0051] Figure 3 This is a schematic diagram of the pulse waveform of the minimum phase SLR pulse used in steps 1 to 4 of Embodiment 1 of the present invention.

[0052] Figure 4 This is a schematic diagram of the basic waveforms for reading gradients GEX and GEY from the Radial Osc UTE sequence in steps 1 to 4 of Embodiment 1 of the present invention.

[0053] Figure 5 This is a schematic diagram of the waveforms of the readout gradients GEX and GEY when i=2 under parameter i=2 in step 1.4 of Embodiment 1 of the present invention;

[0054] Figure 6 The Radial Osc UTE sampling trajectory (kx and ky are the coordinates of the sampling data in two-dimensional k-space) under the parameters of step 1.4 of Embodiment 1 of the present invention;

[0055] Figure 7This refers to the existing Radial UTE sampling trajectory under the parameters of step 1.4 of Embodiment 1 of the present invention;

[0056] Figure 8 This is a schematic diagram comparing the Radial Osc UTE sampling trajectory under the parameters of step 1.4 of Embodiment 1 of the present invention with the existing Radial UTE sampling trajectory. Detailed Implementation

[0057] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to embodiments. The embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0058] Example 1:

[0059] like Figure 1 As shown, a magnetic resonance imaging method for measuring sodium diffusion inside and outside cells includes the following steps:

[0060] Step 1: Using the Inversion Recovery-Diffusion Weighted-Stimulated Echo Acquisition mode – Radial Oscillation ultrashort echo time sequence (IR-DW-STRO sequence), intracellular echoes of the subject's brain cells were acquired. 23 Na image Img IC Specifically, it includes the following steps:

[0061] IR-DW-STRO sequences include IR sequences, DW-STEAM sequences, and Radial Osc UTE sampling sequences, such as... Figure 2 As shown.

[0062] Step 1.1: The subject lies flat on the MRI examination table and wears... 23 Na imaging coil.

[0063] Step 1.2: First, an IR sequence is applied to the subject. The IR sequence includes a radiofrequency pulse RF0 and an inversion recovery time TI. The radiofrequency pulse RF0 is a 180-degree radiofrequency pulse, which can affect the entire brain. 23 Na (including that in brain cells) 23 Na and extracellular brain cells 23 Na) is excited, and after the radio frequency pulse RF0 is excited, the inversion recovery time TI is waited for, due to the brain cells 23The longitudinal relaxation time of Na is much shorter than that of extracellular brain cells. 23 The longitudinal relaxation time of Na, therefore, allows brain cells to relax after the inversion recovery time (TI) ends. 23 The longitudinal magnetization vector of Na is restored, while extracellular brain cells... 23 The longitudinal magnetization vector of Na is suppressed.

[0064] In this invention, both intracellular and extracellular brain regions are within the brain.

[0065] Step 1.3: Apply the DW-STEAM sequence to the subject. The DW-STEAM sequence includes radiofrequency pulses RF1, RF2, and RF3. RF1, RF2, and RF3 are all 90-degree radiofrequency pulses. Both RF1 and RF3 use minimum-phase SLR pulses, which can shorten the [time / length] of the pulse. 23 The echo time TE of Na imaging is equal to the equal time delay time plus the data sampling dead time, where the data sampling dead time is typically 50µs.

[0066] like Figure 3 As shown, in this embodiment, the equal delay time of the minimum phase SLR pulse is 12% of the pulse length of the minimum phase SLR pulse, that is, when a 1ms minimum phase SLR pulse is used for excitation... 23 With Na signals, the isochronous delay time is only 120µs, thus allowing the echo time TE to be much lower than that of the brain at 7T. 23 The transverse relaxation time of Na (typically several milliseconds);

[0067] By employing minimum-phase SLR pulses, the echo time (TE) of the IR-DW-STRO pulse sequence is shortened, thereby enhancing the image signal-to-noise ratio.

[0068] In step 1, the intensities of the diffusion bipolar gradient G1 and diffusion bipolar gradient G2 are set to 0.

[0069] Step 1.4: Apply the Radial Osc UTE sampling sequence to the subject to obtain data from one sampling spoke in k-space.

[0070] The Radial Osc UTE sampling sequence is a sampling sequence obtained by changing the readout gradients GEX and GEY from an existing Radial UTE sampling sequence. The readout gradients GEX and GEY in the Radial Osc UTE sampling sequence are calculated through the following steps:

[0071] like Figure 4 As shown, the gradient vector of the first read gradient GEX and the second read gradient GEY reaches the plateau intensity G0 according to the maximum gradient climb rate.

[0072] The base waveforms G of the readout gradients GEX and GEY after time t0 (the base waveforms of the readout gradients GEX and GEY are the same) are calculated according to the following formula:

[0073]

[0074] In the formula, t0 is the time required for the readout gradient (GEX / GEY) to reach the G0 intensity from 0 with the maximum gradient climb rate; k0 is the k-space distance corresponding to the readout gradient at time t0 in the existing Radial UTE sequence; γ is the gyromagnetic ratio of sodium; and t is the time calculated from time t0 (i.e., the initial time of t is time t0).

[0075] The plateau intensity G0 can be determined based on brain function. 23 The imaging field of view of Na and the sampling bandwidth of the Radial Osc UTE sampling sequence were calculated.

[0076] The readout gradient calculated by formula (1) ensures that the sampling point density within the k-space circle remains constant after time t0.

[0077] like Figure 5 As shown, in order to accelerate the acquisition, sine / cosine modulation is applied to the readout gradient GEX and readout gradient GEY based on formula (1). The readout gradients GEX and GEY after applying sine / cosine modulation are calculated based on the following formulas:

[0078]

[0079]

[0080] In the formula, θ is the angle between two adjacent sampling spokes in the Radial Osc UTE sequence; i = 0, 1, 2, ..., n-1, where n is the total number of sampling spokes; R is the acceleration factor, the value of which indicates that one sampling spoke in the sampling trajectory (i.e., the k-space filling trajectory) of the Radial Osc UTE sequence can simultaneously cover the sampling points of R spokes in the existing Radial UTE sampling trajectory; T osc It reads the gradient oscillation period; t G It is the total time from when the read gradient (GEX or GEY) is turned on to when it is turned off.

[0081] In this embodiment, the plateau intensity G0 is set to 204 mT / m, the acceleration factor R is set to 4 (the actual total number of sampled spokes n is 50, corresponding to the existing Radial UTE spoke count of 200), and the gradient oscillation period T is... osc Set to 52us, t GSet to 334us, θ to 7.2 degrees, and t0 to 125us; For example... Figure 6 , Figure 7 ,as well as Figure 8 As shown, it can be seen that one sampling spoke of the Radial Osc UTE sampling trajectory in this embodiment simultaneously covers the sampling points of four sampling spokes of the existing Radial UTE sampling trajectory.

[0082] Step 1.5: Repeat steps 1.2 to 1.4 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until i increases to n-1 in the nth repetition, thus completing the k-space data filling. Then, perform a non-uniform inverse Fourier transform on the k-space data to obtain the intracellular data of brain cells. 23 Na image Img IC .

[0083] Step 2: Collect whole brain images of the subject using IR-DW-STRO sequence. 23 Na image Img T Then, based on the brain cells 23 Na image Img IC and the brain as a whole 23 Na image Img T Calculations obtained intracellular and extracellular brain regions 23 Na content ratio diagram R map Specifically, it includes the following steps:

[0084] Step 2.1: Repeat steps 1.3 to 1.4 a total of n times. The initial value of i is 0. Each time it is repeated, i increases until it increases to n-1 in the nth repetition, thus completing the k-space data filling. Since the IR sequence of the IR-DW-STRO sequence is not used, the non-uniform inverse Fourier transform of the k-space data yields the whole brain. 23 Na image Img T .

[0085] Step 2.2: The brain cells obtained in Step 1.5... 23 Na image Img IC Divide pixel by pixel by the total brain size obtained in step 2.1 23 Na image Img T Obtain intracellular brain cells 23 Na content distribution diagram C IC (C IC =Img IC / Img T ), and extracellular matrix of brain cells 23 Na content distribution diagram C EC (C EC =1-C IC), intracellular and extracellular space of the brain 23 Na content ratio diagram R map It is calculated using the following formula:

[0086]

[0087] Step 3: Use IR-DW-STRO sequence to collect intracellular data from the subject's brain cells. 23 Na diffusion-weighted image Img IC-b Then, based on the brain cells 23 Na image Img IC and brain cells 23 Na diffusion-weighted image Img IC-b Calculation to obtain brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) IC Specifically, it includes the following steps:

[0088] Step 3.1: First, apply an IR sequence to the subject to induce extracellular irradiation of brain cells. 23 The longitudinal magnetization vector of Na is suppressed.

[0089] Step 3.2: Set the diffusion sensitivity factor b for the IR-DW-STRO sequence, apply the DW-STEAM sequence to the subject, and calculate the strengths of the diffusion bipolar gradient G1 and diffusion bipolar gradient G2 according to the following formula:

[0090]

[0091] In the formula, γ is 23 The gyromagnetic ratio of Na, δ and Δ are the diffusion gradient delay time and diffusion time of the IR-DW-STRO sequence, respectively.

[0092] Step 3.3: Apply the Radial Osc UTE sampling sequence to the subject to obtain data from one sampling spoke in k-space.

[0093] Step 3.4: Repeat steps 3.1 to 3.3 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until i increases to n-1 in the nth repetition, thus completing the k-space data filling. Then, perform a non-uniform inverse Fourier transform on the k-space data to obtain the brain cells with a diffusion sensitivity factor of b. 23 Na diffusion-weighted image Img IC-b .

[0094] Step 3.5, based on the brain cells obtained in Step 1.5 23 Na image Img IC Compared with the brain cells obtained in step 3.4 23 Na diffusion-weighted image ImgIC-b The following formula is used to calculate the intracellular content of brain cells. 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC :

[0095]

[0096] In the formula, ln is the natural logarithm function, i.e., log e .

[0097] Step 4: Collect whole brain images of the subject using IR-DW-STRO sequence. 23 Na diffusion-weighted image Img T-b Then, based on the intracellular and extracellular spaces of the brain... 23 Na content ratio diagram R map Overall brain 23 Na image Img T and brain cells 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC Fitting to obtain extracellular brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) EC And extracellular brain cells when the strengths of diffusion bipolar gradient G1 and diffusion bipolar gradient G2 are 0. 23 The signal strength of Na, S EC Specifically, it includes the following steps:

[0098] Step 4.1: Repeat steps 3.2 to 3.3 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until i increases to n-1 in the nth repetition, thus completing the k-space data filling. Since the IR sequence of the IR-DW-STRO sequence is not used, the non-uniform inverse Fourier transform of the k-space data yields the whole brain with a diffusion sensitivity factor of b. 23 Na diffusion-weighted image Img T-b .

[0099] Step 4.2: Combining the intracellular and extracellular brain data obtained in Step 2.2 23 Na content ratio diagram R map Step 2.1 Obtaining the overall brain 23 Na image Img T and the brain cells obtained in step 3.5 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC The extracellular matrix of brain cells was fitted using the following formula. 23 Apparent diffusion coefficient distribution of Na (ADC) EC And extracellular brain cells when the strengths of diffusion bipolar gradient G1 and diffusion bipolar gradient G2 are 0. 23The signal strength of Na, S EC :

[0100]

[0101] Example 2:

[0102] A magnetic resonance imaging device for measuring sodium diffusion inside and outside cells, comprising:

[0103] Brain cells 23 Na image Img IC The acquisition module is used to implement step 1: acquiring intracellular data of the subject's brain cells using the inversion recovery-diffusion-weighted stimulated echo acquisition mode-radial oscillation ultrashort echo time series (i.e., IR-DW-STRO sequence). 23 Na image Img IC .

[0104] Intracellular and Extracellular Space of the Brain 23 Na content ratio diagram R map The generation module is used to implement step 2: acquiring the whole brain of the subject using IR-DW-STRO sequences. 23 Na image Img T Then, based on the brain cells 23 Na image Img IC and the brain as a whole 23 Na image Img T Calculations obtained intracellular and extracellular brain regions 23 Na content ratio diagram R map .

[0105] Brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) IC The generation module is used to implement step 3: acquiring intracellular data from the subject's brain cells using IR-DW-STRO sequences. 23 Na diffusion-weighted image Img IC-b Then, based on the brain cells 23 Na image Img IC and brain cells 23 Na diffusion-weighted image Img IC-b Calculation to obtain brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) IC .

[0106] Extracellular brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) EC The fitting module is used to perform step 4: acquiring the whole brain of the subject using IR-DW-STRO sequences. 23Na diffusion-weighted image Img T-b Then, based on the intracellular and extracellular spaces of the brain... 23 Na content ratio diagram R map Overall brain 23 Na image Img T and brain cells 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC Fitting to obtain extracellular brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) EC And extracellular brain cells when the strengths of diffusion bipolar gradient G1 and diffusion bipolar gradient G2 are 0. 23 The signal strength of Na, S EC .

[0107] It should be noted that the embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A magnetic resonance imaging method for measuring sodium diffusion inside and outside cells, characterized in that, Includes the following steps: Step 1: Acquire intracellular data of the subject's brain cells using the inversion recovery-diffusion weighted stimulated echo acquisition mode-radial oscillation ultrashort echo time series (IR-DW-STRO) sequence. 23 Na image Img IC IR-DW-STRO sequences include IR sequences, DW-STEAM sequences, and Radial Osc UTE sampling sequences; Step 2: Collect whole brain images of the subject using IR-DW-STRO sequence. 23 Na image Img T Then, based on the brain cells 23 Na image Img IC and the brain as a whole 23 Na image Img T Calculations obtained intracellular and extracellular brain regions 23 Na content ratio diagram R map ; Step 3: Use IR-DW-STRO sequence to collect intracellular data from the subject's brain cells. 23 Na diffusion-weighted image Img IC-b Then, based on the brain cells 23 Na image Img IC and brain cells 23 Na diffusion-weighted image Img IC-b Calculation to obtain brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) IC ; Step 4: Collect whole brain images of the subject using IR-DW-STRO sequence. 23 Na diffusion-weighted image Img T-b Then, based on the intracellular and extracellular spaces of the brain... 23 Na content ratio diagram R map Overall brain 23 Na image Img T and brain cells 23 Apparent diffusion coefficient distribution of Na (ADC) IC Extracellular matrix of the brain is obtained by fitting the following formula. 23 Apparent diffusion coefficient distribution of Na (ADC) EC And extracellular brain cells when the intensity of diffusion bipolar gradient G1 and diffusion bipolar gradient G2 is 0. 23 The signal strength of Na, S EC : b is the diffusion sensitivity factor.

2. The magnetic resonance imaging method for measuring sodium diffusion inside and outside cells according to claim 1, characterized in that, Step 1 includes the following steps: Step 1.1: The subject lies flat on the MRI examination table and wears... 23 Na imaging coil; Step 1.2: First, an IR sequence is applied to the subject. The IR sequence includes a radiofrequency pulse RF0 and an inversion recovery time TI. The radiofrequency pulse RF0 is a 180-degree radiofrequency pulse. The radiofrequency pulse RF0 affects the entire brain. 23 Na is used for excitation. After excitation by radio frequency pulse RF0, the inversion recovery time TI is waited for. After the inversion recovery time TI ends, the brain cells are excited. 23 The longitudinal magnetization vector of Na is restored, while extracellular brain cells... 23 The longitudinal magnetization vector of Na is suppressed; Step 1.3: Apply the DW-STEAM sequence to the subject. The DW-STEAM sequence includes radio frequency pulses RF1, RF2, and RF3. Radio frequency pulses RF1, RF2, and RF3 are all 90-degree radio frequency pulses. Radio frequency pulses RF1 and RF3 both use minimum phase SLR pulses. The intensity of the diffused bipolar gradient G1 and diffused bipolar gradient G2 is set to 0. Step 1.4: Apply a Radial Osc UTE sampling sequence to the subject to obtain data from one sampling spoke in k-space; The readout gradients GEX and GEY in the Radial Osc UTE sampled sequence are calculated as follows: First, the combined gradient vector of the read gradient GEX and the read gradient GEY reaches the plateau intensity G0 according to the maximum gradient climb rate; Then, sine / cosine modulation is applied to the readout gradients GEX and GEY, and the readout gradients GEX and GEY after sine / cosine modulation are calculated based on the following formulas: In the formula, G is the fundamental waveform of the readout gradient GEX and readout gradient GEY after time t0; θ is the angle between two adjacent sampling spokes in the Radial Osc UTE sequence; i = 0, 1, 2, ..., n-1, where n is the total number of sampling spokes; R is the acceleration factor; T osc It reads the gradient oscillation period; t G t0 is the total time from when the readout gradient GEX or readout gradient GEY is turned on to when it is turned off, t0 is the time required for the readout gradient to reach the G0 intensity from 0 with the maximum gradient climb rate, and t is the time calculated from time t0. Step 1.5: Repeat steps 1.2 to 1.4 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 in the i-th repetition, thus completing the k-space data filling. Then, perform a non-uniform inverse Fourier transform on the k-space data to obtain the intracellular data of brain cells. 23 Na image Img IC .

3. The magnetic resonance imaging method for measuring sodium diffusion inside and outside cells according to claim 2, characterized in that, Step 2 includes the following steps: Step 2.1: Repeat steps 1.3 to 1.4 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 in the i-th repetition, thus completing the k-space data filling. Then, a non-uniform inverse Fourier transform is performed on the k-space data to obtain the overall brain data. 23 Na image Img T ; Step 2.2: According to the following formula, extract the intracellular contents of the brain cells obtained in Step 1.

5. 23 Na image Img IC Divide pixel by pixel by the total brain size obtained in step 2.1 23 Na image Img T Obtain intracellular brain cells 23 Na content distribution diagram C IC : C IC =Img IC / Img T Then obtain extracellular brain cells according to the following formula 23 Na content distribution diagram C EC : C EC =1-C IC Finally, the intracellular and extracellular spaces of the brain are calculated using the following formula. 23 Na content ratio diagram R map :

4. The magnetic resonance imaging method for measuring sodium diffusion inside and outside cells according to claim 3, characterized in that, Step 3 includes the following steps: Step 3.1: First, apply an IR sequence to the subject to induce extracellular irradiation of brain cells. 23 The longitudinal magnetization vector of Na is suppressed; Step 3.2: Set the diffusion sensitivity factor b for the IR-DW-STRO sequence, apply the DW-STEAM sequence to the subject, and calculate the strengths of the diffusion bipolar gradient G1 and diffusion bipolar gradient G2 based on the following formula: In the formula, γ is 23 The gyromagnetic ratio of Na, δ and Δ are the diffusion gradient delay time and diffusion time of the IR-DW-STRO sequence, respectively; Step 3.3: Apply a Radial Osc UTE sampling sequence to the subject to obtain data from one sampling spoke in k-space; Step 3.4: Repeat steps 3.1 to 3.3 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 in the i-th repetition, until the k-space data is filled. Then, perform a non-uniform inverse Fourier transform on the k-space data to obtain the brain cells with a diffusion sensitivity factor of b. 23 Na diffusion-weighted image Img IC-b ; Step 3.5, based on the brain cells obtained in Step 1.5 23 Na image Img IC Compared with the brain cells obtained in step 3.4 23 Na diffusion-weighted image Img IC-b The following formula can be used to calculate the intracellular content of brain cells. 23 Image of apparent diffusion coefficient distribution of Na (ADC) IC : In the formula, ln is the natural logarithm function.

5. The magnetic resonance imaging method for measuring sodium diffusion inside and outside cells according to claim 4, characterized in that, Step 4 includes the following steps: Step 4.1: Repeat steps 3.2 to 3.3 a total of n times. The initial value of i is 0. Each time i is repeated, it increases until it increases to n-1 in the i-th repetition, thus completing the k-space data filling. After performing a non-uniform inverse Fourier transform on the k-space data, the whole brain with a diffusion sensitivity factor of b is obtained. 23 Na diffusion-weighted image Img T-b .

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