A method, calculation method and system for rapid in-vivo imaging of blood T1 and T2

Abstract

The present application relates to a method, a calculation method and a system for rapid in-vivo imaging of blood T1 and T2. The imaging method includes several rounds of processes of exciting and sampling an imaging acquisition area including a cross-section of the sagittal sinus. The imaging acquisition area includes a front-end venous blood labeling layer block and a rear-end venous blood image layer block. Each sampling process includes: alternately exciting the corresponding layer block area with a T1b imaging method and a T2b imaging method and sampling a T1b sampling image and a T2b sampling image; both the T1b imaging method and the T2b imaging method in each sampling process are repeated twice, and the two T2b imaging methods respectively use an inversion pulse signal for slice-selective excitation and non-slice-selective excitation of the front-end venous blood labeling layer block to obtain a labeled and controlled image of the rear-end venous blood image layer block. The sequence of the present application is flexible and can control the total sampling time within 25 seconds. The simultaneously obtained T1b does not depend on the repeated sampling time of T2b and can reduce the systematic deviation of T2b through optimized fitting.

Description

Technical Field

[0001] The present application relates to the field of magnetic resonance imaging methods, and particularly to a method and system for rapid real-time in-vivo imaging of blood T1 and T2. Background Art

[0002] T1 and T2 of blood (abbreviated as T1b and T2b) are essential parameters in the quantitative analysis of magnetic resonance angiography. In particular, accurate blood T1 calculation is required in arterial spin labeling (ASL), and blood T2 values are mainly used in the detection of blood oxygen content in the brain. The content of various molecules in blood affects both blood T1 and T2. Therefore, the values of blood T1 and T2 vary among even healthy subjects. Usually, blood T1 and T2 are detected for subjects separately before angiography.

[0003] Real-time blood T1 detection uses a combination of look-locker as a saturation preparation module, usually targeting single-layer scanning of the posterior segment of the superior sagittal sinus venous blood or internal carotid artery blood. Real-time blood T2 detection uses a combination of MLEV (Malcolm Levitt's) composite hard pulses as a preparation module and obtains it using a labeling / control method similar to ASL. Currently, the mainstream is to obtain images of blood T1 and T2 through two methods respectively and then calculate blood T1 and T2 correspondingly.

[0004] For this way of separately obtaining blood T1 and T2, it is equivalent to needing two groups of sequences to be excited respectively to obtain corresponding images of blood T1 and T2. Generally speaking, a complete operation process takes 3 - 5 minutes to collect images. In the determination of vascular diseases, if two additional sequences are added, it will not only be time-consuming but also may affect the real-time diagnosis time. Summary of the Invention

[0005] In order to shorten the acquisition time of images required for calculating blood T1 and T2, the present application provides a method, calculation method and system for rapid in-vivo imaging of blood T1 and T2.

[0006] In a first aspect, a method for rapid in-vivo imaging of blood T1 and T2 provided by the present application adopts the following technical solution:

[0007] A method for rapid in-vivo imaging of blood T1 and T2 includes a process of exciting and sampling an imaging acquisition area including a cross-section of the posterior segment of the superior sagittal sinus venous blood vessel for several rounds. The imaging acquisition area includes a front-end venous blood labeling layer block and a posterior segment venous blood image layer block. Each round of sampling process includes:

[0008] Alternately and repeatedly using the T1b imaging method and the T2b imaging method to excite the corresponding layer block areas and sample T1b sampling images and T2b sampling images;

[0009] Among them, the T1b imaging method and the T2b imaging method in each round of sampling process are both repeated twice. The two T2b imaging methods respectively use an inversion pulse signal to perform slice selection excitation and non-slice selection excitation on the front-end venous blood labeling slice to obtain the labeled image and the control image of the posterior venous blood image slice.

[0010] The sequence designed by this method can significantly shorten the time required to acquire the T1b sampling image and the T2b sampling image, greatly reducing the time required to acquire the corresponding images for calculating the values of T1b and T2b.

[0011] Preferably, the T1b imaging method includes:

[0012] Using an adiabatic half-channel RF pulse for non-slice selection saturation suppression;

[0013] After a preset post-saturation delay time, use a multi-EPI sampling imaging sequence to sample the posterior venous blood image slice, where each EPI sampling imaging interval is the same.

[0014] By adopting the above technical solution, the T1b sampling image obtained by this solution does not depend on the repeated sampling time of the T2b imaging method.

[0015] Preferably, the number of repetitions of the EPI sampling imaging sequence in each round of sampling process is positively correlated with the number of runs of the sampling process.

[0016] By adopting the above technical solution, images at different signal recovery degree intervals are obtained.

[0017] Preferably, the imaging acquisition area includes a planar pre-saturation slice, and the planar pre-saturation slice includes the posterior venous blood image slice.

[0018] The T2b imaging method includes:

[0019] Perform pre-saturation suppression on the planar pre-saturation slice;

[0020] Use an inversion pulse signal to perform slice selection excitation or non-slice selection excitation on the front-end venous blood labeling slice;

[0021] Perform pre-saturation suppression on the planar pre-saturation slice;

[0022] According to the set effective echo time, use the MLEV module to excite the posterior venous blood image slice;

[0023] After finishing exciting the posterior segment venous blood image block using the MLEV module, the EPI sampling imaging sequence is used to sample the posterior segment venous blood image block to correspondingly obtain the labeled image and the control image of the posterior segment venous blood image block.

[0024] Preferably, when using the EPI sampling imaging sequence to sample the posterior segment venous blood image block, the inversion pulse signal is used to restore the anterior segment venous blood labeled block that is layer-selected and excited to the zero-phase state.

[0025] By adopting the above technical solution, when the blood flowing through the brain flows out to the posterior segment venous blood image block, the signal is close to the zero-phase state, and an image with black blood signal will be obtained.

[0026] Preferably, the interval time between finishing exciting the image block using the MLEV module and using the inversion pulse signal to perform layer-selected excitation or non-layer-selected excitation on the anterior segment venous blood labeled block is always the same.

[0027] Preferably, the length of the effective echo time is positively correlated with the number of runs in the sampling process.

[0028] By adopting the above technical solution, images at different intervals of signal recovery degrees are obtained.

[0029] Preferably, the imaging acquisition region includes a background suppression block containing the anterior segment venous blood labeled block, the posterior segment venous blood image block, and the planar presaturation block, and the T2b imaging method further includes:

[0030] After using the inversion pulse signal to perform layer-selected excitation or non-layer-selected excitation on the anterior segment venous blood labeled block, an adiabatic inversion radiofrequency pulse is applied to the background suppression block for background suppression.

[0031] By adopting the above technical solution, the background signal suppression of static tissues is increased, thereby better improving the reliability and time stability of T2b sampling image acquisition.

[0032] In a second aspect, a method for calculating blood T1 and T2 provided by the present application adopts the following technical solution:

[0033] A method for calculating blood T1 and T2 includes calculating the T1b sampling image and the T2b sampling image to obtain the corresponding blood T1 value and T2 value, and the T1b sampling image and the T2b sampling image are sampled by the blood T1 and T2 rapid in-vivo imaging method as described above.

[0034] In a third aspect, a blood T1 and T2 rapid real-time in-vivo imaging system provided by the present application adopts the following technical solution:

[0035] A rapid real-time in-vivo imaging system for blood T1 and T2, comprising:

[0036] A blood T1 acquisition module for performing the T1b imaging method;

[0037] A blood T2 acquisition module for performing the T2b imaging method;

[0038] During the imaging process, it includes several rounds of processes of exciting and sampling an imaging acquisition area including the cross-section of the posterior segment of the superior sagittal sinus venous vessel. The imaging acquisition area includes a front-end venous blood labeling layer block and a posterior segment venous blood image layer block. Each round of sampling process includes:

[0039] Alternately and repeatedly calling the blood T1 acquisition module and the blood T2 acquisition module to excite and sample the corresponding layer block areas to obtain T1b sampling images and T2b sampling images;

[0040] Among them, the blood T1 acquisition module and the blood T2 acquisition module in each round of sampling process are both repeatedly called twice. During the two calls, the blood T2 acquisition module uses an inversion pulse signal to perform slice selection excitation and non-slice selection excitation on the front-end venous blood labeling layer block respectively to obtain a labeled image and a control image of the posterior segment venous blood image layer block.

[0041] In summary, the present application includes at least one of the following beneficial technical effects:

[0042] 1. Greatly reduces the time required to collect and calculate the corresponding images for blood T1 value and blood T2 value. At the same time, the T1 images obtained by this solution do not depend on the repetition sampling time of T2;

[0043] 2. Increases the suppression of the background signal of static tissues, thereby better improving the reliability and time stability of T2 sampling image acquisition. Description of the Drawings

[0044] Figure 1 Is a schematic diagram of a rapid in-vivo imaging sequence for blood T1 and T2.

[0045] Figure 2 Is a schematic diagram of the cross-section of the posterior segment of the superior sagittal sinus venous vessel with the largest area.

[0046] Description of the reference numerals: 1. Front-end venous blood labeling layer block; 2. Background suppression layer block; 3. Plane pre-saturation layer block; 4. Posterior segment venous blood image layer block. Detailed Embodiment

[0047] The following further describes the present application in detail with reference to the attached Figure 1 and 2 drawings.

[0048] The present invention discloses a method for rapid in vivo blood T1 and T2 imaging, comprising several rounds of excitation and sampling of an imaging acquisition region encompassing a cross-section of the posterior superior sagittal sinus vein. Each round of sampling involves alternately and repeatedly using T1b and T2b imaging methods to excite the corresponding slab region to rapidly sample T1b and T2b sampling images. The T1b and T2b imaging methods are repeated twice in each round of sampling.

[0049] As a prerequisite for sampling, the subject needs to lie in the magnetic resonance device, the transmitting coil uses the body coil of the device, and the signal receiving coil is a 32-channel head coil. The subject is required to remain quiet and try not to move the head. Then, use the Siemens image positioning system Auto-Align to automatically position the subject's head for three-dimensional imaging (cross-sectional, sagittal, and coronal). Then, a high-resolution 3D structural phase image of the head is obtained through a predetermined sequence, and manually adjusted to A to P (from front to back) to obtain the largest area of the posterior segment of the superior sagittal sinus vein cross-section, and use this as the center layer selection position (that is, the aforementioned imaging acquisition area, refer to Figure 2 ).

[0050] On this basis, the selected cross section is framed to define the front venous blood marker layer 1 and the posterior venous blood image layer 4. The posterior venous blood image layer 4 encompasses the largest cross-sectional area of the posterior superior sagittal sinus vein. The front venous blood marker layer 1 is located above and to the side of the posterior venous blood image layer 4 to represent the rest of the brain through which the front end of the superior sagittal sinus venous blood flows. Given the anatomy of the human body, the front venous blood that passes through the portion framed by the front venous blood marker layer 1 will flow into the posterior superior sagittal sinus vein where the posterior venous blood image layer 4 is located. Furthermore, the planar presaturation layer 3 and background suppression layer 2 are framed on the selected cross section. The planar presaturation layer 3 encompasses the posterior venous blood image layer 4, and the background suppression layer 2 encompasses all of the aforementioned image layers. However, there is a 10 mm gap between the posterior venous blood image layer 4 and the front venous blood marker layer 1.

[0051] Among them, as a specific method of the sampling process of a single round, based on Figure 1 The sequence presented is described in detail, and includes the following steps:

[0052] Step S1100: performing non-layer-selective saturation suppression using adiabatic half-channel radio frequency pulses.

[0053] Step S1200: After a preset post-saturation delay time, use a multiple-EPI (Echo-Planar Imaging) sampling imaging sequence to sample the posterior segment venous blood image slab 4, where each EPI sampling imaging sequence has the same interval.

[0054] Among them, Step S1100 and Step S1200 are the T1b imaging methods. Layer selection and non-layer selection refer to whether the corresponding pulses are applied to the specifically selected slab, that is, slab selection and non-slab selection. The adiabatic half-passage is the AHP (adiabatic half-passage). Suppression means applying the corresponding pulse after reversing it by 180 degrees.

[0055] In Step S1200, the preset post-saturation delay time is the Figure 1 TI referred to in Figure 1 , and the interval between adjacent EPI sampling imaging sequences is the 2 △TI referred to in 2 . Performing EPI sampling on the posterior segment venous blood image slab 4 refers to the planar echo imaging of the single-layer selected posterior segment venous blood image slab 4, which consists of a layer-selective excitation radiofrequency pulse (RF), a 180-degree refocusing pulse, and a one-time ADC acquisition. To accelerate the imaging speed, the EPI sequence for sampling can perform partial Fourier acquisition in the phase-encoding direction and apply parallel acceleration imaging. Specific parameters of the EPI sampling imaging sequence: echo time 7.98 ms, field of view size 218 x 218 mm

[0056] , matrix size (sampling points) 64 x 64, planar resolution 3.4 x 3.4 mm

[0057] , slice thickness 5 mm, phase-encoding direction: from front to back (A to P), phase-encoding direction partial Fourier imaging coefficient 5 / 8, parallel imaging acceleration factor iPAT 2 (24 reference lines). Among them, the flip angle of the excitation radiofrequency pulse can use 95 degrees instead of 90 degrees to suppress the signals of the tissues around the posterior segment venous vessels of the superior sagittal sinus, and can also effectively reduce the deviation of the blood T1 prediction value caused by the partial volume effect. Generally speaking, the post-saturation delay time and the interval time between adjacent EPI sampling imaging sequences are the same and are 200 ms.

[0058] Here, performing an EPI sampling imaging sequence on each pair of posterior segment venous blood image slabs 4 can obtain a T1b sampling image.

[0057] Step S2100: Perform pre-saturation suppression on the planar pre-saturation slab 3.

[0058] Among them, use an inversion pulse signal to perform layer-selective excitation on the posterior segment venous blood image slab 4 and its surrounding area, so that the venous blood in the posterior segment venous blood image slab 4 area is restored to the zero-phase state, so that the retained venous blood before image acquisition has no signal impact on the subsequent steps.

[0059] Step S2200: Use an inversion pulse signal to perform slice selection excitation on the front venous blood labeled slice block 1.

[0060] Among them, the inversion pulse signal refers to a 180-degree RF (adiabatic inversion RF pulse). After being excited by the inversion pulse signal, the blood signal in the front venous blood labeled slice block 1 will be marked as a state with a -180-degree phase (the original signal is in a state with a 180-degree phase). During the process from the start of the last EPI sampling imaging sequence in the T1b imaging method until the slice selection excitation of the front venous blood labeled slice block 1 by the inversion pulse signal, an interval time of 100 ms is always maintained, that is Figure 1 T referred to in the sequence t 。

[0061] Step S2300: Perform presaturation suppression on the planar presaturation slice block 3.

[0062] Among them, the presaturation suppression in this step needs to be performed twice, and there is no strict time requirement for the interval time between step S2100 and step S2200 and between step S2200 and step S2300.

[0063] Step S2400: Use the MLEV module to excite the posterior venous blood image slice block 4 according to the set effective echo time.

[0064] Among them, the MLEV (Malcolm Levitt's) module consists of a series of hard pulses, and the echo spacing time is set to 10 ms, which is a fixed module existing in the magnetic resonance sequence. The effective echo time (eTE effective TE) refers to the total excitation duration of the MLEV module. Different excitation times of the MLEV module will result in different brightnesses of the blood signal in the subsequent acquired T2b sampling images.

[0065] Step S2500: After finishing the excitation of the posterior venous blood image slice block 4 using the MLEV module, use the EPI sampling imaging sequence to sample the posterior venous blood image slice block 4 to obtain a labeled image.

[0066] Among them, the EPI sampling imaging method in this step is the same as the EPI sampling imaging method in step S1200.

[0067] It's important to note that during EPI sampling and imaging, the blood signal marked by the inverted pulse signal in step S2200 must be restored to a zero-phase state. Consequently, the image captured by this suppressed blood signal after EPI sampling will appear black. Furthermore, based on blood flow in the human brain, the blood marked by the inverted pulse signal resides in the front venous blood marker layer 1. After a period of time, this blood will flow into the rear venous blood image layer 4, and fresh blood will flow into the area framed by the front venous blood marker layer 1.

[0068] In addition, the interval between the end of MLEV module excitation of the image layer and the use of the inversion pulse signal to selectively excite the front venous blood marker layer 1 is always the same, that is, no matter what the effective echo time is, the time node for EPI sampling imaging is always constant. The longer the effective echo time, the earlier the initial moment of MLEV module excitation will be in the sequence. Generally speaking, the time interval between the selective excitation of the front venous blood marker layer 1 by the inversion pulse signal and the EPI sampling imaging is always 1050ms. Figure 1 The sequence is recorded as PLD, that is, PLD=1050ms.

[0069] Step S3100: using a non-layer-selective adiabatic half-channel radio frequency pulse to perform saturation suppression on the imaging acquisition area.

[0070] Step S3200: After a preset post-saturation delay time, the image layer block is sampled using multiple EPI sampling imaging, wherein the interval of each EPI sampling imaging is the same.

[0071] Steps S3100 and S3200 are the same as the aforementioned steps S1100 and S1200. Generally speaking, during each round of the blood T1 and T2 rapid in vivo imaging method, the EPI sampling imaging in steps S1200 and S3200 is repeated the same number of times.

[0072] Step S4100: performing pre-saturation pressing on the planar pre-saturation layer block 3.

[0073] Step S4200: performing non-slice-selective excitation using an inversion pulse signal.

[0074] The non-layer selective excitation in this step refers to directly using the inversion pulse signal to excite without selecting any position, which is equivalent to not resonating with hydrogen ions, so the inversion pulse signal of the excitation will not affect the marked position.

[0075] Step S4300: performing pre-saturation pressing on the planar pre-saturation layer block 3.

[0076] Step S4400: After exciting the posterior segment venous blood image block 4 using the MLEV module according to the set effective echo time.

[0077] Step S4500: After finishing exciting the posterior segment venous blood image block 4 using the MLEV module, sample the posterior segment venous blood image block 4 using EPI sampling imaging to obtain a control image.

[0078] Among them, after performing step S4200, the blood signal of the front-end venous blood labeling block 1 is not affected. Therefore, when using EPI sampling imaging to collect the control image in step S4500, a control image with a high blood signal at the posterior segment venous blood image block 4 will be obtained. Here, the interval time between finishing exciting the image block using the MLEV module and performing non-slice-selective excitation using an inversion pulse signal is also always the same, which is also 1050 ms, that is Figure 1 the PLD marked in the sequence of

[0079] Generally speaking, during the execution of each round of the blood T1 and T2 rapid in-vivo imaging method, the effective echo times in step S2400 and step S4400 are the same. Therefore, the variables of the control images and the labeled images obtained in step S2500 and step S4500 are less. Among them, step S2200 and step S4200 are collectively called SICORE (Superior venous blood labeling using superior Inversion of magnetization with a Control for Off-Resonance Effects, i.e., inverting magnetization to label the front-end venous blood / using non-resonant inversion as a control image). After performing the T2b imaging method twice, the labeled image and the control image at the posterior segment venous blood image block 4 will be obtained respectively, which is convenient for subtraction operations when calculating the blood T2 value.

[0080] In addition, an adiabatic inversion radiofrequency pulse can be applied to the background suppression block 2 between performing step S2200 and step S2300 and between performing step S4200 and step S4300 for background suppression. There will be two background suppressions at random times each time the T2b imaging method is performed, but the times of the background suppressions in the two T2b imaging methods in the same round are always the same in the time series (that is, TI1 and TI2 need to be the same respectively). The labeled images and the control images after background suppression can improve the contrast between the high signal at the posterior segment venous blood image block 4 and other regions, which is convenient for subsequent delineating the range of the posterior segment venous blood image block 4.

[0081] For a complete in-vivo rapid imaging method, a total of four rounds of the aforementioned sampling processes need to be performed. In each round of the sampling process, the number of EPI sampling imaging in steps S1200 and S3200, and the effective echo time in steps S2400 and S4400 are positively correlated with the number of runs of the sampling process, so that the acquired images have different signal recovery degrees. If the slice-selective excitation of the inversion pulse signal in step S2200 is defined as a label, and the non-slice-selective excitation of the inversion pulse signal in step S4200 is defined as a control, the flow of the complete in-vivo rapid imaging method can be as follows:

[0082] 1. T1b imaging method: 2 EPIs; T2b imaging method: label, eTE = 0 ms;

[0083] 2. T1b imaging method: 2 EPIs; T2b imaging method: control, eTE = 0 ms;

[0084] 3. T1b imaging method: 4 EPIs; T2b imaging method: label, eTE = 40 ms;

[0085] 4. T1b imaging method: 4 EPIs; T2b imaging method: control, eTE = 40 ms;

[0086] 5. T1b imaging method: 8 EPIs; T2b imaging method: label, eTE = 80 ms;

[0087] 6. T1b imaging method: 8 EPIs; T2b imaging method: control, eTE = 80 ms;

[0088] 7. T1b imaging method: 16 EPIs; T2b imaging method: label, eTE = 160 ms;

[0089] 8. T1b imaging method: 16 EPIs; T2b imaging method: control, eTE = 160 ms;

[0090] It can be seen that between 1 and 2, 3 and 4, 5 and 6, and 7 and 8, a complete round of sampling process is formed. Since there is only 1 EPI sampling imaging in the T2b imaging method, a complete in-vivo imaging method can obtain a total of 60 T1b sampling images and 8 T2b sampling images. Among them, the 8 T2b sampling images are 4 label images and 4 control images respectively. And through the delay at each time node, it can be calculated that the total time of the aforementioned complete in-vivo rapid imaging method can be controlled within 25 seconds (excluding the time required for equipment debugging).

[0091] Before analyzing the images, it is also necessary to turn off Figure 1All RFs (excitation radiofrequency pulses) in the shown sequence are used to obtain pure noise image information, which is used to eliminate the influence of thermal noise in subsequent analysis processes and improve the signal-to-noise ratio.

[0092] For the specific analysis process of the images, first, the images obtained by the T1b imaging method are preprocessed. Specifically, the T1b sampling images obtained from the EPI sampling imaging sequence at the same moment in the sequence are averaged. Since the number of EPI sampling imaging sequences collected by the T1b imaging method in each round will gradually increase, the T1b sampling images closer to the front end of the sequence will have more sample numbers. For example, there are a total of 16 T1b sampling images from the first and second EPI sampling imaging, while there are only 2 T1b sampling images from the last EPI sampling imaging. After preprocessing by the T1b imaging method, a total of 16 T1b imaging images will be retained.

[0093] For the preprocessing of the labeled images and control images obtained by the T2b imaging method, the method of subtracting the labeled images and control images obtained in each sampling process is used to obtain 4 T2b imaging images.

[0094] After obtaining the T1b imaging images and T2b imaging images, it is necessary to manually select the position of the cross-section of the posterior segment of the superior sagittal sinus vein in the highlighted area of the image, and select points from the areas where all images are highlighted as the ROI (region of interest), and the obtained pure noise image information will also select the same ROI.

[0095] As the calculation method of T1b, it follows the formula where, S(T sr ) is the average blood signal measured at the T sr saturation recovery time, that is, the average value of the signal values of the ROI areas of each obtained T1b imaging image, T sr refers to the saturation recovery time of the target T1b imaging image, that is, the time required for the EPI sampling imaging sequence executed from the non-slice-selective saturation suppression using the adiabatic half-channel radiofrequency pulse to obtaining the T1b imaging image, S0 is the average blood proton density weighted signal (obtained through coil sensitivity and image gain, and its target image is the cross-section of the posterior segment of the superior sagittal sinus vein with the largest area found by manually adjusting A to P), T1B represents the estimated blood T1 value, C n represents the estimated thermal noise. C n can be obtained from the average result of reading the signal at the blood vessel position on the pure noise image information.

[0096] where, , N is the number of times of EPI sampling imaging sequence executed when performing the T1b imaging method.

[0097] It can be seen that each obtained T1b imaging image can be correspondingly calculated to obtain S(T sr ) and T sr . Therefore, the T1B value corresponding to each T1b imaging image can be obtained through the above formula. Subsequently, the nonlinear least squares model fitting method is used for all the obtained T1B values to correspondingly obtain T1b.

[0098] As the calculation method of T2b, since the four T2b imaging images obtained in the foregoing T2b imaging method have different total saturation recovery times (Ttsr, that is, the time required from the saturation suppression using the adiabatic half-channel radio frequency pulse for non-slice selection in the sequence to the last executed EPI sampling imaging sequence) and different eTEs due to the influence of the T1b imaging method process, the T2b imaging image signal cannot be directly used to obtain the blood T2 (that is, the average value of the signal values in the ROI region of the T2 imaging image), but the signal after T1-weighted influence compensation is required. Among them, , N LL represents the number of repetitions of the EPI sampling imaging sequence in the T1b imaging method in the same round.

[0099] Follow the formula . Among them, T1B is calculated from the blood T1.

[0100] Therefore, since four values can be correspondingly obtained in the T2b imaging image, thus also corresponds to four.

[0101] For the calculation of T2b, follow , where T2B represents the estimated blood T2 value.

[0102] According to the four obtained and the corresponding four eTE values, four corresponding T2B can be obtained, and the nonlinear least squares model fitting method is used for the four obtained T2B to correspondingly obtain T2b.

[0103] In addition, the above steps can also split the T1b imaging method and the T2b imaging method to separately obtain the T1b sampling image and the T2b sampling image. However, as can be seen from the calculation method of T2b, at least one T1b sampling image needs to be collected before the sequence for collecting the T2b sampling image.

[0104] Based on the same inventive concept, the embodiment of the present application also discloses a blood T1 and T2 rapid real-time in-vivo imaging system, which includes:

[0105] A blood T1 acquisition module for performing the T1b imaging method.

[0106] A blood T2 acquisition module for performing the T2b imaging method.

[0107] During the imaging process, it includes several rounds of processes of exciting and sampling the imaging acquisition area including the cross-section of the posterior segment of the superior sagittal sinus venous blood vessel. The imaging acquisition area includes the front-end venous blood marking layer block 1 and the posterior segment venous blood image layer block 4. Each round of sampling process includes.

[0108] Alternately and repeatedly call the blood T1 acquisition module and the blood T2 acquisition module to excite the corresponding layer block areas and sample the T1b sampling image and the T2b sampling image.

[0109] Among them, the blood T1 acquisition module and the blood T2 acquisition module in each round of sampling process are both repeatedly called twice. During the two calls, the blood T2 acquisition module uses the inversion pulse signal to perform slice selection excitation and non-slice selection excitation on the front-end venous blood marking layer block 1 respectively to obtain the marking image and the control image of the posterior segment venous blood image layer block 4.

[0110] The blood T1 acquisition module is used to perform the following process:

[0111] Step S11: Use an adiabatic half-channel RF pulse for non-slice selection saturation suppression.

[0112] Step S12: After a preset post-saturation delay time, use a multi-EPI sampling imaging sequence to sample the posterior segment venous blood image layer block 4, where each EPI sampling imaging sequence has the same interval.

[0113] The blood T2 acquisition module is used to perform the following process:

[0114] Step S21: Perform pre-saturation suppression on the planar pre-saturation layer block 3.

[0115] Step S22: Use the inversion pulse signal to perform slice selection excitation or non-slice selection excitation on the front-end venous blood marking layer block 1.

[0116] Step S23: Perform pre-saturation suppression on the planar pre-saturation layer block 3.

[0117] Step S24: Use the MLEV module to excite the posterior segment venous blood image layer block 4 according to the set effective echo time.

[0118] Step S25: After finishing using the MLEV module to excite the posterior segment venous blood image layer block 4, use EPI sampling imaging to sample the posterior segment venous blood image layer block 4 to correspondingly obtain the marking image and the control image of the posterior segment venous blood image layer block 4.

[0119] Specifically, the calling sequence of the blood T1 acquisition module and the blood T2 acquisition module by the complete fast real-time in-vivo imaging system is as follows:

[0120] 1. Blood T1 acquisition module: 2 times of EPI; Blood T2 acquisition module: Marking (using an inversion pulse signal to perform slice selection excitation on the front-end venous blood marking slice block 1), eTE = 0 ms;

[0121] 2. Blood T1 acquisition module: 2 times of EPI; Blood T2 acquisition module: Control (using an inversion pulse signal for non-slice selection excitation), eTE = 0 ms;

[0122] 3. Blood T1 acquisition module: 4 times of EPI; Blood T2 acquisition module: Marking, eTE = 40 ms;

[0123] 4. Blood T1 acquisition module: 4 times of EPI; Blood T2 acquisition module: Control, eTE = 40 ms;

[0124] 5. Blood T1 acquisition module: 8 times of EPI; Blood T2 acquisition module: Marking, eTE = 80 ms;

[0125] 6. Blood T1 acquisition module: 8 times of EPI; Blood T2 acquisition module: Control, eTE = 80 ms;

[0126] 7. Blood T1 acquisition module: 16 times of EPI; Blood T2 acquisition module: Marking, eTE = 160 ms;

[0127] 8. Blood T1 acquisition module: 16 times of EPI; Blood T2 acquisition module: Control, eTE = 160 ms.

[0128] Those skilled in the art can clearly understand that for the convenience and conciseness of description, only the above division of each functional module is used as an example for illustration. In practical applications, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. For the specific working processes of the system, device, and unit described above, reference can be made to the corresponding processes in the foregoing method embodiments, which will not be elaborated here.

[0129] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections between each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0130] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0131] In addition, each functional unit in various embodiments of the present application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0132] As mentioned above, the above embodiments are only used to introduce the technical solutions of the present application in detail. However, the description of the above embodiments is only used to help understand the method and its core idea of the present invention, and should not be construed as a limitation of the present invention. Those skilled in the art of this technology can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all of them should be covered within the protection scope of the present invention.

Claims

1. A method for rapid in vivo imaging of blood T1 and T2, characterized in that, It includes a process of exciting and sampling an imaging acquisition area including cross-sectional images of the posterior segment of the superior sagittal sinus vein. The imaging acquisition area includes a front-end venous blood marking layer block (1) and a posterior segment venous blood image layer block (4). Each sampling process includes: Alternately and repeatedly using the T1b imaging method and the T2b imaging method to excite the corresponding layer block areas and sample T1b sampling images and T2b sampling images; Among them, the T1b imaging method and the T2b imaging method in each sampling process are both repeated twice. The two T2b imaging methods respectively use an inversion pulse signal to perform slice selection excitation and non-slice selection excitation on the front-end venous blood marking layer block (1) to obtain a marking image and a control image of the posterior segment venous blood image layer block (4); The T1b imaging method includes: Using an adiabatic half-channel radiofrequency pulse for non-slice selection saturation suppression; After a preset post-saturation delay time, using a multi-shot EPI sampling imaging sequence to sample the posterior segment venous blood image layer block (4), where the interval of each EPI sampling imaging is the same; The imaging acquisition area includes a planar pre-saturation layer block (3), and the planar pre-saturation layer block (3) includes the posterior segment venous blood image layer block (4), The T2b imaging method includes: Performing pre-saturation suppression on the planar pre-saturation layer block (3); Using an inversion pulse signal to perform slice selection excitation or non-slice selection excitation on the front-end venous blood marking layer block (1); Performing pre-saturation suppression on the planar pre-saturation layer block (3); Exciting the posterior segment venous blood image layer block (4) using the MLEV module according to the set effective echo time; After finishing the excitation of the posterior segment venous blood image layer block (4) using the MLEV module, using an EPI sampling imaging sequence to sample the posterior segment venous blood image layer block (4) to correspondingly obtain a marking image and a control image of the posterior segment venous blood image layer block (4); When using the EPI sampling imaging sequence to sample the posterior segment venous blood image layer block (4), the front-end venous blood that has been slice selection excited using an inversion pulse signal on the front-end venous blood marking layer block (1) is restored to the zero-phase state; The imaging acquisition area includes a background suppression layer block (2) including the front-end venous blood marking layer block (1), the posterior segment venous blood image layer block (4), and the planar pre-saturation layer block (3). The T2b imaging method further includes: After using an inversion pulse signal to perform slice selection excitation or non-slice selection excitation on the front-end venous blood marking layer block (1), applying an adiabatic inversion radiofrequency pulse to the background suppression layer block (2) for background suppression.

2. The rapid in-vivo imaging method for blood T1 and T2 according to claim 1, characterized in that: The number of repetitions of the EPI sampling imaging sequence in each sampling process is positively correlated with the number of runs of the sampling process.

3. The rapid in-vivo imaging method for blood T1 and T2 according to claim 1, characterized in that: The interval time between finishing the excitation of the image layer block using the MLEV module and using an inversion pulse signal to perform slice selection excitation or non-slice selection excitation on the front-end venous blood marking layer block (1) is always the same.

4. The rapid in-vivo imaging method for blood T1 and T2 according to claim 1, characterized in that: The length of the effective echo time is positively correlated with the number of runs of the sampling process.

5. A method for calculating blood T1 and T2, characterized in that, It includes calculating the T1b sampled image and the T2b sampled image to obtain the corresponding blood T1 value and T2 value, and the T1b sampled image and the T2b sampled image are sampled by the imaging method described in any one of claims 1-4.

6. A blood T1 and T2 rapid real-time in-vivo imaging system, characterized in that, It includes, A blood T1 acquisition module for performing the T1b imaging method; A blood T2 acquisition module for performing the T2b imaging method; During the imaging process, it includes several rounds of processes of exciting and sampling the imaging acquisition area including the cross-section of the posterior segment of the superior sagittal sinus venous vessel. The imaging acquisition area includes the front-end venous blood labeling slice block (1) and the posterior segment venous blood image slice block (4). Each round of sampling process includes: Alternately and repeatedly calling the blood T1 acquisition module and the blood T2 acquisition module to excite and sample the corresponding slice block areas to obtain the T1b sampled image and the T2b sampled image; Among them, the blood T1 acquisition module and the blood T2 acquisition module in each round of sampling process are both repeatedly called twice. During the two calls, the blood T2 acquisition module respectively uses an inversion pulse signal to perform slice selection excitation and non-slice selection excitation on the front-end venous blood labeling slice block (1) to obtain the labeling image and the control image of the posterior segment venous blood image slice block (4); The T1b imaging method includes: Using an adiabatic half-channel RF pulse for non-slice selection saturation suppression; After a preset post-saturation delay time, using a multi-EPI sampling imaging sequence to sample the posterior segment venous blood image slice block (4), where the imaging interval of each EPI sampling is the same; The imaging acquisition area includes a planar presaturation slice block (3), and the planar presaturation slice block (3) includes the posterior segment venous blood image slice block (4), The T2b imaging method includes: Performing presaturation suppression on the planar presaturation slice block (3); Using an inversion pulse signal to perform slice selection excitation or non-slice selection excitation on the front-end venous blood labeling slice block (1); Performing presaturation suppression on the planar presaturation slice block (3); Exciting the posterior segment venous blood image slice block (4) using the MLEV module according to the set effective echo time; After finishing exciting the posterior segment venous blood image slice block (4) using the MLEV module, using an EPI sampling imaging sequence to sample the posterior segment venous blood image slice block (4) to correspondingly obtain the labeling image and the control image of the posterior segment venous blood image slice block (4); When using the EPI sampling imaging sequence to sample the posterior segment venous blood image slice block (4), the front-end venous blood that uses the inversion pulse signal to perform slice selection excitation on the front-end venous blood labeling slice block (1) is restored to the zero-phase state; The imaging acquisition area includes a background suppression slice block (2) including the front-end venous blood labeling slice block (1), the posterior segment venous blood image slice block (4), and the planar presaturation slice block (3). The T2b imaging method further includes: After using the inversion pulse signal to perform slice selection excitation or non-slice selection excitation on the front-end venous blood labeling slice block (1), applying an adiabatic inversion RF pulse to the background suppression slice block (2) for background suppression.

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