阅读说明：本技术 一种无创三维经颅脑组织黏弹性和流性成像装置及方法 (Noninvasive three-dimensional transcranial tissue viscoelasticity and fluidity imaging device and method ) 是由 万明习 于建军 郭昊 姜力元 张红梅 于 2021-07-09 设计创作，主要内容包括：本发明公开的一种无创三维经颅脑组织黏弹及流性成像装置,包括经颅低频振动激励系统、经颅振动调节反馈系统和三维经颅超声旋转扫描装置。实现了经颅条件下基于剪切波成像的脑组织三维黏弹流性的检测。使用了KVFD模型进行多频率的剪切波速度拟合,可以得到弹性、黏性、流性等多参量的组织力学特性,弥足了现有技术仅能进行脑组织黏弹性成像的局限性,黏性与流性对于阿尔兹海默症、脑中风等脑疾病更加敏感,对促进该疾病的早期诊断技术在临床的发展具有巨大潜力。(The invention discloses a noninvasive three-dimensional transcranial brain tissue viscoelastic and fluid imaging device which comprises a transcranial low-frequency vibration excitation system, a transcranial vibration regulation feedback system and a three-dimensional transcranial ultrasonic rotary scanning device. The detection of the three-dimensional visco-elastic fluidity of the brain tissue based on shear wave imaging under the transcranial condition is realized. The KVFD model is used for carrying out multi-frequency shear wave speed fitting, the tissue mechanics characteristics of multiple parameters such as elasticity, viscosity and fluidity can be obtained, the limitation that the prior art can only carry out brain tissue viscoelasticity imaging is overcome, the viscosity and the fluidity are more sensitive to brain diseases such as Alzheimer's disease and cerebral apoplexy, and the method has great potential for promoting the development of early diagnosis technology of the diseases in clinic.)

1. A non-invasive three-dimensional transcranial brain tissue viscoelasticity and fluidity imaging device is characterized by comprising a transcranial low-frequency vibration excitation system, a vibration measurement feedback device and a three-dimensional transcranial ultrasonic rotation scanning device;

the transcranial low-frequency vibration excitation system is used for applying transcranial vibration to the cranium, and the vibration measurement feedback device is used for determining the optimal fitting pressure between the low-frequency vibration excitation system and the cranium;

the three-dimensional transcranial ultrasonic rotary scanning device comprises an outer sleeve (10), an inner sleeve (16), an acoustic transmission membrane (9), an inlet and outlet valve (11) and a driving device;

the sound transmission membrane (9) is covered at one end of the outer sleeve, the inner sleeve is sleeved in the outer sleeve, the driving device is connected with the inner sleeve to enable the inner sleeve to rotate, the ultrasonic probe (7) is located in the inner sleeve and fixedly connected, and the inlet and outlet valve (11) is arranged on the outer sleeve, so that the air-water removing and sound transmission membrane jointly play a role in transcranial ultrasonic coupling.

2. The apparatus of claim 1, wherein the driving device comprises a motor and a transmission gear, the transmission gear is fixedly sleeved on the inner sleeve and located outside the outer sleeve, and the transmission gear is engaged with an output shaft of the motor.

3. A non-invasive three-dimensional transcranial tissue visco-elastic and fluidic imaging device according to claim 1, characterized in that a sealing gasket (17) is arranged at the end of the ultrasonic probe (7), the sealing gasket (17) is positioned at the end of the inner sleeve and is connected with the inner sleeve in a sealing manner through a fastening cover (18).

4. The apparatus of claim 1, wherein the inner sleeve is fitted with a bearing.

5. The apparatus according to claim 1, wherein the vibration measurement feedback device comprises a laser vibrometer and a pressure sensor, the laser vibrometer is used for acquiring a signal of transcranial vibration, and determining an optimal bonding pressure between a flexible vibrating plate of the low-frequency vibration excitation system and the skull according to the frequency characteristic of the signal, and the pressure sensor is disposed on the flexible vibrating plate.

6. A method of imaging a non-invasive three-dimensional transcranial tissue viscoelastic and fluid imaging apparatus according to any one of claims 1-5, comprising the steps of:

step 1, under the synchronous triggering condition of a vibration exciter and ultrasonic imaging equipment, rotationally scanning to obtain radio frequency signals of a plurality of vibration frequencies at different angles;

step 2, solving the estimated value of the shear wave speed corresponding to each obtained radio frequency data;

step 3, obtaining viscosity, elasticity and fluidity of the brain tissue at each angle according to the estimated value of the shear wave velocity of the multiple frequencies at each angle;

step 4, constructing two-dimensional viscoelasticity and fluidity images according to the viscosity, elasticity and fluidity of brain tissues at all angles to obtain the two-dimensional viscoelasticity and fluidity images at all angles;

and 5, performing three-dimensional reconstruction according to the two-dimensional viscoelasticity and fluidity images at all angles to obtain a three-dimensional visual viscoelasticity and fluidity image.

7. The imaging method of the noninvasive three-dimensional transcranial tissue viscoelastic and fluid imaging device according to the claim 5, wherein the method for acquiring the radio frequency signals in the step 1 is as follows:

s101, placing a three-dimensional ultrasonic rotary scanning detection device on a temporal window of a skull, triggering an ultrasonic imaging device and low-frequency transcranial vibration synchronously, and acquiring a radio-frequency signal by the ultrasonic imaging device;

s102, adjusting the frequency of low-frequency vibration, and collecting radio frequency signals under different frequencies;

and S103, driving the ultrasonic probe to rotate through the stepping motor, repeating the step S102, and acquiring radio frequency signals under different frequencies until the rotary scanning data required by three-dimensional reconstruction is completed.

8. The imaging method of the noninvasive three-dimensional trans-craniocerebral tissue viscoelastic and fluidic imaging device according to claim 6, characterized in that the data acquisition in step 1 is completed and then the space-time calibration is performed, so that the rotating coordinate systems of the ultrasonic probe and the stepping motor are synchronized, and the pose information of the stepping motor is kept consistent with the acquisition time of the radio-frequency signals.

9. The imaging method of the noninvasive three-dimensional transcranial tissue viscoelastic and fluidic imaging device according to the claim 6, wherein the PNN algorithm is adopted for three-dimensional reconstruction in the step 5.

10. The imaging method of the apparatus for non-invasive three-dimensional trans-craniocerebral tissue viscoelastic and fluidic imaging according to claim 6, further comprising a step 6 of obtaining a three-dimensional visualization image of a predetermined imaging effect by using a three-dimensional image processing method.

Technical Field

The invention relates to the technical field of medical ultrasonic imaging, in particular to a noninvasive three-dimensional transcranial tissue viscoelastic and fluid imaging device and method.

Background

The brain is an important component of the human central nervous system. When the brain tissue is subjected to traumatic injury or has pathological changes in the brain, such as Alzheimer's disease, brain tumors, ischemic and hypoxic encephalopathy and the like, the mechanical properties of the brain tissue can be obviously changed. Therefore, noninvasive evaluation of mechanical characteristics such as viscoelasticity and fluidity of brain tissue is of great significance for research and clinical diagnosis of related diseases. In clinic, Magnetic Resonance Elastography (MRE) is often used to evaluate brain tissue viscoelasticity, but has problems of too long operation time, low dynamic resolution, inaccurate description of dynamic mechanical properties of brain tissue, and the like. In contrast, in recent years, ultrasonic Shear Wave Elastography (SWE) has been developed rapidly, has higher practicability, and has been applied to clinical applications. The SWE can make up the defects of low MRE dynamic resolution and the like, and the mechanical characteristics of brain tissues can be more accurately described by matching with a Kelvin-Voigt fractional order (KVFD) model.

At present, most of brain tissue mechanical property imaging is two-dimensional viscoelastic imaging, the relative position relation of focuses is difficult to observe, and the dependency on experience knowledge of an operator is strong. Three-dimensional viscoelastic imaging can perform three-dimensional visual imaging on the viscoelasticity of brain tissue compared with two-dimensional imaging, and can be visual in any direction. In clinical diagnosis, repeated examination of the region of interest can be performed for multiple times, and the region of interest is fused with other 3D image modes, so that the reliability of a disease diagnosis result is improved.

The existing three-dimensional imaging is to perform three-dimensional reconstruction on tissues without bone occlusion, and a three-dimensional viscoelastic imaging device and a three-dimensional viscoelastic imaging method for brain tissues occluded by skull are not mature. The traditional ultrasonic three-dimensional mechanical rotary scanning device has the problems that tissue deformation artifacts can be generated during three-dimensional reconstruction, patients feel strong uncomfortable, the acoustic coupling effect is difficult to guarantee in the rotating process of the special-shaped surfaces, the probe universality is poor, and the like. The above problems plague the three-dimensional visualization of two-dimensional viscoelastic images of brain tissue under transcranial conditions. Therefore, it is very important to develop a set of noninvasive transcranial three-dimensional brain tissue viscoelastic imaging device capable of realizing high time resolution, and develop a method capable of measuring and accurately describing dynamic mechanical properties of brain tissue matched with the device.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a three-dimensional measuring device and an imaging method for obtaining the viscoelasticity of transcranial ultrasonic brain tissue based on low-frequency transcranial vibration excitation, which solve the limitation that the existing device can only carry out two-dimensional imaging on the elasticity of the brain tissue.

The invention is realized by the following technical scheme:

a non-invasive three-dimensional transcranial brain tissue viscoelasticity and fluidity imaging device comprises a transcranial low-frequency vibration excitation system, a vibration measurement feedback device and a three-dimensional transcranial ultrasonic rotation scanning device;

the transcranial low-frequency vibration excitation system is used for applying transcranial vibration to the cranium, and the vibration measurement feedback device is used for determining the optimal fitting pressure between the low-frequency vibration excitation system and the cranium;

the three-dimensional transcranial ultrasonic rotary scanning device comprises an outer sleeve, an inner sleeve, an acoustic transmission membrane, an inlet and outlet valve and a driving device;

the sound transmission membrane is covered at one end of the outer sleeve, the inner sleeve is sleeved in the outer sleeve, the driving device is connected with the inner sleeve to enable the inner sleeve to rotate, the ultrasonic probe is located in the inner sleeve and fixedly connected, and the inlet and outlet valve is arranged on the outer sleeve, so that the air removal water and the sound transmission membrane jointly play a role in transcranial ultrasonic coupling.

Preferably, the driving device comprises a motor and a transmission gear, the transmission gear is fixedly sleeved on the inner sleeve and positioned outside the outer sleeve, and the transmission gear is meshed with an output shaft of the motor.

Preferably, the end of the ultrasonic probe is provided with a sealing gasket, and the sealing gasket is positioned at the end of the inner sleeve and is connected with the inner sleeve in a sealing mode through a fastening cover.

Preferably, the inner sleeve is sleeved with a bearing.

Preferably, the vibration measurement feedback device comprises a laser vibration meter and a pressure sensor, the laser vibration meter is used for acquiring a transcranial vibration signal, the optimal bonding pressure between a flexible vibration plate of the low-frequency vibration excitation system and the skull is determined according to the frequency characteristic of the signal, and the pressure sensor is arranged on the flexible vibration plate.

An imaging method of a root non-invasive three-dimensional transcranial brain tissue viscoelastic and fluid imaging device comprises the following steps:

step 1, under the synchronous triggering condition of a vibration exciter and ultrasonic imaging equipment, rotationally scanning to obtain radio frequency signals of a plurality of vibration frequencies at different angles;

step 2, solving the estimated value of the shear wave speed corresponding to each obtained radio frequency data;

step 3, obtaining viscosity, elasticity and fluidity of the brain tissue at each angle according to the estimated value of the shear wave velocity of the multiple frequencies at each angle;

step 4, constructing two-dimensional viscoelasticity and fluidity images according to the viscosity, elasticity and fluidity of brain tissues at all angles to obtain the two-dimensional viscoelasticity and fluidity images at all angles;

and 5, performing three-dimensional reconstruction according to the two-dimensional viscoelasticity and fluidity images at all angles to obtain a three-dimensional visual viscoelasticity and fluidity image.

Preferably, the method for acquiring the radio frequency signal in step 1 is as follows:

s101, placing a three-dimensional ultrasonic rotary scanning detection device on a temporal window of a skull, triggering an ultrasonic imaging device and low-frequency transcranial vibration synchronously, and acquiring a radio-frequency signal by the ultrasonic imaging device;

s102, adjusting the frequency of low-frequency vibration, and collecting radio frequency signals under different frequencies;

and S103, driving the ultrasonic probe to rotate through the stepping motor, repeating the step S102, and acquiring radio frequency signals under different frequencies until the rotary scanning data required by three-dimensional reconstruction is completed.

Preferably, the data in step 1 is subjected to space-time calibration after the data acquisition is completed, so that the rotating coordinate systems of the ultrasonic probe and the stepping motor are synchronized, and the pose information of the stepping motor is consistent with the acquisition time of the radio frequency signal.

Preferably, the PNN algorithm is used for three-dimensional reconstruction in step 5.

Preferably, the method further comprises a step 6 of obtaining a three-dimensional visual image with a preset imaging effect by using a three-dimensional image processing method.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention provides a noninvasive three-dimensional transcranial brain tissue viscoelastic and fluid imaging device which comprises a transcranial low-frequency excitation system and a three-dimensional transcranial ultrasonic rotary scanning device. Adopt adjusting device to adjust laser oscillator, vibrating arm and flexbile plate to the horizontality, control shear wave along vertical direction propagation, make shear wave propagation perpendicular to every supersound scanning line, and then try to get the shear wave velocity of every scanning line, carry out two-dimentional shear wave formation of image, lay the basis for three-dimensional formation of image. The laser vibration meter is introduced into the regulation feedback system, and the effectiveness of the transcranial low-frequency excitation system can be fed back by matching with the readings of the pressure sensor, and the repeatability of the operation can also be improved. After one-time two-dimensional image acquisition, the transcranial low-frequency vibration system is kept still, the ultrasonic probe is rotated by the three-dimensional transcranial ultrasonic rotary scanning device, the acquisition is repeated, and then three-dimensional reconstruction is carried out to obtain three-dimensional viscoelastic and fluid imaging. The three-dimensional imaging breaks through the limitation of two-dimensional imaging, can accurately judge the position relation of the brain focus, and provides diagnostic value for the formulation of an operation scheme, targeted drug-loading treatment and the like. And can be fused with other imaging modes to complement each other and provide more detailed diagnostic information. And finally, the vibration of human muscles is absorbed by adopting the damping support, so that the vibration noise is reduced, and the imaging effect is improved.

The three-dimensional transcranial ultrasonic rotary scanning device provided by the invention solves the problems of three-dimensional reconstruction tissue deformation artifacts, strong patient discomfort, difficulty in ensuring an acoustic coupling effect on a special-shaped surface in a rotating process, poor probe universality and the like of the traditional ultrasonic three-dimensional mechanical rotary scanning device. The system adopts a mode of combining an outer sleeve with an inner sleeve, the inner sleeve is responsible for driving an ultrasonic probe to perform mechanical rotary scanning, the outer sleeve is responsible for performing specific acoustic coupling on irregular skull, parts such as an acoustic transmission membrane, an inlet and outlet valve and a sealing washer are additionally arranged aiming at the outer sleeve, and after the degassing water is filled, good acoustic coupling on the irregular facial skull can be completed. In the process of rotary scanning, the outer sleeve does not produce relative motion on the skull, thereby avoiding the soft tissue deformation in the process of mechanical scanning and reducing the ultrasonic three-dimensional reconstruction artifacts. Meanwhile, in the acquisition process, friction and forced movement do not exist between the outer sleeve and the patient, so that the discomfort of the patient is obviously reduced, and the success rate of the acquisition of the rotational scanning data is improved. In addition, the special probe loading mode of the device enables application scenes with different performance requirements on the ultrasonic probes to be faced, and the mechanical rotary scanning can be completed by using the ultrasonic probes of different models only by replacing probe sealing gaskets specially manufactured according to the shapes of the probes of different models, so that the ultrasonic three-dimensional imaging is realized. The popularization cost of the three-dimensional ultrasonic rotation detection device is reduced, and the three-dimensional ultrasonic rotation detection device has good universality.

The measuring method of the invention uses the KVFD model to carry out multi-frequency shear wave velocity fitting, can obtain the tissue mechanics characteristics of multiple parameters such as elasticity, viscosity, fluidity and the like, overcomes the limitation that the traditional brain tissue elasticity imaging can only be carried out, and the viscosity and fluidity are more sensitive to brain diseases such as Alzheimer disease, cerebral apoplexy and the like, and has the potential to effectively diagnose the diseases at an early stage.

Drawings

FIG. 1 is a diagram of a three-dimensional low frequency excitation device for obtaining transcranial ultrasound brain tissue viscoelasticity and fluidity according to the present invention;

FIG. 2 is a block diagram of a three-dimensional transcranial ultrasound rotational scanning apparatus of the present invention;

FIG. 3 is an exploded view of a three-dimensional transcranial ultrasound rotational scanning device in accordance with the present invention;

FIG. 4 is a block diagram of a three-dimensional transcranial ultrasound brain tissue viscoelastic and fluidic data acquisition system in accordance with the present invention;

FIG. 5 is a block diagram of a three-dimensional transcranial ultrasound brain tissue viscoelastic and fluidic data processing algorithm according to the present invention.

In the figure: 1, a modal vibration exciter; 2, a stepping motor; 3, a vibrating rod; 4, a pressure sensor; 5, a flexible vibrating plate; 6, a three-dimensional ultrasonic rotation detection device; 7, an ultrasonic probe; 8, fixing the structure; 9, an acoustically transparent membrane; 10, an outer sleeve; 11, an inlet and outlet valve; 12, a bearing; 13, a bearing seal; 14, a stepper motor; 15, a transmission gear; 16, an inner sleeve; 17, a probe sealing ring; and 18, fastening the cover by the probe.

Detailed Description

The present invention will now be described in further detail with reference to the attached drawings, which are illustrative, but not limiting, of the present invention.

Referring to fig. 1, a non-invasive three-dimensional transcranial tissue viscoelastic and fluid imaging device comprises a transcranial low-frequency vibration excitation system, a transcranial vibration regulation feedback system and a three-dimensional transcranial ultrasonic rotary scanning device.

The transcranial low-frequency vibration excitation system comprises a signal generator, a power amplifier and a modal vibration exciter 1 which are sequentially connected, wherein the vibration exciter 1 is supported on a support and can adjust the levelness through a stepping motor 2. Be provided with the spirit level on the vibrating arm 3, the one end of vibrating arm 3 is passed through the M5 screw and is connected with vibroscope 1, and the other pot head of vibrating arm 3 is equipped with flexbile diaphragm 5, is provided with the spirit level on flexbile diaphragm 5, and flexbile diaphragm 5's both ends are through adopting the bolt fastening on vibrating arm 3. The bottom surface of the flexible vibrating plate 5 is a concave micro-arc surface and is used for being attached to the top of a skull, and the pressure sensor 4 is embedded in the flexible vibrating plate and is used for feeding back the attachment condition of the vibrating plate and the head of a patient.

Preferably, the flexible vibrating plate 5 is applied to the position of the intersection point of the coronal plane corresponding to the temporal bone and the median sagittal plane of the human body on the top of the skull, and the position is a small arc of the skull, so that the fitting performance is tighter.

Preferably, the flexible vibrating plate 5 is an inwards concave micro-arc surface, and is a hollow plate made of soft silica gel, and the concave micro-arc surface is attached to the soft leather material, so that the transcranial vibration quality is improved, the use feeling of a patient is more comfortable, and the transcranial propagation of shear waves is utilized.

Preferably, the transcranial vibration frequency should be selected to be between 40-160 Hz. Within this range, the modal exciter can achieve good single frequency transcranial vibrations at low power without producing large abrupt accelerations in brain tissue.

The transcranial vibration regulation feedback system comprises a laser vibrometer and a pressure sensor 4. After the transcranial vibration is finished through adjustment, the micro displacement of the transcranial vibration is measured through a laser vibration meter, and whether the adjustment is proper or not is fed back. The pressure sensor 4 is arranged on the cambered surface of the flexible vibrating plate 5 and used for detecting the attaching condition of the flexible vibrating plate 5 and the skull, and the pressure sensor 4 is in data connection with the control unit.

Referring to fig. 2 and 3, the three-dimensional transcranial ultrasonic rotary scanning device comprises a three-dimensional ultrasonic rotary detection device 6, a low-frequency transcranial ultrasonic probe 7 and an ultrasonic imaging device for controlling the low-frequency transcranial ultrasonic probe 7, wherein the three-dimensional ultrasonic rotary scanning detection device 6 has three functions of acoustic coupling, probe loading and rotary scanning driving.

The three-dimensional ultrasonic rotation detection device 6 comprises an outer sleeve 10, an inner sleeve 16, an acoustically transparent membrane 9, an access valve 11 and a drive device.

The outer sleeve 10 is of a structure with openings at two ends, the sound transmission membrane 9 is covered at one end of the outer sleeve, the inner sleeve is sleeved in the outer sleeve through the other end, the driving device is connected with the inner sleeve to enable the inner sleeve to rotate, the ultrasonic probe 7 is positioned in the inner sleeve and fixedly connected, the inlet and outlet valve 11 is arranged on the outer sleeve and used for inputting the deaerated water into the outer sleeve and simultaneously exhausting the air, and the deaerated water and the sound transmission membrane jointly play a role in transcranial ultrasonic coupling.

The sound-transmitting membrane 9 is fixed at the front end of the outer sleeve 10 by a fixing structure 8, and the fixing structure 8 is clamped with the end part of the outer sleeve 10.

The inlet and outlet valve is composed of two miniature electromagnetic valves, and when in use, the air-removing water can be manually controlled or the controller can inject the air into the outer sleeve and release the air to balance the air pressure, so that the air-removing water completely fills the inner space of the outer sleeve, and the air-removing water and the sound permeable membrane jointly play a role in transcranial ultrasonic coupling.

A rotating device is arranged between the outer sleeve and the inner sleeve to enable the inner sleeve to rotate in the outer sleeve, the rotating device comprises a bearing 12 and a bearing sealing ring 13, the bearing 12 is sleeved on the inner sleeve, and the bearing sealing ring 13 is located at the end of the bearing. The outer sleeve 10 and the inner sleeve 16 are connected by bearings 12 so that the inner and outer sleeves can rotate relative to each other without axial displacement. This allows the outer sleeve to remain relatively stationary during the three-dimensional rotational scan, reducing ultrasound artifacts and improving patient comfort. The bearing seal ring 13 is mounted on the bearing 12 to ensure that no leakage occurs at the bearing.

The driving device comprises a stepping motor 14 and a transmission gear 15, the transmission gear 15 is fixed on the inner sleeve 16 and is positioned at the end part of the outer sleeve, the stepping motor 14 is fixed on the outer sleeve 10, and an output shaft of the stepping motor 14 is meshed with the transmission gear 15 to drive the inner sleeve 16 to rotate. The stepper motor 14 is connected to the controller.

The end of the ultrasonic probe 7 is provided with a sealing gasket 17, a groove for assembling the end of the ultrasonic probe 7 is arranged in the sealing gasket 17, one end of the ultrasonic probe 7 is fixed in the groove, then the ultrasonic probe 7 is extended into the inner sleeve, and the sealing gasket is positioned at the end of the inner sleeve, is fixed on the inner sleeve through a probe fastening cover 18 and is screwed, so that the probe is firmly loaded on the inner sleeve and does not leak.

The shape of the ultrasonic probe 7 is opened to customize the probe sealing gasket 17, and silica gel is used as a preparation material of the sealing gasket 17 to ensure the sealing effect. According to the ultrasonic probes of different models, the ultrasonic probe sealing gasket can be suitable for the ultrasonic probes of various shapes only by manufacturing the probe sealing gasket again to ensure the sealing effect under the atmospheric pressure, and the universality is realized.

The ultrasonic probe 7 is placed at the temporal window of the skull, the low-frequency transcranial ultrasonic probe 7 can observe the brain tissue along the corresponding coronal plane of the temporal bone, the thinnest part of the skull is about 1.6mm, and the attenuation of the ultrasound is the minimum.

Referring to fig. 4 and 5, the following describes in detail the imaging method of the above mentioned non-invasive three-dimensional transcranial brain tissue viscoelastic and fluid imaging device, including the following steps:

and step 110, under the condition that the vibration instrument and the ultrasonic imaging equipment are synchronously triggered, scanning, rotating and acquiring radio frequency signals of a plurality of vibration frequencies at different angles. The method comprises the following specific steps:

s101, enabling the patient to sit still and visually observe the front. The flexible plate is attached to the top of the skull of a patient, the signal generator and the power amplifier generate transcranial low-frequency vibration through the modal vibration meter 1, the attachment degree is changed through the stepping motor 2, the transcranial vibration is adjusted until the transcranial low-frequency vibration measured by the laser vibration meter is a single-frequency sinusoidal signal, and data of the pressure sensor at the moment are recorded so as to facilitate repeated tests.

And S102, placing the three-dimensional ultrasonic rotary scanning detection device 6 near a temporal window of the skull through an acoustic coupling pad. Here the thinnest of the skull and at the smallest radius of curvature, so that the attenuation of the ultrasound is reduced for better imaging quality. The ultrasonic imaging equipment controls the ultrasonic probe to generate ultra-high frame frequency ultrasonic plane waves with multi-angle of 2000 Hz. The ultrasonic imaging device is triggered synchronously with the low-frequency transcranial vibration, so that ultrasonic acquisition and transcranial vibration are generated simultaneously, and the minimum time sequence error is ensured. The ultrasonic imaging equipment acquires radio frequency signals and stores the radio frequency signals to the multi-channel ultrasonic platform.

S103, adjusting the frequency of low-frequency vibration, collecting radio-frequency signals under various frequencies under 40-160Hz low-frequency transcranial vibration excitation by taking 20Hz as a step length, and finishing the first round of data collection.

S104, keeping the readings of the pressure sensor unchanged, and enabling the stepping motor in the three-dimensional ultrasonic rotary scanning detection device 6 to drive the inner sleeve to rotate for a certain angle through the controller, wherein the ultrasonic probe and the inner sleeve synchronously rotate at the angle. And after the probe rotates, repeating the step S103 to acquire and collect radio frequency signals under various frequencies.

And S105, determining the minimum step length and the rotation angle range of the rotary scanning of the ultrasonic probe according to clinical requirements, and repeating the acquisition operation of the step S104 until the rotary scanning data required by the three-dimensional reconstruction is completed. And finishing the data acquisition process of three-dimensional viscoelastic and fluid imaging.

And step 210, performing space-time calibration to synchronize the rotating coordinate systems of the ultrasonic probe and the stepping motor, so that the pose information of the stepping motor is consistent with the acquisition time of the radio-frequency signals.

And 310, respectively performing beam synthesis by using the acquired radio frequency data, and acquiring micro displacement data of the brain tissue by using a cross-correlation algorithm.

Specifically, after the cross-correlation algorithm, 3 × 10 matrix median filtering is used for denoising, and then an inverse Fourier transform filter is used for denoising, so that the brain tissue micro displacement is obtained.

And step 410, obtaining an estimated value of the shear wave velocity corresponding to each displacement data according to the displacement data and by combining a Radon change velocity algorithm.

Specifically, for calculating the shear wave velocity of the two-dimensional ultrasound image at different rotation angles α, the shear wave velocity should be calculated by using the pull transform, and then divided by | cos α |, to correct the shear wave velocity.

And step 510, calculating the estimated values of the shear wave speeds of the multiple frequencies at each angle by using a KVFD model to obtain the viscosity, elasticity and fluidity of the brain tissue at each angle.

And step 610, constructing two-dimensional viscoelastic and fluid images according to the viscosity, elasticity and fluid of the brain tissue at each angle to obtain the two-dimensional viscoelastic and fluid images at each angle.

Specifically, the obtained viscoelasticity and fluidity correspond to the displacement matrix obtained by the cross-correlation algorithm one by one, and three tension mechanics parameter two-dimensional images are obtained, which respectively represent elasticity, viscosity and fluidity.

And 710, performing three-dimensional reconstruction according to the two-dimensional viscoelasticity and fluidity images at all angles. Representing the spatial position of each pixel in the sequence ultrasonic scanning image by using the motor pose information after time-space calibration; and selecting a Pixel Nearest Neighbor, and performing regularized voxel grid reconstruction by using a PNN three-dimensional interpolation algorithm, thereby determining a voxel value corresponding to the regularized voxel grid.

Preferably, the PNN algorithm is used for three-dimensional reconstruction, the reconstruction speed is fastest, and the characteristics of high time resolution and real-time diagnosis of ultrasound are guaranteed.

And 810, obtaining a three-dimensional visual image with a preset imaging effect by adopting a three-dimensional image processing method.

After GUI visual display is carried out on the data in Matlab, a visual image required clinically is obtained by selecting a slice projection method, a surface rendering method and a volume rendering method, operations such as area selection and measurement are carried out on the visual image, and the size and the volume of the target are measured.

After the three-dimensional reconstruction is completed, storing the regularized voxel grid, and performing GUI visual display on the data in Matlab; the voxel grid can also be derived according to slices in the depth direction to obtain a regular tomographic sequence image, and the sequence image can be visualized after being opened by using three-dimensional visualization software developed herein or other visualization software (such as mics,3D slicer) for image segmentation, region growing and the like.

Preferably, a visualized image required clinically is obtained by selecting different slice projection, surface rendering and volume rendering methods, the visualized image is subjected to region selection, measurement and other operations, and the size and volume of the target are measured. Meanwhile, the method can be compared with images obtained by other imaging modes and fused to complement the defects, so that more diagnostic information is provided.

The invention discloses a noninvasive three-dimensional transcranial brain tissue viscoelastic and fluid imaging device which comprises a transcranial low-frequency vibration excitation system, a transcranial vibration regulation feedback system and a three-dimensional transcranial ultrasonic rotary scanning device. The detection of the three-dimensional visco-elastic fluidity of the brain tissue based on shear wave imaging under the transcranial condition is realized. The invention adopts the low-frequency vibration excitation within the frequency band range of 40-160Hz, reduces the power of low-frequency vibration and ensures the safety of clinical application. A laser vibration meter is introduced into the regulation feedback system, and the defect of poor operation repeatability of the traditional low-frequency excitation device is overcome by matching with a digital display type pressure sensor.

Furthermore, the KVFD model is used for carrying out multi-frequency shear wave velocity fitting, so that the tissue mechanical characteristics of multiple parameters such as elasticity, viscosity and fluidity can be obtained, and the limitation that the existing imaging only can carry out brain tissue elasticity is overcome. The detection of viscosity and fluidity has great significance for the initial diagnosis of brain diseases such as Alzheimer disease, cerebral apoplexy and the like.

Furthermore, the invention provides a three-dimensional transcranial ultrasonic rotary detection device for a human transcranial, which can drive an ultrasonic probe to carry out rotary scanning and acquire micro displacement of brain tissues under the low-frequency vibration excitation of the transcranial in a multi-angle manner. And by combining a three-dimensional reconstruction algorithm, three-dimensional viscoelastic and fluid multi-mechanical parameter imaging can be formed. For clinical diagnosis, more visual and reliable lesion information is provided, the specific position relation of the lesion is provided, and the dependence on abundant clinical experience of doctors is reduced. The three-dimensional viscoelasticity and fluid imaging can also be combined with nuclear magnetic resonance elastography to carry out combined diagnosis, so that the defects are mutually compensated, and a multi-way basis is provided for pathological judgment of the focus.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.