Conformal ultrasonic system for enforcing medicaments to permeate blood brain barrier

[0028] Example 1. Composition and mode of action to promote the penetration of drugs through the blood-brain barrier system

[0029] Such as figure 1 As shown, the conformal ultrasound system that promotes the penetration of drugs through the blood-brain barrier is mainly composed of a central computer 1 and a phased-array ultrasound transmitter 7. The phased-array ultrasound transmitter 7 is composed of 512 ultrasound transmitters. Each ultrasound transmitter The unit is composed of a single-chip microcomputer system 2, a high-frequency excitation unit 3, a power amplifier 4, a coupling unit 5 and a phased array piezoelectric array element 6. The single-chip system 2 controls the high-frequency excitation unit 3 to synthesize high-frequency sine waves or high-frequency square waves. The high-frequency sine waves or high-frequency square waves can be generated by a digital frequency synthesizer, or can be generated by an LC self-excited oscillation circuit, and a power amplifier 4 Amplify the high-frequency sine wave or high-frequency square wave power, and drive the phased array piezoelectric element 6 containing piezoelectric crystals through the coupling unit 5 to transmit ultrasound. The coupling unit 5 can be realized by capacitive coupling or transformer coupling. ;

[0030] The central computer 1 wirelessly transmits the ultrasound radiation treatment parameters to the single-chip microcomputer, and controls the phased array ultrasound transmitter 7 to generate ultrasound with adjustable focus position, power size, focal spot size, and radiation time, and realizes the information during the treatment process through the central computer 1 Transmission and central control; the phased array ultrasonic transmitter 7 is monitored by the central computer 1; the main functions of the central computer 1 are: effect control and image recognition analysis, positioning control, and treatment parameter setting.

[0031] Combine figure 2 As shown, the system also includes a driver 8 of the phased array ultrasonic transmitter 7, and the central computer 1 controls the driver 8 to move the phased array ultrasonic transmitter 7 to an appropriate position for radiation. The system also includes an MRI auxiliary system 9, which includes an MRI transmitter, an MRI receiver, and MRI signal processing and imaging three parts, which transmit the spatial position information of the brain and the functional imaging information of the brain. To the central computer 1 for the location of the brain lesions in the early stage and the inspection of the treatment effect in the later stage. After the central computer 1 obtains the spatial position of the brain lesion and the phased array array element emission space position through the MRI auxiliary system 9, the central computer 1 calculates the spatial distance between each array element and the lesion; The phase delay parameter corresponding to the array element, so that the ultrasound reaching the lesion site has the optimal power. The system also includes a circulating water bag 12, the phased array ultrasonic transmitter 7 and the brain are coupled through the circulating water bag 12 to reduce the attenuation of ultrasound, and the output end of the circulating water bag 12 is connected to the degassing device 10 and the temperature control device 11. , In order to eliminate the bubbles in the water bag due to ultrasonic cavitation and control the temperature in the water bag.

[0032] The appearance design and specific working conditions of the phased array ultrasonic transmitter 7 are as follows:

[0033] Such as image 3 As shown, the phased array ultrasonic transmitter 7 is a spherical cap with a radius of 15 cm, and its aperture radius is 11 cm. The array elements are uniformly distributed on the inner side of each circle of the spherical cap in a concentric circle. Let a be the angle deviating from the positive semi-axis of x in the xy plane, the value range is 0 to 2π, and b is the angle of the negative semi-axis of z offset, the value range is 0 to π/4, the spherical center of the spherical cap is at At (0, 0, R), the space coordinates of the spherical cap are:

[0034] x = R * cos a * sin b y = R * sin a * sin b z = R * ( 1 - cos b ) (Formula 1)

[0035] 0≤a≤2π,0≤b≤π/4

[0036] The array element is designed to have 16 concentric circles with a total of 544 elements. For the outermost circle, only 32 elements are used, and the final design is 512 elements. The interval of b is π/64, and the interval of a on the i-th circle is 2π/(4*i), so that the space coordinates of 512 elements can be obtained, such as image 3 It is the outline diagram of the transducer. Let I (i, j) Is the (i, j)-th array element, i represents the offset measure of b, which ranges from 1 to 16, and j represents the offset measure of a, which ranges from 0 to 4*i-1, so I (i, j) One-to-one correspondence with each element. When determining the spatial location of the lesion, the distance D between each element and the lesion can be calculated (i, j).

[0037] Take min(D)={D (i, j) } (Equation 2)

[0038] Suppose the time for the element with the shortest distance from the lesion to emit ultrasound is t 0 , Then the launch time of each array element after delay is:

[0039] t ( i , j ) = min ( D ) - D ( i , j ) c + t 0 (Equation 3)

[0040] Assuming that the lesion is at the focal position (0, 0, 15) of the spherical cap, the spatial coordinate position of each element is obtained by (Equation 1), and the distance between each element and the lesion is obtained:

[0041] D ( 1,1 ) = ( 0.73602 ) 2 + ( 0 ) 2 + ( 0.018068 - 15 ) 2 D ( 1,2 ) = ( 0 ) 2 + ( 0.73602 ) 2 + ( 0.018068 - 15 ) 2 . . . D ( 16,64 ) = ( 10.556 ) 2 + ( - 1.0396 ) 2 + ( 4.3934 - 15 ) 2

[0042] Through cyclic comparison, we can get the smallest one of the 512 distances min(D)={D (i, j) }, and then according to (Equation 3) to get the launch time of each array element after delay:

[0043] t ( 1,1 ) = min ( D ) - D ( 1,1 ) c + t 0 t ( 1,2 ) = min ( D ) - D ( 1,2 ) c + t 0 . . . t ( 16,64 ) = min ( D ) - D ( 16,64 ) c + t 0

[0044] The MRI auxiliary system 9 completes the determination of the spatial position of the lesion. The spatial position relationship of each array element has been obtained above. The central computer 1 obtains the calculation of the delay time of each array element through the above algorithm, and then through wireless communication The control parameters are sent to the single-chip microcomputer system 2 of each array element to complete the respective delays of 512 array elements. Such as Figure 4 As shown, the peak positions of the focused beam distributions obtained by using different delays are obviously different, that is, the focus positions of the two are different. It can be seen that as long as we accurately calculate different time delays for each array element, we can generate a focused sound beam with a certain power at the required spatial position. Ultrasonic radiation parameters are: frequency 1-2MHZ, sound intensity 1-5W/cm 2 , Radiation energy 20-200W, pulse width 100ms, time 10-30s.

[0045] Example 2. Methods of using drugs to promote the penetration of the blood-brain barrier system

[0046] First, let the patient lie on a horizontally movable bed, wear a hat-shaped water bag on the head, and then send the patient into the treatment area of ​​the instrument.

[0047] When the patient is lying flat, activate the MRI transmitter device in the MRI auxiliary monitoring system 9, receive the brain function image from the MRI receiver device, and transmit the brain function information to the center through the MRI signal processing and imaging unit computer.

[0048] The doctor checks the location of the lesion on the computer and clicks on the mouse to determine the location of the lesion.

[0049] The driver 8 is used to move the phased array ultrasound transmitter 7 to the ideal treatment site to emit ultrasound; then the central computer 1 calculates the spatial distance of the current ultrasound probe element relative to the lesion, and the delay corresponding to each element Time, the calculation method has been mentioned above.

[0050] The doctor sets the treatment parameters on the computer according to the condition, including power, radiation area, and radiation exposure time.

[0051] After the treatment parameters are set, press the start ultrasound button, and the computer wirelessly transmits the relevant control parameters of the single-chip microcomputer 2 of each array element, and performs ultrasound treatment on the specified points.

[0052] After the treatment, start the MRI auxiliary system 9 again to check the treatment effect.

[0053] The degassing device 10 and the temperature control device 11 have been working throughout the process to ensure a good environment for the brain.

[0054] Example 3, the therapeutic effect of promoting drugs to penetrate the blood-brain barrier system

[0055] The effect display is divided into two parts: in vitro experiment and in vivo experiment.

[0056] The establishment of an in vitro blood-brain barrier model was achieved by co-cultivating white rabbit brain microvascular endothelial cells and astrocytes. Studies have proved that under specific ultrasound parameters, ultrasound can significantly increase the permeability of cell membranes, allowing macromolecular gene drugs to enter the cell for expression, with a transfection rate of 40%, the intensity of gene expression in the cell and the amount of specific control parameters It is closely related to the conclusion that it can be safely used for gene delivery under a precise effect scale control system. Figure 5 It can be seen that through scanning electron microscopy, the repairable micropores on the S180 cell membrane caused by ultrasound, that is, ultrasound opens the micropores on the cell membrane due to its mechanical properties; at the same time, through observation, it can be found when the action time is within 5 minutes Obvious traces of micropore healing, that is, the cell membrane micropores are reversible under the appropriate intensity of ultrasound radiation; but when the radiation exceeds 8 minutes, the cells begin to die in large numbers, that is, the parameters of ultrasound radiation are particularly important for the permeability of the cell membrane important.

[0057] In the in vivo experiment, the head of a white rabbit was irradiated, and Evans Blue solution was injected intravenously, combined with a fluorescent reporter gene, to determine the location of the drug in the brain tissue and the efficiency of crossing the blood-brain barrier. The ultrasound was determined by comparison with a control group that did not use ultrasound. The effect of macromolecular drugs across the blood-brain barrier under the action. Scanning electron microscope and flow cytometer were used to detect brain tissue damage and apoptosis, and analyze the damage of brain tissue. Among them, Evan's blue in the Evan's blue disappearance experiment is a powdery dye that quickly binds to albumin almost 100% after entering the blood. Albumin has a molecular weight of 67kDa, which can hardly penetrate the blood-brain barrier under normal circumstances. When the permeability of the blood-brain barrier increases, albumin bound to Evans blue can pass through the blood-brain barrier and enter the brain tissue. When the excitation light wavelength is 550nm, red fluorescence can be seen under the fluorescence microscope.

[0058] When Evans Blue was used to detect changes in the permeability of the blood-brain barrier, it was found that after low-frequency ultrasound irradiation, the content of Evans blue in the brain tissue of the white rabbits increased compared with the control group.

[0059] In addition, through transmission electron microscopy, it was found that after ultrasound irradiation, the content of Evans blue will have a peak over time, but it will gradually decrease later. Observing the changes in the microstructure of the blood-brain barrier through transmission electron microscopy, we found that after ultrasound irradiation, with the passage of time, the degree of tight junctions of vascular endothelial cells in the experimental group is different, and the degree of opening is the largest within a period of time. But it gradually decreased, and there was no opening between vascular endothelial cells in the control group. These results indicate that ultrasound with appropriate radiation parameters can cause the reversible opening of the blood-brain barrier in white rabbits.

[0060] Experiments have shown that under normal circumstances, Evan’s blue is used as a tracer to bind to serum albumin, and albumin cannot pass through the blood-brain barrier due to its large molecular weight. After ultrasound radiation, it can be seen under a fluorescence microscope that there is Significant increase in permeability of the blood-brain barrier. At the same time, the content of Evan's blue in the hippocampus, hypothalamus and cerebellum of the white rabbits in the radiation exposure group was determined. Compared with the normal control group, the content of Evans blue was significantly increased, and the content of Evans blue was lower after 12 hours after the exposure, and compared with the normal group Not significant, indicating that ultrasound radiation can cause reversible changes in the permeability of the blood-brain barrier in rats. And using scanning electron microscope and flow cytometer to detect brain tissue damage and apoptosis, it is found that there is no obvious damage to brain tissue within the range of radiation parameters we set.