A transcranial ultrasound microvessel microbubble imaging method

Abstract

The present invention discloses a transcranial ultrasound microvessel microbubble imaging method, belonging to the field of brain ultrasound technology, which solves technical problems such as low sensitivity and signal-to-noise ratio for small vessel detection in existing imaging microbubble imaging technologies. The transcranial ultrasound microvessel microbubble imaging method, through the use of multiple low-frequency short pulse sequence transmission / reception, combined with spatiotemporal filtering, adaptive beamforming, and low-frequency narrowband decorrelation microbubble detection enhanced power Doppler detection imaging technology, can significantly suppress skull and tissue signal interference, improve the sensitivity and signal-to-noise ratio of transcranial ultrasound microvessel microbubble detection, and improve imaging contrast and resolution while maintaining a high frame rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of brain ultrasound, and in particular relates to a transcranial ultrasound microvessel microbubble imaging method. Background Art

[0002] Due to its portability, real-time nature, and non-invasiveness, ultrasound imaging equipment is playing an increasingly important role in disease diagnosis. Ultrasound has excellent tissue penetration and can be used to penetrate the skull for transcranial vascular detection and imaging. Ultrasound microbubble contrast agents, with a radius comparable to that of a red blood cell, exhibit strong acoustically driven nonlinear vibration and scattering characteristics, exceeding the half-wavelength resolution limit of conventional ultrasound. They are widely used in the early diagnosis, treatment evaluation, and postoperative examination of cardiovascular and tumor diseases, offering advantages in high sensitivity and high-contrast imaging of tiny brain vessels. However, transcranial imaging suffers from the skull acoustic occlusion effect, which significantly attenuates the echo amplitude and causes a certain degree of phase distortion. Furthermore, due to imaging bandwidth limitations, transcranial ultrasound has a narrow available bandwidth, significantly limiting conventional detection and imaging using the broadband nonlinear scattering characteristics of microbubbles. This significantly reduces the sensitivity of transcranial ultrasound for small vessel detection.

[0003] Cerebrovascular diseases primarily occur in small brain microvessels. Doppler imaging is often used to improve the sensitivity of transcranial ultrasound blood flow detection in small brain microvessels. Doppler imaging is widely used clinically for the diagnosis of cerebral vascular diseases, including cerebral vasospasm, cerebral artery stenosis, and intraoperative cerebral blood flow monitoring. To improve the signal-to-noise ratio and robustness of the detection signal, Doppler imaging often employs a wall filter. This filter filters out surrounding tissue clutter, but it impairs detection of extremely low-velocity blood flow near the cerebral vessel walls and extremely high-velocity blood flow at stenotic sites. This wall filter prevents this method from achieving high-sensitivity detection of small brain vessels. In summary, while microbubble contrast imaging improves the signal-to-noise ratio of transcranial blood flow imaging, it significantly reduces sensitivity for small brain microvessels. Traditional Doppler imaging presents challenges in achieving high-sensitivity detection of small brain microvessels and extremely high-velocity blood flow. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a transcranial ultrasound microvessel microbubble angiography imaging method to solve the technical problems of the existing angiography microbubble imaging technology being limited by skull acoustic occlusion attenuation and bandwidth, resulting in low sensitivity and signal-to-noise ratio of intracranial blood flow signal detection, lower sensitivity of low-speed and small microvessel detection, and worse imaging signal-to-noise ratio.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention discloses a transcranial ultrasound microvessel microbubble imaging method, comprising the following steps:

[0007] S1: Signal detection and imaging are performed by transmitting a series of low-frequency short pulse combinations to obtain echo signals of several small brain capillaries;

[0008] S2: Recombining the echo signals of small brain capillaries transmitted at different angles with the same amplitude and phase encoding to obtain a number of echo composite matrices, and performing filtering on the multiple echo composite matrices to obtain a number of intracranial signal matrices;

[0009] S3: performing phase and amplitude summation calculations on several intracranial signal matrices and performing beam synthesis to obtain scan line data; then performing microbubble angiography signal detection on the scan line data to obtain an intracranial microangiography matrix;

[0010] S4: Repeat the process of S1 to S3, perform power Doppler calculation on the obtained intracranial microangiography matrix to obtain the intracranial angiography power Doppler matrix, and perform composite imaging display of the intracranial angiography power Doppler matrix and the intracranial microangiography matrix.

[0011] Furthermore, in S1, an ultrasonic array probe is used to transmit a plurality of low-frequency short pulse combination sequences for signal detection and imaging; the amplitude and phase of each cycle of the same pulse in the low-frequency short pulse combination sequence are the same; the cycles between different pulses in the low-frequency short pulse combination sequence adopt different amplitudes and phases; the transmission frequency range of the ultrasonic array probe is 1 to 3.5 MHz; the number of cycles of each pulse in the low-frequency short pulse combination sequence is the same, and the number of cycles of each pulse is ≤5.

[0012] Furthermore, in S1, the amplitude of the pulses after the second pulse in the low-frequency short pulse combination sequence is 0.25 to 3 times that of the first pulse in the low-frequency short pulse sequence, and the phase is 0° to 360°.

[0013] Furthermore, in S1, the types of the plurality of low-frequency short pulse combination sequences include focused waves, wide beams, plane waves, or diverging waves; the number of the plurality of low-frequency short pulse combination sequences is L, where L=2 to 5; the pulses in the plurality of low-frequency short pulse sequences are transmitted in a manner that adopts a plurality of transmission line beams or surface waves with tilted angles; when the transmission mode is focused waves, the number of tilted angle transmissions I≤256; when the transmission mode is wide beam, plane wave, or diverging waves, the number of tilted angle transmissions I≤30;

[0014] In the wide beam, plane wave or diverging wave transmission mode, the lth short pulse in the L low-frequency short pulse combination sequence has I tilt angle transmissions, where the tilt angle is φ; the angle between the i-th tilt angle transmission and the normal direction of the central element of the phased array is θ i ; Among them, the step length between the tilt angles is Δθ; the echo signals R of several small brain capillaries are obtained i .

[0015] Furthermore, in S2, the echo signal R of the brain microvessels i According to the tilt angle at the time of transmission, the composite matrix of the first echo is obtained.

[0016] The resulting composite matrix The space-time filter is used for filtering, and the eigenvector threshold of the space-time filter is used for filtering to obtain the lth intracranial signal matrix of the brain microvessels.

[0017] Repeat the above steps to obtain the intracranial signal matrix of all L low-frequency short pulse sequences

[0018] Furthermore, in S3, the intracranial signal matrix of L low-frequency short pulse sequences is Performing a summation calculation of the phase amplitude to obtain a summation matrix, and performing beam synthesis on the summation matrix according to an adaptive parallel beam synthesis method to obtain scan line data of a focused wave, a wide beam, a plane wave, or a diverging wave;

[0019] The acoustically driven generalized decorrelation microbubble detection method is used to detect low-frequency narrowband and decorrelation microbubble angiography signals on the scan line data. The intracranial microangiography matrix is ​​obtained by calculating the point-by-point sliding solution of the sampling window.

[0020] Furthermore, in S4, the L low-frequency short pulse combination sequences and their transmission modes defined in S1 are repeatedly transmitted N times according to the repetition rate η; J intracranial microangiography matrices are obtained.

[0021] The intracranial microangiography matrix of group J was sequentially Perform power Doppler calculation to obtain two orthogonal components and two delayed orthogonal components, and obtain the intracranial angiography power Doppler matrix D through complex conjugate multiplication and J-time accumulation. The intracranial angiography power Doppler matrix D is combined with the intracranial microangiography matrix After the imaging area coordinates are transformed and pseudo-color coded according to the intensity signal, composite imaging is displayed.

[0022] Furthermore, the φ≤60°; -φ / 2≤θi ≤φ / 2; R i In the equation, 1≤i≤I; as described above, Δθ=φ / I.

[0023] Furthermore, the Among them, 1≤l≤L, 1≤i≤I.

[0024] Furthermore, the N is less than or equal to 15 times;

[0025] J = (N × L / a) - 1, where a is a factor of N × L. where 1≤j≤J.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention discloses a transcranial ultrasound microvessel microbubble angiography imaging method. Through the technology of multiple low-frequency short pulse combination sequence transmission / reception, joint space-time filter filtering, adaptive beam synthesis and low-frequency narrow-band decorrelation microbubble detection enhanced power Doppler detection imaging, the method can significantly suppress skull and tissue signal interference, improve the sensitivity and signal-to-noise ratio of transcranial ultrasound microvessel microbubble detection, and improve imaging contrast and resolution while maintaining a high frame rate. The scheme of combining low-frequency, multiple low-frequency short pulse sequences with free adjustment of their amplitude and phase can reduce the acoustic attenuation effect of the skull and the destruction rate of microbubbles, while maximally stimulating the decorrelation scattering characteristics of microbubbles and ensuring good axial resolution; the multi-angle compound and fast adaptive parallel beam synthesis method is adopted to improve the signal-to-noise ratio of transcranial vascular imaging, improve the lateral resolution, and ensure high-speed and real-time imaging; at the same time, the combination of spatiotemporal filter filtering and multi-pulse decorrelation microbubble detection technology greatly suppresses the interference of skull and tissue scattering signals, maximizes the sensitivity of contrast microbubble detection, and imaging signal-to-noise ratio and contrast; the transcranial ultrasound microvessel microbubble contrast imaging method disclosed in the present invention can obtain high signal-to-noise ratio, high contrast, and high resolution transcranial ultrasound microvessel imaging with higher microbubble-enhanced microvascular blood flow detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flowchart of the implementation steps of the transcranial ultrasound microvessel microbubble imaging method disclosed in the present invention;

[0029] Figure 2 This is a schematic diagram showing an example of the results of transcranial ultrasound microbubble contrast imaging phantom;

[0030] Figure 3 This is a schematic diagram illustrating an example of the cerebral vascular phantom imaging results obtained using the technology of the present invention. DETAILED DESCRIPTION

[0031] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0033] Herein, all features such as values, amounts, amounts, and concentrations defined in numerical ranges or percentage ranges are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values ​​within the range (including integers and fractions).

[0034] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0035] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0036] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0037] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0038] Example 1

[0039] A transcranial ultrasound microvessel microbubble imaging method comprises the following steps:

[0040] S1: There are a total of L low-frequency short pulse sequences. In the wide-beam, plane-wave, or diverging-wave transmission mode, the lth short pulse has I tilt-angle transmissions, where the tilt angle is φ;

[0041] The angle between the first tilt angle launch and the normal direction of the central element of the phased array is θ i ; where -φ / 2≤θ i ≤φ / 2, the step size between tilt angles is Δθ;

[0042] Get the echo signals R of several small brain capillaries i ; The φ≤60°; R i 1≤i≤I; as mentioned above, Δθ=φ / I;

[0043] S2: Echo signal R of small capillaries in the brain i According to the tilt angle at the time of transmission, the composite matrix of the first echo is obtained. described Among them, 1≤l≤L, 1≤i≤I;

[0044] The resulting composite matrix The lth intracranial signal matrix of brain microvessels is obtained by filtering according to the eigenvector threshold of the spatiotemporal filter.

[0045] Repeat the above steps to obtain the intracranial signal matrix of all L low-frequency short pulse sequences

[0046] S3: Intracranial signal matrix for L low-frequency short pulse sequences Performing a summation calculation of the phase amplitude to obtain a summation matrix, and performing beam synthesis on the summation matrix according to an adaptive parallel beam synthesis method to obtain scan line data of a focused wave, a wide beam, a plane wave, or a diverging wave;

[0047] The acoustically driven generalized decorrelation microbubble detection method is used to detect low-frequency narrowband and decorrelation microbubble angiography signals on the scan line data. The intracranial microangiography matrix is ​​obtained by calculating the point-by-point sliding solution of the sampling window.

[0048] S4: Repeat the L low-frequency short pulse combination sequence and its transmission mode defined in step 1 N times according to the repetition rate η; obtain J intracranial microangiography matrices

[0049] The intracranial microangiography matrix of group J was sequentially Perform power Doppler calculation to obtain two orthogonal components and two delayed orthogonal components, and obtain the intracranial angiography power Doppler matrix D through complex conjugate multiplication and J-time accumulation. The intracranial angiography power Doppler matrix D is combined with the intracranial microangiography matrix After the imaging area coordinates are transformed and pseudo-color coded according to the intensity signal, composite imaging is displayed; N is less than or equal to 15 times; J = (N × L / a) - 1; where a is the N × L factor; where 1≤j≤J.

[0050] Example 2

[0051] A transcranial ultrasound microvessel microbubble imaging method, using a phased array ultrasound transcranial vascular phantom as an example, includes the following steps:

[0052] S1: First, a phased array ultrasound probe can be used to transmit a series of low-frequency short pulse combinations through the temporal window to detect and image the microvessel microbubble angiography signals of the brain's small capillaries, thereby obtaining echo signals of the brain's small capillaries. The transmission frequency of the phased array ultrasound probe is 2 MHz, and the low-frequency short pulse combination sequence contains L short pulses, namely: T1, T2, T3…T L ; Each pulse cycle in the above low-frequency short pulse combination sequence has the same length, and the number of cycles is 5. The amplitude and phase of each cycle of the same pulse in the low-frequency short pulse combination sequence are the same; the amplitudes of the L short pulses are respectively recorded as: A1, A2, A3...A L , the phases are recorded as: B1, B2, B3…B L , the phase B needs to be distributed within the range of 360° according to the period, and the amplitude A is distributed according to the rule of adding the echo phase amplitude and the principle of canceling the linear echo to distribute A and B of each short pulse; the amplitude of the pulse after the second pulse in the low-frequency short pulse combination sequence is 0.25 to 3 times that of the first pulse in the low-frequency short pulse sequence, and the phase is 0° to 360°; among the above-mentioned L short pulses, a plurality of inclined angle transmission beams are used for transmission, the number of angles is I = 15, and the difference between each two angles is 2°. Under the low-frequency short pulse combination sequence and transmission mode defined above, the microvessel microbubble angiography signal of the brain is detected and imaged through the temporal window of the skull.

[0053] As mentioned above, the number of angles of each short pulse transmission beam is I=15. Secondly, the transmission tilt angle is φ=30, and the angle between the lth (1≤l≤L) and the i-th (1≤i≤15) tilt angle transmission and the normal direction of the phased array center element is θ i ; 15≤θ i≤15, the step length between the inclination angles is Δθ=φ / I=2°. Each short pulse is emitted 15 times to obtain the echo signals or complex signals R1, R2, R3…R of 15 brain microvessels. 15 ;

[0054] S2: Echo signal R of small capillaries in the brain i According to the tilt angle at the time of transmission, the composite matrix of the first echo is obtained. described Repeat the above steps to obtain the intracranial signal matrix of 15 low-frequency short pulse sequences The intracranial signal matrix of the obtained 15 low-frequency short pulse sequences Perform summation calculations and use spatiotemporal filters to perform singular value decomposition. Based on the situation of intracranial microvascular shadow signals and tissue signals in the composite matrix, remove background tissue interference and retain microvascular angiography signals as the standard, select a suitable eigenvector as the threshold, remove the signal below the vector, and reconstruct the composite matrix of the echo obtained by each type of short pulse emission at different angles after filtering with the spatiotemporal filter.

[0055] S3: Intracranial signal matrix for L low-frequency short pulse sequences Perform sum calculation: each column of the matrix represents the echo signal of the brain microvessels obtained by each array element of the ultrasound probe, and the matrix row represents the number of sampling points of each array element. For the echo matrix of L short pulse Perform matrix summation calculation, that is, according to the principle of phase and amplitude to offset the linear echo signal, sum the weights assigned to each echo to obtain the echo matrix of L short pulse amplitude phase modulation and linear echo cancellation. The scan line data is obtained; the scan line data is beamformed according to the fast adaptive parallel beamforming method, wherein the fast adaptive parallel beamforming method combines the scattering characteristics of microbubbles, and the aperture and array element echo weights are adaptively adjusted, and accelerated by machine learning, and the plane wave scan line RF data is obtained after beamforming, and then the sound-driven generalized decorrelation microbubble detection method is used to perform low-frequency narrow-band decorrelation microbubble angiography signal detection on the intracranial small microvascular scan line data after beamforming, and the intracranial angiography matrix is ​​obtained by sliding decorrelation calculation point by point through the sampling window.

[0056] S4: Based on the L low-frequency short pulse combination sequences and transmission modes defined in S1, in this step, the same method is repeated 10 times according to a certain overlap rate, wherein the overlap rate refers to the ratio of the number of low-frequency short pulse combination sequences in the previous group to the number of each low-frequency short pulse combination sequence when performing the amplitude and phase summation calculation in S3 when the same low-frequency short pulse combination sequence is repeatedly transmitted 10 times. In this embodiment, the maximum overlap rate is used for calculation, wherein

[0057] According to the above repetition rate, and using the same step size of 1, the sum of the results is calculated by sliding backward with a window size of L, and the obtained J = (10*L / 1)-1 is taken as an integer echo matrix and S2 is repeated to obtain J intracranial angiography matrices The repetition period of the low-frequency short pulse sequence is T, and J intracranial angiography matrices are imaged once. Perform power Puller signal detection, each After orthogonal demodulation, two orthogonal components and two orthogonal components delayed by T are obtained; after complex conjugate multiplication and J accumulations, the intracranial angiography power Doppler matrix D is obtained; the intracranial angiography matrix obtained in S3 is The obtained intracranial angiography power Doppler matrix D is resampled, dynamically adjusted, and transformed into phased array coordinates, and different forms of pseudo-color encoding are performed according to the intensity signal. The resulting images are then composited into one image for display, completing the process of transcranial ultrasound microvessel microbubble angiography imaging.

[0058] A human cerebral vascular phantom was selected for microbubble angiography. A MatLab-based programmable ultrasound device was used with a phased array probe to transmit the low-frequency short pulse combination sequence described in the above steps through the temporal window of the phantom skull. The above steps S1 to S4 were implemented according to the above steps. Figure 1 Follow the process described in . Figure 2 The figure shows the transcranial ultrasound microbubble contrast imaging phantom results obtained after executing steps S1 to S3. It can be seen from the figure that although the image obtained by the traditional contrast imaging mode can see the general structure of the intracranial blood vessels, some parts are still missing and the complete intracranial blood flow cannot be seen. Figure 3 The figure shows the final cerebral vascular phantom imaging result obtained by the method of the present invention. Compared with the traditional angiography imaging method, this method can see more intracranial blood flow information, the intracranial blood flow condition is more complete, and can make up for the lack of some tiny blood flows in the traditional method, thereby improving the signal-to-noise ratio and sensitivity of transcranial angiography.

[0059] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A transcranial ultrasound microvessel microbubble imaging method, characterized in that: The following steps are involved: S1: By transmitting a series of low-frequency short pulse combinations to detect and image the transcranial microbubble echo signal amplitude, the echo signals of several small brain capillaries are obtained; S2: Recombining the echo signals of small brain capillaries transmitted at different angles with the same amplitude and phase encoding to obtain a number of echo composite matrices, and performing spatiotemporal filtering on the multiple echo composite matrices to obtain a number of intracranial signal matrices; S3: performing phase and amplitude summation calculations on several intracranial signal matrices and performing beam synthesis to obtain scan line data; then performing microbubble angiography signal detection on the scan line data to obtain an intracranial microangiography matrix; S4: repeat the process of S1 to S3, perform power Doppler calculation on the obtained intracranial microangiography matrix to obtain the intracranial angiography power Doppler matrix, and perform composite imaging display of the intracranial angiography power Doppler matrix and the intracranial microangiography matrix; In S1, an ultrasonic array probe is used to transmit a plurality of low-frequency short pulse combination sequences for signal detection and imaging; the amplitude and phase of each cycle of the same pulse in the low-frequency short pulse combination sequence are the same; and the amplitudes and phases of the cycles between different pulses in the low-frequency short pulse combination sequence are different; The transmitting frequency range of the ultrasonic array probe is 1-3.5 MHz; the number of cycles of each pulse in the low-frequency short pulse combination sequence is the same, and the number of cycles of each pulse is ≤5; In S1, the amplitude of the pulses after the second pulse in the low-frequency short pulse combination sequence is 0.25 to 3 times that of the first pulse in the low-frequency short pulse combination sequence, and the phase is 0° to 360°; In S1, the types of the several low-frequency short pulse combination sequences include focused wave, wide beam, plane wave or diverging wave; the number of the several low-frequency short pulse combination sequences is L , L = 2 to 5; the pulse emission mode of the low-frequency short pulse combination sequence is formed by a plurality of tilt angle emission beams or surface waves; when the focused wave emission mode is used, the number of tilt angles is ≤256; when the transmission mode is wide beam, plane wave or diverging wave, the number of transmissions at the tilt angle ≤30; In wide beam, plane wave or diverging wave transmission mode, L The first of a series of low-frequency short pulse combinations Among the short pulses The tilt angle is launched at a certain angle, where the tilt angle is ;No. The angle between the sub-tilt angle and the normal direction of the central element of the phased array is ; where the step size between tilt angles is ; Get the echo signals of several small blood vessels in the brain ; In S2, the echo signal of small blood vessels in the brain According to the tilt angle at the time of launch, the first echo complex matrix ; The resulting composite matrix The space-time filter is used for filtering, and the eigenvector threshold of the space-time filter is used for filtering to obtain the first intracranial signal matrix ; Repeat the above steps to get all L Intracranial signal matrix of low-frequency short pulse sequences ; In S3, L Intracranial signal matrix of low-frequency short pulse sequences Performing a summation calculation of the phase amplitude to obtain a summation matrix, and performing beam synthesis on the summation matrix according to an adaptive parallel beam synthesis method to obtain scan line data of a focused wave, a wide beam, a plane wave, or a diverging wave; The acoustically driven generalized decorrelation microbubble detection method is used to detect low-frequency narrowband and decorrelation microbubble angiography signals on the scan line data. The intracranial microangiography matrix is ​​obtained by calculating the point-by-point sliding solution of the sampling window. ; In S4, the definition in S1 L A low-frequency short pulse combination sequence and its transmission method according to the repetition rate η Repeat the launch N times; get J intracranial microangiography matrix ; In turn J intracranial microangiography matrix Perform power Doppler calculation to obtain two orthogonal components and two delayed orthogonal components, which are multiplied by complex conjugate and J The accumulation of times , the intracranial angiography power Doppler matrix D ; Power Doppler matrix for intracranial angiography D intracranial microangiography matrix After the imaging area coordinates are transformed and pseudo-color coded according to the intensity signal, composite imaging is displayed.

2. The transcranial ultrasound microvessel microbubble imaging method according to claim 1, characterized in that: described ≤60°; ; 1 of ≤i≤ ; said, .

3. The transcranial ultrasound microvessel microbubble imaging method according to claim 1, characterized in that: described , where 1≤ ≤ L, 1≤i≤ .

4. The transcranial ultrasound microvessel microbubble imaging method according to claim 1, characterized in that: described N ≤15 times; ; J=(N×L / a)-1 ; where a is a factor of N×L; 1≤ j≤J .

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