Microdevice Tracking and Visualization System

Abstract

A system (18) for localizing a microdevice inside a target body part (10), comprising: a microdevice that is remotely operated and controlled from outside the target body part (10); a control unit (20) including a memory (28) for storing one ultrasound image (29) of the target body part (10); one probe (22) in contact with a fixed body part (24) of a patient; and at least one tracker connected to the microdevice, wherein the probe (22) and the tracker communicate via ultrasound, thereby enabling the control unit (20) to localize the tracker in real time within an internal reference (R) defined relative to the probe (22), and the control unit (20) displays the ultrasound image (29) on a screen (30) and displays the localization of the microdevice on the ultrasound image (29) in real time.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to ultrasound placement and imaging used for device localization within a target body structure of a patient, using the same probe. [Background technology]

[0002] Background of the Invention Some advanced medical treatments may involve the use of microrobots inserted into a patient's target body part to deliver, for example, very precise amounts of drugs to very precise points. For safety reasons, these microrobots should be as autonomous as possible, most preferably controlled contactlessly from outside the patient's body. To this end, the microdevices require a wireless localization system with internal references so that they can be tracked and precisely positioned as they move within the target body part. This system should also enable precise 3D visualization of the microrobot's localization within the target body part, allowing the surgeon full control of the situation.

[0003] There is a need to improve the tracking system, especially the localization, for this type of microrobot, by adapting it to the anatomical structure of the target body part. The location of the microrobot relative to anatomical features, such as functional regions, blood vessels, or nerves, is of utmost importance, as it defines the robot's path and target point within the target body part. Therefore, 3D imaging modalities are necessary to anticipate these features and perform path planning. Furthermore, the imaging modality and the microrobot positioning must be perfectly co-registered with an accuracy of 1 mm or better. Therefore, it is important that the imaging and positioning systems are implemented with the same internal reference, ideally through the same technology.

[0004] Additionally, in the case of the brain, even when encased within the skull, it can move, distort, swell, and expand. Microrobots themselves may alter the surrounding anatomical structures as they move through tissue. Tissue physiology, such as blood flow, may be affected by the microrobot and its motion. Consequently, to obtain up-to-date spatial information of the microrobot localized within a reference space, it would be ideal to provide frequent image updates with the microrobot's position. A commonly known wireless communication channel between the two elements is ultrasonic communication. Such a technique can be used to position the robot. Ultrasound imaging is also a commonly known method for obtaining reliable 3D body images. Therefore, both techniques can be performed alternately with similar or identical equipment.

[0005] Several implementations exist for 3D ultrasound imaging, including brightness mode, elastography, and Doppler. One possibility for imaging vascular networks with high precision is ultrasound localization microscopy (ULM). The core concept of ULM is generally known as highly accurate ultrasound imaging, where sparse point sources are introduced into the imaged medium to highlight specific areas. These point sources are typically air microbubbles, or more precisely, millions of microbubbles, also known as contrast agents. To obtain ULM images of a target body structure, such as the cerebral vasculature, microbubbles are injected into the patient. Many 3D transcranial images are acquired. The microbubbles are localized, resulting in a 3D ULM image within minutes. Thanks to these microbubbles, the vasculature can be resolved below the diffraction limit (reaching λ / 10 accuracy). Thus, a super-resolution image is constructed by separately localizing each bubble center and accumulating their positions to reconstruct the vascular network, which is several times smaller than the wavelength. The use of microbubbles (1-3 μm in diameter), due to their high deformability, allows imaging systems to exceed the accuracy limit imposed by classical wave diffraction theory, which is roughly half the wavelength, and avoid the usual compromise between wave transmission (favoring low wave frequency ranges) and image resolution (favoring high wave frequency ranges). This makes it possible to visualize details that are invisible in images constructed by conventional ultrasound examinations, especially Doppler ultrasound examinations. With regard to the vascularity of the brain in particular, this technology can create highly accurate images that allow for precise 3D mapping of a patient's cerebral vasculature.

[0006] The proposed technique in ULM can also be implemented to improve the positioning of microrobots in ultrasound. Microbubble localization in ULM is not limited by wavelength resolution, but rather by the signal-to-noise ratio (SNR) that leads to microbubble detection. A similar concept can be implemented to enable robot localization that can yield very high SNRs, thus enabling very precise localization. This precision can be well below 100 micrometers (<3 MHz) at frequencies that can penetrate the skull.

[0007] The present invention aims to solve the visualization and tracking accuracy problems by co-registering ultrasound signals used either to acquire 3D images of a target body part or to track a microdevice. Summary of the Invention

[0008] overview To this end, the present invention relates to a microdevice tracking and visualization system configured to monitor a target body part of a patient and for localizing a microdevice within the target body part, the tracking system comprising: a microdevice designed to be remotely operated and controlled from outside the target body part; - a control unit including a memory, the memory configured to store at least one ultrasound image of a target body part; - at least one probe configured to contact an immobilized body part of a patient, the body immobilization part at least partially surrounding the target body part; - at least one tracker configured to be connected to the micro device; - at least one screen; Including, the at least one probe and the at least one tracker communicate utilizing ultrasound technology such that the control unit can localize in real time the at least one tracker within the target body part within an internal reference defined for the at least one probe; The control unit is further designed to display at least one stored ultrasound image on a screen and to display in real time the localization of the microdevice on the at least one ultrasound image.

[0009] This approach ensures the localization of the microdevice and perfect alignment with the ultrasound image, allowing for accurate visualization of the microdevice inside the target body part, and for precise and appropriate control and path planning of the microdevice.

[0010] The tracking system according to the invention may include one or more of the following features, taken separately from each other or in combination with each other: - ultrasound images may be acquired utilizing at least one probe; - at least one ultrasound image may be an ULM image; - at least one probe may include at least one ultrasonic transducer and at least one tracker includes at least one ultrasonic sensor; - at least one probe may include at least one ultrasonic sensor and at least one tracker may include at least one ultrasonic transducer; at least one tracker may include a piezoelectric transducer; The microdevice may have a diameter of 3 μm to 3 mm and a length of up to 2 cm; the localization of the microdevice may reach an accuracy better than half the size of the wavelength of the ultrasound used to perform the localization; - the memory of the control unit may be configured to store successive ultrasound images of the target body structure, with each new ultrasound image replacing the previous image; - the acquisition of ultrasound images may be performed in real time, with the acquisition of a new ultrasound image starting as soon as the acquisition of the previous ultrasound image has finished, and each new ultrasound image replacing the previous image as soon as the acquisition of the new image has finished; The target body part may be the patient's brain; The microdevice may be designed to instill at least one contrast agent inside the target body part, and the control unit may be able to localize and display the at least one contrast agent on the ultrasound image.

[0011] The present invention also relates to a microdevice tracking and localization method implemented using a tracking system according to any one of the preceding features, said method comprising: - Real-time tracking of microdevices; - real-time localization of microdevices within an internal reference; - real-time localization of the device within the target body structure; may be simultaneously enabled, The method further comprises: - visualization on a screen of an ultrasound image of the patient's target body part aligned with an internal reference; - real-time display of the microdevice localization within the displayed ultrasound image on the screen; simultaneously.

[0012] The method may include the following steps taken separately from each other or in combination with each other: - At least one probe has two operating modes: an acquisition mode in which at least one probe is acquiring ultrasound images; a tracking mode in which at least one probe is in communication with at least one tracker; and the at least one probe may be switched from an acquisition mode to a tracking mode at least once; - Ultrasound images - planning at least one microdevice path; - monitoring microdevice path tracking in real time; - determining in real time whether there are obstacles on the planned path; - Planning new microdevice paths to avoid obstacles, if necessary; It may also be used for [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an ultrasound image of a target body structure. [Figure 2] 1 is a schematic diagram of a tracking system according to the present invention; [Figure 3]FIG. 1 is a schematic diagram of two trackers fixed to a microdevice according to the present invention. [Figure 4] 1 is an example of a visualization obtained using the tracking system according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0014] Detailed Description As can be seen in Figure 1, a typical target body part 10, such as the cerebral vasculature 12, has a surprising number of blood vessels 14. To treat some health problems, such as tumors, some treatments may involve a microdevice 16, e.g., a microrobot, specifically targeting a precise point in the target body part 10 and delivering a given amount of drug to this point. Such microdevices 16 are typically 3 µm to 3 mm in diameter and up to 2 cm in length.

[0015] To be able to operate at the scale of the microdevice 16 and to obtain sufficient accurate visualization of the microdevice 16 while it is moving inside the target body part 10, it is essential to rely on a highly accurate remote tracking system, such as the tracking system 18 according to the present invention. This remote paradigm imposes strict constraints on the volume of the implanted tracker and the energy used. In this regard, the tracking system must meet several stringent requirements: sub-millimeter positional accuracy, depth of 100 mm or more, real-time updates (from 20 Hz), non-invasive, minimally and maximally micro-sized, maximally energetically inert, and non-harmful to the human body.

[0016] To achieve this visualization, the tracking system 18 a control unit 20; at least one probe 22 configured to be removably fixed to a fixed body part 24 at least partially surrounding the target body part 10 of the patient; - at least one tracker 26 configured to be connected to a microdevice 16 introduced inside the target body part 10; Includes.

[0017] 2, the system 18 includes two probes, each of which is fixed to the patient's temple, so that the fixed body part 24 in this embodiment is the patient's forehead, or more precisely, the skull.

[0018] At least one probe 22 is in contact with the fixed body part 24. In some embodiments (not shown), the probe 22 is manually manipulated around the fixed body part 24. For technical reasons, it is commonly known to apply a small amount of gel onto the body part 24 and the at least one probe 22. Nevertheless, the at least one probe 22 is considered to be in contact with the fixed body part 24. In some alternative embodiments, the probe 22 is fixed to the body part 24, for example, using a helmet or an elastic holder, as seen in FIG. 2 . The probe 22 may also be fixed directly to the fixed body part 24, for example, using a screw system. In this case, the probe 22 should be surgically fixed to the patient's fixed body part 24.

[0019] Each probe 22 is in constant communication with the control unit 20 on the one hand and with at least one tracker 26 fixed to the microdevice 16 on the other hand. Each probe 22 includes at least one ultrasonic transducer, for example a piezoelectric transducer.

[0020] In this application, the term "transducer" is used synonymously with "emitter" and the term "sensor" is used synonymously with "receptor."

[0021] This transducer transmits ultrasound waves to a tracker 26 on a microdevice 16 inside the target body part 10 (as seen in FIG. 4). In some embodiments, the tracker 26 is a passive tracker, including an encapsulating gas pocket 27, such as that shown in FIG. 3. In this passive paradigm, a probe 22 (an external transducer in the embodiment shown in FIG. 2) fixed to a fixed body part 24 of the patient (in this case, the skull) transmits ultrasound waves into the interior of the target body part 10 (in this case, the human brain). The passive tracker 26 receives and scatters the incident waves. The waves travel back toward the probe 22 and back to the fixed body part 24 (in this case, the skull). The time of flight from initial transmission to reception is used to obtain the distance traveled by the waves. By utilizing multiple probes 22, the 3D position of the tracker 26 relative to the probes 22 can be obtained.

[0022] In some alternative embodiments, tracker 26 may be an active tracker that actively emits signals to probes 22. In those cases, each probe 22 includes at least one ultrasonic sensor, and tracker 26 includes at least one ultrasonic transducer, such as a piezoelectric transducer. The overall functionality of the system is the same: ultrasonic waves are emitted by tracker 26 and travel toward probes 22 to fixed portion 24.

[0023] As mentioned above, in some embodiments, the passive tracker 26 may include at least one encapsulated gas pocket 27 attached to the microdevice 16. This solution is based on the principles of ultrasound contrast agents. In this embodiment, each encapsulated gas pocket 27 is formed as a highly ultrasonically reflective object. These encapsulated gas pockets 27 have a large acoustic impedance compared to tissue. This allows the gas pockets 27 to efficiently scatter incident ultrasound transmitted from the probe 22, thereby enhancing local contrast. Because object localization accuracy depends on the signal-to-noise ratio, microdevices 16 smaller than a wavelength can be tracked noninvasively in the target brain region 10, especially deep within the brain. In this embodiment, the tracker 26 combines multiple encapsulated gas pockets 27 separated by more than half a detection wavelength to construct a complete 3D orientation and localization tracker 26. At least two encapsulated gas pockets 27 are required to obtain the orientation of the microdevice 16.

[0024] The control unit 20 further includes a memory 28 that stores an internal reference R. This internal reference R is defined relative to the absolute position of each probe 22 with respect to the target body part 10.

[0025] The memory 28 also stores at least one ultrasound image 29 of the target body part 10. The ultrasound image 29 can be an ULM image, a B-mode image, a Doppler image, or an elastography image. All of the ultrasound images 29 can be performed with the same ultrasound probe. An internal reference R enables co-registration of the ultrasound tracking of the tracker 26 with the ultrasound image 29 acquisition. In some embodiments, the memory also stores at least one pre-prepared image of the fixed body part 24 to which each probe 22 is fixed. In these cases, the control unit 20 aligns at least two images within the internal reference R to accurately position the target body part relative to each probe 22. In either case, the control unit 20 can accurately position any point of the target body part 10 within the internal reference R.

[0026] The information sensed by each probe 22 is then transmitted in real time to the control unit 20, which is thus able to localize at least one tracker 26 within the target body part 10 in real time relative to an internal reference R.

[0027] As previously mentioned, the memory 28 is configured to store at least one ultrasound image 29 of the target anatomy 10, such as the image shown in FIG. 1 . This ultrasound image may be, for example, a ULM image. The control unit 20 aligns each stored ultrasound image 29 with an internal reference R. This aligned ultrasound image 29 provides an accurate 3D mapping of the patient's target anatomy 10. In the case of a ULM image, this provides a highly accurate 3D mapping of the target anatomy 10. This ultrasound image 29 is obtained either before the system 18 monitors the target anatomy 10 or while the system 18 is monitoring the target anatomy 10. More specifically, in some embodiments, to improve co-registration, the ultrasound image 29 is performed with the same probe 22 as that used to track and position the tracker 26.

[0028] To reach the desired co-alignment, at least one probe 22 may be operated in two modes: an acquisition mode in which at least one probe 22 is acquiring ultrasound images 29; a tracking mode in which at least one probe 22 is in communication with at least one tracker 26 using ultrasound; , and at least one probe 22 is switched from acquisition mode to tracking mode at least once, thereby enabling the system 18 to simultaneously track the microdevice 16 and acquire ultrasound images 29.

[0029] In some embodiments, the memory 28 of the control unit 20 may store multiple ultrasound images 29 of the target body part 10. The memory 28 may thus store consecutive ultrasound images 29 of the target body structure 10. In some embodiments, to reduce storage energy, each new ultrasound image 29 replaces the previous image within the memory 28. To increase precision and accuracy of mapping the target body part 10 during monitoring by the system 18, ultrasound image acquisition is performed in real time. Depending on the ultrasound technology, ultrasound image 29 acquisition may last for several minutes and still be considered real-time acquisition. This provides real-time mapping of the target body part 10 and can take into account rapid structural changes. In real-time mapping, the control unit 20 begins acquiring a new ultrasound image 29 as soon as it finishes acquiring the previous ultrasound image 29, such that as soon as each new ultrasound image 29 finishes acquiring, the new ultrasound image 29 replaces the previous image. As an example, the first ultrasound image 29 may be a ULM image, which is then replaced by a more quickly acquired Doppler image.

[0030] The control unit 20 is also designed to display each acquired and / or stored ultrasound image 29 on a screen 30. This is shown in FIG.

[0031] By combining real-time ultrasound information obtained from each probe 22 regarding at least one tracker 26 with the stored ultrasound image 29, the control unit 20 can display in real-time the localization of at least one tracker 26 on the ultrasound image 29. This allows the surgeon to know exactly where the microdevice 16 is located.

[0032] The control unit 20 may further include a user interface 32, for example, by which an operator can instruct the microdevice 16 on the exact point to reach inside the target body part 10. This user interface may also allow the operator to instruct the microdevice in a contactless manner.

[0033] Improved visualization of the microdevice 16 using ultrasound super-resolution technology (such as ULM technology) allows surgeons to accurately monitor the microdevice in deeper areas of any target body part 10, such as the brain. Using conventional ultrasound imaging, an image resolution of 0.75 mm can be achieved at a wave frequency of 1 MHz. Using super-resolution imaging technology, a resolution of 0.15 mm is possible at the same frequency. Super-resolution imaging technology also enables visualization of small veins that cannot be visualized using conventional ultrasound imaging. This helps surgeons remotely navigate the microdevice 16 around the veins, thereby avoiding damaging or injuring one of the veins or causing internal bleeding.

[0034] The microdevice 16 can be actuated by either an external engine (e.g., an external coil, see document PCT / US2019 / 059096) or an internal engine. Therefore, the microdevice 16 can move in any type of biological medium, even inside the human body. Control can be achieved directly with a joystick or through a more complex controller (such as a Phantom Haptic Controller) operated by the user. Control can also be achieved automatically by following a pre-set path. Control signals can be transmitted either wirelessly or using wires connected to the microdevice.

[0035] Utilizing super-resolution ultrasound technology for tracking further allows localization of microdevice 16 to reach an accuracy of better than half the size of the wavelength of the ultrasound used to perform the localization. More specifically, when using ULM technology, localization can reach an accuracy of λ / 10 and visualization can reach an accuracy of λ / 5.

[0036] The ultrasound image 29 thus allows the surgeon to visualize the microdevice 16 and the exact point where the microdevice 16 should land. - planning at least one path to be followed by the microdevice 16; - monitoring in real time the microdevice 16 following the path; - determining in real time whether there are obstacles on the planned path; - planning a new path for the microdevice 16 to avoid obstacles, if necessary; can be done.

[0037] Thus, the tracking system 18 according to the present invention can implement a method for tracking and localizing the microdevice 16, the method comprising: - Real-time tracking of microdevices16; - real-time localization of the microdevice 16 within an internal reference (R); - real-time localization of the device 16 inside the target body structure 10; This can be done.

[0038] The method further comprises: - visualization on a screen 30 of at least one ultrasound image 29 of the patient's target body structure 10 aligned with an internal reference R; - real-time display on the screen of the ultrasound image 29 of the localization of the device 16; This can be done.

[0039] If the same probe 22 is used to acquire the ultrasound image 29 and track the tracker 26, the method thus allows the system 18 to - obtaining ultrasound images; - tracking microdevices 16; This allows for improved real-time tracking of the microdevice 16 and improved real-time visualization of the target body part 10.

[0040] For example, to inform the surgeon that a drug has been sufficiently delivered or to allow the microdevice 16 to accurately monitor the target point to be reached within the target body part 10, the microdevice may be designed to instill at least one contrast agent into the target body part 10. The instillation of the contrast agent may be surgeon-guided or pre-programmed. The contrast agent may be, for example, microbubbles. Once the at least one contrast agent is instilled within the target body part 10, it may be sensed by each probe 22, and the control unit 20 may thus localize and display the at least one contrast agent on the ultrasound image 29, which visualization increases the accuracy of the system 18.

Claims

1. A microdevice (16) tracking and visualization system (18) configured to monitor a target body part (10) of a patient and to localize a microdevice (16) within the target body part (10), the tracking and visualization system (18) comprising: a microdevice (16) designed to be operated and controlled remotely from outside said target body part (10); a control unit (20) including a memory (28), said memory being configured to store at least one ultrasound image (29) of said target body part (10); at least one probe (22) configured to contact a fixed body part (24) of the patient, said fixed body part (24) at least partially surrounding said target body part (10); at least one tracker (26) configured to be connected to said microdevice (16); at least one screen (30); Including, the at least one probe (22) and the at least one tracker (26) communicate using ultrasound technology to enable ultrasonic tracking of the at least one tracker (26), such that the control unit (20) can localize the at least one tracker (26) in real time within the target body-part (10) within an internal reference (R) defined for the at least one probe (22), the internal reference (R) enabling co-registration of the at least one tracker (26) with the at least one ultrasound image (29); The system (18), wherein the control unit (20) is further designed to display the at least one stored ultrasound image (29) on the screen (30) and to display the localization of the microdevice (16) on the at least one ultrasound image (29) in real time.

2. The system (18) of claim 1, wherein the ultrasound images (29) are acquired utilizing the at least one probe (22).

3. The system (18) of claim 1 or 2, wherein the at least one ultrasound image (29) is an ULM image.

4. The system (18) of any one of claims 1 to 3, wherein the at least one probe (22) includes at least one ultrasonic transducer and the at least one tracker (26) includes at least one ultrasonic sensor.

5. The system (18) of claim 1, wherein the at least one probe (22) includes at least one ultrasonic sensor and the at least one tracker (26) includes at least one ultrasonic transducer.

6. The system (18) of any one of claims 1 to 5, wherein the at least one tracker (26) includes a piezoelectric transducer.

7. The system (18) of any one of claims 1 to 6, wherein the microdevice (16) has a diameter of between 3 μm and 3 mm and a length of up to 2 cm.

8. 8. The system (18) of any one of claims 1 to 7, wherein the memory (28) of the control unit (20) is configured to store successive ultrasound images (29) of the target body structure (10), each new ultrasound image (29) replacing the previous image.

9. 9. The system (18) of claim 8, wherein the acquisition of ultrasound images is performed in real time, with the acquisition of a new ultrasound image starting as soon as the acquisition of a previous ultrasound image has finished, and each new ultrasound image (29) replacing the previous image as soon as the acquisition of the new image has finished.

10. The system (18) according to any one of claims 1 to 9, wherein the target body part (10) is the brain of a patient.

11. The system (18) of any one of claims 1 to 10, wherein the microdevice (16) is designed to instill at least one contrast agent inside the target body part (10), and the control unit (20) is capable of localizing and displaying the at least one contrast agent on the ultrasound image (29).

12. A method for tracking and localizing a microdevice (16) implemented using a tracking and visualization system (18) according to any one of claims 1 to 11, said method comprising: - tracking said microdevice (16) in real time; - localization of said microdevice (16) within said internal reference (R) in real time; - localization of the device (16) inside the target body structure (10) in real time; At the same time, The method further comprises: - visualization on a screen (30) of an ultrasound image (29) of the patient's target body part (10) aligned with said internal reference (R); - displaying, in real time, on a screen (30), the localization of said microdevice (16) within said displayed ultrasound image (29); A method that makes both possible at the same time.

13. The at least one probe (22) has two modes of operation: an acquisition mode during which said at least one probe (22) acquires said ultrasound images (29); a tracking mode in which said at least one probe (22) is in communication with said at least one tracker (26); Display The method of claim 12, wherein the at least one probe (22) is switched from the acquisition mode to the tracking mode at least once.

14. The ultrasound image (29) - planning the path of at least one microdevice (16); - monitoring in real time the tracking of the path of said microdevice (16); - determining in real time whether there are obstacles on the planned path; - planning, if necessary, a new microdevice (16) path to avoid said obstacles; The method according to any one of claims 11 and 12, wherein the method is used for

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