Devices and methods for treating patients with high-intensity focused ultrasound (HIFU)

Abstract

The present invention relates to an apparatus (1) and a method for avoiding artifacts in second circulation mode imaging during ultrasound treatment of a patient's body (P). Specifically, and among other effects, the present invention provides a well-controlled way, in particular of opening and closing the fluid circulation (12) in a cavity (7), so as to avoid artifacts while still achieving practical imaging.

Description

Technical Field

[0001] This invention relates to apparatus and methods for treating patients using high-intensity focused ultrasound (HIFU) according to the independent claims. Background Technology

[0002] HIFU treatments can perform non-invasive ablation of anatomical targets within the body. They are typically guided by imaging modalities such as magnetic resonance imaging or ultrasound, especially B-mode imaging.

[0003] Several devices known in the prior art have an ultrasound imaging transducer embedded in a treatment head, which also includes, for example, a treatment transducer described in WO2006 / 129045. This arrangement allows for real-time imaging.

[0004] To ensure acoustic coupling with the patient's anatomical structures, a deformable coupling balloon can be used. An example of such a deformable coupling balloon is described in WO2011 / 064209.

[0005] When using high-intensity focused ultrasound (HIFU) devices, the treatment head is typically positioned roughly over the area to be ablated (referred to here as the target). Precise positioning of the focal point relative to the target is achieved through mechanical movement and positioning of the treatment head (e.g., if mounted on a robot) or through electronic focusing, guided by images provided by a relevant imaging modality (B-mode, MRI, etc.). The focal point refers to the area to which energy will be delivered by the treatment head.

[0006] Imaging techniques in the context of ultrasound therapy are known in the prior art. In particular, B-mode imaging is widely known as a method for providing grayscale images of tissue anatomy.

[0007] On the other hand, Doppler imaging provides information about flow and / or fluid within the target tissue. Typically, Doppler flow maps are superimposed on B-mode images of the anatomical structure. This superposition is often referred to as duplex imaging.

[0008] Elastography is a known method for mapping the elastic properties of tissues. Prior art methods known for performing elastography using ultrasound, particularly those referred to as quasi-static elastography, strain imaging, acoustic radiation force pulse imaging (ARFI), shear wave elastography (SWEI), ultrasonic shear imaging (SSI), and transient elastography, are known to employ ultrasound.

[0009] In the context of this invention, the terms "Doppler imaging," "color Doppler," and "Doppler imaging mode" should include any imaging technique containing information based on Doppler technology. Specifically, those terms may refer to superimposing a color Doppler image onto a B-mode image (duplex).

[0010] Fluid ensures acoustic coupling between the treatment head and the patient's tissue. To contain the coupling fluid, the treatment head includes a hollow space at its distal end enclosed by a membrane (called a balloon), which is the part applied to the patient.

[0011] The fluid is typically circulated using one or more pumps. The fluid pressure within the balloon can be controlled to ensure the balloon conforms to the patient's anatomy. The fluid temperature can also be controlled to ensure cooling of the treatment transducer and the patient's skin.

[0012] When treatment is guided by ultrasound imaging, color Doppler and / or elastography can be useful tools, such as for target localization during HIFU treatment of veins.

[0013] However, fluid flow within the balloon can cause artifacts on Doppler and / or elastography images, which can make target localization difficult, for example, if there is little blood flow within the target. Summary of the Invention

[0014] Therefore, the object of the present invention is to overcome the shortcomings of the prior art, and in particular to provide an apparatus and method for treating tissues, wherein Doppler imaging can be performed during HIFU treatment, and especially without interference.

[0015] This and other effects can be achieved by the apparatus and method according to the independent claims of the invention.

[0016] The device for treating a patient via HIFU includes a treatment head. The treatment head includes a HIFU transmitting unit, particularly a transducer, for emitting HIFU pulses. The device also includes an imaging apparatus adapted to operate at least in a Doppler imaging mode and / or an elastography mode, as well as a conventional imaging mode, preferably mode B or another mode that does not include Doppler and / or elastography information. The Doppler imaging mode may be, in particular, dual-power Doppler, tri-power Doppler, color Doppler, or another mode that includes color Doppler information. Specifically, if the imaging apparatus includes an imaging probe, particularly an ultrasound probe, for emitting and receiving ultrasound waves and a scanner adapted to process the received signals and generate images, then the imaging probe is preferably arranged within the treatment head. The device also includes at least one pump for circulating fluid in a cavity located between the treatment head and a contact surface of the device adapted to contact the patient's skin. A control unit is provided to control the operation of the imaging apparatus and the pump. The control unit is adapted to operate the fluid circulation in at least a second circulation mode different from the conventional circulation mode. In particular, the control is adapted to start and stop the fluid circulation according to the operating mode of the imaging apparatus.

[0017] The control unit can be adapted to operate fluid circulation in more than these two modes, and in particular, it can include other modes for transitioning between Doppler imaging mode and conventional imaging mode. Specifically, the control unit can be adapted to start and stop fluid circulation according to the operating mode of the imaging device.

[0018] Specifically, the present invention provides a method for properly starting and stopping fluid circulation based on the operating mode of an ultrasonic (US) monitoring device.

[0019] The main idea is to stop or reduce fluid circulation when Doppler imaging mode and / or elastography mode are activated. This is considered counterintuitive because it means reducing the cooling effect on the skin.

[0020] In a preferred embodiment, when the Doppler imaging mode and / or elastography mode are activated, the control unit is thereby adapted to switch to a second circulation mode that includes stopping fluid circulation. When the Doppler imaging mode and / or elastography mode are stopped, the control unit may be further adapted to switch to a conventional circulation mode, which includes restarting fluid circulation or increasing fluid. Thus, the preferred second circulation mode may be a Doppler circulation mode. Alternatively, the second circulation mode may be an elastography circulation mode.

[0021] Artifacts in Doppler and / or elastography images can be avoided by reducing or stopping fluid circulation.

[0022] Preferably, when the monitoring mechanism is switched to Doppler imaging mode and / or elastography mode, the fluid pump operation is automatically set to a second circulation mode. Normally, the monitoring mechanism operates based on a conventional imaging mode, particularly in mode B, and can switch to Doppler imaging mode and / or elastography mode. When the imaging mechanism switches to Doppler imaging mode and / or elastography mode, fluid circulation enters the second circulation mode. Preferably, when the Doppler imaging mode and / or elastography mode stops and the system typically switches back to the conventional imaging mode, the pump and pressure control then return to the conventional mode. Alternatively, the user interface includes a controller to switch between the second circulation mode and the conventional circulation mode.

[0023] In a preferred embodiment, the treatment head includes a balloon through which the fluid circulates. The controller is then preferably adapted to control the fluid circulation so that a preset pressure is reached within the balloon in a normal circulation mode. When the pump stops, the balloon geometry no longer changes according to the patient's anatomy. Specifically, the fluid pressure increases or decreases, respectively, if some action is performed toward or away from the patient (e.g., using a robot). Pressure control is restored when the fluid control is set back to the normal circulation mode and the monitoring mechanism is switched back to the normal imaging mode. The pump then restarts to inflate or deflate the balloon, respectively, returning it to the pressure setpoint.

[0024] In a particularly preferred embodiment, the method further includes a step of restarting the regular cyclic mode after a delay following the sending of a command to switch to a regular imaging mode.

[0025] Preferably, the control unit is adapted to restart the regular cycle after the imaging device has switched to the regular imaging mode and while it is operating in the regular imaging mode. Specifically, the restart of the regular cycle mode may be based on receiving a signal from the imaging device indicating that the regular imaging mode is operating normally.

[0026] When an echo sounder is switched from color Doppler imaging mode and / or elastography mode to conventional imaging mode, especially from tri-power Doppler to B mode, there is usually a time window during which the image is frozen. Therefore, if two commands are set simultaneously ("Switch to conventional imaging mode" and "Switch to conventional loop mode"), the balloon may deflate or inflate while the real-time image is frozen.

[0027] In this situation, anatomical structures may move, but the user cannot see this movement. In the case of a treated vein, the vein is almost invisible in B-mode. Doppler ultrasound can then be used to observe the vein. When pressure modulation is restored, image freezing may prevent the user from visually following the movement of the vein in the image.

[0028] To overcome this limitation, it is preferable not to send the two commands at the same time.

[0029] In a preferred embodiment, a "switch to normal imaging mode" command is sent first, and a "switch to normal loop mode" command is sent only if real-time imaging is available in normal imaging mode (or after a fixed delay). Thus, if the balloon deflates or inflates after the "switch to normal loop mode" command, the user can visually track the movement of the target on real-time images.

[0030] Pressure regulation can be performed using at least two pumps, with at least one pump used as an infeed pump and at least one pump used as an outlet pump.

[0031] Alternatively, when Doppler imaging mode and / or elastography mode are activated, pressure regulation may resume upon reaching certain recovery conditions (using the same or different parameters in regular cycle mode) and / or stop again upon reaching a certain stopping condition. Possible recovery conditions include, but are not limited to, (i) triggering movement of the treatment head along any axis, (ii) triggering movement of the treatment head toward or away from the patient, (iii) the measured pressure value being higher or lower than a certain threshold relative to the current pressure setting (e.g., pressure setting ± 1 mBar), and (iv) assessment that the skin geometry has been deformed by an automatic detection algorithm or by user-activated dedicated controls such as buttons.

[0032] Under conditions (i) or (ii), the movement itself can be triggered at the same time, before, or after the "Restore Pressure Regulation" command is issued.

[0033] Preferably, the control unit is adapted to switch back from the temporary pressure control mode to the second cycle mode based on the stop condition.

[0034] Possible stopping conditions include, but are not limited to:

[0035] -(i) No movement is triggered and / or detected along any axis from a certain preset time period; (ii) No movement is triggered and / or detected towards or away from the patient from a certain time period; (iii) The pressure is within a preset range near the pressure setpoint; (iv) The pressure stabilizes within a certain time period (e.g., 0.5 seconds) (e.g., assessed by the standard deviation of motion); (v) In the case of pressure regulation using two pumps, the rates of the feed pump and the discharge pump are sufficiently close to each other for a certain time period as determined by the feedback loop, particularly 0.1 seconds to 10 seconds, more preferably 0.5 seconds to 3 seconds; (vi) The pressure feedback loop has been restored for more than a certain time period (e.g., 1 second), i.e., after a certain time period; or (vii) The user activates a dedicated input, such as a button.

[0036] If this solution is implemented, there should be no noticeable balloon inflation or deflation when exiting the second cycle mode. Therefore, in this case, the commands "Switch to Normal Imaging Mode" and "Switch to Normal Cycle Mode" can be sent simultaneously or not simultaneously.

[0037] In an alternative embodiment of the invention, instead of stopping fluid circulation, the flow rate of the liquid is reduced to a "low-speed level" when Doppler imaging is initiated. This achieves the maintenance of pressure regulation (albeit more slowly) while still reducing the artifacts formed. Alternatively, in this mode, the speed is constant to maintain cooling only, but pressure regulation is ineffective.

[0038] Preferably, the control unit is adapted to reduce the fluid velocity to a preset speed. In one embodiment, the "low speed level" is fixed. Alternatively, the user can manually set this speed based on the presence of artifacts. Preferably, the interface can eventually stop the pump if needed. Alternatively, based on the automatic detection of artifacts on the Doppler image, a change to a normal mode, and especially the flow rate, can be automatically or manually set.

[0039] Preferably, switching to a “low speed level” is performed as described above in the context of stopping and resuming pressure control, especially when switching to Doppler imaging mode and / or elastography mode.

[0040] Alternatively, when the color Doppler is activated, the "low level speed" can be stopped and started using the same stop and start conditions as when the pump is stopped and started.

[0041] The controller could, of course, be adapted to reduce or completely stop fluid circulation in the second circulation mode. For example, it is conceivable that when in the second circulation mode, the user could set the device to only reduce or stop fluid circulation. Alternatively, the device could be adapted to automatically adjust the second circulation mode.

[0042] The present invention also relates to a method of treating a patient with HIFU. The method includes the step of treating a target of the patient with HIFU pulses. In another step, fluid is circulated in a cavity between the treatment head and a contact surface of the device adapted to contact the patient's skin. In yet another step, the target is monitored using an imaging device temporarily operating in Doppler imaging mode and / or elastography mode, and during monitoring in Doppler imaging mode and / or elastography mode, fluid circulation is at least temporarily changed to Doppler imaging mode and / or elastography mode.

[0043] In a preferred embodiment, the method further includes a step of switching back to a normal circulation mode, which includes stopping or reducing at least one of the fluid circulation when the Doppler imaging mode and / or elastography mode are activated, so that the Doppler imaging mode and / or elastography mode are not activated unless a second circulation mode is also activated.

[0044] In a particularly preferred embodiment, the method further includes a step of switching back to a conventional cyclic mode, which includes starting the cycle or increasing the flow when the Doppler mode is stopped, so that the Doppler imaging mode and / or elastography mode are not activated unless a second cyclic mode is also activated.

[0045] In another preferred embodiment, an apparatus including a mode-B imaging device is employed. The method further includes the step of activating the mode-B imaging device when the Doppler imaging device is stopped and the normal mode of fluid circulation is resumed.

[0046] In another preferred embodiment, a treatment device comprising a balloon through which fluid is circulated. The method further includes a step of controlling fluid circulation to achieve a preset pressure within the balloon during a normal circulation pattern.

[0047] In a particularly preferred embodiment, the method further includes the step of restarting the conventional cyclic mode after a delay following the sending of the command to switch to the conventional imaging mode.

[0048] Preferably, the control unit is adapted to restart the conventional cyclic mode after the imaging device has switched to the conventional imaging mode and is operating in the conventional imaging mode. Specifically, the restart of the conventional cyclic mode may be based on receiving a signal from the imaging device indicating that the conventional imaging mode is operating normally.

[0049] In yet another preferred embodiment, the method also includes the step of temporarily changing to a pressure control mode and, in particular, a regular cyclic mode based on at least one of the following conditions: i) the treatment head moves along any axis, in particular toward or away from the patient; ii) the measured pressure value is higher or lower than a certain threshold relative to the current pressure setting; iii) the geometry of the skin is assessed to be deformed by an automatic detection algorithm; and / or iv) preferably, dedicated control is initiated by the user.

[0050] In a preferred embodiment, the method is performed by a device comprising at least two pumps.

[0051] In a particularly preferred embodiment, the method further includes a step of switching back from the temporary pressure control mode to the second cyclic mode based on at least one of the following conditions: i) no movement is detected along any axis from a preset time period, especially no movement toward or away from the patient; ii) the pressure is within a preset range near the pressure setpoint; iii) the pressure is sufficiently stable; iv) when pressure regulation is performed using two pumps, the rates of the feed pump and the discharge pump are sufficiently close to each other for a period of time, as determined by the feedback loop, particularly 0.1 to 10 seconds, or even more preferably 0.5 to 3 seconds; v) after a certain period of time; and / or vi) preferably initiated by a user-defined input.

[0052] In another preferred embodiment, the method further includes a step of reducing the fluid velocity in a second circulation mode. Preferably, the fluid velocity is reduced to a preset velocity. Additionally or alternatively, the fluid velocity is reduced to a user-defined velocity. Attached Figure Description

[0053] The invention will be described in detail below with reference to the following figures, which are shown in the figures:

[0054] Figure 1 This is a schematic diagram of the device according to the present invention;

[0055] Figures 2a-2e This is a schematic diagram illustrating the working principle of a preferred embodiment of the present invention;

[0056] Figure 3 A flowchart illustrating the relevant steps of the method according to the present invention is shown;

[0057] Figure 4This is a schematic diagram illustrating the overall concept of the present invention. Detailed Implementation

[0058] Figure 1 A device 1 is shown for treating a target T within a body part of a patient P using HIFU pulses. The device 1 includes a treatment head 3. The treatment head 3 is provided with a treatment transducer 5 and an imaging transducer 6. The treatment head is also provided with a cavity 7 for a fluid 9, which in this embodiment is in the form of a balloon 7. The balloon 7 consists of a membrane 8 capable of being filled with the fluid 9. The fluid 9 can be circulated 12 through the balloon via a pumping system 10, which is connected to the balloon 7 via an operative connector, such as a tube 11. The device also includes a control unit 20, which is operatively connected 21 to the treatment head 3 and controls the imaging transducer 6, the treatment transducer 5, and the pumping system 10.

[0059] Figure 2a The treatment head 3, in contact with the skin of the patient P, is schematically shown. The pump 10 is activated via the control unit 20, causing fluid 9 to circulate 12 within the balloon 7 placed in the treatment head 2. Figure 2a In the embodiment configuration shown, the device operates in mode B imaging. Figure 2b The diagram illustrates an intermediate state before switching to Doppler imaging mode and / or elastography mode, where pump 10 is shut off, causing fluid circulation within balloon 7 to cease. This corresponds to the second circulation mode of the pumping system, while imaging continues in mode B. Figure 2c The treatment head is shown after switching to Doppler imaging mode and / or elastography mode. Figure 2d The diagram shows an intermediate state when switching back to B-mode imaging, where the pumping system 10 keeps the pump off, resulting in no cycling but switching the imaging back to B-mode. Figure 2e The illustration schematically shows the treatment head after the pumping system 10 has been pumped following the restoration of mode B imaging.

[0060] Figure 3The method according to the invention is illustrated with the aid of a flowchart. In treatment step 31, conventional HIFU treatment is being performed, with the imaging device operating in conventional imaging mode. A command to switch modes can be issued using trigger step 41. As long as trigger 51 is not activated, the device images in conventional imaging mode and the pumping system is in conventional cyclic mode. If, in first step 32, the operator issues a command to switch to Doppler imaging mode and / or elastography mode 52, the pumping system is switched to a second cyclic mode. Typically, in the second cyclic mode, the pumping system shuts off the pump. However, the second cyclic system may also include reducing the pump flow instead of shutting it off. Once the pumping system is in the second cyclic mode, the imaging device is switched to Doppler imaging mode and / or elastography mode in another step of method 33. Once steps 32 and 33 have been performed, the device is ready to perform Doppler imaging 34 without artifacts. The user can use another trigger 42 to switch back to mode B. As long as trigger 53 is not activated, the device remains in the second cyclic mode. Once trigger 54 is activated, the imaging device is first switched back to conventional imaging mode in a step 35. Only after step 35 has been performed will the pumping system be switched back to normal circulation mode in another step 36 to restore fluid circulation. Returning to mode B allows treatment step 31 to resume, and the method can optionally be repeated.

[0061] Figure 4 The general concept of the invention is schematically illustrated by showing the on and off states of the pumping system modes (Doppler and conventional) and the imaging system modes (Doppler and B-mode). Initially, as described herein, the device (1) operates in B-mode imaging while the pumping system (10) is in conventional mode. At time t1, the user may decide to switch to Doppler imaging. The control unit (20) first switches the pumping system (10) to a second loop mode and only switches to Doppler imaging mode at time t2 once the second loop mode is established, resulting in a delay time Δt1. Similarly, if the user issues a command to switch back to B-mode imaging at time t3, the control unit (20) first switches the imaging device (6) back to conventional imaging mode, and after the imaging device (6) generates a real-time image in B-mode, at time t4, switches the pumping system back to conventional loop mode. This results in another delay time Δt2 and ensures that the pumping system never switches while in Doppler imaging mode but only in regular imaging mode, thus making motion visible in the image due to pressure changes in B mode.

Claims

1. A device (1) for treating a patient with high-intensity focused ultrasound, the device comprising: - Treatment head (3), which includes a high-intensity focused ultrasound emitting unit (5) for generating high-intensity focused ultrasound pulses, - An imaging probe suitable for operation in at least Doppler imaging mode and / or elastography mode, as well as conventional imaging mode. - A pump (10) for circulating (12) fluid (9) in the cavity between the treatment head (3) and the contact surface (8) of the device adapted to contact the skin of the patient (P). - A control unit (20) for controlling the operation of the imaging probe (6) and the pump (10), The control unit (20) is adapted to operate the fluid circulation (12) in at least a second circulation mode different from the conventional circulation mode, and to start or increase the fluid circulation (12) when the Doppler imaging mode and / or the elastography mode is deactivated, and to stop or decrease the fluid circulation (12) when the Doppler imaging mode and / or the elastography mode is activated.

2. The apparatus of claim 1, wherein the control unit (20) is adapted to switch to the conventional circulation mode when the Doppler imaging mode and / or the elastic imaging mode is deactivated, the conventional circulation mode including reactivating the fluid circulation or increasing the flow.

3. The device (1) according to any one of claims 1 to 2, wherein the treatment head (3) includes a balloon (7), the fluid (9) is circulated (12) through the balloon, and wherein the control unit (20) is adapted to control the fluid circulation (10) such that a preset pressure is reached within the balloon (7) during the normal circulation mode.

4. The apparatus (1) according to claim 3, wherein the control unit (20) is adapted to restart the conventional cyclic mode with a delay after sending a command to switch to the conventional imaging mode.

5. The apparatus (1) according to claim 3, wherein the control unit (20) is adapted to restart the conventional cyclic mode after the imaging probe has been switched to the conventional imaging mode and is operating in the conventional imaging mode.

6. The apparatus (1) according to claim 4 or 5, wherein the control unit (20) is adapted to temporarily switch to a pressure control mode based on at least one of the following recovery conditions: -The treatment head (3) moves along any axis; -The measured pressure value is higher or lower than a certain threshold relative to the current pressure setpoint; - An automatic detection algorithm assesses whether the skin's geometry has been deformed; -Start a dedicated control unit.

7. The apparatus of claim 6, wherein the control unit (20) is adapted to change back from the temporary pressure control mode to the second cycle mode based on at least one of the following conditions: - No motion was detected along any axis starting from a certain preset time period; - This pressure is within a preset range near the pressure setpoint; -The pressure is sufficiently stable; - In the case of using two pumps to perform pressure regulation, the rates of the feed pump and the discharge pump are sufficiently close to each other for a certain period of time, as determined by the feedback loop; -After a certain period of time; - A dedicated input for startup.

8. The apparatus of claim 1, wherein the control unit (20) is adapted to reduce the velocity of the fluid in the second circulation mode.

9. The apparatus according to claim 8, wherein the control unit (20) is adapted to reduce the velocity of the fluid (9) to a preset velocity.

10. The apparatus of claim 8 or 9, wherein the apparatus includes an interface that allows the velocity of the fluid (9) to be reduced to a user-defined velocity.

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