Ultrasound ocular imaging probe

Abstract

The invention relates to an ultrasound ocular imaging probe, comprising: - a transducer (2) which is configured to emit, from an emission surface, an ultrasound beam in a first direction (Z'); - a first support (6) carrying the transducer (2), the first support (6) being supported such that it can rotate about a second direction by a first pivot point (8); - a second support (12) carrying the first pivot point (8), the second support (12) being supported such that it can rotate about a third direction by a second pivot point (14); - a frame (20) which supports the second pivot point (14); wherein the first support (6) comprises a first magnet (10), and the second support (12) comprises a second magnet, the probe (1) comprising a first coil (30) which is configured to control the movement of the first magnet (10), and a second coil (40) which is configured to control the movement of the second magnet.

Description

[0001] Description

[0002] Ocular ultrasound imaging probe

[0003] technical field

[0004] The present invention belongs to the field of ocular imaging, and more specifically relates to three-dimensional ocular ultrasound imaging using an ultrasound probe.

[0005] State of the art

[0006] Ocular ultrasound is a method of examining the eye that uses the physical properties of ultrasound to allow an operator to visualize a representation of the eye. Ocular ultrasound is a non-invasive imaging technique that can quickly provide useful and easily obtainable information on certain typical eye lesions using general-purpose equipment. It is particularly useful when the cornea or certain intraocular media are opaque.

[0007] While two-dimensional representations have often been used, these can only depict a small portion of the eye and are therefore less effective than three-dimensional representations. Ultrasonic probes enabling three-dimensional acquisition, notably using arrays of transducer elements, have been developed for other applications, but these probes are not suitable for ocular imaging, being too bulky and offering resolutions too low for this purpose.

[0008] Indeed, ocular imaging has its own specific characteristics. In particular, the three-dimensional image must be acquired with high resolution and rapidly, within seconds, due to frequent eye movements. Furthermore, since the probe must be brought into contact with the eye, typically via an intermediate coupling medium such as a balanced salt solution (BSS) and / or an ophthalmic gel, the probe must be compact and lightweight. Presentation of the invention

[0009] The invention aims to provide an ocular ultrasound imaging probe that allows for the rapid acquisition of a three-dimensional representation of a part of an eye, while remaining compact.

[0010] For this purpose, an ocular ultrasound imaging probe is proposed, comprising:

[0011] - an ultrasonic transducer configured to emit an ultrasound beam from an emitting surface in a first direction and to receive ultrasound;

[0012] - a first support carrying the transducer, the first support being mobile in rotation around a second direction by a first pivot;

[0013] - a second support carrying the first pivot, the second support being carried mobile in rotation around a third direction by a second pivot;

[0014] - a chassis carrying the second pivot; in which the first support includes a first magnet, and the second support includes a second magnet, the probe comprising a first winding configured to control the movement of the first magnet of the first support and a second winding configured to control the movement of the second magnet of the second support.

[0015] The invention is advantageously complemented by the following features, taken alone or in any technically feasible combination thereof:

[0016] - the second support has a second two-element magnet located on either side of the second pivot;

[0017] - the first magnet is located at a second end of the first support opposite a first end carrying the ultrasonic transducer;

[0018] - the first magnet comprises two magnet elements arranged at the second end;

[0019] - the probe further includes at least one position sensor configured to acquire measurements representative of an evolution of the position of the transducer caused by the first magnet and / or the second magnet;

[0020] - at least one position sensor is a magnetic field sensor configured to measure a change in magnetic field caused by the first magnet and / or by the second magnet.

[0021] The invention also relates to an ocular ultrasound imaging system comprising:

[0022] - an ultrasonic imaging probe as previously described; - a power supply device for the coils;

[0023] - a processor configured to control an electrical flow in the windings that causes a displacement of the first support and the second support.

[0024] Preferably, the processor is configured to guide a two-dimensional trajectory, inscribed within a portion of an ellipsoid defining a displacement surface, to a center of the emission surface using the displacements of the first and second supports. Preferably, the trajectory does not intersect any points as it traverses the displacement surface. Measurement points along the trajectory, where the probe is configured to emit an ultrasound beam, are preferably uniformly distributed across the displacement surface.

[0025] Presentation of the figures

[0026] The invention will be better understood from the following description, which relates to embodiments and variants of the present invention, given by way of non-limiting examples and explained with reference to the accompanying schematic drawings, in which:

[0027] - Figure 1 is a cross-sectional view of an example of a probe according to one possible embodiment of the invention;

[0028] - Figure 2 shows a first support and a second support of an example of a probe according to a possible embodiment of the invention;

[0029] - Figure 3 shows the second support and pivots of an example of a probe according to one possible embodiment of the invention;

[0030] - Figure 4a shows an example of a trajectory formed by lines distributed according to an angular step;

[0031] - Figure 4b shows an example of a spiral trajectory; and

[0032] - Figure 4c shows an example of a trajectory with triangular movements.

[0033] Detailed description

[0034] With reference to Figures 1, 2, and 3, the ocular ultrasound imaging probe 1 extends along a longitudinal direction Z. Hereafter, radial denotes a direction perpendicular to this longitudinal direction Z. The ocular ultrasound imaging probe 1 includes an ultrasonic transducer 2 configured to emit an ultrasound beam from an emitting surface in an emitting direction constituting a first direction Z' and to receive ultrasound. The ultrasonic transducer 2 may be a single element, or it may comprise several elements, typically fewer than 10 elements and preferably 5 elements or fewer, for example, arranged in a circular geometry exhibiting rotational symmetry on the emitting surface 4. For example, concentric rings may be used as transducer elements.Ultrasonic transducer 2 is for example of type 15 MHz (single-element) or 20 MHz (5 rings), and for example is a piezoelectric transducer.

[0035] As an example, the emitting surface of ultrasonic transducer 2 extends over a diameter of 2 to 20 mm, and preferably from 4 to 12 mm. Ultrasonic transducer 2 is configured to emit ultrasound in a frequency range of 5 to 100 MHz, and preferably from 12 to 50 MHz.

[0036] The probe 1 also includes a first support 6 carrying the transducer 2. The first support 6 is rotatable about a second direction Y by a first pivot 8. The first support 6 includes a first magnet 10. The first support 6 extends in the first direction Z' between a first end and a second end. The first magnet 10 is preferably located at one end of the first support 6, while the transducer 2 is located at the other end. The first pivot 8 extends between the transducer 2 and the first magnet 10 in the direction of the second direction Y, which is transverse to the first direction Z'. The first pivot 8 extends on both sides of the first support 6.

[0037] The first magnet 10 is configured to follow a two-dimensional path inscribed within a portion of a sphere. Therefore, the first magnet 10 can ideally have a shape that conforms to a portion of the sphere. However, obtaining such a first magnet 10 can be difficult and expensive. It is then possible, as in the illustrated example, for the first magnet 10 to be composed of one or more magnet elements 10a, 10b, the whole forming a single magnet. The faces of the magnet elements 10a, 10b should preferably have reversed or opposite poles. In the illustrated example, for one magnet element 10a, the south pole is closer to the pivot 8 than its north pole, while for the other magnet element 10b, the north pole is closer to the pivot 8 than its south pole.

[0038] In the illustrated example, the first magnet 10 consists of two magnet elements 10a, 10b, which are cylindrical but could be of another shape, such as a rectangular prism or partially spherical. These two magnet elements 10a, 10b each extend along a respective direction of extension, which is perpendicular to the second direction Y and intersects the first pivot 8. Preferably, these two different directions of extension lie in the same plane perpendicular to the first direction Y. The two directions of extension have the same angular separation from the first direction Z', which is, for example, between 1 and 50°, and preferably between 15 and 30°. When several magnet elements 10a, 10b are present, they are angularly distributed around the first direction Z', and their respective directions of extension are preferably the same with respect to the first direction Z'.Thus, during the rotation of the first support 6 around the second direction Y, the magnet elements 10a, 10b travel a greater amplitude over the portion of the sphere.

[0039] The first pivot 8 is supported by a second support 12, which is made mobile in rotation around a third direction X by a second pivot 14. The second support 12 surrounds the first support 6 which passes through the second support 12 at the level of a central opening 16 made in the second support 12. The first pivot 8 passes through this central opening 16, typically in the middle of this central opening, in the second direction Y.

[0040] The second support 12 includes a second magnet 18, preferably located on an outer periphery opposite the central opening 16 in the second Y direction. Preferably, the second magnet 18 extends over at least 50% of a perimeter of a plane of the second support 12 passing through the third X direction, and preferably over at least 70%. The second magnet 18 may consist of two elements 18a, 18b located on either side of the second pivot 14. This arrangement maximizes the resulting torque.

[0041] The second magnet 18 thus preferably comprises a first element 18a of a second magnet 18 and a second element 18b of a second magnet 18, arranged on the outer periphery of the second support 12 in opposite positions on either side of the central opening 16. Each element 18a, 18b of the second magnet 18 can be made up of a whole magnet, with a south pole and a north pole. In this case, the poles of one magnet element 18a, 18b are opposite to the poles of the other magnet element 18a, 18b of the second magnet 18. Thus, by traversing the periphery of the second support 12, one finds successively a north pole of a first element 18a of the second magnet 18, a south pole of the first element 18a of the second magnet 18, a north pole of a second element 18b of the second magnet 18, a south pole of the second element 18b of the second magnet 18. Alternatively, the second magnet 18 can be of a single piece, whose poles are located on either side of the second axis 14, on the periphery of the second support 12.For example, such a second monobloc magnet 18 can pass through the first pivot 8.

[0042] The second pivot 14 is supported by a frame 20 defining an interior space 22 in which the first support 6 and the second support 12 are housed at least in part.

[0043] As illustrated in Figure 1, the probe also includes a first winding 30 configured to control the movement of the first magnet of the first support 6. The first winding 30 is supplied with a power supply, and the current flowing through the first winding 30, interacting with the magnet 10, generates a force acting on the magnet. Since the first support 6 is mounted to rotate about the second direction Y, the force acting on the first magnet 10 results in a rotation of the first support 6 about the first pivot 8, and therefore a similar rotation of the transducer 2 about the second direction Y. The emitting surface of the transducer 2 is thus displaced, and the first direction Z', which constitutes the direction of emission of the ultrasound beam, is therefore angularly displaced with the same angular amplitude as the rotation of the first support 6 about the first pivot 8.Thus, depending on the current flowing in the first winding 30, it is possible to adjust the angular position of the ultrasound beam around the second direction Y.

[0044] The first winding 30 is wound around the longitudinal direction Z, outside the frame 20, such that at least one plane perpendicular to the longitudinal direction Z intersects the first winding 30 and the first magnet 10. Preferably, the frame 20 includes cavities 24 accommodating the first winding 30, in order to limit the obstacles between the first winding 30 and the first magnet 10.

[0045] The probe 1 also includes a second winding 40 configured to control the movement of the second magnet 18 of the second support 12. Preferably, the second winding 40 extends around the longitudinal direction Z and is parallel to the first winding 30. The second winding 40 is supplied with a power supply, and the current flowing through the second winding 40, interacting with the magnet 18, generates a force acting on the magnet. Since the second support 12 is mounted to rotate about the third direction X, the force acting on the second magnet 18 results in a rotation of the second support 18 about the second pivot 14, relative to the frame 20 carrying the second pivot 14. This results in a rotation of the first support 6 of the same angular amplitude about the third direction X, and therefore a similar rotation of the transducer 2 about the third direction X.The emitting surface of transducer 2 is therefore displaced, and the first direction Z', constituting the emission direction of the ultrasound beam, is thus angularly displaced with the same angular amplitude. Therefore, depending on the current flowing in the second winding 40, it is possible to adjust the angular position of the ultrasound beam around the third direction X.

[0046] It should be noted that since the first pivot 8 is supported by the second support 12, the second direction Y is itself modified by the rotation of the second support 12 around the third direction X. The rotation of the second direction Y is however perpendicular to the third direction X.

[0047] The second winding 40 is wound around the longitudinal direction Z, outside the frame 20, such that at least one plane perpendicular to the longitudinal direction Z intersects the second winding 40 and the second magnet 18. Preferably, the frame 20 includes cavities 26 accommodating the second winding 40, in order to limit the obstacles between the second winding 40 and the second magnet 18.

[0048] To allow regulation of the angular positions of the ultrasound beam around the second Y direction and the third X direction, the probe 1 includes at least one position sensor 50, 52 configured to acquire measurements representative of a change in the position of the transducer caused by the first magnet and / or the second magnet. Preferably, a first position sensor 50 is configured to acquire measurements representative of a change in the position of the first magnet carried by the first support 6, and a second position sensor 52 is configured to acquire measurements representative of a change in the position of the second magnet carried by the second support 8. The measurements taken by the position sensors 50, 52 allow the position of the transducer 2 to be determined.

[0049] Preferably, the first position sensor 50 is mounted on the frame 20 and is located outside of said frame 20, i.e., outside the internal space 22. Preferably, the first position sensor 50 extends radially outside the first winding 30. Preferably, the probe 1 comprises at least three first sensors 50, and preferably at least four first sensors 50. Preferably, at least two first sensors 50 are angularly spaced at least 70° apart about the longitudinal direction Z, and preferably at least three first sensors 50 are angularly spaced at least 70° apart. The first position sensor 50 is, for example, implemented by one or more magnetic Hall effect position sensors, preferably four in number.

[0050] Preferably, the second position sensor 52 is mounted on the chassis 20 and is located outside of said chassis 20, i.e., outside the internal space 22. Preferably, the second sensor 52 extends radially outside the second winding 40. The second sensor 52 is, for example, implemented by one or more magnetic Hall effect position sensors, preferably three in number. Preferably, at least two second magnetic sensors 50 are angularly spaced at least 70° apart about the longitudinal direction Z, and preferably at least three second magnetic sensors 50 are angularly spaced at least 70° apart.

[0051] All of these sensors can be replaced by a magnetometer type sensor 51, at least biaxial, which then constitutes the position sensor configured to acquire measurements representative of an evolution of the position of the transducer caused by the first magnet and / or the second magnet.

[0052] The probe 1 is part of an ocular ultrasound imaging system further comprising a winding power supply and a processor configured to control an electrical current in the windings 30, 40 to cause a displacement of the first support 6 and the second support 12. Typically, the processor receives a measurement position command corresponding to the location where the ultrasound beam is to be emitted, and measurements from the magnetic sensors 50, 52. From this data, the processor determines the current to be circulated in the windings 30, 40 to modify the position of the magnets 10, 18, and thus the rotation of the first support 6 and the second support 12. Preferably, the processor is also configured to control the transducer 2 to emit the ultrasound, typically as soon as the measurement position is reached.The ultrasound received by the transducer 2 is converted by it into a measurement signal corresponding to the measurement position, which reports a measurement in Taxe of the first direction Z' for this measurement position.

[0053] As mentioned above, the proposed probe 1 allows the direction of the emitted ultrasound beam to be modified along two axes of rotation, thus enabling the emitting surface to scan an entire two-dimensional area. This results in the ability to scan the observation space of an eye, allowing for a three-dimensional representation of the eye. Since the movement is achieved through coils 30, 40 interacting with magnets 10, 18, very rapid, smooth, and highly precise movements are possible. Preferably, the ultrasound measurement for the three-dimensional representation of an eye includes measurement signals for at least 5,000 different measurement positions, and preferably for at least 30,000 different measurement positions, obtained in less than 10 seconds, preferably 5 seconds or less.

[0054] The processor is thus configured to guide a center of the emission surface, defining a measurement position, along a two-dimensional trajectory inscribed within a portion of a sphere, designated as the displacement surface, by means of the displacements of the first support 6 and the second support 12. The imaged space extends in the form of a truncated cone from this displacement surface.

[0055] To ensure that the ultrasound beams effectively cover the measurement space, different strategies for traversing the measurement positions can be adopted. For example, as illustrated in Figure 4a, it is possible to traverse measurement positions aligned along a line before traversing another line of measurement positions that is angularly offset from the first. However, this approach is not optimal, as it leads to an overrepresentation of measurement positions where the lines meet, typically at the center of the measurement position travel area. To avoid this bias, a possible decrease in the density of measurement positions along the trajectory as the path intersects can be considered, although this would involve longer travel times and a reduction in the number of measurement positions reachable within a given time.It is preferable to adopt a movement strategy in which the path between measurement points does not intersect itself, and ideally in which the measurement points are evenly distributed across the movement surface. In the example in Figure 4b, a spiral path, preferably with regular spacing between the spirals, maximizes movement efficiency and thus the number of measurement points in a given time. Other approaches can be used, as in the example in Figure 4c, where the path consists of a series of broken lines.

[0056] As shown in Figure 1, a cover 60 attached to the chassis 20 can close the internal space 22 and cover the transducer 2 to protect and seal it. In addition, an external enclosure can be provided, for example, a housing 62 extending around the probe 1.

[0057] The invention is not limited to the embodiment described and shown in the accompanying figures. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Demands 1. Ocular ultrasound imaging probe (1), comprising: - an ultrasonic transducer (2) configured to emit from an emitting surface an ultrasonic beam in a first direction (Z') and to receive ultrasound; - a first support (6) carrying the transducer (2), the first support (6) being carried mobile in rotation around a second direction (Y) by a first pivot (8); - a second support (12) carrying the first pivot (8), the second support (12) being carried mobile in rotation around a third direction (X) by a second pivot (14); - a chassis (20) carrying the second pivot (14); in which the first support (6) includes a first magnet (10), and the second support (12) includes a second magnet (18), the probe (1) including a first winding (30) configured to control the movement of the first magnet (10) of the first support (6) and a second winding (40) configured to control the movement of the second magnet (18) of the second support (12).

2. Imaging probe according to claim 1, wherein the second support (12) has a second magnet (18) with two elements (18a, 18b) located on either side of the second pivot (14).

3. Imaging probe according to any one of claims 1 and 2, wherein the first magnet (10) is located at a second end of the first support (6) opposite a first end carrying the ultrasonic transducer (2).

4. Imaging probe according to any one of claims 1 to 3, wherein the first magnet comprises two magnet elements (10a, 10b) arranged at the second end.

5. Imaging probe according to any one of claims 1 to 4, further comprising at least one position sensor (50, 51, 52) configured to acquire measurements representative of an evolution of the position of the transducer (2) caused by the first magnet and / or the second magnet.

6. Imaging probe according to claim 5, wherein at least one position sensor (50, 51, 52) is a magnetic field sensor configured to measure a variation in magnetic field caused by the first magnet and / or by the second magnet.

7. Ocular ultrasound imaging system comprising: - an ultrasonic imaging probe (1) according to any one of claims 1 to 6; - a device for supplying electrical power to the windings; - a processor configured to control an electrical flow in the windings that causes a displacement of the first support and the second support.

8. Imaging system according to claim 7, wherein the processor is configured to cause a center of the emission surface to travel, by means of the displacements of the first support (6) and the second support (12), a two-dimensional trajectory inscribed in a portion of an ellipsoid defining a displacement surface.

9. Imaging system according to claim 8, wherein the trajectory does not exhibit any intersecting when traversing the displacement surface.

10. Imaging system according to any one of claims 8 and 9, wherein measurement points along the trajectory where the probe is configured to emit an ultrasound beam are uniformly distributed over the displacement surface.

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