阅读说明：本技术 相对于超声图像平面跟踪介入设备 (Tracking an interventional device relative to an ultrasound image plane ) 是由 M·梅珍斯 H·R·施塔伯特 M·H·戈库尔勒尔 S·范德帕斯 J·科特斯米特 F·H·范 于 2019-08-02 设计创作，主要内容包括：一种用于确定介入设备(11)相对于由超声成像探头(13)限定的图像平面(12)的位置的系统(10)。所述位置是基于在所述超声成像探头(13)与被附接到所述介入设备(11)的超声换能器(15)之间传输的超声信号来确定的。图像重建单元(IRU)提供重建超声图像(RUI)。位置确定单元(PDU)基于最大检测强度(I-(Smax))超声信号的飞行时间(TOF-(Smax))来计算所述超声换能器(15)相对于所述图像平面(12)的横向位置(LAP-(TOFSmax,θIPA))。所述位置确定单元(PDU)还计算所述超声换能器(15)与所述图像平面(12)之间的平面外距离(D-(op))。计算所述平面外距离(D-(op))涉及将所述最大检测强度(I-(Smax))与描述平面内最大检测强度(I-(SmaxInplane))随飞行时间的预期变化的模型(MO)进行比较。(A system (10) for determining a position of an interventional device (11) relative to an image plane (12) defined by an ultrasound imaging probe (13). The position is determined based on an ultrasound signal transmitted between the ultrasound imaging probe (13) and an ultrasound transducer (15) attached to the interventional device (11). An Image Reconstruction Unit (IRU) provides a Reconstructed Ultrasound Image (RUI). Position Determination Unit (PDU)) Based on maximum intensity of detection (I) Smax ) Time of flight (TOF) of ultrasonic signals Smax ) To calculate a lateral position (LAP) of the ultrasound transducer (15) relative to the image plane (12) TOFSmax,θIPA ). The Position Determination Unit (PDU) further calculates an out-of-plane distance (D) between the ultrasound transducer (15) and the image plane (12) op ). Calculating the out-of-plane distance (D) op ) Involving the maximum detection intensity (I) Smax ) And describing the maximum in-plane detection intensity (I) SmaxInplane ) The Model (MO) of the expected variation with time of flight is compared.)

1. A system (10) for determining a position of an interventional device (11) relative to an image plane (12) defined by an ultrasound imaging probe (13) of a beamforming ultrasound imaging system (14), wherein the position of the interventional device (11) is determined based on ultrasound signals transmitted between the ultrasound imaging probe (13) and an ultrasound transducer (15) attached to the interventional device (11), the system (10) comprising:

an Image Reconstruction Unit (IRU) configured to provide a Reconstructed Ultrasound Image (RUI) corresponding to an image plane (12) defined by the ultrasound imaging probe (13);

a Position Determination Unit (PDU) configured to:

based on a maximum detected intensity (I) transmitted between the ultrasound imaging probe (13) and the ultrasound transducer (15)_Smax) Time of flight (TOF) of ultrasonic signals_Smax) To calculate the ultrasonic transducer (15) relativeAt a lateral position (LAP) of the image plane (12)_{TOFSmax,θIPA})；

Intensity (I) of the ultrasonic signal based on the maximum detected intensity_Smax) And said time of flight (TOF)_Smax) To calculate an out-of-plane distance (D) between the ultrasound transducer (15) and the image plane (12)_op) (ii) a Wherein the out-of-plane distance (D) is calculated_op) Including the maximum detection intensity (I)_Smax) And is described in said maximum detection intensity (I)_Smax) The time of flight (TOF) of an ultrasonic signal_Smax) In-plane maximum detected intensity (I)_SmaxInplane) Comparing the Models (MO) of expected variation with time of flight; and is

Indicating the out-of-plane distance (D) in the Reconstructed Ultrasound Image (RUI)_op)。

2. The system (10) according to claim 1, wherein the out-of-plane distance (D) is indicated_op) Including in the calculated transverse position (LAP)_{TOFSmax,θIPA}) Providing a first icon (C)_op) The first icon (C)_op) Indicating having an out-of-plane distance (D)_op) A circular area of corresponding radius.

3. The system (10) according to claim 2, wherein the radius is based on basing the maximum detected intensity (I)_Smax) Scaled to the maximum detection intensity (I)_Smax) The time of flight (TOF) of an ultrasonic signal_Smax) Expected in-plane maximum detected intensity (I)_SmaxInplane) To be determined.

4. The system (10) according to claim 2 or claim 3, wherein the first icon (C)_op) Comprises a perimeter, and wherein the first icon (C)_op) Is configured to be based on the maximum detected intensity (I)_Smax) At said maximum detection intensity (I)_Smax) The time of flight (TOF) of an ultrasonic signal_Smax) At said expected in-plane maximum detected intensity (I)_SmaxInplane) Is changed; the first icon (C)_op) Is configured to: if I) the maximum detection intensity (I)_Smax) At said maximum detection intensity (I)_Smax) The time of flight (TOF) of an ultrasonic signal_Smax) At said expected in-plane maximum detected intensity (I)_SmaxInplane) Or ii) the maximum detected intensity (I)_Smax) Within a predetermined range, by at least one of:

changing the first icon (C)_op) The color of the perimeter of (a);

changing the first icon (C)_op) The contrast of the perimeter of (a);

indicating the first icon (C) with a dot or a dashed line_op) The perimeter of (a);

making the first icon (C)_op) Is pulsed over time.

5. The system (10) according to any one of claims 2-4, wherein the radius has a minimum value, and wherein the position determination unit is further configured to: if I) the maximum detection intensity (I)_Smax) At said maximum detection intensity (I)_Smax) The time of flight (TOF) of an ultrasonic signal_Smax) At said expected in-plane maximum detected intensity (I)_SmaxInplane) Or ii) the maximum detected intensity (I)_Smax) Exceeding a predetermined value, the radius is limited to the minimum value.

6. The system (10) according to any one of claims 2-5, wherein the Position Determination Unit (PDU) is further configured to: if I) the maximum detection intensity (I)_Smax) At said maximum detection intensity (I)_Smax) The time of flight (TOF) of an ultrasonic signal_Smax) At said expected in-plane maximum detected intensity (I)_SmaxInplane) Or ii) the maximum detected intensity (I)_Smax) Below a predetermined value, the provision of said first icon (C) in said Reconstructed Ultrasound Image (RUI) is inhibited_op)。

7. The system (10) according to claim 2, wherein the interventional device (11) includes a feature (11a), and wherein the ultrasound transducer (15) is at a predetermined distance (L) from the interventional device feature (11a)_p) Is attached to the interventional device (11); and is

Wherein the Position Determination Unit (PDU) is further configured to provide a second icon (C) in the Reconstructed Ultrasound Image (RUI)_de) Said second icon (C)_de) Indicating that there is the predetermined distance (L) from the ultrasound transducer (15) and the interventional device feature (11a)_p) A circular region of corresponding radius; and is

Wherein the first icon (C)_op) And the second icon (C)_de) Sharing a common center.

8. The system (10) according to claim 1, wherein the second icon (C)_de) Defining a portion of the image plane (12) corresponding to a range of possible positions of the interventional device feature (11 a).

9. The system (10) according to any one of claims 7-8, wherein the interventional device feature (11a) is one of:

a distal end of the interventional device (11);

an opening of a channel in the interventional device (11);

a biopsy sampling point of the interventional device (11);

an incision edge of the interventional device (11);

a sensor of the interventional device (11);

a surgical tool integrated in the interventional device (11);

a drug delivery point of the interventional device (11);

an energy delivery point of the interventional device (11).

10. According to any one of claims 7-9The system (10) of (1), wherein the Position Determination Unit (PDU) is further configured to determine when the out-of-plane distance (D)_op) Less than or equal to said predetermined distance (L)_p) Time-shift the first icon (C)_op) And the second icon (C)_de) The appearance of at least one of the same.

11. The system (10) according to claim 10, wherein the first icon (C)_op) And the second icon (C)_de) Each having a perimeter, and wherein the first icon (C)_op) And the second icon (C)_de) Is configured to be changed by at least one of:

changing the first icon (C)_op) Or the second icon (C)_de) The color of the perimeter of;

changing the first icon (C)_op) Or the second icon (C)_de) The contrast of the perimeter of (a);

indicating the first icon (C) with a dot or a dashed line_op) Or the second icon (C)_de) A perimeter of;

making the first icon (C)_op) Or the second icon (C)_de) The perimeter of (a) pulsates over time;

making the first icon (C)_op) And the second icon (C)_de) Merging into a common icon;

disabling the provision of said first icon (C) in a Reconstructed Ultrasound Image (RUI)_op) Or the second icon (C)_de)。

12. The system (10) according to any one of claims 6-11, wherein the first icon (C)_op) Is equal to the second icon (C)_de) And wherein when the out-of-plane distance (D)_op) Less than or equal to said predetermined distance (L)_p) When the first icon (C) is displayed_op) Is limited to said minimum value.

13. The system (10) according to any preceding claim, further comprising an interventional device (11) having an ultrasound transducer (15) attached thereto.

14. A method of determining a position of an interventional device (11) relative to an image plane (12) defined by an ultrasound imaging probe (13) of a beamforming ultrasound imaging system (14), wherein the position of the interventional device (11) is determined based on ultrasound signals transmitted between the ultrasound imaging probe (13) and an ultrasound transducer (15) attached to the interventional device (11); the method comprises the following steps:

generating (GENRUI) a Reconstructed Ultrasound Image (RUI) corresponding to an image plane (12) defined by the ultrasound imaging probe (13);

based on the maximum detected intensity (I) at the ultrasound imaging probe (13)_Smax) Of the ultrasonic transducers (15) is transmitted with a maximum detection intensity (I)_Smax) Time of flight (TOF) of ultrasonic signals_Smax) To Calculate (CLP) a lateral position (LAP) of the ultrasound transducer (15) relative to the image plane (12)_{TOFSmax,θIPA})；

Intensity (I) of the ultrasonic signal based on the maximum detected intensity_Smax) And said time of flight (TOF)_Smax) To Calculate (CDOP) an out-of-plane distance (D) between the ultrasound transducer (15) and the image plane (12)_op) (ii) a Wherein calculating the out-of-plane distance comprises comparing the maximum detected intensity (I)_Smax) And is described in said maximum detection intensity (I)_Smax) The time of flight (TOF) of an ultrasonic signal_Smax) In-plane maximum detected intensity (I)_SmaxInplane) Comparing the models of expected variation with time of flight; and is

Indicating (INDOPO) the out-of-plane distance (D) in the Reconstructed Ultrasound Image (RUI)_op)。

15. A computer program product comprising instructions which, when run on a processor of a system (10) for determining a position of an interventional device (11) relative to an image plane (12) defined by an ultrasound imaging probe (13) of a beamforming ultrasound imaging system (14), wherein the position of the interventional device (11) is determined based on ultrasound signals transmitted between the ultrasound imaging probe (13) and an ultrasound transducer (15) attached to the interventional device (11), cause the processor to perform the steps of the method according to claim 14.

Technical Field

The invention relates to determining a position of an interventional device relative to an image plane of a beamforming ultrasound imaging probe.

Background

Because the reflections of interventional devices such as medical needles, catheters and surgical tools are of a specular nature, particularly at unfavorable angles of incidence, it is often difficult to visualize these interventional devices in ultrasound images.

In this respect, documents WO 2011138698 a1, WO 2015101949 a1 and WO 2016009350 a1 describe systems for tracking an instrument in an ultrasound field with an ultrasound receiver mounted to the instrument. The position of the ultrasound receiver is then displayed in an ultrasound image corresponding to the ultrasound field.

Document US 2016/038119 a1 relates to an ultrasound system comprising an ultrasound unit comprising: an ultrasound probe for acquiring an anatomical image of a human body and for positioning a medical instrument relative to the image, the ultrasound probe comprising a first set of imaging transducer elements and a second set of positioning transducer elements, wherein the first set of imaging transducer elements is different from and non-intersecting with the second set of positioning transducer elements, and a sensor console, wherein: the first set of imaging transducer elements is configured to: generating ultrasound imaging emissions into the human body, wherein the ultrasound imaging emissions are focused into an image scan plane and reflections of the ultrasound imaging emissions are received for generating a two-dimensional anatomical image corresponding to the image scan plane; and wherein the second set of positioning transducer elements is configured to generate ultrasound positioning transmissions into the human body for positioning the medical instrument relative to the anatomical image, wherein the ultrasound positioning transmissions extend out of the image scan plane, and wherein at least two transducer elements from the second set are spaced apart from each other in a direction perpendicular to the image scan plane; the sensor console is used for receiving signals corresponding to positioning emission from the transducer; wherein the ultrasound system is configured to process the received signals to determine a position of the medical instrument within the human body relative to the ultrasound probe based on the received signals.

Another document, US 2017/202625 a1, relates to a system for tracking instruments. The system includes two or more sensors disposed along a length of the instrument and spaced apart from adjacent sensors. The interpretation module is configured to select and update image slices from the three-dimensional image volume according to the positions of the two or more sensors. The three-dimensional image volume includes the positions of two or more sensors relative to a target in the volume. The image processing module is configured to generate an overlay indicative of a reference position in the image slice. The reference position includes the position of the two or more sensors and the relative offset from the image slice in the display to provide feedback information for the positioning and orientation of the instrument.

However, when the ultrasound receiver in such a system is located outside the image plane (i.e. is "out-of-plane"), it may be difficult to determine the position of the ultrasound receiver and ultimately the interventional device.

In this respect, document WO 2018060499 a1 describes a system for indicating a position of an interventional device feature of an interventional device relative to an image plane defined by an ultrasound imaging probe of a beamforming ultrasound imaging system, wherein the position of the interventional device feature is determined based on ultrasound signals transmitted between the ultrasound imaging probe and an ultrasound transducer attached to the interventional device at a predetermined distance from the interventional device feature. The icon providing unit provides a first icon indicating a circular area having a radius corresponding to a predetermined distance. The first icon is displayed in a fused image that includes a reconstructed ultrasound image from the beamforming ultrasound imaging system. In this document, the change in signal strength and the out-of-plane distance D for a determined range are based on_opTo calculate the out-of-plane distance.

Despite these solutions, there is room for improvement in techniques for determining the position of an interventional device relative to an ultrasound imaging plane.

Disclosure of Invention

In seeking to provide improved tracking of an interventional device, a system for determining a position of an interventional device relative to an image plane defined by an ultrasound imaging probe of a beamforming ultrasound imaging system is provided, wherein the position of the interventional device is determined based on ultrasound signals transmitted between the ultrasound imaging probe and an ultrasound transducer attached to the interventional device. The system comprises an image reconstruction unit and a position determination unit. The image reconstruction unit provides a reconstructed ultrasound image corresponding to an image plane defined by the ultrasound imaging probe. The position determination unit calculates a lateral position of the ultrasound transducer relative to the image plane based on a time of flight of a maximum detected intensity ultrasound signal transmitted between the ultrasound imaging probe and the ultrasound transducer. The position determination unit further calculates an out-of-plane distance between the ultrasound transducer and the image plane based on the intensity of the maximum detected intensity ultrasound signal and the time of flight. Calculating the out-of-plane distance includes comparing the maximum detected intensity to a model describing an expected variation of in-plane maximum detected intensity with time of flight at a time of flight of the maximum detected intensity ultrasound signal. The position determination unit then indicates the out-of-plane distance in the reconstructed ultrasound image.

Thus, the model used to calculate the out-of-plane distance describes the expected variation of the in-plane maximum detected intensity with time of flight. In-plane detection intensities may exhibit low variability between different ultrasound imaging probes, and therefore the same model may be used for the same type of ultrasound imaging probe. Furthermore, the model requires only one-dimensional calibration data (i.e. intensity versus time of flight), which requires only a limited amount of calibration data. Furthermore, since the search only needs to be done in one dimension (i.e. time of flight), the out-of-plane distance can be determined in use with low delay.

According to one aspect, indicating the out-of-plane distance includes providing a first icon at the calculated lateral position, the first icon indicating a circular region having a radius corresponding to the out-of-plane distance. Using an icon with a circular region indicating an out-of-plane distance at the calculated position intuitively indicates to the user whether the interventional device is advancing towards or retreating away from the image plane based on whether the circle is increasing or decreasing. This allows for an improved guidance of the interventional device.

According to another aspect, the radius is determined based on scaling the maximum detected intensity to an expected in-plane maximum detected intensity at the time of flight of the maximum detected intensity ultrasound signal. With out-of-plane distance D_opThe maximum detection intensity is usually reduced. However, this property of variation with out-of-plane distanceThe quality may depend on the time of flight; in other words, the range between the ultrasound imaging probe and the ultrasound detector. Determining the radius based on scaling the maximum detected intensity to the expected in-plane maximum detected intensity achieves a qualitative indication of the out-of-plane distance. Such an indication provides the user with sufficient feedback for the user to accurately navigate the interventional device to the image plane and does not require full three-dimensional calibration data that might otherwise be required to be used to determine the exact out-of-plane distance and the delay associated with searching such three-dimensional data to determine the out-of-plane distance.

According to another aspect, the first icon includes a perimeter. The appearance of the first icon is configured to: change based on a comparison of the maximum detected intensity with the expected in-plane maximum detected intensity at the time of flight of the maximum detected intensity ultrasound signal if i) a ratio of the maximum detected intensity to the expected in-plane maximum detected intensity at the time of flight of the maximum detected intensity ultrasound signal or ii) the maximum detected intensity is within a predetermined range. Changing the appearance of the perimeter has the effect of indicating to the user the position of the interventional device at the predetermined position relative to the imaging plane. This feature allows a quick indication of the general position of the interventional device relative to the imaging plane to the user. For example, the icon may be green in color when the maximum detected intensity or a ratio thereof indicates a value close to the expected in-plane maximum detected intensity; and for values within the contiguous range, the color of the icon may be red; and for positions outside this range the color of the icon may be white. This quickly indicates to the user whether the interventional device is currently in-plane or not.

According to another aspect, the radius corresponding to the out-of-plane distance has a minimum value. The position determination unit limits the radius to the minimum value if i) a ratio of the maximum detected intensity to the expected in-plane maximum detected intensity at the time of flight of the maximum detected intensity ultrasound signal or ii) the maximum detected intensity exceeds a predetermined value. The user is typically interested in the process of positioning the interventional device in the imaging plane; thus, in this embodiment, the icon may change, for example, when it is just within a predetermined range in the imaging plane. In this way, the user may relax their attention to some extent when the interventional device is positioned sufficiently well. This avoids the user constantly fine-tuning the position of the interventional device, thereby focusing them on other tasks.

According to another aspect, the position determination unit inhibits the provision of the first icon in the reconstructed ultrasound image if i) a ratio of the maximum detected intensity to the expected in-plane maximum detected intensity at the time of flight of the maximum detected intensity ultrasound signal or ii) the maximum detected intensity falls below a predetermined value. If any of these parameters falls below a predetermined value, the system may not be sensitive enough to reliably indicate the position of the interventional device relative to the imaging plane. Weakly detected ultrasound signals may be confused by electromagnetic interference or noise. In this case, it is preferable to inhibit the provision of the first icon in the reconstructed ultrasound image in order to avoid indicating a position that may be inaccurate.

According to another aspect, the interventional device includes a feature (e.g., a distal end of the interventional device). The ultrasound transducer is attached to the interventional device at a predetermined distance from the interventional device feature. The position determination unit is further configured to provide a second icon in the reconstructed ultrasound image, the second icon indicating a circular region having a radius corresponding to the predetermined distance between the ultrasound transducer and the interventional device feature. The first icon and the second icon share a common center, i.e., at the calculated lateral position. The second icon indicates a range of possible positions of a feature (e.g., distal end) of the interventional device. Providing these two icons in the reconstructed ultrasound image advantageously indicates the position of the feature of the interventional device relative to the image plane. Two extreme scenarios are now described to indicate the benefit of providing these two icons.

In a first scenario, the interventional device feature and the ultrasound transducer are both located in an image plane. The reconstructed ultrasound image includes a first icon indicating an out-of-plane location and centered on the location of the ultrasound transducer. As described above, the first icon indicates that the transducer is in the image plane. The interventional device feature is located at a position around the perimeter of the circular region indicated by the overlapping second icon; this is because the radius of the circular region corresponds to a predetermined distance between the ultrasound transducer and the interventional device feature. Thus, during an in-plane procedure, when the circles overlap, the perimeter of the icon indicates the location of the interventional device feature. Based on the user's needle insertion progress and approximate trajectory, the user will also generally know which portion of the perimeter of the circular area the distal end of the medical needle is actually located. Furthermore, the user will know this trajectory from intermittently reconstructed ultrasound images of the shaft of the medical needle 11. Thus, the user can mentally enhance the information provided by the first icon to more accurately identify where on the perimeter of the circular region the interventional device feature is located.

In a second scenario, the interventional device feature is located in the image plane, while the ultrasound transducer is located generally above or below the image plane relative to a line along which the feature is passed. Here, the reconstructed ultrasound image includes a first icon centered on a position where the ultrasound transducer is projected onto the image plane. Such projection can involve: i) projecting the position of the ultrasound transducer in a direction normal to the image plane, or ii) projecting a range between the ultrasound imaging probe and the ultrasound transducer onto the image plane, or iii) projecting the position of the ultrasound transducer in a direction perpendicular to the range between the ultrasound imaging probe and the ultrasound transducer. The first icon indicates an out-of-plane distance. Due to the normal positioning of the ultrasound transducer relative to the ultrasound image plane, the center of the second icon indicates the location of a feature (i.e., distal end) of the interventional device. When the first icon overlaps the second icon (i.e. when they indicate the same distance), the interventional device feature has just reached the image plane.

In an intermediate scenario, the interventional device feature is located somewhere between the center of the circular region indicated by the second icon and the perimeter of its circular region.

Since the interventional device feature is known to be on or within the perimeter of the circular region defined by the second icon, improved localization of the interventional device feature relative to the image plane is provided. In other words, it is confident for a user of the system that the interventional device features do not affect image features located outside the circular region. Advantageously, the localization can be provided using only a single ultrasound transducer, thereby simplifying the manufacturing of the interventional device.

According to another aspect, the position determination causes an appearance of at least one of the first icon and the second icon to change when the out-of-plane distance is less than or equal to the predetermined distance. In this way, during the aforementioned out-of-plane procedure, the user is alerted to the fact that the interventional device feature is in the center of the image plane.

According to another aspect, a minimum value of the radius of the first icon is equal to a radius of the second icon, and wherein the radius of the first icon is limited to the minimum value when the out-of-plane distance is less than or equal to the predetermined distance. As described above, by so limiting the size of the first icon as the interventional device approaches the image plane, the user can somewhat relax their attention during out-of-plane procedures when the first icon reaches a minimum size to let the user know that sufficient positioning accuracy has been reached.

According to other aspects, methods and corresponding computer program products are provided that may be used in conjunction with the system.

It should be noted that various aspects described with respect to the system may be combined to provide further advantageous effects. Moreover, various aspects of the system may be used interchangeably with the method, and vice versa.

Drawings

Fig. 1 illustrates a beamforming ultrasound imaging system 14 in combination with an in-plane interventional device 11 and an embodiment of the present invention in the form of a system 10.

FIG. 2 illustrates a distance D from being disposed out-of-plane_opThe interventional device 11 of (a) a combined beamforming ultrasound imaging system 14 and an embodiment of the invention in the form of a system 10.

FIG. 3 illustrates the maximum detected intensity I in the description plane_SmaxInplane(dB) model MO of expected variation with time of flight TOF.

Fig. 4A, 4B, 4C each illustrate a reconstructed ultrasound image RUI comprising a region of interest ROI and a first icon C_opThe first icon C_opIndicating having an out-of-plane distance D_opA circular area of corresponding radius.

Fig. 5A, 5B, 5C each illustrate a reconstructed ultrasound image RUI comprising a region of interest ROI, a first icon C_opAnd a concentric second icon C_deThe second icon C_deThe indication has a distance L from the ultrasound transducer 15 and the interventional device feature 11a_pA circular area of corresponding radius.

Fig. 6 illustrates an interventional device 11 suitable for use with the system 10.

Fig. 7 illustrates various method steps of a method that may be used with system 10.

Detailed Description

To illustrate the principles of the present invention, various systems are described in which the position of an interventional device, such as a medical needle, is indicated relative to an image plane defined by a linear array of 2D ultrasound imaging probes. Further, in some examples, the location of a feature (e.g., distal end) of the medical device is also tracked.

However, it should be understood that the present invention may also be applied to other interventional devices, such as, but not limited to, catheters, guide wires, probes, endoscopes, electrodes, robots, filter devices, balloon devices, stents, mitral valve clamps, left atrial appendage occlusion devices, aortic valves, pacemakers, intravenous tubing, drainage tubes, surgical tools, tissue sealing devices, tissue cutting devices, or implantable devices. Tracked features of such an interventional device may illustratively include a distal end of the interventional device, a biopsy sampling point of the interventional device, an incision edge of the interventional device, an opening of a channel in the interventional device, a sensor of the interventional device (e.g., for sensing flow, pressure, temperature, etc.), a surgical tool integrated in the interventional device (e.g., a spatula), a drug delivery point of the interventional device, or an energy delivery point of the interventional device.

Furthermore, it should be understood that the exemplary linear array of a 2D ultrasound imaging probe is only one example of an array of ultrasound transceivers in which the beamforming ultrasound imaging system of the present invention may be used. The invention also finds application in other types of beamforming ultrasound imaging systems whose associated ultrasound transceiver arrays illustratively include 2D arrays (or in biplane views) of 3D imaging probes, "TRUS" transrectal ultrasound probe, "IVUS" intravascular ultrasound probe, "TEE" transesophageal probe, "TTE" transthoracic probe, "TNE" transnasal probe, "ICE" intracardiac probe.

Fig. 1 illustrates a beamforming ultrasound imaging system 14 in combination with an in-plane interventional device 11 and an embodiment of the present invention in the form of a system 10. In fig. 1, a beamforming ultrasound imaging system 14 comprises a 2D ultrasound imaging probe 13, the 2D ultrasound imaging probe 13 being in communication with an image reconstruction unit IRU, an imaging system processor ISP, an imaging system interface ISI and a display DISP. The units IRU, ISP, ISI and DISP are typically located in a console in wired communication with the 2D ultrasound imaging probe 13. It is also contemplated that wireless communication may occur using, for example, optical, infrared, or RF communication links instead of wired links. It is also contemplated that some of the elements IRU, ISP, ISI, and DISP may alternatively be incorporated into the 2D ultrasound imaging probe 13, for example in a Philips Lumify ultrasound imaging system. In fig. 1, the 2D ultrasound imaging probe 13 includes a linear ultrasound transceiver array 16, the linear ultrasound transceiver array 16 transmitting and receiving ultrasound energy within an ultrasound field that intercepts a volume of interest VOI. The ultrasound field is fan-shaped in fig. 1 and comprises a plurality of ultrasound beams B defining an image plane 12_1..k. Note that the fan beam is illustrated in fig. 1 for illustrative purposes only, and the present invention is not limited to a particular shape of ultrasound field. The beamforming ultrasound imaging system 14 may also include electronic driver and receiver circuitry, not shown, configured to amplify and/or adjust the phase of signals transmitted or received by the 2D ultrasound imaging probe 13 in order to generate and detectBeam B_1..kOf (2) an ultrasonic signal. Thus, electronic driver and receiver circuitry may be used to steer the transmitted and/or received ultrasound beam direction.

In use, the beamforming ultrasound imaging system 14 is operated in the following manner. The operator may plan the ultrasound procedure via the imaging system interface ISI. Once the operational flow is selected, the imaging system interface ISI triggers the imaging system processor ISP to run application specific programs that generate and interpret the signals transmitted and detected by the 2D ultrasound imaging probe 13. The beamforming ultrasound imaging system 14 may also include memory (not shown) for storing such programs. The memory may, for example, store ultrasound beam control software configured to control the sequence of ultrasound signals transmitted and/or received by the ultrasound imaging probe 13. The image reconstruction unit IRU, which may alternatively form part of the imaging system processor ISP, reconstructs the data received from the ultrasound imaging probe 13 into an image corresponding to the image plane 12, which image thus intercepts the volume of interest VOI, and subsequently displays the image on the display DISP. A planar cross-section through the volume of interest VOI is referred to herein as a region of interest ROI. The reconstructed ultrasound image RUI may thus comprise a region of interest ROI. The reconstructed image may be, for example, an ultrasound intensity mode "B-mode" image, or referred to as a "2D-mode" image, a "C-mode" image, or a doppler mode image, or indeed any ultrasound planar image.

Also illustrated in fig. 1 is a medical needle 11 as an example of an interventional device and an embodiment of the invention, system 10, which system 10 may be used to indicate the position of the interventional device 11 (i.e. the medical needle) relative to an image plane 12 of an ultrasound imaging probe 13. This embodiment (system 10) comprises an image reconstruction unit IRU and a position determination unit PDU. These units communicate with each other as illustrated by the interconnecting arrows. It is also contemplated that one or more of the units PDU, IRU may be incorporated within the memory or processor of the beamforming ultrasound imaging system 14, such as within the memory or processor which also provides the functionality of the unit ISP. The tracked medical needle 11 comprises an ultrasound transducer 15The ultrasound transducer 15 may be positioned at a predetermined distance L from the distal end 11a of the interventional device 11_pTo (3).

In use, the position determination unit PDU calculates the position of the interventional device 11 relative to the image plane 12, or more specifically the position of the ultrasound transducer 15 attached to the interventional device 11 relative to the image plane 12, based on ultrasound signals transmitted between the ultrasound transceiver array 16 and the ultrasound transducer 15.

In one configuration, the ultrasound transducer 15 is a receive and beam B_1..kA detector of the corresponding ultrasound signal. The position determination unit PDU identifies the lateral position LAP of the ultrasound transducer 15 with respect to the image plane 12 by correlating (i.e. comparing) the ultrasound signals emitted by the ultrasound transceiver array 16 with the ultrasound signals detected by the ultrasound transducer 15. More specifically, this correlation is based on i) the detection by the ultrasound transducer 15 corresponding to each beam B_1..kAnd ii) on a per beam B basis_1..kThe time delay (i.e., the time of flight) between the time of emission of the ultrasound transducer 15 and the time it is detected by the ultrasound transducer 15 to determine the best-fit position of the ultrasound transducer 15 relative to the image plane 12. This can be explained as follows. When the ultrasound transducer 15 is near the image plane 12, the secondary beam B will be detected with a relatively large intensity_1..kThe closest beam to the transducer, while the more distant beams will be detected with relatively less intensity. Generally, the beam detected with the maximum detection intensity is identified as the beam closest to the ultrasound detector 15. In other words, the maximum detection intensity I_SmaxThe ultrasound signal identifies the in-plane angle Θ between the ultrasound transceiver array 16 and the ultrasound transducer 15_IPA. At the beam (from beam B)_1..k) The time of flight between the time of transmission of (a) and the time it is subsequently detected indicates the range between the ultrasound transceiver array 16 and the ultrasound transducer 15. Thus, with maximum detection intensity I_SmaxTime delay of ultrasound signals in detected beams (i.e., TOF)_Smax) Is an ultrasound signal selected from the ultrasound signals of all beams. Since time of flight indicates this range, in polar coordinates, the time of flight exceedsThe lateral position of the acoustic transducer 15 with respect to the image plane 12 may be determined by the LAP_{TOFSmax,θIPA}To indicate. If desired, the range may be determined by multiplying the time delay by the speed of ultrasound propagation.

In another configuration, the ultrasound transducer 15 is a transmitter that transmits one or more ultrasound pulses. Such pulses may be transmitted, for example, during tracking frames interleaved between ordinary imaging frames of the ultrasound imaging system 14. In such a tracking frame, the ultrasound transceiver array 16 may only operate in a receive mode, in which the ultrasound transceiver array 16 listens for ultrasound signals originating near the image plane 12. Thus, the ultrasound transceiver array 16 is configured as a beamformer for only one-way reception. The position determination unit PDU identifies that the pulse(s) originate from beam B based on the ultrasound signal emitted by the ultrasound transducer 15 and the ultrasound signal detected by the ultrasound transceiver array 16_1..kWhich beam of (a). When in the above configuration, the position determination unit PDU may use a correlation procedure that identifies in the same way the closest beam and thus the point at which the ultrasound signal is transmitted (i.e. the lateral position LAP of the ultrasound signal) based on the ultrasound signal detected at maximum intensity and its time of flight_{TOFSmax,θIPA}). Thus, when the ultrasound transducer 15 is a transmitter, the correlation (i.e., comparison) procedure may again be used to determine the best-fit position relative to the image plane 12 for each tracking frame.

In another configuration, the ultrasonic transducer 15 may be configured to function as both a receiver and a transmitter, or to include both a receiver and a transmitter. In this configuration, upon receiving an ultrasound signal from the ultrasound transceiver array 16, the ultrasound transducer 15 is triggered to emit one or more ultrasound pulses. Optionally, a delay equal to one or more frame periods of the ultrasound imaging system 14 is followed. In this manner, the ultrasound transceiver array 16 receives the pulses emitted by the ultrasound transducer 15 during the imaging mode as being in the trigger beam B1_..kThe form of the echoes in the reconstructed ultrasound at the corresponding in-plane angular positions (i.e., in the image lines). Thus, ultrasonic transductionThe device 15 appears as a bright spot in the reconstructed image. The position determination unit PDU can then identify this bright spot in the reconstructed image and thus calculate again the transverse position LAP of the ultrasound transducer 15 relative to the image plane 12_{TOFSmax,θIPA}。

In yet another configuration (not shown), the ultrasound imaging probe 13 may further include at least three ultrasound transmitters attached to the ultrasound imaging probe 13. The at least three ultrasound transmitters are in communication with a position determination unit PDU. Furthermore, the position determination unit PDU is configured to calculate the position of the ultrasound transducer 15 relative to the image plane 12 based on ultrasound signals transmitted between the ultrasound transducer 15 and at least three ultrasound transmitters attached to the ultrasound imaging probe 13. In this configuration, the position determination unit PDU determines the range between each transmitter and the ultrasonic transducer 15 based on the time of flight of the ultrasonic signal transmitted by each transmitter. Triangulation is then used to determine the three-dimensional position of the ultrasound transducer 15. This provides the position of the ultrasound transducer 15 in three dimensions with respect to the ultrasound imaging probe 13, or more specifically the position of the ultrasound transducer 15 in three dimensions with respect to the image plane 12, since at least three transmitters are attached to the ultrasound imaging probe 13. The three-dimensional position can then be mapped to the image plane 12 and thus again by the LAP_{TOFSmax,θIPA}To indicate. In this configuration, an ultrasonic transmitter is preferable because it is easier to supply a transmitter with a high-power ultrasonic signal necessary for accurate positioning over a wide range when the transmitter is close to the ultrasonic imaging probe 13 from which power is easily available. Therefore, this arrangement is preferred compared to positioning a high power transmitter on the interventional device 11. Thus, in use, the lateral position of the interventional device 11, or more specifically of the ultrasound transducer 15 attached to the interventional device 11, relative to the image plane 12 is calculated again by the position determination unit PDU based on the ultrasound signals transmitted between the at least three transmitters and the ultrasound transducer 15.

In summary, in such an in-plane arrangement in which the ultrasound transducer 15 is in the image plane, the position determination unit PDU shown in fig. 1 may be used in any of the above configurations to calculate the lateral position of the ultrasound transducer 15 with respect to the image plane 12 based on the ultrasound signals transmitted between the ultrasound imaging probe 13 and the ultrasound transducer 15.

When the ultrasound transducer 15 is arranged far away from the image plane (i.e. out of plane), the same procedure can be used to determine the lateral position of the ultrasound transducer 15, i.e. the position projected onto the image plane 12. Using also the maximum intensity of detection I_SmaxIntensity of ultrasonic signal I_SmaxAnd time of flight TOF_SmaxTo estimate the distance of the ultrasound transducer 15 from the image plane 12. In this regard, FIG. 2 illustrates a distance D from being disposed out-of-plane_opThe interventional device 11 of (a) a combined beamforming ultrasound imaging system 14 and an embodiment of the present invention in the form of a system 10. Although beam B of the ultrasound imaging probe 13_1.kShown in plane 12, but of limited thickness, and for small out-of-plane displacements, a reduced ultrasonic signal can generally be detected. In the present invention, these signals are used to estimate the out-of-plane distance D of the ultrasound transducer 15_op。

To this end, FIG. 3 illustrates a description of the in-plane maximum detected intensity I_SmaxInplane(dB) model MO of expected variation with time of flight TOF. The model MO indicated by the solid curve indicates: with increasing time of flight TOF (i.e., depth of entry into tissue), the in-plane maximum detected intensity I of the detected ultrasound signal_SmaxInplaneFirst slowly, then more quickly, and then more slowly. The shape of the model is affected by the attenuation of the ultrasound signal and can be determined from theoretical calculations or empirical measurements of the in-plane maximum intensity obtained in the tissue or corresponding substance. The model MO depends only on the time of flight and does not follow the in-plane angle θ_IPABut may vary. Note that the model MO does not measure the maximum intensity I_SmaxInplaneModeled as a function of out-of-plane distance. Thus, the model MO only requires a limited amount (i.e. one-dimensional) of calibration data. Since the search need only be made in one dimension (i.e. the time-of-flight dimension), it can be utilized with low in-use, as compared to, for example, a three-dimensional modelThe model MO of the retardation determines the out-of-plane distance. It has been found that the modeled in-plane maximum detected intensity I_SmaxInplaneDifferent beamforming ultrasound imaging probes of the same type are reliably represented, which means that the same model can be used for the same type of beamforming ultrasound imaging probe.

Referring to fig. 2 and 3, in use, the out-of-plane distance D is calculated_opIncluding maximum detection intensity I_SmaxAnd comparing with the model MO. The out-of-plane distance D may then be indicated in the reconstructed ultrasound image RUI_op. The out-of-plane distance may be indicated, for example, numerically or may be expressed in terms of D_opBut varying icon size or color.

Maximum detection intensity I_SmaxThe comparison with the model MO may, for example, involve determining the detection intensity I_SmaxAnd at the calculated transverse position LAP_TOFSmaxCorresponding time of flight TOF_SmaxIn-plane maximum detected intensity I_SmaxInplaneThe difference or the ratio between them. In an exemplary embodiment, the LAP may thus be at a calculated lateral position with the ultrasound transducer_{TOFSmax,θIPA}Maximum detection intensity of_SmaxScaled to lie at the calculated transverse position LAP_{TOFSmax,θIPA}Corresponding time of flight TOF_SmaxIn-plane maximum detected intensity I_SmaxInplane. A qualitative indication of the out-of-plane distance can then be indicated in the reconstructed ultrasound image RUI. For example, an icon may be displayed, the size of which varies according to the following equation:

and wherein k₁And k₂Is a constant, and k₁May include zero.

In another exemplary embodiment, referring to fig. 3, the color of the icon may be configured to be based on the maximum detection intensity I_SmaxWith respect to time of flight TOF_SmaxOf (A) to_SmaxInplaneIs changed. For exampleRefer to fig. 3; is represented by_SmaxIs within a predetermined range or I_SmaxRelative to I_SmaxInplaneThe regions I, II and III of the predetermined range of ratios of (A) may define different colors of an icon displayed in the reconstructed ultrasound image, each color at the maximum detected intensity I_SmaxWithin their respective ranges.

Thus, in summary, with reference to fig. 1-3, a system 10 for indicating a position of an interventional device 11 relative to an image plane 12 defined by an ultrasound imaging probe 13 of a beamforming ultrasound imaging system 14, wherein the position of the interventional device 11 is determined based on ultrasound signals transmitted between the ultrasound imaging probe 13 and an ultrasound transducer 15 attached to the interventional device 11, the system 10 comprising:

an image reconstruction unit IRU providing a reconstructed ultrasound image RUI corresponding to an image plane 12 defined by an ultrasound imaging probe 13; and

a position determination unit PDU that:

based on the maximum detected intensity (I) transmitted between the ultrasound imaging probe 13 and the ultrasound transducer 15_Smax) Time of flight TOF of ultrasonic signals_SmaxTo calculate the transverse position LAP of the ultrasound transducer 15 relative to the image plane 12_{TOFSmax,θIPA}(ii) a And is

Based on the maximum intensity of detection I_SmaxIntensity of ultrasonic signal I_SmaxAnd time of flight TOF_SmaxTo calculate the out-of-plane distance D between the ultrasound transducer 15 and the image plane 12_op(ii) a Wherein the out-of-plane distance D is calculated_opIncluding maximum detection intensity I_SmaxAnd is described at maximum intensity of detection I_SmaxTime of flight TOF of ultrasonic signals_SmaxIn-plane maximum detected intensity I_SmaxInplaneComparing the model MO of expected change along with the flight time; and is

Indicating an out-of-plane distance D in a reconstructed ultrasound image RUI_op。

In some exemplary embodiments, this may be accomplished by having a distance D from the out-of-plane_opCircular area of corresponding radius to indicate out-of-plane distance D_op. To this endFig. 4A, 4B, 4C each illustrate a reconstructed ultrasound image RUI comprising a region of interest ROI and a first icon C_opThe first icon C_opIndicating a circular area having a radius corresponding to the out-of-plane distance D_op. Referring to FIG. 4, an out-of-plane distance D is indicated_opMay include the LAP at the calculated lateral position_{TOFSmax,θIPA}Provide a first icon C_opThe first icon C_opIndicating having a direction out of plane D_opA circular area of corresponding radius. Fig. 4 also indicates a region of interest ROI, and within this region of interest ROI the lateral position LAP of the ultrasound transducer 15 is determined. In fig. 4A, the ultrasound sensor 15 is located at a distance, such as a circle C, from the image plane 12_opAs indicated by the radius of (a). Throughout fig. 4B and 4C, the ultrasound transducer 15 is moved closer to the image plane 12, resulting in a circle C_opThe radius of (a) correspondingly decreases. Although circles are indicated in fig. 4, other icons than complete circles and also indicating circular regions may be used in the same manner, including circular arrangements such as dots or dashed lines, circular arrangements of radial lines or arrows (the tips of which indicate circular regions), and so forth. Using an icon with a circular region indicating an out-of-plane distance at the calculated position intuitively indicates to the user whether the interventional device is advancing towards or retreating away from the image plane based on whether the circle is increasing or decreasing. This allows for an improved guidance of the interventional device.

In some exemplary embodiments, the maximum detection intensity is based on_SmaxScaled to be at maximum detection intensity I_SmaxFlight TOF of ultrasonic signals_SmaxDesired in-plane maximum detected intensity I_SmaxInplaneTo determine the distance D from the outside of the plane_opThe corresponding radius. Thus, as described above with reference to FIG. 3, circle C in FIG. 4_opWill change as the ultrasound transducer 15 moves towards and away from the image plane 12.

As can be seen from FIG. 3, the maximum in-plane intensity I is detected_SmaxInplaneGenerally decreasing with increasing time of flight TOF. However, this varies with out-of-plane distanceMay also depend on the time of flight. Based on maximum detection intensity I_SmaxScaling to the expected in-plane maximum detected intensity I_SmaxInplaneDetermining the radius achieves a qualitative indication of the out-of-plane distance and avoids surrounding intensity I_SmaxThe problem of out-of-plane variations. Such an indication is sufficient for the user to accurately navigate the interventional device to the image plane and does not require complete three-dimensional calibration data that might otherwise be required to be used to determine the exact out-of-plane distance and the delay associated with searching such three-dimensional data to determine the out-of-plane distance.

In some exemplary embodiments, the first icon C_opHas a perimeter, and a first icon C_opIs configured to be based on the maximum detected intensity I_SmaxAt maximum detection intensity I_SmaxTime of flight TOF of ultrasonic signals_SmaxExpected in-plane maximum detected intensity I_SmaxInplaneIs changed. If I) the maximum detection intensity I_SmaxAt maximum detection intensity I_SmaxTime of flight TOF of ultrasonic signals_SmaxExpected in-plane maximum detected intensity I_SmaxInplaneOr ii) maximum detection intensity I_SmaxWithin a predetermined range, the first icon C_opMay be changed by at least one of:

changing the first icon C_opThe color of the perimeter of;

changing the first icon C_opThe contrast of the perimeter of (a);

indicating a first icon C by means of a dot or dashed line_opA perimeter of;

make the first icon C_opThe perimeter of (a) pulsates over time;

other features of the icon may also change similarly, for example, under these conditions, the first icon C_opMay take the form of a partially transparent circular area.

Changing the appearance of the perimeter has the effect of indicating to the user the position of the interventional device at the predetermined position relative to the imaging plane. This feature allows a quick indication of the general position of the interventional device relative to the imaging plane to the user. For example, referring to zones I-III in fig. 3, when the maximum detected intensity or a ratio thereof indicates a value close to the expected in-plane maximum detected intensity (i.e., in zone I), the color of the icon may be green, while for values within the contiguous range (i.e., in zone II), the color of the icon may be red, while for positions outside the range (i.e., in zone III), the color of the icon may be white.

In some exemplary embodiments, the distance D from the out-of-plane_opThe corresponding radius has a minimum value. Furthermore, if I) the maximum detection intensity I_SmaxAt maximum detection intensity I_SmaxTime of flight TOF of ultrasonic signals_SmaxExpected in-plane maximum detected intensity I_SmaxInplaneOr ii) maximum detection intensity_ISmaxThe position determination unit may limit the radius to a minimum value if a predetermined value is exceeded. The predetermined value may for example be a desired in-plane maximum detected intensity I_SmaxInplane90% or 95%, or in a predetermined millivolt or milliwatt range.

The user is typically interested in the process of positioning the interventional device in the imaging plane; thus, in this embodiment, for example, when the first icon C_opThe first icon C is within a predetermined range in the imaging plane_opMay be limited to a minimum radius. In this way, the user may relax their attention to some extent when the interventional device is positioned sufficiently well. This avoids the user constantly fine-tuning the position of the interventional device, thereby focusing them on other tasks.

In some exemplary embodiments, if I) the maximum detection intensity I_SmaxAt maximum detection intensity I_SmaxTime of flight TOF of ultrasonic signals_SmaxExpected in-plane maximum detected intensity I_SmaxInplaneOr ii) maximum detection intensity I_SmaxFalling below a predetermined value, the position determination unit PDU may inhibit the provision of the first icon C in the reconstructed ultrasound image RUI_op. If any of these parameters falls below a predetermined value, the system may not be sensitive enough to be usefulThe position of the interventional device relative to the imaging plane is indicated by ground. Weakly detected ultrasound signals may be confused by electromagnetic interference or noise. In this case, it is preferable to inhibit the provision of the first icon in the reconstructed ultrasound image in order to avoid indicating a position that may be inaccurate.

Referring to fig. 5, in some exemplary embodiments, the interventional device 11 includes a feature 11 a. To this end, fig. 5A, 5B, 5C each illustrate a reconstructed ultrasound image RUI comprising a region of interest ROI, a first icon C_opAnd a concentric second icon C_deThe second icon C_deThe indication has a distance L from the ultrasound transducer 15 and the interventional device feature 11a_pA circular area of corresponding radius. As illustrated in fig. 1, the feature may be the distal end 11a of the interventional device. Furthermore, the ultrasound transducer 15 is at a predetermined distance L from the interventional device feature 11a_pIs attached to the interventional device 11. In such an embodiment, the position determination unit PDU provides a second icon C in the reconstructed ultrasound image RUI_deThe second icon C_deIndicating a circular region having a predetermined distance L from the ultrasound transducer 15 and the interventional device feature 11a_pThe corresponding radius. In addition, the first icon C_opAnd a second icon C_deSharing a common center.

Referring to fig. 5, in fig. 5, the ultrasound transducer 15 is progressively advanced from fig. 5A-5C towards the image plane 12, icon C_opIs gradually reduced in size, and the second icon C_deIs fixed. In fig. 5C, the two icons overlap.

Second icon C_deA portion of the image plane 12 corresponding to a range of possible positions of the interventional device feature 11a is defined. As described above, since the feature 11a of the interventional device is known to consist of the second icon C_deOn or within the perimeter of the defined circular region, thus providing improved positioning of the interventional device features relative to the image plane. In other words, it is confident for a user of the system that the interventional device features do not affect image features located outside the circular region. Furthermore, the positioning can be provided using only a single ultrasound transducer, thus being simpleThe manufacture of the interventional device is facilitated.

The location of an alternate feature of the interventional device 11 may be indicated in a similar manner, such as, but not limited to, a biopsy sampling point of the interventional device, an incision edge of the interventional device, an opening of a channel in the interventional device, a sensor of the interventional device (e.g., for sensing flow, pressure, temperature, etc.), a surgical tool integrated in the interventional device (e.g., a spatula), a drug delivery point of the interventional device, or an energy delivery point of the interventional device.

In this regard, fig. 6 illustrates an interventional device 11 suitable for use within the system 10. The ultrasound transducer 15 is attached at a predetermined distance L from the feature (i.e., the distal end 11a of the interventional device 11)_pTo (3). The ultrasound transducer 15 may be attached to the interventional device 11 by various means including the use of adhesives. The electrical conductors that transmit the electrical signals from the ultrasound transducer 11 to the position determination unit PDU are also shown, but as mentioned above, it is contemplated that the transducer signals may alternatively be transmitted to the position determination unit PDU using a wireless link.

The ultrasonic transducers 15 described above with reference to fig. 1, 2 and 6 may be provided by a variety of piezoelectric materials. Both hard and soft piezoelectric materials are suitable. Micromechanical electromechanical structures (i.e., MEMS devices), such as capacitive micromachined ultrasonic transducers (i.e., CMUTs), are also suitable. When the ultrasound transducer is a detector, it is preferably formed from polyvinylidene fluoride (also known as PVDF), the mechanical properties and manufacturing process of which lend itself to attachment to curved surfaces (e.g., medical needles). Alternative materials include PVDF copolymers (e.g., polyvinylidene fluoride trifluoroethylene), PVDF terpolymers (e.g., P (VDF-TrFE-CTFE)). Preferably, the ultrasound transducer is wound around the axis of the interventional device in order to provide sensing of 360 degrees of rotation about the axis, but this is not always the case.

In some exemplary embodiments, the out-of-plane distance D_opLess than or equal to the predetermined distance L_pThe position determination unit PDU may cause the first icon C_opAnd/or a second icon C_deThe appearance of (2) changes. During the envisioned procedure, the user is primarily aimed at positioning the feature 11a of the interventional device at image levelThis process is of interest in the face. Therefore, when the maximum detection intensity I_SmaxCorresponding to the estimated out-of-plane distance D_op＝L_pThen, the first icon C_opAnd/or a second icon C_deThe change in appearance of (a) alerts the user to the occurrence of such a condition. In this way, the user is alerted to the fact that the device feature is in the center of the image plane by a change in appearance, for example, during out-of-plane flow. First icon C_opAnd a second icon C_deMay illustratively each have a perimeter. In addition, the first icon C_opAnd a second icon C_deThe appearance of at least one of the following may be changed by at least one of: changing the first icon C_opOr a second icon C_deThe color of the perimeter of; changing the first icon C_opOr a second icon C_deThe contrast of the perimeter of (a); indicating a first icon C by means of a dot or dashed line_opOr a second icon C_deA perimeter of; make the first icon C_opOr a second icon C_deThe perimeter of (a) pulsates over time; make the first icon C_opAnd a second icon C_deMerging into a common icon; disabling the provision of the first icon C in the reconstructed ultrasound image RUI_opOr a second icon C_de。

In some exemplary embodiments, the out-of-plane distance D_opLess than or equal to the predetermined distance L_pThen, the first icon C_opIs equal to the second icon C_deAnd the first icon C_opMay be limited to a minimum value. As described above, by so limiting the size of the first icon as the interventional device approaches the image plane, the user can somewhat relax their attention during out-of-plane procedures when the first icon reaches a minimum size to let the user know that sufficient positioning accuracy has been reached.

Fig. 7 illustrates various method steps of a method that may be used with system 10. Referring to fig. 7, a method determines a position of an interventional device 11 relative to an image plane 12 defined by an ultrasound imaging probe 13 of a beamforming ultrasound imaging system 14, wherein the position of the interventional device 11 is determined based on ultrasound signals transmitted between the ultrasound imaging probe 13 and an ultrasound transducer 15 attached to the interventional device 11; the method comprises the following steps:

generating a reconstructed ultrasound image RUI with the genui corresponding to the image plane 12 defined by the ultrasound imaging probe 13;

based on the maximum detected intensity I of the ultrasound signal transmitted between the ultrasound imaging probe 13 and the ultrasound transducer 15_SmaxTime of flight TOF of ultrasonic signals_SmaxTo calculate the transverse position LAP of the CLP ultrasound transducer 15 with respect to the image plane 12_{TOFSmax,θIPA}；

Based on the maximum intensity of detection I_SmaxIntensity of ultrasonic signal I_SmaxAnd time of flight TOF_SmaxTo calculate the out-of-plane distance D between the CDOP ultrasound transducer 15 and the image plane 12_op(ii) a Wherein calculating the out-of-plane distance comprises calculating the maximum detected intensity I_SmaxAnd is described at maximum intensity of detection I_SmaxTime of flight TOF of ultrasonic signals_SmaxIn-plane maximum detected intensity I_SmaxInplaneComparing the models of expected variation with time of flight; and is

Indicating INDOPO-PLANE OUTSTANCE D in reconstructed ultrasound image RUI_op。

It should be noted that other embodiments of the method may additionally incorporate one or more aspects described with respect to embodiments of the system.

The method steps shown in fig. 7 (optionally including other method steps described herein) may be stored on a computer program product as instructions executable by a processor. The computer program product may be provided by means of dedicated hardware or hardware capable of executing software in association with appropriate software. When provided by a processor, the functions can be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which can be shared. Moreover, explicit use of the term "processor" or "controller" should not be construed to refer exclusively to hardware capable of executing software, and can implicitly include, without limitation, digital signal processor "DSP" hardware, read-only memory for storing software "ROM ", random access memory" RAM ", non-volatile storage devices, and the like. Furthermore, embodiments of the invention can take the form of a computer program product accessible from a computer-usable or computer-readable storage medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable storage medium can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system or apparatus or device or a propagation medium. Examples of a computer-readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory "RAM", a read-only memory "ROM", a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory "CD-ROM", compact disk-read/write "CD-R/W", Blu-Ray^TMAnd a DVD.

In this regard, a computer program product for use with the system 10 is also provided. The computer program product comprises instructions which, when executed on a processor of the system 10, cause the processor to perform the aforementioned method steps, the system 10 for determining a position of the interventional device 11 relative to an image plane 12 defined by an ultrasound imaging probe 13 of a beamforming ultrasound imaging system 14, wherein the position of the interventional device 11 is determined based on ultrasound signals transmitted between the ultrasound imaging probe 13 and an ultrasound transducer 15 attached to the interventional device 11.

In summary, a system for determining a position of an interventional device relative to an image plane defined by an ultrasound imaging probe of a beamforming ultrasound imaging system has been described, wherein the position of the interventional device is determined based on ultrasound signals transmitted between the ultrasound imaging probe and an ultrasound transducer attached to the interventional device. The system comprises an image reconstruction unit and a position determination unit. The image reconstruction unit provides a reconstructed ultrasound image corresponding to an image plane defined by the ultrasound imaging probe. The position determination unit calculates a lateral position of the ultrasound transducer relative to the image plane based on a time of flight of a maximum detected intensity ultrasound signal transmitted between the ultrasound imaging probe and the ultrasound transducer. The position determination unit further calculates an out-of-plane distance between the ultrasound transducer and the image plane based on the intensity of the maximum detected intensity ultrasound signal and the time of flight. Calculating the out-of-plane distance involves comparing the maximum detected intensity to a model describing the expected variation of the in-plane maximum detected intensity with time of flight at the time of flight of the maximum detected intensity ultrasound signal. The position determination unit also indicates an out-of-plane distance in the reconstructed ultrasound image.

While the invention has been illustrated and described in detail in the drawings and foregoing description with respect to medical needles, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any reference signs in the claims shall not be construed as limiting the scope of the invention. Furthermore, it should be understood that the various examples, embodiments, and examples illustrated herein may be combined to provide various systems and methods for determining the position of an interventional device relative to an image plane of a beamformed ultrasound imaging system.