3D ultrasound imaging with FOV adaptation

Abstract

A method is provided for adapting a 3D field of view (FOV) in ultrasound data acquisition to minimize the FOV volume in a controlled and precise manner. The method includes defining a volumetric region for which 3D ultrasound data is desired, and then adapting the data acquisition field of view (FOV) in response to the defined volumetric region to encompass the region. This is achieved based on adapting the scan line length (or scan depth) of each individual scan line based on the defined volumetric region. In some embodiments, the volumetric region is defined based on an anatomical segmentation of the reference ultrasound data set acquired in an initial step, and the volumetric region can be set in response to the boundaries of the identified object of interest. In a subset of embodiments, the volumetric region may be set as the region occupied by the detected anatomical object of interest.

Description

[Technical field]

[0001] The present invention relates to a method for acquiring 3D ultrasound image data with an adaptive FOV. [Background technology]

[0002] Three-dimensional (3D) ultrasound data acquisition (or volumetric ultrasound) is a developing technology field.

[0003] One useful application of 3D ultrasound is for imaging the heart, as it allows for a more accurate view of cardiac structures such as the heart chambers and valves, however, 3D ultrasound can be usefully applied to image any anatomical region or structure.

[0004] Four-dimensional (4D) ultrasound data acquisition involves the acquisition of a time sequence of 3D ultrasound image frames.

[0005] Acquisition of 4D ultrasound data involves a trade-off between 3D spatial resolution, temporal resolution, and the size of the 3D field of view (FOV). For a fixed temporal resolution (i.e., frames per second), a larger 3D field of view means reduced spatial resolution within each 3D frame, and vice versa. Similarly, for a fixed FOV size, an increase in temporal resolution requires a reduction in spatial resolution.

[0006] Therefore, in most cases, this means that the FOV size must be kept relatively large and the temporal or spatial resolution must be reduced to ensure that the required anatomical object or region is completely captured within the FOV. The FOV captured by a 3D ultrasound scan is typically either a cone or pyramid shape emanating from the ultrasound source. Reducing the size of the cone or pyramid runs the risk of cutting off part of the object being imaged.

[0007] For example, in cardiac images, portions of the heart are often cut off, either at the apex, lateral wall, or right ventricle. If the acquisition is wide enough to cover the complete heart, the frame rate ends up being very slow.

[0008] This frame rate not only affects the clinician's diagnostic ability, but also the accuracy of automated segmentation and quantification algorithms applied to the data to identify the dimensions of anatomical objects and to determine physiological parameters (e.g., hemodynamic parameters in the case of cardiac images). Such algorithms and models require high frame rates, for example, in the case of 3D coronary artery disease detection by regional wall motion analysis. In the current clinical setting, to achieve the required frame rates, 2D images have to be used instead of 3D. Some 2D sequences are acquired at high frame rates (e.g., up to 50 Hz). The sonographer then has to mentally compile or integrate these 2D results to make a diagnosis, since in principle the motion anomaly analysis is a 3D problem. This stitching process is complex and can lead to misinterpretations. Summary of the Invention [Problem to be solved by the invention]

[0009] It is an objective to find a technical solution to address one or more of the problems identified above. [Means for solving the problem]

[0010] The invention is defined by the claims.

[0011] According to one aspect of the invention, there is provided a computer-implemented method that includes acquiring reference 3D ultrasound data of an anatomical region in a first 3D FOV, the reference ultrasound data including a series of scan lines of data, each scan line having a scan angle relative to first (φ) and second (θ) angular scan directions and a maximum scan depth (d) along the direction of the scan line.

[0012] The method further includes defining a volumetric region within the anatomical region, the volumetric region having one or more boundaries.

[0013] The method further includes adjusting one or more scan parameters and acquiring new 3D ultrasound data with the adjusted 3D FOV, where adjusting the scan parameters is performed according to a boundary of the volumetric region, where the adjusted 3D FOV completely encompasses the volumetric region, and where adjusting the scan parameters includes adjusting a maximum scan depth (d) of each individual scan line.

[0014] The method further includes acquiring new 3D ultrasound data for the adjusted 3D FOV using the adjusted scan parameters.

[0015] The method is therefore based on modifying the individual scan line depths (or lengths) to allow acquisition of 3D FOVs of any shape and size. This allows the 3D FOV to be reduced in size in a more controlled and directed manner, thereby reducing the risk of missing parts of the anatomical structure of interest. For example, adjusting the maximum scan depth (d) of each individual scan line may include adjusting the duration of the receive phase of the transmit / receive sequence of one or more transducers used to acquire the associated scan line.

[0016] As a result, in the context of 4D imaging, the frame rate can be increased. This can improve the quality of the results derived from automated quantification operations that determine physiological parameters from ultrasound image data. It can also enable new applications, such as the analysis of regional wall motion abnormalities in 3D, where high frame rates are required.

[0017] The volumetric region may be a 3D volume that is smaller than the entire anatomical region covered by the reference scan. It can therefore be acquired in less time. Acquisition is made possible by controlling the scan depth of each individual scan line to match the desired 3D FOV. This ensures that the relevant anatomical sub-region is captured (this region can be user-defined or automatically detected through segmentation).

[0018] Scan line depth means the depth along the direction of the scan line, i.e., along an axis parallel to the propagation path of the scan line through the body. In other words, scan line depth in this context is synonymous with the length of the scan line. The scan line depth is adjustable by controlling the acquisition or transmission parameters (i.e., the driving parameters of the transducer array). Thus, the scan line depth is adjusted at the transducer level (e.g., rather than being adjusted by post-processing of the acquired ultrasound signal data). In this way, the acquisition speed can be improved by limiting the scan line depth to only the depth required to acquire a volumetric region.

[0019] In particular, most commonly, scan line depth is controlled by controlling the duration of the receive phase of the transmit / receive sequence of the associated transducer used to acquire the associated scan line.

[0020] There are various ways in which the area covered by the adapted FOV can be defined. It can be defined manually, for example using user input. It can be defined according to a preconfigured control scheme. In a further example, it can be defined automatically using anatomical image analysis applied to the reference image data. In all cases, the technical effect of reducing the total spatial volume in which data needs to be acquired is achieved, which is achieved by modifying the FOV at the level of each individual scan line, i.e. adapting the length of each scan line to capture a 3D FOV with arbitrarily customizable boundaries.

[0021] In some cases, the adjusted FOV may have a set of boundaries that coincide with at least a subset of the boundaries of the defined volumetric region.

[0022] In some (but not all) embodiments, the method includes applying an anatomical segmentation, and the volumetric region is defined in dependence on the anatomical segmentation.

[0023] There are various ways to control the scan parameters to allow the acquisition of a tailored FOV, which will be briefly outlined here.

[0024] In at least one set of embodiments, the scan parameters are adjusted to define a set of scan lines having a set of scan depths such that each scan line ends at a scan line intersection with a most distal one of the boundaries or boundaries of the defined volumetric region. Most distal means furthest along the length of the scan line from the ultrasound source. All scan lines may be set in this manner, or only a portion may be set in this manner. For example, only the set of scan lines that coincides with the volumetric region may be set in this manner.

[0025] As a variation of this, in some embodiments, the method may include, for each scan line, defining an end point for each scan line depth, identifying the detected line depth (or length) for an intersection with the boundary of the volumetric region, adding a defined margin to this intersection depth, and setting the line depth of the adjusted FOV equal to this depth with the margin added. This allows for a certain margin or spacing around the volumetric region in the depth direction.

[0026] The method can further include identifying a subset of scan lines that do not intersect the defined volumetric region, where the non-intersecting scan lines are deactivated when scanning the adjusted FOV, meaning that these scan lines are not generated / fired when acquiring ultrasound data for the adjusted 3D field of view.

[0027] In some cases, all of the scan lines that do not intersect the volumetric region are deactivated. In this variation, in some embodiments, some of the non-intersecting scan lines may be retained, for example, to capture a predetermined margin or spacing region around the volumetric region, as will be described more fully below.

[0028] The scan lines in each of the reference and new 3D ultrasound data may be understood to span each of a series of 2D planes, the series of 2D planes spanning the respective 3D FOV across a first angular direction (φ), the scan lines forming each plane spanning the plane across a second angular direction (θ), and each 2D scan plane having an angular orientation along the first angular direction.

[0029] In some embodiments, adjusting the scan parameters comprises:

[0030] For each individual 2D scan plane, adjust the maximum angular width (Δθ) along a second angular direction spanned by a scan line in the 2D plane, and adjust the maximum angular width (Δφ) along a first angular direction spanned by a series of scan planes.

[0031] Scan lines outside the maximum angular width are disabled.

[0032] The maximum angular width can be set according to the boundaries of the identified volumetric region.

[0033] In some cases, the maximum angular width (Δθ) of each plane is set to the minimum width required for said plane to completely encompass the boundary of the volumetric region. The same can be applied to the maximum angular width (Δφ) along the first angular direction spanned by the series of scan planes. In this case, the adjusted 3D FOV is sized to just encompass the desired volumetric region.

[0034] In another example, the maximum angular width (Δθ) of each plane is set to the minimum width required for said plane to completely encompass the boundary of the volumetric region plus a defined angular margin, and the same may apply to the maximum angular width (Δφ) along said first angular direction spanned by the series of scan planes.

[0035] The 2D plane is the elevation plane.

[0036] In some examples, each 2D plane of ultrasound data may be acquired by successively firing a series of scan lines that successively increment or decrement the scan angle along a second angular direction θ relative to the transducer arrangement, all lines lying in the same plane. This process is then repeated successively for a series of planes, each plane having an angle oriented along the first angular dimension φ with respect to the z-axis.

[0037] The plane may typically be a triangle or a truncated triangle, and the angular width of the plane refers to the angle of the apex of the plane.

[0038] According to any of the above-mentioned approaches, in some cases, the adjusted 3D FOV may include a subset of scan lines that do not intersect the volumetric region (e.g., when a margin or spacing is desired around the volumetric region). In these cases, optionally, a maximum scan depth for the subset of scan lines is set based on a scan depth set for the closest scan line that intersects the object of interest.

[0039] Closest may mean angularly closest, i.e., the intersecting line whose scan angles θ, φ are closest to the respective non-intersecting scan line.

[0040] There are different approaches for defining the volumetric region. In some embodiments, it may be defined manually, for example through user input. In some cases, it may be pre-determined. In a preferred set of embodiments, it is defined depending on the results of an automatic anatomical segmentation procedure applied to the baseline ultrasound data.

[0041] Thus, according to at least one set of embodiments, the method includes applying segmentation to the reference 3D ultrasound data to detect a boundary of an anatomical object of interest in the reference 3D ultrasound data, and defining a volumetric region within the anatomical region in response to the detected boundary of the anatomical object of interest. In particular, the volumetric region may be defined to completely include the detected boundary of the anatomical object of interest.

[0042] Within this set of embodiments, there are further options for how the volumetric regions are defined based on the segmentation.

[0043] For example, in a simple case, the boundary of the detected anatomical object of interest is simply used as the boundary of the volumetric region, in other words, the boundary of the volumetric region is set to coincide with the boundary of the detected anatomical object of interest.

[0044] As a variation on this, the boundary of the volumetric region may instead be defined to completely include the detected boundary of the anatomical object of interest in addition to a predefined interval or margin around the boundary of the object of interest, e.g. to accommodate movement of the object.

[0045] In some embodiments, defining the volumetric region may include defining a 3D shape for the volumetric region and, optionally, defining a scale size of the shape that is minimal that can accommodate a boundary of the anatomical object of interest, in addition to a defined spacing around the boundary.

[0046] Here, defining the 3D shape of the volumetric region may include defining the shape according to a predefined shape template (e.g., a cylinder, a cuboid, an ellipsoid, a pyramid, a truncated pyramid, an elliptical cylinder, or any other shape), or may include determining a custom shape based on a detected boundary of the object. In the latter case, for example, defining the shape may include determining a custom shape based on a detected boundary of the object, where the custom shape is a convex hull. In some cases, for example, detecting the boundary of the anatomical object may include detecting segmentation mesh vertex points that span the boundary of the object, or may include detecting voxels that span the boundary of the object, where the convex hull is defined to connect the vertex points or voxels.

[0047] As mentioned above, in some cases, the volumetric region is defined to include an interval around the object of interest for accommodation movement. The determination of the interval can be performed automatically based on reference ultrasound data in some cases. In particular, when the reference ultrasound data is 4D ultrasound data (i.e., includes a series of frames of 3D ultrasound data), when the volumetric region is defined to completely include the detected boundary of the anatomical object of interest in addition to a predetermined interval around the object boundary, in some embodiments, the extent of the interval around the boundary can be determined based on the detection of the maximum extent of the object of interest boundary over a series of frames.

[0048] A further aspect of the present application provides a computer program product comprising code means configured to, when executed on a processor communicatively coupled to an ultrasound imaging device, cause the processor to perform any embodiment outlined in the present disclosure or a method according to the present invention in accordance with any claim of the present application.

[0049] Another aspect of the invention provides a processing arrangement comprising an input / output for bidirectional communication with an ultrasound imaging device and one or more processors.

[0050] The one or more processors are adapted to perform at least the following steps:

[0051] Acquire input / output 3D reference ultrasound data of an anatomical region for a first 3D FOV, where the reference ultrasound data comprises data for a series of scan lines, each scan line having a first (φ) and a second (θ) angular scan direction, and a maximum scan depth (d) along the direction of the scan line.

[0052] A volumetric region is defined within the anatomical region, the volumetric region having one or more boundaries.

[0053] adjusting one or more scan parameters to acquire new 3D ultrasound data with the adjusted 3D FOV, where adjusting the scan parameters is performed according to a boundary of the volumetric region, where the adjusted 3D FOV completely encompasses the volumetric region, where adjusting the scan parameters includes adjusting a maximum scan depth (d) of each individual scan line, and communicating the adjusted scan parameters to an ultrasound imaging device to cause the device to acquire new 3D ultrasound data for the adjusted 3D FOV using the adjusted scan parameters.

[0054] A further aspect of the present invention provides a system comprising an ultrasound imaging device and a processing arrangement according to any embodiment of the examples outlined in this disclosure or according to any claim of the present application, the processing device being communicatively coupled to the ultrasound imaging device for receiving ultrasound image data and communicating adjusted scan parameters to the ultrasound imaging device.

[0055] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0056] For a better understanding of the invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Brief description of the drawings]

[0057] [Figure 1] 1 illustrates an exemplary system and processing configuration in accordance with one or more embodiments of the present invention. [Diagram 2] 1 shows the geometry of the capture scan lines and scan planes. [Diagram 3] 3D field of view (FOV) acquisition is shown. [Figure 4] 1 illustrates an exemplary volumetric region defined within a first FOV. [Diagram 5] 1 illustrates the acquisition of scan data for one plane within an adjusted FOV, the adjusted FOV having boundaries set dependent on boundaries of a defined volumetric region. [Figure 6] 4 shows a further example of the first FOV. [Figure 7] 13 shows further examples of adjusted FOVs. [Figure 8] 1 shows image data acquired over an adjusted FOV relative to a wider first FOV. [Figure 9] 1 shows an exemplary volumetric region defined according to a shape template sized to be the smallest that can accommodate the segmented boundary of an anatomical object of interest. [Figure 10]FIG. 11 illustrates an outline of a block diagram of components of an exemplary ultrasound imaging device, showing further exemplary volumetric regions defined to encompass sub-regions of a segmented anatomical object. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] The present invention will now be described with reference to the drawings.

[0059] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems, and methods, are for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the devices, systems, and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the figures to denote the same or similar parts.

[0060] The present invention provides a method for adapting a 3D field of view (FOV) in ultrasound data acquisition to minimize the FOV volume in a precisely controllable manner. The method includes defining a volumetric region for which 3D ultrasound data is desired, and then adapting the data acquisition field of view (FOV) in response to the defined volumetric region to encompass the region. This is achieved based on adapting the scan line length (or scan depth) of each individual scan line based on the defined volumetric region. In some embodiments, the volumetric region is defined based on an anatomical segmentation of the reference ultrasound data set acquired in an initial step, and the volumetric region can be set in response to the boundaries of the identified object of interest. The volumetric region may be set as the region occupied by the detected anatomical object of interest in a subset of embodiments.

[0061] Aspects of the present invention provide computer-implemented methods as described below.

[0062] The computer implemented method may be implemented by a processing arrangement, a processing arrangement adapted to carry out the method forming a further aspect of the invention.

[0063] In carrying out the method, the processing device may be operatively coupled to an ultrasound imaging device for acquiring ultrasound data. A system including the processing device and the ultrasound imaging device also forms another aspect of the invention. The system may include further components, such as a user interface with a display that may be controlled to display a rendering of the acquired ultrasound imaging data.

[0064] By way of illustration, Figure 1 illustrates a schematic diagram of an exemplary system 10 in accordance with one or more embodiments of the present invention. The system includes a processing device 20. The processing device includes an input / output (I / O) 22 for bidirectional communication with an ultrasound imaging device 30, and further includes one or more processors ("proc") 24. The one or more processors are adapted to implement a method as outlined below. The system 10, processing device 20, and methods described below may each be provided independently as respective aspects of the present invention.

[0065] In summary, a computer-implemented method according to one or more embodiments includes: acquiring reference 3D ultrasound data of an anatomical region in a first 3D FOV 42; defining a volumetric region 52 within the anatomical region, the volumetric region having one or more sets of boundaries; adjusting one or more scan parameters to acquire new 3D ultrasound data with an adjusted 3D FOV 44, where adjusting the scan parameters is performed according to a boundary of the volumetric region, such that the adjusted 3D FOV completely encompasses the volumetric region, and adjusting the scan parameters comprises adjusting a maximum scan depth d for each individual scan line; acquiring new 3D ultrasound data for the adjusted 3D FOV using the adjusted scan parameters; has.

[0066] Adjusting the scan parameters includes adjusting the maximum scan depth (d) of each individual scan line. For example, it may include adjusting the maximum scan depth of the line for at least a subset of the scan lines depending on the detected intersection between the most distal (along the direction of the line from the ultrasound source) boundaries of the volumetric region. For example, the end points of each scan line may be set to coincide with the detected intersection. For some scan lines, the line depth may be set to zero (i.e., the line is deactivated or not generated at all).

[0067] The reference 3D ultrasound data may be passively acquired, for example it is received at an input / output of the processing device from an ultrasound imaging device that acquired it. Alternatively, the method may include actively controlling an ultrasound transducer configuration configured by the imaging device to acquire the data, or may issue one or more control commands to the ultrasound imaging device to cause the imaging device to acquire the reference ultrasound imaging data.

[0068] The method is further illustrated by Figures 2 to 7 which show the acquisition of ultrasound data using an ultrasound transducer unit 32 comprising an ultrasound transducer arrangement 34 which provides a source of ultrasound radiation.

[0069] 2-7, both the reference 3D ultrasound data and the new 3D ultrasound data can be understood as including a series of scan lines 16 of data that span each of a series of elevation 2D planes 14. The series of elevation 2D planes together span the first 3D FOV 42 over a first angular direction φ (see FIG. 3b), and the scan lines forming each plane span the plane over a second angular direction θ (FIG. 2a). Thus, each 2D scan plane 14 j is an angular direction φ along the first angular direction jThe second angular direction θ is orthogonal to the first angular direction φ. i is a scan line angle (φ) that defines the angular direction from the ultrasound source relative to each of the first φ and second angular directions θ. i , θ i Each scan line can also be completely defined by a maximum scan depth d along the scan line direction. i For each given scan plane 14 j Within, scan line 16 i all have the same scan angle in a first angular direction φ, and each plane φ j , which varies across the face 14 in a second angular direction θ (FIG. 2b).

[0070] Each 2D scan surface 14 j has a maximum angular width Δθ along the second angular direction that spans a scan line 16 in the scan plane (see, for example, FIG. 3b).

[0071] The complete 3D FOV further comprises a maximum angle Δφ along said first angular direction across the series of scan planes (see FIG. 3b).

[0072] The first angular dimension φ and the second angular dimension θ may be defined relative to a central z-axis, or central origin, which is centered on the ultrasonic radiation source (ie, the transducer arrangement 32).

[0073] FIG. 2a illustrates a series of scan lines 16 spanning an angular width Δθ of a plane across a second angular dimension θ. i By continuously generating j Each plane of ultrasound data is formed along a second angular direction θ relative to the transducer arrangement 34 at a scan angle θ iThe data is acquired by firing successive scan lines with successive increments or decrements of , all of which are in the same plane 14. In this way, data for a full plane is compiled sequentially, one scan line at a time. As shown in Figure 3b, this step is repeated for a series of planes 14. j , each plane being subtended by a direction angle φ along the first dimension φ with respect to the z axis. j (See FIG. 3a.) FIG. 2a is only schematic and in practice more or fewer scan lines may be used.

[0074] FIG. 2b illustrates the scan angle θ of the scan line along a second angular direction θ for a single exemplary scan line 16. i and the scan depth d of the scan line along the line direction i 1 is a schematic diagram showing a scanning depth of each individual scan line. The scanning depth of each individual scan line can be individually adjusted, for example, through control of the duration of the receive phase of the transmit / receive sequence of the associated transducer(s) used to acquire the associated scan line. In particular, the scan line is acquired using a transmit / receive sequence in which an ultrasonic pulse signal is transmitted from a transducer, immediately after which the same transducer or an adjacent transducer begins to sense or sample the returning echo of the transmitted signal (echo signal) during a specific sampling time window, sometimes referred to as the receive phase window. By controlling the duration of the receive phase time window, the depth at which the echo signal is sampled is controlled, since the later received echo signal portion corresponds to a deeper location in the body from which the echo signal portion was back-reflected. Thus, in this manner, the scanning depth of each scan line can be individually controlled by controlling the corresponding transducer receive phase time window.

[0075] More specifically, control of the transducer transmit / receive sequence can be implemented using a timing table that controls the length of each scan line. Each line effectively begins with a transmit pulse. A few microseconds after the transmit pulse, returning echoes begin to be received back from the body for that line. A scan line effectively ends when the system stops measuring or sampling the returning echo signals. If the same transducer is used for both transmitting and sensing (with alternating duty cycles), the scan line effectively ends when the transmit pulse for the next line is generated. Thus, controlling the scan depth of each scan line can actually involve configuring a timing table that controls the transmit / receive phase timing of each scan line, which can be configured by the controller of the system.

[0076] FIG. 2c illustrates a single exemplary 2D scan plane 14 j 10A and 10B show schematic diagrams of the maximum angular width Δθ of a plane intersecting the second angular direction θ for

[0077] FIG. 3a illustrates a single exemplary 2D scan plane 14 j , the direction angle φ of the plane along the first dimension φ with respect to the z-axis j Shows.

[0078] Figure 3b shows diagrammatically the acquisition of a full volumetric data set covering a 3D FOV in an anatomical region by successively acquiring data across a series of 2D scan planes 14a-14e, which together span a maximum angular width Δφ across a first directional dimension φ. Although five planes 14 are shown in Figure 3b, in practice more or fewer planes may form the 3D FOV.

[0079] For purposes of explanation, the 3D FOV shown in FIG. 3b is considered to be the first 3D FOV 42 referred to above, and the ultrasound data for which form the reference ultrasound data referred to above. In this embodiment, the first 3D FOV may, for example, span a maximum angular width in both the first φ and second θ directions and each plane 14. i It is understood that all possible FOVs have the same shape (e.g., using cone or pyramid shaped geometric possibilities). In other words, it is a complete possible FOV. However, this is not required.

[0080] 4 illustrates defining an exemplary volumetric region 52 within the anatomical region covered by the first 3D FOV 42. In this example, the volumetric region 52 is a sub-region of the volume spanned by the first 3D FOV 42, i.e., it defines a volume that is smaller than the first 3D FOV. However, this is not required and the volumetric region may be larger than the first 3D FOV.

[0081] The first 3D FOV 42 acts as a survey scan that can be used, for example, to inform the definition of the volumetric region 52 .

[0082] In the illustrated example, the volumetric region 52 is simply set as a predefined geometric shape, in this case a cylinder. However, as will be explained in more detail below, in other examples, the shape of the volumetric region can be arbitrarily defined and can have any regular or irregular 3D geometry. The volumetric region 52 may be defined manually, e.g., via user input, e.g., by a pre-set control scheme, or automatically based on anatomical image analysis applied to the reference image data (as will be discussed in more detail later). For example, the method may include applying a segmentation to the reference 3D ultrasound data, and the volumetric region may be defined depending on the boundary of the identified anatomical object of interest obtained from the segmentation. The boundary of the volumetric region may simply be set as the boundary of the identified object, or may be set differently, e.g., to a shape that encompasses the boundary of the anatomical object, plus some margin or interval.

[0083] Once the volumetric region 52 is defined, one or more scan parameters are adjusted to acquire new 3D ultrasound data with an adjusted 3D FOV 44 having boundaries set depending on the boundaries of the volumetric region 52. The adjusted 3D FOV should at least completely encompass the volumetric region.

[0084] There are at least two main approaches to doing this.

[0085] First, the scan line 16 intersects at least one boundary of the volumetric region 52. i identifying a subset of the identified scan lines, identifying intersections of each of the identified subset of scan lines with a boundary of the defined volumetric region, and then aligning each of the scan lines 16 such that the end points of the scan lines coincide with the identified intersection points of the scan lines. i depth d iThe first step is to adjust the FOV to a boundary that is preferably the distal-most boundary of the volumetric region along the direction of the scan lines. The remaining non-intersecting scan lines 16 are deactivated (in other words, non-intersecting scan lines are not generated / fired when scanning the adjusted FOV to acquire new ultrasound data). This results in an adjusted FOV with a boundary that at least partially matches or maps to the boundary of the volumetric region.

[0086] In a variation of this technique, scan line 16 i depth d i Instead of setting x = 0, scan line end points may instead be set based on identifying, for each scan line, the line depth / length relative to the intersection, adding a defined margin to the depth of this intersection, and then setting the line depth for the adjusted FOV equal to this depth with the margin added, so that the scan line terminates at said intersection. This optionally allows the adjusted FOV to include a spacing or margin around the volumetric region in the line depth direction.

[0087] The second approach is similar to the first approach, except that instead of simply deactivating scan lines that do not intersect the volumetric region, it involves determining a maximum scan width Δθ of each scan plane 14 in the second angular direction and a maximum scan width Δφ spanned by the collection of planes 14 over the first angular direction, which are determined according to the identified boundaries of the volumetric region 52. This allows for greater flexibility and control in the size and geometry of the adjusted FOV for the volumetric region of interest 52. This allows, for example, to optionally include in the adjusted FOV scan lines that do not intersect the volumetric region, for example allowing a specific spacing or margin around the volumetric region. Thus, in particular, for each plane 14j, the maximum angular width Δθ may be set to the minimum width necessary for said plane to completely encompass the boundary of the volumetric region 51, or the maximum angular width may be set to the minimum width necessary for said plane 14 to completely encompass the boundary of the volumetric region plus a defined angular margin or spacing. Scan lines 16 outside the maximum angular width are deactivated. The same may be applied for setting a maximum angular width Δφ along said first angular direction spanned by a series of scan planes.

[0088] Determining the minimum angular widths Δθ, Δφ to completely encompass the boundary of the volumetric region can be done by identifying the angular coordinates of points on the boundary (e.g., boundary surface) of the volumetric region within the same coordinate system used to define the scan lines 16 and the scan locations 14, and then identifying the maximum between these points, e.g., the maximum angular position between these points in each of the first angular direction φ and the second angular direction θ.

[0089] To further illustrate, an example is considered below in which it is desirable for the adjusted FOV to be set such that its boundaries at least partially coincide or map to the boundaries of the volumetric region (i.e., without any gaps or margins).

[0090] To achieve this, each scan plane 14 j Each scan line in iThe scan depths of the scan lines are individually adjusted to set the scan depth equal to an identified intersection point of the respective scan line with the outer boundary of the volumetric region 52. Thus, the method can include, after defining the volumetric region, determining an intersection point of each scan line with the outer boundary of the defined volumetric region, and setting the scan line depth of each scan line such that the scan line terminates at said intersection point. In this manner, the adjusted FOV 44 has a 3D shape that at least partially matches the 3D shape of the defined volumetric region 52. If a scan line coincides with more than one boundary of the volumetric region, its depth can be set to terminate at the intersection point with the boundary of the volumetric region that is furthest away from the ultrasound source along its length, i.e., the most distal boundary.

[0091] To further illustrate, FIG. 5 shows a single plane 14 within a calibrated viewing angle 44. j As shown, the scan depths of the scan lines 16 in the plane are individually adjusted to terminate at their intersections with the outer boundary of the volumetric region. The resulting scan plane 14 j has a shape defined by a set of outer boundaries, a subset of which boundaries coincide with a subset of the boundaries of the volumetric region 52. The plane also has a further boundary extending from the ultrasound source, spanning the region of scan line propagation from the ultrasound source towards the volumetric region. The resulting total adjusted 3D FOV 44 similarly includes a set of outer boundaries, a subset of which coincide with the boundaries of the volumetric region 52. In particular, the distal-most boundary of the volumetric region along the direction of ultrasound propagation from the ultrasound source coincides with the distal-most boundary of the adjusted 3D FOV along said direction of propagation.

[0092] As a further schematic illustration, Figure 6 shows a further exemplary first FOV 42 with data forming an exemplary reference ultrasound data set. Figure 7 shows a further exemplary adjusted FOV 44 having a shape configured according to a defined volumetric region within the first FOV. As shown, in this example, the shape is a curved pyramid.

[0093] 8 shows the adjusted FOV 44 from a different angle within the context of the first FOV 42. As can be seen, the adjusted FOV 44 in this case is smaller than the original FOV 42.

[0094] As mentioned above, the volumetric region 52 may be defined based on the results of an anatomical segmentation applied to the reference ultrasound data. The volumetric region may simply be defined as the volume occupied by the detected anatomical feature or object, i.e., the boundary of the volumetric region is set to match the boundary of the detected anatomical object. In some other examples, the volumetric region may be set as a shape template sized and positioned to encompass the volume occupied by the detected anatomical object. The latter may, for example, allow for some of the scan line depth calculations to be partially performed in advance, which may be more computationally efficient.

[0095] Thus, by way of further explanation, in accordance with one advantageous set of embodiments, the method includes applying segmentation to the reference 3D ultrasound data to detect a boundary of an anatomical object of interest in the reference 3D ultrasound data, and further includes defining a volumetric region within the anatomical region in response to the detected boundary of the anatomical object of interest, the volumetric region being defined to at least completely include the detected boundary of the anatomical object of interest.

[0096] For example, segmentation may comprise the application of a model-based segmentation operation and / or machine learning based segmentation. The output of the segmentation may be a mesh including connected vertices that define the outer boundary of the segmented object of interest. An example of an output segmentation mesh 64 is shown in FIG. 8 (bottom right). In this example, the anatomical object of interest is the heart.

[0097] Regarding the implementation of model-based segmentation, various segmentation algorithms are known in the art.

[0098] See, for example, the paper by Olivier Ecabert et al., "Automatic Model-Based Segmentation of the Heart in CT Images," IEEE Trans. Medical Imaging, 27(9):1189-1201, Sep. 2008, which reviews one exemplary segmentation algorithm.

[0099] Reference is made to the article by Olivier Ecabert et al., "Segmentation of the Heart and Great Vessels in CT Images Using a Model-Based Adaptive Engine," Medical Image Analysis, 15(6):863-876, 2011, which outlines further exemplary segmentation algorithms.

[0100] In some examples, the volumetric region 52 is defined to completely include the detected boundary of the anatomical object of interest, for example, in addition to a predetermined interval around the object boundary to accommodate object motion. For example, at least the new 3D ultrasound data acquired with the adjusted FOV may actually be 4D ultrasound data that includes multiple frames of 3D ultrasound data. Thus, object motion may occur, for example, when the object exhibits periodic motion, such as the heart or lungs.

[0101] In some examples, defining the volumetric region can include defining a 3D shape for the volumetric region, the 3D shape including the anatomical object of interest. To associate the volumetric region with the anatomical object of interest, the method can optionally further include defining a scale size of the shape that is the smallest that can accommodate a boundary of the anatomical object of interest in addition to a defined spacing around the boundary (for accommodation movements).

[0102] There are various ways to define the 3D shape of a volumetric region. These are described in more detail below.

[0103] The 3D shape of the volumetric region can be defined according to a predefined shape template. By way of non-limiting example, the predefined shape template can be one of a cylinder, a cuboid, an ellipsoid, a pyramid shape, a truncated or truncated pyramid shape, an elliptical cylinder shape, or any other 3D shape.

[0104] In a further example, the method further includes determining a custom shape based on a detected boundary of the object. For example, defining the shape can include determining a custom shape based on a detected boundary of the object. The custom shape can be a convex hull. For example, detecting the boundary of the anatomical object can include detecting segmentation mesh vertex points that span the boundary of the object, or can include detecting pixels that span the boundary of the object, and the convex hull is defined to connect the vertex points or pixels. This effectively results in a volumetric region having a boundary that matches (as closely as possible) the boundary of the detected anatomical object of interest.

[0105] As described above, a technical advantage of the FOV adaptation method according to embodiments of the present invention is that it enables improved frame rates in 4D imaging by minimizing the size of the 3D FOV without the risk of excluding important anatomical detail.

[0106] Thus, in some embodiments, the adjusted 3D FOV 44 may be set to be smaller in volume than the first 3D FOV, and the method further includes increasing the acquisition frame rate of the 4D ultrasound data after the FOV is adjusted.

[0107] As a further illustration of the present invention, a further example according to at least one set of embodiments will now be described in detail. For illustrative purposes, this will be described with reference to 4D ultrasound images of the heart. However, the same principles can be applied to images of any anatomical object or region of interest, and 4D images are not required.

[0108] In this embodiment, 3D anatomical intelligence is used to calculate the volumetric area acquired with a minimally calculated 3D scan pattern necessary to capture the anatomical region of interest. This allows the highest possible frame rate in the context of 4D imaging. This makes it possible to avoid, for example, the (error-prone) extraction of 3D information from 2D image data.

[0109] The method flow according to this embodiment follows the outline already provided above and explained with reference to figures 2 to 5. In summary, the method flow is as follows.

[0110] As a first step, a first 3D ultrasound image of the heart is acquired, which can use a standard or default FOV geometry, for example with a cone or pyramid shaped FOV, which forms the reference 3D ultrasound data.

[0111] The reference 3D ultrasound image is then processed using a segmentation operation to derive the anatomical context. This may include, for example, model-based segmentation, or application of a deep learning-based artificial neural network. The output of the segmentation may be, for example, a labeled segmentation mesh that includes connected vertices that together span the anatomical object of interest, i.e., in this case the outer boundary of the heart. In a further example, the output may be a segmentation mask that defines one or more pixel lines and / or surfaces in the reference 3D image that represent the boundary of the object of interest.

[0112] Neural networks for general 2D or 3D image segmentation (voxel classification / labeling) are known in the general art.

[0113] A mesh or mask is used to define a 3D volumetric region that includes within it all cardiac structures for which imaging data is desired, and optionally also an additional margin that covers cardiac motion over the cardiac cycle, i.e., from beat to beat. Such a margin can also ensure that the target structures are imaged in some spatial anatomical context.

[0114] This can be accomplished, for example, by processing all the vertices of a mask, or all the voxels of a mask, and recording the corresponding scan angle (θ,φ) relative to the z-axis where each voxel's vertex lies. From this, one can determine the minimum scan width Δφ that needs to be spanned across a series of scan planes to capture all the vertices or voxels. In addition, one can determine the minimum required width Δθ of each plane needed to contain all the vertices or voxels. Scan lines outside of these angular widths may be deactivated, i.e., not used subsequently in data collection.

[0115] Furthermore, from the recorded scan angles of each vertex or voxel, a 3D volumetric region can be defined relative to the ultrasound device coordinate system (d, θ, φ) that contains the entire detected boundary of the anatomical object of interest. For example, a standard 3D shape such as a circular, elliptical, or rectangular angular region can be determined, or a custom shape can be defined, for example a convex hull that connects the vertices of the boundary mesh or the voxels / pixels of the boundary mask.

[0116] It should be noted that the resulting angular region of the adjusted 3D FOV may be wider or narrower than the first FOV of the reference scan. For example, the adjusted FOV may be larger if a certain portion of the target anatomical object is not completely covered in the first FOV. In other cases, the adjusted FOV may be smaller than the first FOV. Most commonly, the adjusted FOV overlaps with the first FOV.

[0117] In the next step, the required scan depth is calculated for each scan line having a scan angle within the planned maximum angular range Δφ, Δθ of the adjusted FOV. For each scan line (i.e., each scan angle θ, φ), the method involves determining the distance along the length of the line between the ultrasound source and the boundary of a previously defined volumetric region (where this is defined either by the boundary of the anatomical structure itself (possibly plus a defined margin around it), or by a shape that includes such a structure).

[0118] For example, if the output of the segmentation is represented as a triangular mesh, the volumetric region may be defined to have a boundary that matches the shape of the defined mesh. Thus, to determine the scan depth for each scan line, the method may comprise determining all triangles of the mesh boundary structure that are intersected by the scan line and calculating the distance of the associated intersections. If the segmentation is instead represented as a voxel mask, the method may include determining all voxels of the mask that are intersected by the scan line and calculating the distance along the scan line from the ultrasound source to each voxel (e.g., to the voxel center of the voxel or the most distal corner of the voxel).

[0119] For a given scan line, if it intersects the volumetric region boundary at more than one point, the farthest intersection point is used, resulting in a set of intersection point coordinates for each scan line.

[0120] As an example, Figure 9 shows a slice through a volumetric ultrasound data set. The image shows an exemplary set of segmentation boundaries 64 for the heart, and also shows the boundary of a defined volumetric region 52 that includes the entirety of the heart.

[0121] 10 shows a further example where the anatomical object of interest is instead only a portion of the heart (the left ventricle). The boundary of the entire heart 64 can be segmented and then a volumetric region 52 is defined that covers only the anatomical object / region of interest (i.e., the left ventricle).

[0122] As mentioned above, in some examples, the adjusted 3D FOV 44 includes a margin or interval region around the detected anatomical object. The defined margin or interval around the anatomical object may be predefined, based on user input, or determined from a detected motion pattern of the object over a series of frames if the acquired reference ultrasound data is 4D ultrasound data. In other words, the extent of the interval around the boundary may be determined based on detecting the maximum extent of the boundary of the object of interest over a series of frames.

[0123] After setting the adjusted 3D FOV, new 3D ultrasound data can be acquired, which may be 4D ultrasound data that includes a series of frames of 3D ultrasound data. Areas outside the adjusted FOV (i.e., beyond the newly set length / depth of the scan line) are not scanned; that is, each beam (scan line) is acquired only up to the scan line depth designed for that scan line. In this way, higher frame rates are enabled.

[0124] The method may further include controlling a display of a user interface to display a visual representation of the newly acquired image data, such that the adapted field of view is directly visible.

[0125] In some embodiments, a user interface may be used to generate a user warning if the currently set FOV does not cover a given anatomical object or region of interest. The user may manually trigger an FOV adjustment method to adapt the FOV to the anatomical object. During execution of the instructions of the method, if the current FOV is indeed appropriate, a hint may be provided to the user that the positioning of the ultrasound transducer unit needs to be adjusted.

[0126] A further aspect of the present application provides a computer program product comprising code means configured to, when executed on a processor communicatively coupled to an ultrasound imaging device, cause the processor to perform a method according to any of the invention or embodiments outlined above or according to any claim of the present application.

[0127] As briefly outlined above with reference to Figure 1, another aspect of the present invention provides a system 10 comprising an ultrasound imaging device 30 and a processing arrangement 20 adapted to perform a method according to any of the examples or embodiments outlined above. The processor is communicatively coupled to the ultrasound imaging device for receiving ultrasound image data and communicating adjusted scan parameters to the ultrasound imaging device.

[0128] With reference to FIG. 11, the general operation of an exemplary ultrasound imaging device will now be described in further detail.

[0129] The device comprises an array transducer probe 104 having a transducer array 106 for transmitting ultrasound waves and receiving echo information. The transducer array 106 may comprise a CMUT transducer, a piezoelectric transducer formed from a material such as PZT or PVDF, or any other suitable transducer technology. In this example, the transducer array 106 is a two-dimensional array of transducers 108 capable of scanning either a 2D plane or a three-dimensional volume of an area of ​​interest. In another example, the transducer array may be a 1D array.

[0130] The transducer array 106 is coupled to a microbeamformer 112 that controls reception of signals by the transducer elements. The microbeamformer is capable of at least partial beamforming of signals received by subarrays of transducers (commonly referred to as "groups" or "patches"), as described in U.S. Patent Nos. 5,997,479 (Savord et al.), 6,013,032 (Savord), and 6,623,432 (Powers et al.).

[0131] It should be noted that the microbeamformer is generally entirely optional. Additionally, the device includes a transmit / receive (T / R) switch 116 to which the microbeamformer 112 can be coupled to switch the array between transmit and receive modes and to protect the main beamformer 120 from high energy transmit signals when the microbeamformer is not used and the transducer array is operated directly by the main system beamformer. The transmission of ultrasound beams from the transducer array 106 is directed by a transducer controller 118 coupled to the microbeamformer by the T / R switch 116 and a main transmit beamformer (not shown) that can receive input from user operation of a user interface or control panel 138. The controller 118 can include transmit circuitry configured to drive the transducer elements of the array 106 (directly or via the microbeamformer) during transmission mode.

[0132] In a typical line-by-line imaging sequence, the beamforming system in the probe may operate as follows: During transmit, the beamformer (which may be a microbeamformer or a main system beamformer, depending on the implementation) activates a transducer array, or a subaperture of a transducer array. A subaperture may be a one-dimensional line of transducers, or a two-dimensional patch of transducers within a larger array. In transmit mode, the focus and steering of the ultrasound beam generated by the array or a subaperture of the array is controlled as described below.

[0133] Upon receiving the backscattered echo signals from the subject, the received signals undergo receive beamforming (as described below) to align the received signals, and if subapertures are used, the subaperture is shifted, for example, by one transducer element, and then the shifted subaperture is activated and the process is repeated until all of the transducer elements of the transducer array have been activated.

[0134] For each line (or sub-aperture), the total received signal used to form the associated line of the final ultrasound image is the sum of the voltage signals measured by the transducer elements of the given sub-aperture during the receive period. The resulting line signals, following the beamforming process, are usually referred to as radio frequency (RF) data. Each line signal (RF data set) generated by the various sub-apertures then undergoes additional processing to generate a line of the final ultrasound image. The change in amplitude of the line signal with time contributes to the change in brightness of the ultrasound image with depth, with high amplitude peaks corresponding to bright pixels (or groups of pixels) in the final image. Peaks appearing near the beginning of the line signal represent echoes from shallow structures, while peaks appearing gradually later in the line signal represent echoes from structures of greater depth within the subject.

[0135] One of the functions controlled by the transducer controller 118 is the direction in which the beam is steered and focused. The beam may be steered straight ahead (orthogonal) from the transducer array, or at a different angle to a wider field of view. The steering and focusing of the transmit beam may be controlled as a function of the activation time of the transducer elements.

[0136] Two methods can be distinguished in general ultrasound data acquisition: plane wave imaging and "beam steering" imaging. The two methods are distinguished by the presence of beamforming in the transmit ("beam steering" imaging) and / or receive modes (plane wave imaging and "beam steering" imaging).

[0137] Looking first at the focusing function, by activating all of the transducer elements simultaneously, the transducer array creates a plane wave that diverges as it travels through the subject. In this case, the beam of ultrasound remains unfocused. By introducing position-dependent time delays in the activation of the transducers, it is possible to focus the wavefront of the beam to a desired point, called a focal zone. A focal zone is defined as a point where the lateral beam width is less than half the transmit beam width. In this way, the lateral resolution of the final ultrasound image is improved.

[0138] For example, if a time delay activates the transducer elements successively, starting with the outermost elements of the transducer array and finishing with the central elements, a focal zone is formed along the central elements at a predetermined distance from the probe. The distance of the focal zone from the probe varies according to the time delay between each subsequent round of transducer element activation. After the beam passes through the focal zone, it begins to diverge, forming a far-field imaging region. It is noted that with focal zones located close to the transducer array, the ultrasound beam diverges rapidly in the far field, leading to beamwidth artifacts in the final image. Typically, the near field located between the transducer array and the focal zone shows little detail due to the large overlap of the ultrasound beams. Thus, changing the location of the focal zone can result in significant changes in the quality of the final image.

[0139] It should be noted that in transmit mode, only one focal point may be defined, unless the ultrasound image is divided into multiple focal zones (each of which may have a different transmit focal point).

[0140] Also, when echo signals are received from within the subject, the above process can be reversed to achieve receive focusing. In other words, the input signals can be subjected to electronic time delays before being received by the transducer elements and passed on to the device for signal processing. The simplest example of this is called delay-and-sum beamforming. It is possible to dynamically adjust the receive focus of the transducer array as a function of time.

[0141] Looking now at the function of beam steering, through the correct application of time delays to the transducer elements, it is possible to give the ultrasound beam a desired angle as it exits the transducer array. For example, by activating transducers on a first side of the transducer array and then activating the remaining transducers in a sequence ending on the opposite side of the array, the wavefront of the beam is angled toward the second side. The magnitude of the steering angle relative to the normal of the transducer array depends on the magnitude of the time delay between the activation of subsequent transducer elements.

[0142] Furthermore, it is possible for the total time delay applied to each transducer element to focus the steering beam with the sum of both the focusing time delay and the steering time delay, in which case the transducer array is called a phased array.

[0143] For CMUT transducers that require a DC bias voltage for activation, the transducer controller 118 can be coupled to control a DC bias control 145 for the transducer array. The DC bias control 145 sets the DC bias voltage applied to the CMUT transducer elements.

[0144] For each transducer element of the transducer array, an analog ultrasound signal, typically called channel data, enters the system via a receive channel, where a partially beamformed signal is generated from the channel data by the microbeamformer 112 and then passed to the main receive beamformer 120, where the partially beamformed signals from the individual patches of the transducer are combined into a fully beamformed signal, called radio frequency (RF) data. The beamforming performed at each stage may be performed as described above or may include additional functions. For example, the main beamformer 120 may have 128 channels, each of which receives partially beamformed signals from patches of tens or hundreds of transducer elements. In this way, the signals received by thousands of transducers of the transducer array can be efficiently contributed to a single beamformed signal.

[0145] The beamformed received signals are coupled to a signal processor 122. The signal processor 122 can process the received echo signals in various ways, such as bandpass filtering, decimation, I and Q component separation, and harmonic signal separation, which acts to separate linear and nonlinear signals to allow identification of nonlinear (harmonic of fundamental frequency) echo signals returning from tissue and microbubbles. The signal processor can also perform additional signal enhancements, such as speckle reduction, signal synthesis, and noise removal. The bandpass filters in the signal processor can be tracking filters whose passband slides from higher to lower frequency bands as echo signals are received from increasing depths, thereby eliminating noise at higher frequencies from greater depths that typically lack anatomical information.

[0146] The beamformers for transmit and receive can be implemented with different hardware and have different functions. Of course, the receiver beamformer is designed to take into account the characteristics of the transmit beamformer. In Fig. 11, for simplicity, only the receiver beamformers 112, 120 are shown. In a complete system, there is also a transmit chain with a transmit microbeamformer and a main transmit beamformer.

[0147] The function of the microbeamformer 112 is to provide an initial combination of signals to reduce the number of analog signal paths, which is typically performed in the analog domain.

[0148] Final beamforming occurs in the main beamformer 120, typically after digitization.

[0149] The transmit and receive channels use the same transducer array 106 with a fixed frequency band. However, the bandwidth occupied by the transmit pulses can vary depending on the transmit beamforming used. The receive channels can capture the entire transducer bandwidth (classical approach) or use bandpass processing to extract only the bandwidth containing the desired information (e.g., harmonics of the main harmonic).

[0150] The RE signals may then be coupled to a B-mode (i.e., intensity mode, or 2D imaging mode) processor 126 and a Doppler processor 128. The B-mode processor 126 performs amplitude detection on the received ultrasound signals for imaging of structures within the body such as organ tissues and blood vessels. For line-by-line imaging, each line (beam) is used to generate an intensity value for which the associated RE signal amplitude is assigned to a pixel in the B-mode image. The exact location of a pixel in the image is determined by the location of the amplitude measurement associated with the RE signal and the number of lines (beams) of the RF signal. B-mode images of such structures can be formed in harmonic or fundamental imaging modes, or a combination of both, as described in US Pat. No. 6,283,919 (Roundhill et al.) and US Pat. No. 6,458,083 (Jago et al.). The Doppler processor 128 processes the temporally distinct signals resulting from tissue motion and blood flow for detection of moving material such as flow of blood cells within the image field. The Doppler processor 128 typically includes a wall filter having parameters set to pass or reject echoes returned from selected types of materials within the body.

[0151] The structural and motion signals generated by the B-mode and Doppler processors are coupled to the scan converter 132 and the multiplanar reformatter 144. The scan converter 132 arranges the echo signals in the spatial relationship from which they were received and in the desired image format. In other words, the scan converter acts to convert the RF data from a cylindrical coordinate system to a Cartesian coordinate system suitable for displaying ultrasound images on the image display 140. For a B-mode image, the brightness of a pixel at a given coordinate is proportional to the amplitude of the RF signal received from that location. For example, the scan converter can arrange the echo signals in a two-dimensional (2D) sector format, or a pyramidal three-dimensional (3D) image. The scan converter can overlay a B-mode structural image with a color corresponding to the motion at the point in the image field, where the Doppler estimated velocity produces a given color. The combined B-mode structural image and color Doppler image depict the tissue motion and blood flow within the structural image field. As described in U.S. Patent 6,443,896 (Detmer), a multiplanar reformatter converts echoes received from points in a common plane within a volumetric region of the body into an ultrasound image of that plane. As described in U.S. Patent 6,530,885 (Entrekin et al.), a volume renderer 142 converts the echo signals of a 3D data set into a projected 3D image viewed from a given reference point.

[0152] The 2D or 3D images are coupled from the scan converter 132, the multiplanar reformatter 144, and the volume renderer 142 to the image processor 130 for further enhancement, buffering, and temporary storage for optional display on the image display 140. The imaging processor may be adapted to remove certain imaging artifacts from the final ultrasound image, such as, for example, acoustic shadowing caused by strong attenuators or refraction, back enhancement caused by, for example, weak attenuators, and reverberation artifacts where, for example, highly reflective tissue interfaces are located in close proximity. In addition, the image processor may be adapted to process certain speckle reduction functions to improve the contrast of the final ultrasound image.

[0153] In addition to being used for the images, the blood flow values ​​produced by the Doppler processor 128 and the tissue structure information produced by the B-mode processor 126 are coupled to a quantification processor 134. The quantification processor produces measurements of different flow conditions, such as volumetric velocity of blood flow, in addition to structural measurements such as organ size and gestational age. The quantification processor can receive input from a user control panel 138, such as the points within the anatomical structures in the image where measurements are to be taken.

[0154] Output data from the quantification processor is coupled to a graphics processor 136 for reproducing measurement graphics and values ​​with images on a display 140 and audio output from the display device 140. The graphics processor 136 can also generate graphic overlays for display with the ultrasound images. These graphic overlays can include standard identification information such as the patient name, the date and time of the image, imaging parameters, etc. For these purposes, the graphics processor receives inputs such as the patient name from a user interface 138. The user interface is also coupled to a transmit controller 118 for controlling the generation of ultrasound signals from the transducer array 106 and thus the generation of images generated by the transducer array and the ultrasound imaging device. The transmit control function of the controller 118 is only one of the functions performed. The controller 118 also takes into account the operating mode (given by the user) and the corresponding required transmitter settings and bandpass settings in the receiver analog-to-AD converter. The controller 118 can be a state machine with fixed states.

[0155] The user interface is also coupled to a multiplanar reformatter 144 for selection and control of multiple multiplanar reformat (MPR) image planes that can be used to perform quantified measurements in the image field of the MPR image.

[0156] The above-described embodiments of the invention use a processing device. A processing arrangement may generally comprise a single processor or multiple processors. It may be located in a single containing device, structure, or unit, or may be distributed among multiple different devices, structures, or units. Thus, a reference to a processing arrangement being adapted or configured to perform a particular step or task may correspond to that step or task being performed by any one or more of multiple processing components, alone or in combination. A person skilled in the art will understand how such a distributed processing device can be implemented. The processing device includes a communication module or input / output for receiving data and outputting data to further components.

[0157] The one or more processors of the processing arrangement may be implemented in a number of ways using software and / or hardware to perform the various functions required. A processor typically uses one or more microprocessors that may be programmed using software (e.g., microcode) to perform the necessary functions. A processor may be implemented as a combination of dedicated hardware to perform some functions and one or more programmed microprocessors and associated circuitry to perform other functions.

[0158] Examples of circuitry that may be used in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0159] In various implementations, the processor may be associated with one or more storage media, such as volatile and non-volatile computer memories, such as RAM, PROM, EPROM, and EEPROM. The storage media may be encoded with one or more programs that, when executed on the one or more processors and / or controllers, perform the necessary functions. The various storage media may be fixed within the processor or controller, or may be portable, such that the one or more programs stored thereon may be loaded into the processor.

[0160] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0161] A single processor or other unit may fulfill the functions of several items recited in the claims.

[0162] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0163] The computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium, provided together with or as part of other hardware, but may also be distributed in other forms, such as over the Internet or other wired or wireless telecommunications systems.

[0164] It should be noted that when the term "adapted for" is used in the claims or description, it is intended to be equivalent to the term "configured for."

[0165] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. 1. A computer-implemented method comprising: acquiring reference 3D ultrasound data of an anatomical region for a first 3D field of view (FOV), the reference ultrasound data comprising data for a series of scan lines, each scan line having a scan angle along a first angular scan direction (φ) and a second angular scan direction (θ), and a maximum scan depth (d) along the direction of the scan line; applying segmentation to the reference 3D ultrasound data to detect boundaries of anatomical objects of interest within the reference 3D ultrasound data; defining a volumetric region within the anatomical region, the volumetric region having one or more boundaries, the volumetric region being defined dependent on a detected boundary of the anatomical object of interest, the volumetric region being defined to completely include the detected boundary of the anatomical object of interest; adjusting one or more scan parameters to acquire new 3D ultrasound data using an adjusted 3D FOV, wherein adjusting the scan parameters is performed dependent on a boundary of the volumetric region, such that the adjusted 3D FOV completely encompasses the volumetric region, and adjusting the scan parameters comprises adjusting a maximum scan depth (d) of each individual scan line; acquiring new 3D ultrasound data for the adjusted 3D FOV using the adjusted scan parameters; A method comprising:

2. 2. The method of claim 1, wherein adjusting the maximum scan depth (d) of each individual scan line comprises adjusting a duration of a receive phase of a transmit / receive sequence of one or more transducers used to acquire the associated scan line.

3. 2. The method of claim 1, wherein the scan parameters are adjusted to define a set of scan lines having a set of scan depths (d), each scan line terminating at an intersection of the scan line with a most distal one of one or more boundaries of the defined volumetric region.

4. 4. The method of claim 3, further comprising identifying a subset of scan lines that do not intersect the defined volumetric region, wherein the subset of scan lines that do not intersect are deactivated when scanning the adjusted 3D FOV.

5. The scan lines in each of the reference and new 3D ultrasound data span each of a series of 2D scan planes, the series of 2D planes together spanning the respective 3D FOV across the first angular direction (φ), the scan lines forming each plane span the plane across the second angular direction (θ), and each 2D scan plane spans an angular direction (φ) along the first angular direction. j ) and The step of adjusting the scan parameters includes: adjusting, for each individual 2D scan plane, a maximum angular width (Δθ) along the second angular direction spanned by a scan line in the 2D plane; adjusting a maximum angular width (Δφ) along the first angular direction spanned by the series of scan planes; The method of claim 1 further comprising:

6. For each 2D scan plane, the maximum angular width (Δθ) is set to the minimum width necessary for the 2D scan plane to completely encompass the boundary of the volumetric region; or the maximum angular width (Δθ) is set to the sum of the minimum width required for the plane to completely encompass the boundary of the volumetric region and a defined angular margin; The method of claim 5.

7. 4. The method of claim 3, wherein the adjusted 3D FOV includes a subset of scan lines that do not intersect with the volumetric region, and a maximum scan depth (d) for each of the subset of scan lines is set based on a scan depth set for a nearest scan line that intersects with the volumetric region.

8. The method of claim 1 , wherein the boundary of the volumetric region is set as the boundary of the anatomical object of interest.

9. 2. The method of claim 1, wherein defining the volumetric region comprises defining a 3D shape for the volumetric region and, optionally, defining a minimum shape scale size that can accommodate a boundary of the anatomical object of interest, in addition to a defined spacing around the boundary.

10. The step of defining a 3D shape of the volumetric region comprises: defining the shape according to a predefined shape template, for example a cylinder, a rectangular parallelepiped, an ellipsoid, a pyramid, a truncated pyramid, or an elliptical cylinder; or determining a custom shape based on the detected boundary of the object; 10. The method of claim 9, comprising:

11. defining the shape comprises determining a custom shape based on a detected boundary of the object, the custom shape being a convex hull; Optionally, detecting a boundary of the anatomical object of interest comprises detecting segmentation mesh vertices that span a boundary of the object, or detecting voxels that span a boundary of the object, wherein the convex hull is defined connecting the vertices or voxels. The method of claim 10.

12. The reference ultrasound data is 4D ultrasound data having a series of frames of 3D ultrasound data; Optionally, said volumetric region is defined to completely include the detected boundary of said anatomical object of interest in addition to a predefined interval around said object boundary; the extent of the spacing around the boundary is determined based on finding a maximum extent of a boundary of interest across the series of frames; The method of claim 1.

13. A computer program product having code means configured, when executed on a processor communicatively coupled to an ultrasound imaging device, to cause the processor to perform a method according to any one of claims 1 to 12.

14. A processing device comprising: an input / output for bidirectional communication with an ultrasound imaging device; one or more processors, acquiring reference 3D ultrasound data of an anatomical region for a first 3D field of view (FOV) at the input / output unit, the reference ultrasound data having data for a series of scan lines, each scan line having a scan angle along a first angular scan direction (φ) and a second angular scan direction (θ), and a maximum scan depth (d) along the direction of the scan line; applying segmentation to the reference 3D ultrasound data to detect boundaries of anatomical objects of interest within the reference 3D ultrasound data; defining a volumetric region within the anatomical region, the volumetric region having one or more boundaries, the volumetric region being defined dependent on the detected boundaries of the anatomical object of interest, the volumetric region being defined to completely include the detected boundaries of the anatomical object of interest; adjusting one or more scan parameters to acquire new 3D ultrasound data using an adjusted 3D FOV, wherein adjusting the scan parameters is performed dependent on a boundary of the volumetric region, the adjusted 3D FOV completely encompassing the volumetric region, and adjusting the scan parameters adjusts the maximum scan depth (d) of each individual scan line; communicating the adjusted scan parameters to the ultrasound imaging device to cause the device to acquire new 3D ultrasound data for the adjusted 3D FOV using the adjusted scan parameters; a processor configured to execute A processing device comprising:

15. An ultrasound imaging device; The processing device according to claim 14; An ultrasound system comprising:

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