DE102013219746A1 - Ultrasound system with three-dimensional volume representation - Google Patents

Abstract

The invention relates to an ultrasound system (10) for generating a 3-dimensional volume representation of an examination tissue (40, 70) with a first ultrasound head (12). A gauze (20) is provided which has reflecting elements (21) which partially reflect the ultrasonic waves, the reflecting elements being arranged in a predetermined pattern. An evaluation unit (16) evaluates the ultrasonic waves reflected by the transmitting and receiving unit and generates an ultrasound image. By a relationship, how predetermined signal components generated by the reflective elements (21) of the gauze (20) in the reflected ultrasonic waves are formed in the reflected ultrasonic waves depending on the position of the ultrasonic head (12) on the gauze, determines Evaluation unit (16) with the help of the context and the reflected ultrasonic waves, the position of the ultrasound head (12) on the gauze (20) and stores the position of the ultrasound head in conjunction with the associated ultrasound image. A computing unit (18) calculates a 3-dimensional volume of the examination tissue (40, 70) from the position of the ultrasound head in a first ultrasound image, from the position of the ultrasound head in a second ultrasound image.

Description

The present invention relates to an ultrasound system for generating a three-dimensional volume representation of an examination tissue and a method therefor.

In the use of hand-guided investigations in general, but also in more detailed investigations by the combination of different sound emitters, for example, for additional information such as elastographic tissue properties or higher Eindrangtiefe or extension of the field of view by oblique radiation, it is currently not possible from the individual ultrasound images a total volume to relate locally or to relate partial volumes locally. Exceptions to this are systems in which the ultrasound head departs a predefined path that is reproducible. However, these systems are complicated and difficult to reproduce in temporally spaced examinations of a tissue. The lack of a local embedding of sound images also means an increased effort in the written documentation of the investigation. Likewise, it is difficult to determine a difference between before and after in staggered post-controls, since it can not be ensured that the tissues are identically examined in both staggered examinations.

Overall, in clinical use it is only possible to calculate volumes from regions of the ultrasound images when the ultrasound transducers travel a predetermined known travel path. There are methods based on feature-based registration of the image data that could generate a composite volume. However, these are error-prone and, in particular, can not place partial volumes (or recordings of several different transducers) in a local relationship.

It is therefore an object of the present invention to propose an ultrasound system or method that makes it easier to perform volume calculations based on ultrasound images.

This object is solved by the features of the independent claims. Preferred embodiments are described in the dependent claims.

According to a first aspect of the invention, an ultrasound system for generating a three-dimensional volume representation of an examination tissue is provided, wherein the ultrasound system has a first ultrasound head, for. B. a linear sound head, having at least one transmitting and receiving unit, which is designed to emit ultrasonic waves and to receive reflected ultrasonic waves. Furthermore, a gauze is provided which has reflecting elements which partially reflect the ultrasonic waves. The reflective elements are arranged in a predetermined pattern. The ultrasound system has an evaluation unit, which evaluates ultrasound waves reflected by the transceiver unit and which, inter alia, generates an ultrasound image. The system further comprises a storage unit in which a relationship is stored as predetermined patterns formed by the reflective elements of the gauze in the reflected ultrasonic waves are formed in the reflected ultrasonic waves depending on the position of the ultrasonic head on the gauze. The evaluation unit then uses this stored relationship and the reflected ultrasonic wave to determine the position of the ultrasonic head on the gauze and stores the position of the ultrasonic head in conjunction with an ultrasound image generated at the associated position of the ultrasonic head. The evaluation unit stores the position of the ultrasound head for a first ultrasound image and a further position of the ultrasound head for at least one second ultrasound image.

The arithmetic unit can then calculate a three-dimensional volume of the examination tissue from the position of the ultrasound head in the first ultrasound image, the ultrasound image, from the position of the ultrasound head in the at least one second ultrasound image and the at least one second ultrasound image or the two images can in a 3D volume be arranged correctly to each other.

By using the reflective elements, predetermined signal patterns or signal components are generated in the reflected ultrasound waves. Since the predetermined patterns of the reflective elements are known, by identifying the predetermined signal components in the reflected ultrasound signals, it is possible to deduce the position of the ultrasound head on the gauze. Therefore, the position of the ultrasound head on the gauze can be determined by the reflective elements present in the predetermined pattern and stored together with the image. If the position of the gauze on the examined tissue is known or has not been changed between measurements, ultrasound measurements can be compared at different times since volume calculations of tissue portions in the ultrasound image are possible and thus volumes at different time points can be compared, for example before and after a treatment.

The stored relationship is either a precise mathematical description of the relationship between the pattern of reflective elements and the resulting signal components. The memory unit may further store, for example, information such as the predetermined signal components generated by the reflected elements of the gauze in the reflected ultrasonic waves in which reflected ultrasonic waves are formed depending on the position of the ultrasonic head on the gauze, the evaluation unit including the reflected ultrasonic waves can compare the signal components stored in the memory unit and determines the position of the ultrasound head on the gauze from the comparison.

Furthermore, it is possible for the storage unit to have a table which links the predetermined signal components occurring in the reflected ultrasound waves to a position of the ultrasound head. The evaluation unit can identify the signal components in the reflected ultrasound waves that are caused by the reflected elements and can compare the identified signal components with the signal components stored in the table, the comparison of which determines the position of the ultrasound transducer by referring to the signal component from the table which coincides with the signal component in the reflected wave, the corresponding position is determined.

The gauze may have an upper side surface facing the transducer and a lower side surface that is the examination tissue. The reflective elements can be arranged on the upper or on the lower side surface. In another embodiment, the reflective elements may be disposed on the upper side surface and on the lower side surface.

It is also possible that the gauze has first reflective elements at a first distance to the transducer and second reflective elements which are arranged at a second distance to the transducer. If the location of the first mark differs from the location of the second mark in the ultrasound image, the orientation of the transducer on the gaze, i. H. the tilt angle relative to the gauze can be determined. The greater the distance between the first reflective elements and the second reflective elements, the greater the accuracy in determining the tilt angle. It is possible between the first gauze and the second gauze to arrange a spacer which keeps the first gauze and the second gauze at a distance and which is filled with non-liquid ultrasound gel, or any other medium that reflects the ultrasonic waves little and that Distance between the first and second reflective elements generated.

If two reflective elements are now provided at different distances from the ultrasound head, the evaluation unit can identify a first signal component generated by the first reflective elements and a second signal component has been generated by the second reflective elements. From the identified first signal component and the second identified signal component, it is then possible to deduce the position of the transducer and the tilt angle of the transducer relative to the gauze.

The evaluation unit can examine the upper region of the B-mode image in order to detect the signal components reflected by the reflected elements. This means that the evaluation unit examines the reflected ultrasonic waves from an ultrasonic pulse, which are detected by the transmitting and receiving unit at the beginning of a time window in which the reflected waves of the ultrasonic pulse are detected. Since the gauze is closer to the transducer than the tissue to be examined, and thus also the reflective elements, the signal components of the reflective elements are included in the earliest reflected ultrasound waves, which corresponds to the upper region of the B-mode image.

The system may further comprise a plurality of laterally offset ultrasonic heads, wherein the evaluation unit for each of the ultrasonic heads performs the calculation described above, d. H. examines the reflected ultrasonic waves in consideration of the stored relationship and closes with the reflected ultrasonic waves to the position of the respective ultrasonic head and stores for each ultrasonic head the ultrasound images generated in the associated position in connection with the position. The arithmetic unit is then able to calculate a three-dimensional volume of the examination tissue with the positions of the ultrasound heads and the ultrasound images generated by the different ultrasound heads.

Furthermore, a further ultrasound head can be provided which has a second transmitting and receiving unit which is designed to emit an ultrasonic wave having a lower sound frequency than the first ultrasound head, wherein the evaluation unit can be designed to have a specific one in the ultrasound image of the further transducer identify and store anatomical markers.

According to another aspect of the invention, there is provided a method of generating a three-dimensional representation in which a gauze is placed on the examination tissue and the gauze has reflective elements that at least partially reflect the ultrasonic waves and are arranged in a predetermined pattern. Furthermore, ultrasonic waves are emitted by the first ultrasonic head and the reflected ultrasonic waves are received, wherein a first ultrasonic image is generated at a first position of the ultrasonic head on the gauze and at least a second ultrasonic image is generated at a further position of the ultrasonic head. Subsequently, the position of the ultrasonic head on the gauze is determined in consideration of the relationship stored in the storage unit, the relationship indicating how predetermined signal components generated by the reflected elements of the gauze in the reflected ultrasonic waves are reflected in the reflected ultrasonic waves depending on the position of the ultrasonic head are formed on the gauze using the reflected ultrasonic waves. The position of the ultrasound head on the gauze is determined in each case for the first and the at least one second ultrasound image and stored with the associated images, so that subsequently a three-dimensional volume can be calculated taking into account the ultrasound images and the positions of the ultrasound heads in the different images.

Preferably, the position is calculated by using a table in which the predetermined signal components occurring in the reflected ultrasonic waves are associated with positions of the ultrasonic head. The ultrasonic waves identified in the reflected ultrasonic waves can then be compared with the various predetermined signal components in the table, and if coincident, corresponding signal components in the predetermined signal components are identified and the associated position of the ultrasonic transducer is determined using the table.

Of course, the features described above and the embodiments described in detail below may be used individually or the features may be combined with each other in any combination.

The invention will be described in more detail below with reference to the accompanying drawings.

1 schematically shows an ultrasound system with which the calculation of a volume of ultrasound images is possible,

2 shows a side view of a part of the ultrasound system with a gauze and the reflective elements,

3 shows a top view of the gauze with the ultrasound head and the reflective elements, which are arranged in a first pattern,

4 shows schematically a side view of a gauze having first reflective elements and second reflective elements separated by a gel pad,

5 Fig. 12 shows schematically how a three-dimensional volume can be calculated by different positions of the ultrasound head, wherein by use of a second ultrasound head a fixed landmark is identified, which can be used for a registration of different ultrasound images,

6 shows a flowchart with the steps that are performed for the volume calculation of ultrasound images, and

7 shows schematically how can be closed by two different reflective elements of the gauze on the tilt of the transducer.

It will be explained below how a three-dimensional volume representation of examination tissue, especially of objects in the examination tissue, can easily be carried out with an ultrasound system. In 1 is schematically an ultrasound system 10 shown in which an ultrasonic generator 11 Ultrasonic waves generated. These ultrasonic waves can be from different ultrasonic heads 12a . 12b or 13 be broadcast. As known in ultrasound systems, each ultrasound head has at least one transmitting and receiving unit (not shown), the transmitting unit emitting the ultrasonic wave and the receiving unit detecting the ultrasonic wave reflected by a tissue. The ultrasound head may be, for example, a piezoelectric sound head, which converts an electrical pulse into a sound impulse. How generally ultrasound images can be generated from the reflected ultrasound waves is familiar to the person skilled in the art and will not be explained in more detail here.

Via an input unit 14 For example, an operator can control the ultrasound system and the ultrasound images generated can hereby be displayed on a display unit 16 being represented. An evaluation and image generation unit 16 is provided which evaluates the sound waves reflected by the ultrasound head and, as will be explained in detail later, which calculates the position of the ultrasound head with the aid of the detected reflection waves, which has led to the ultrasound image or the reflected ultrasonic waves. As will be explained in more detail below, the evaluation unit identifies 16 in the reflected sound waves predetermined signal portions which have been reflected by reflective elements contained in a gauze. A relationship is stored in a memory unit as to how the predetermined signal components are formed depending on the position of the ultrasound head on the gauze. In one embodiment, the memory unit may store a table, this table containing various predetermined signal portions, wherein for the various predetermined signal portions each still a position of the ultrasound head is stored. The table thus contains an associated position of the ultrasound head for each predetermined signal component. The evaluation unit 16 can compare the signal components occurring in the reflected ultrasonic waves with the predetermined signal components of the memory unit. If a match occurs, the position corresponding to the predetermined matching signal is determined in the table. The evaluation unit can furthermore store the specific position of the ultrasound head with the associated ultrasound image, for example in the so-called header of the ultrasound image.

In another embodiment, the storage unit may also include algorithms, or a mathematical equation describing the relationship between the known pattern of the reflective elements in the gauze and the signal components in the reflected waves. This means that the table described above does not necessarily have to be present.

An arithmetic unit 18 can finally determine a three-dimensional volume data set with the help of the generated ultrasound images and the stored ultrasound head position in different ultrasound images.

The ultrasound heads 12a and 12b may be the same ultrasound heads, so that a tissue to be examined can be examined simultaneously with several ultrasound heads that are freely movable against each other on the gauze. Furthermore, another ultrasonic head 13 be used, for example, emits lower frequency ultrasonic waves than the ultrasonic head 12 , This achieves a greater penetration depth into the examined tissue. As related later 5 This transducer can be explained 13 be used to identify a fixed predetermined anatomical mark, for example, deeper in the tissue, such as a bone, a joint or a rib. With this anatomical marking, different ultrasound images recorded at different times can then be better compared with one another by registering the ultrasound images with the aid of the anatomical marking.

In 2 a side view is shown as the system of 1 can be used. An ultrasound head like one of the heads 12a and 12b is on a gauze 20 arranged as known, an ultrasound gel or an ultrasound lotion 30 is used between ultrasound head and the gauze 20 or the tissue to be examined 40 , As in 2 can be seen schematically, the gauze encoding in the form of reflective elements 21 exhibit. The reflective elements 21 can be placed on the front or the back of the gauze, or on both sides of the gauze as it will be related later among others 4 and 7 is explained. The reflective elements are now arranged in the gauze so that they have a specific pattern. As in 3 is shown schematically in plan view, the gauze 20 provided, with the reflective elements 21 are formed so that can be closed by the shape or geometry of the elements clearly on the location on the gauze. In the example shown, they are mutually perpendicular elements, each tapering ( 3 ). In the embodiment of 2 the reflective elements have a different thickness, so the reflective element 21a a smaller thickness than the reflective element 21c Has.

These reflective elements or this coding now carries a signal component in the reflected ultrasonic waves. Signal components are present in the reflected ultrasonic waves, which are reflected by the reflective elements 21 and depending on the shape and pattern of the reflective elements 21 produce certain patterns in the reflected ultrasound signal. For example, this coding of the ultrasonic signal can be detected in the upper region of the B-mode image, ie if the transmitting unit emits an ultrasonic pulse and the reflected ultrasonic waves are detected in a time window, then the signal components reflected by the reflecting elements can be detected at the beginning of the time window because the reflective elements are arranged in the immediate vicinity of the transducer. This corresponds to the upper portion of the B-mode image of an ultrasound image.

In the 3 illustrated embodiment of the reflective element can be used, for example, in the ultrasound imaging of the female breast. In each ultrasound image, a partial area of the pattern is included, whereby the position of the ultrasound head with the help of the reflected waves and the memory unit 17 certainly can be. This makes it possible, for example, that ultrasound images of the breast, taken from different sides, are combined with each other to calculate volumes. Furthermore, it is known that in so-called ABVS measurements of the breast (Anatomic Breast Volume Scan) several individual volumes of the breast are taken from different angles. So far, the combination of these individual volumes is not possible. With a gauze and the reflective elements, however, a combination of the individual volumes is possible because the position of the ultrasound head can be calculated for each ultrasound image.

Preferably, the pattern of the reflective elements is formed such that each subregion of the pattern exists only once on the gauze. As a result, it is possible to deduce directly from the signal components, which are caused by the pattern of the reflective elements, the position of the transducer on the gauze.

It is possible that the gauze has two coding elements arranged at a distance from one another. At the in 4 illustrated embodiment is a first gauze 20 provided with the reflective elements 21 , Furthermore, a second gauze 20 be provided with reflective elements 21 , In the illustrated embodiment, the gauze and the reflective elements or the pattern of the reflective elements are identical, but it is also possible that different gauzes are used, which have different patterns and reflective elements. The two gauze are spaced from each other and are held at a fixed distance from each other by a cushion 35 from non-liquid ultrasound gel. This increases the distance between the two reflective elements. This increases the distance of the signal components generated by the reflective elements. This allows a better separation of the signal components. As the gauze adapts to the body shape, the determination of the gauze deflection can be improved and thus the determination of the transducer position. In another embodiment, only one gauze is provided, which is provided at its front and back respectively with reflective elements.

Relating to 7 explains how it can be concluded with two coding patterns on the tilt angle of the ultrasound head. In 7 is a transducer 12 in a first position and at a first tilt angle relative to the gauze 20 and the examination tissue 40 shown, wherein the gauze has two mutually spaced encodings or reflective elements. In the picture right in 7 schematically shows how the reflected signals, which were reflected at the reflecting elements, are detected one above the other in the reflected signal. If now the transducer of the tilt angle α relative to the surface of the gauze and thus tilted to the surface of the tissue, in the representation in 7 in the lower picture by the angle α, so are the reflective elements 21a no longer perceived among each other, but offset each other. Since the distance between the two reflective elements to each other is known, can from the arrangement of the signal components to each other, each of the reflective elements 21a come closed, in which tilt angle α the ultrasound head rests on the tissue. For each ultrasound image, it is thus possible to determine not only the position, but also the orientation, ie the tilt angle, relative to the examination tissue. This information can then be stored, for example, in the header of the ultrasound image with the ultrasound image. In this embodiment, the table stores in the storage unit 17 still information for which tilt angle of the transducer resulting in which shifts of the two patterns to each other.

In general, the pattern of the reflective elements may be configured such that some movement of the transducer beyond a minimum path length is necessary in order to shift from the reflected signal components to the position of the transducer on the gauze.

In 5 is shown schematically as a transducer 12 at a first position, an ultrasound image having a first field of view 61 in which a part of an organ 70 while creating the field of view at a second position 62 another area of the organ 70 contains. If the position of the ultrasound head alone or the position and the tilt are determined for each of the two positions, it may be possible, for example, to calculate a volume of the portion of the organ which is in the visual fields 61 and 62 lies. Of course, other visual fields can be used that cover the entire organ 70 so that the total volume of the organ or point of interest of interest can be calculated. The organ here is the examination tissue from which a three-dimensional volume representation is to be calculated. The examination tissue may also include a larger portion of the visual field from which a volume representation is to be calculated, or only a portion thereof, e.g. B. a portion of the organ. In dashed line is still a second ultrasonic head 13 shown. This ultrasonic head can emit a low frequency sound wave compared to the ultrasonic wave passing through the transducer 12 is sent out. This allows them to have a greater penetration depth, so that in addition to the organ 70 also the anatomical marking 80 included in the picture. This anatomical marking can be, for example, a bone, a joint or a rib. This anatomical marking is preferably stationary. This makes it possible to carry out a delayed check. Before a treatment, for example, a 3D volume of the examined tissue can be calculated. In time, a 3D volume can be calculated in a follow-up check. If the follow-up also an ultrasound image with the anatomical mark 80 recorded, it can be a registration of the two calculated volumes, and it can be determined which changes have resulted in volume. The low-frequency transducer 13 can also be in the transducer 12 be integrated.

For example, if a larger tissue area is to be scanned, it is possible to have two transducers simultaneously, for example, the transducers 12a and 12b to use, which are arranged laterally offset on the gauze. This alignment of the transducers with each other need not be rigid, so that each transducer can adapt individually to the conditions of the tissue. Since the position and orientation of each transducer can be determined, it is still possible to calculate a correct volume.

As related to 7 has been explained above, the tilt angle of the transducer can be calculated on the relative distances of the reflected signals and the shifts of the two characteristic patterns against each other.

In 6 summarizes the main process steps that can be applied to a three-dimensional volume calculation method for ultrasound images. In a first step S1, ultrasound images are taken. For example, a volume of interest can be scanned by simply shutting down the transducer. When taking the ultrasound images in step S1, the coded gauze is placed between the tissue and the ultrasound head as shown in FIG 2 to 5 and 7 is shown. In a step S2, in the reflected ultrasonic waves, the patterns or signal portions which are reflected by the reflecting elements can be identified. By comparing the incoming signals in step S3 with predetermined signal components or patterns in the memory unit, it is possible in step S4 to determine the position of the transducer and possibly the orientation on the gauze. In step S5, this position can be stored together with the generated ultrasound image. Alternatively, the position information can also be stored in the post-processing of the entire data set of ultrasound images for each instantaneous image. With the aid of the calculated ultrasound images and the calculated positions of the transducers, it is then possible to calculate a three-dimensional volume in step S6.

In summary, the invention enables the simplified calculation of volumes in ultrasound images. These volumes can then be stored and archived, which also simplifies the documentation of the ultrasound examination. A fixed path of the ultrasonic head as in the prior art is no longer necessary for this.

LIST OF REFERENCE NUMBERS

10

ultrasound system

12, 12a, 12b, 13

ultrasound probe

16

Evaluation and image generation unit

17

storage unit

18

computer unit

20

gauze

21

reflective elements

30

Ultrasound gel or ultrasound lotion

35

spacer

40, 70

survey tissue

70

organ

80

mark

61, 62

Facial field

Claims (12)

Ultrasound system ( 10 ) for generating a 3-dimensional volume representation of an examination tissue ( 40 . 70 ), comprising: - a first ultrasonic head ( 12 ) with at least one transmitting and receiving unit, which is designed to emit ultrasonic waves and to receive reflected ultrasonic waves, - a gauze ( 20 ), which reflective elements ( 21 ), which partially reflect the ultrasonic waves, the reflecting elements being arranged in a predetermined pattern, - an evaluation unit ( 16 ), which evaluates the ultrasonic waves reflected by the transmitting and receiving unit and generates an ultrasound image, - a memory unit ( 17 ), in which a relationship is stored, such as predetermined signal components coming from the reflective elements ( 21 ) the gauze ( 20 ) are generated in the reflected ultrasonic waves, in the reflected ultrasonic waves as a function of the position of the ultrasonic head ( 12 ) are formed on the gauze, wherein the evaluation unit ( 16 ) with the help of the stored relationship and the reflected ultrasonic waves, the position of the ultrasound head ( 12 ) on the gauze ( 20 ) and stores the position of the ultrasound head in conjunction with an ultrasound image generated at the associated position of the ultrasound head, wherein the evaluation unit ( 16 ) one Stores the position of the ultrasound head for a first ultrasound image and stores a further position of the ultrasound head for at least one second ultrasound image, 18 ), from the position of the ultrasound head in the first ultrasound image, the first ultrasound image, from the position of the ultrasound head in the at least one second ultrasound image and at least one second ultrasound image, a 3-dimensional volume of the examination tissue ( 40 . 70 ). Ultrasound system ( 10 ) according to claim 1, characterized in that the gauze has an upper side surface which faces the transducer and a lower side surface which faces the examination tissue, the reflective elements ( 21 ) are arranged on the upper side surface or the lower side surface. Ultrasound system ( 10 ) according to claim 1, characterized in that the gauze has an upper side surface facing the transducer and a lower side surface facing the examination tissue, the reflective elements being disposed on the upper side surface and on the lower side surface. Ultrasound system ( 10 ) according to one of the preceding claims, characterized in that the evaluation unit ( 16 ) examines the reflected ultrasonic waves from an ultrasonic pulse which are detected by the transmitting and receiving unit at the beginning of a time window in which the reflected ultrasonic waves of the ultrasonic pulse are detected to detect the predetermined signal portions reflected by the reflecting elements. Ultrasound system ( 10 ) according to one of the preceding claims, characterized in that the gauze ( 20 ) first reflective elements ( 21 ) at a first distance to the transducer and second reflective elements ( 21 ) at a second distance to the transducer different from the first distance. Ultrasound system ( 10 ) according to one of the preceding claims, characterized by a first gauze ( 20 ), which first reflective elements ( 21 ) which partially reflect the ultrasonic waves and which are arranged in a predetermined pattern, and a second gauze (FIG. 20 ), which second reflective elements ( 21 ) which partially reflect the ultrasonic waves and which are arranged in a predetermined pattern, wherein between the first gauze and the second gauze a spacing element ( 35 ), which holds the first gauze and the second gauze at a distance from each other and filled with non-liquid ultrasound gel Ultrasound system ( 10 ) according to claim 4 or 5, characterized in that the evaluation unit ( 16 ) is configured to identify first signal components generated in the reflected ultrasonic waves by the first reflecting elements and to identify second signal components generated by the second elements, wherein the evaluation unit ( 16 ) is formed, from the identified first signal components and from the identified second signal components, the position of the transducer on the gauze and the tilt angle of the transducer ( 12 ) relative to the gauze. Ultrasound system ( 10 ) according to one of the preceding claims, characterized in that a plurality of laterally mutually offset ultrasonic heads ( 12a . 12b ), wherein the evaluation unit for each of the ultrasonic heads ( 12a . 12b ) the reflected ultrasonic waves with those in the memory unit ( 17 ) used to close the position of the respective ultrasound head on the gauze and to store the position of the respective ultrasound head in conjunction with an ultrasound image generated at the associated position of the ultrasound head, wherein the arithmetic unit ( 18 ) with the positions of the ultrasound heads and in the case of the ultrasound images generated by the different ultrasound heads, a 3-dimensional volume of the examination tissue is calculated. Ultrasound system according to one of the preceding claims, characterized by a further ultrasound head ( 13 ), which has a second transmitting and receiving unit which is designed to emit an ultrasonic wave having a lower sound frequency than the first ultrasonic head ( 12 ), wherein the evaluation unit is formed, in the ultrasound image of the further transducer a predetermined anatomical mark ( 80 ) identified. Ultrasound system according to one of the preceding claims, characterized in that the memory unit ( 17 ) has a table which connects the predetermined signal component occurring in the reflected ultrasonic waves respectively to a position of the ultrasonic head, the evaluation unit identifying the signal components in the reflected ultrasonic waves caused by the reflective elements and the identified signal components with those stored in the table compares predetermined signal components, and determines the position of the ultrasonic head from the comparison. Method for generating a 3-dimensional volume representation of an examination tissue by an ultrasound system ( 10 ), with the following steps Providing a gauze ( 20 ) on the examination tissue ( 40 . 70 ), wherein the gauze reflective elements ( 21 ), which at least partially reflect the ultrasonic waves and which are arranged in a predetermined pattern, - emitting ultrasonic waves through a first ultrasonic head ( 12 ) disposed on the gauze and receiving the reflected ultrasonic waves, wherein a first ultrasonic image at a first position of the ultrasound head ( 12 ) on the gauze ( 20 ) and at least one second ultrasound image at a further position of the ultrasound head on the gauze, - determining the position of the ultrasound head ( 12 ) on the gauze ( 20 ) by using a relationship stored in a memory unit, which indicates how predetermined signal components are transmitted by the reflective elements (FIG. 21 ) of the gauze are generated in the reflected ultrasonic waves in which reflected ultrasonic waves are formed depending on the position of the ultrasonic head on the gauze, and by using the reflected ultrasonic waves, determining the position of the ultrasonic head on the gauze for the first and the at least a second ultrasound image, - storing, for the first and the at least one second ultrasound image, the position of the ultrasound head in conjunction with an ultrasound image generated at the associated position of the ultrasound head, and - calculating a 3-dimensional volume from the position of the ultrasound head in the first ultrasound image, the first ultrasound image, from the position of the ultrasound head in the at least one second ultrasound image and the at least one second ultrasound image. The method of claim 11, wherein the memory unit comprises a table connecting predetermined signal portions appearing in the reflected ultrasonic waves respectively to a position of the ultrasonic head, the position of the ultrasonic head being determined by identifying the signal portions in the reflected ultrasonic waves caused by the reflective elements are and by comparing the identified signal component with the predetermined patterns stored in the table.

Images