PRESENTATION OF AN INTERESTING AREA

Description

[0001] The invention relates to a method for displaying a region of interest, an image reconstruction device and a tomosynthesis system.

[0002] There are a variety of diagnostic methods for the early detection of breast cancer. In addition to the traditional medical examination by palpation, two-dimensional X-ray images of the breast, known as mammograms, are often taken. The problem with these images is that the superimposition of various tissue structures often obscures pathological changes in the tissue and thus prevents them from being detected. Attempts to compensate for this problem are made by taking images of the breast from two different angles, for example, once craniocaudal (CC), i.e., from the head to the feet, and once at a 45° angle to this angle (mediolateral oblique, MLO).

[0003] However, the projection images do not yet provide any information about the benign nature of the change. It therefore remains unclear whether the tissue change is benign or malignant. To determine this, a tissue sample must usually be taken as part of a biopsy, and the changes in the histological structure are then examined histologically. For the sample collection, it is possible to localize the tissue change using two stereotactic images acquired with the breast compressed and the detector stationary at acquisition angles of +15° and -15° of the X-ray source to a normal of the detection surface.

[0004] Another well-known technique is tomosynthesis. It describes an imaging procedure in which the breast is imaged from a variety of different angles. During a tomosynthesis scan, for example, with the breast compressed, projections are acquired at angles of 15 to 50 degrees from the X-ray source to a normal of the stationary detection surface, with the total dose roughly corresponding to that of two classic two-dimensional mammograms (e.g., CC and MLO). Images of individual layers of the breast tissue are usually calculated, i.e. reconstructed, from the acquired projection data. To reconstruct a volume dataset of an area to be examined from the acquired projection data, the method of filtered backprojection is frequently used. The resulting volume dataset can be viewed layer by layer for diagnostic purposes.Since layers above and below the currently selected layer can be hidden during the diagnostic evaluation, pathological tissue changes are generally easier to detect. However, the layers are displayed from only one direction, so depending on the direction of the tissue change, it may still be difficult to identify and precisely localize it.

[0005] During a subsequent biopsy using a biopsy needle, images are usually taken before or after the actual sample is taken to check the position of the needle. Due to the needle being inserted into the beam path, acquiring a complete tomosynthesis scan is difficult, as disturbing artifacts are caused, particularly by large vacuum biopsy systems. Therefore, in purely stereotactic mode, only two projections from fixed angles are often taken as control images. However, these make it difficult to obtain a good spatial impression of the needle position.

[0006] From the document US 2016 / 235380 A1, a method for performing a procedure on a patient's breast is known, which comprises compressing the patient's breast with a paddle of an imaging system and performing an initial imaging procedure on the patient's breast. The initial imaging procedure comprises imaging the breast with an X-ray source at a first energy to obtain a first image and a second energy to obtain a second image. A composite image is generated from the first image and the second image and displayed. A region of interest on the composite image is targeted, and a biopsy is performed.

[0007] From US 2016 / 089090 A1, a radiation imaging system, an image processing device, a radiation imaging method, and a non-transitory computer-readable recording medium with an image processing program recorded thereon are known, which facilitate the confirmation of a positional relationship between an object of interest and a biopsy needle. In the system, which uses a radiation imaging device as a mammography device, when performing a biopsy of a person's breast, the positional relationship is confirmed using a radiation image (projection image) obtained by tomosynthesis imaging. A control unit reconstructs the projection image to generate a tomographic image in a state where the needle is inserted into the breast and generates a reprojection image at a predetermined angle from the tomographic image.The control unit extracts an image of the needle from the projection image, inserts the extracted image of the needle into the projection image while aligning it, and displays the projection image.

[0008] It is therefore an object of the present invention to enable an improved spatial impression of an area of ​​interest inside the examination object by means of a tomosynthesis system, despite an examination instrument being introduced into the examination object.

[0009] This object is achieved by a method for displaying according to claim 1, an image reconstruction device according to claim 7 and a tomosynthesis system according to claim 8.

[0010] The method mentioned above for visualizing a region of interest within an examination object into which an examination instrument is inserted is carried out using a tomosynthesis system. It comprises at least the steps according to claim 1.

[0011] The examination object can, for example, be an organ of a human or animal patient, but is preferably a breast of a human patient. Therefore, without loss of generality, the terms "examination object" and "patient's breast" are used synonymously below. The area of ​​interest is, for example, a microcalcification located inside the examination object, i.e., within the breast. Microcalcifications potentially indicate carcinoma, as proliferating cells become necrotic over time and accumulate calcium. This area is displayed or visualized using the method according to the invention in such a way that a good spatial determination or localization is possible. This is particularly advantageous for a biopsy, as the positioning of the examination instrument, e.g.the biopsy needle, according to the invention can be spatially well determined and thus visually checked, as will be explained in more detail later.

[0012] The raw data required for this purpose preferably comprise a plurality of projection images, i.e. - unlike a stereotactic examination - preferably more than two.

[0013] In principle, they can be acquired, for example, by retrieving them from a storage device or via a network, but they are preferably acquired as part of a preparatory step using a tomosynthesis device. For this purpose, the majority of projection images of the examination object are created by penetrating the object with X-rays. The object to be examined is arranged between an X-ray source and a non-rotating detector. The X-ray source emits X-rays, which the detector detects after being projected through the object. The X-ray source is preferably adjustable within a certain angular range relative to a central axis extending perpendicular to the detector. The central axis can extend in any direction relative to the patient's body.Preferably, it corresponds to a craniocaudal direction (CC) or a mediolateral oblique direction (MLO). The X-ray source thus projects the X-rays from different defined acquisition angles through the examination subject onto the detector, which acquires the projection images of the breast as raw data sets. Alternatively, both the detector and the X-ray source can be rotated around the examination subject, thus acquiring projection images as raw data sets from different acquisition angles.

[0014] According to the invention, the raw data are recorded – preferably only – from lateral acquisition angles, meaning the projection is oblique to the central axis. In contrast to a conventional tomosynthesis scan, the acquisition angles in a region around the central axis are omitted, and no central projection images are generated. This is because, according to the invention, the examination instrument, e.g., a biopsy device, in particular with a vacuum biopsy needle, is arranged in the region of the central axis. This would cause artifacts during reconstruction in the central projection images, which would complicate imaging or reconstruction.

[0015] By using the lateral acquisition angles when capturing the raw data, these

[0016] Interference can be largely avoided. At the same time, radiation exposure to the patient is advantageously reduced.

[0017] The individual projection images are preferably acquired with such a low radiation dose that the entire acquisition advantageously uses approximately the same radiation dose as a standard mammogram. As a result, the contrast on the individual projection images is not sufficient to reveal details of the examination subject, especially the region of interest. For this purpose, synthetic projections are first generated from the raw data.

[0018] The synthetic projections can be generated from the raw data, for example, by first reconstructing a volume data set using known methods such as filtered backprojection. The volume data set is then projected onto a virtual detector as part of a forward projection, thereby obtaining a virtual or synthetic projection. However, a complete reconstruction of a volume data set is preferably not performed; instead, only individual, particularly preferably exactly one, thin slice(s) are reconstructed, from which the virtual projections are obtained using forward projections. This is described, for example, in the document US 2014 / 0294138 A1. Alternatively, the synthetic projections are reconstructed directly from the raw data, which advantageously saves computing power compared to a complete volume reconstruction.This is described, for example, in document DE 10 2011 087 337 B4.

[0019] The number of synthetic projections can be equal to the number of projection images acquired as raw data, but it can also vary depending on the requirements and type of reconstruction, i.e. it can include more or fewer projection images.

[0020] The synthetic projections can be output, for example, to a memory of a processing unit (computer), via a network, and / or on a screen. The synthetic projections are preferably displayed as a limited-rotation mammogram, which particularly preferably rotates essentially only within the same angular range as the acquisition angles. This enables better spatial classification and greater accuracy of localization in the z-direction, i.e., perpendicular to the image slices, compared to a tomographic representation of a conventional tomosynthesis scan.

[0021] The image reconstruction device mentioned above for displaying a region of interest within an examination object into which an examination instrument is inserted comprises a capture unit, a determination unit, and an output unit. It is designed to carry out the steps of a display method according to the invention.

[0022] The tomosynthesis system mentioned above comprises a tomosynthesis device with a source-detector arrangement designed to record raw data of the examination object from defined acquisition angles, as well as an image reconstruction device according to the invention.

[0023] Preferably, the tomosynthesis system also comprises a biopsy device with an examination instrument, i.e., a biopsy needle, which is inserted into the examination subject to take a tissue sample during a biopsy not covered by the invention. During the biopsy, the method according to the invention can then be performed with the tomosynthesis system, so that the most comprehensive, detailed, and intuitive visualization possible is achieved for monitoring and / or documenting the examination, thus facilitating a successful examination.

[0024] According to the information obtained from the method according to the invention, the biopsy device can be readjusted automatically or by operating personnel, for example, before the actual sample collection - not covered by the invention - which advantageously ensures more precise positioning during the procedure.

[0025] The essential components of the image reconstruction device according to the invention can predominantly be implemented as software components. In principle, however, these components can also be partially implemented, particularly when particularly fast calculations are required, in the form of software-supported hardware, such as FPGAs or the like. Likewise, the required interfaces, for example, when only data is transferred from other software components, can be implemented as software interfaces. However, they can also be implemented as hardware interfaces controlled by suitable software.

[0026] In particular, the image reconstruction device according to the invention can be part of a user terminal of a tomosynthesis system.

[0027] A largely software-based implementation has the advantage that even previously used image reconstruction devices can be easily retrofitted with a software update to operate in the manner according to the invention. In this respect, the object is also achieved by a corresponding computer program product with a computer program that can be loaded directly into a memory device of an image reconstruction device of a tomosynthesis system, with program sections for executing all steps of the method according to the invention when the program is executed in the image reconstruction device. Such a computer program product can, in addition to the computer program, optionally comprise additional components such as documentation and / or additional components, including hardware components such as hardware keys (dongles, etc.) for using the software.

[0028] A computer-readable medium, such as a memory stick, a hard disk, or another portable or permanently installed data storage device, can be used for transport to the image reconstruction device and / or for storage on or in the image reconstruction device. The computer-readable medium stores the program sections of the computer program that can be read and executed by a computer unit of the image reconstruction device. For this purpose, the computer unit can, for example, have one or more cooperating microprocessors or the like.

[0029] Further, particularly advantageous embodiments and developments of the invention emerge from the dependent claims and the following description, wherein the independent claims of a claim category can also be developed analogously to the dependent claims or description parts of another claim category and, in particular, individual features of different embodiments or variants can be combined to form new embodiments or variants.

[0030] Since the arrangement of the examination instrument, the central projection images in particular contribute to the creation of imaging artifacts during raw data acquisition, the raw data sets are preferably acquired with acquisition angles of at least 10°, particularly preferably at least 15°, to a central axis. As previously mentioned, the central axis extends in a direction of the patient's body, e.g., craniocaudal (CC) or mediolateral oblique (MLO).

[0031] The raw data sets are preferably acquired at acquisition angles of no more than 60°, particularly preferably no more than 45°, and most preferably no more than 25°, relative to a central axis. The synthetic projections derived from these raw data allow a good spatial impression of the area of ​​interest to be obtained.

[0032] Preferably, the number of lateral acquisition angles or the number of projection images acquired as raw data is at least 10, particularly preferably 20. With 10 projection images, for example, 5 images per side are acquired relative to the central axis in an angular range of 15° to 25° to the central axis with angular intervals of 2°. With 20 projection images, for example, 10 images per side are acquired relative to the central axis in an angular range of 15° to 25° to the central axis with angular intervals of 1°. With this number of projection images, synthetic projections of sufficient quality can already be created, and the radiation exposure for the patient is thus advantageously kept low.

[0033] In the method according to the invention, preferably two raw data sets are acquired, each from acquisition angles that are arranged opposite one another with respect to a central axis. The raw data sets are therefore preferably recorded or acquired with opposite acquisition angle ranges on both sides of the central axis. Two image sequences are preferably determined from the raw data sets, each of which represents the region of interest in a rotating manner from two different sides or from two different (central) directions. This enables even better spatial localization of the region of interest.

[0034] The output of the synthetic projections preferably includes a maximum intensity projection (MIP). Maximum intensity projections allow for a particularly intuitive spatial representation of data representing a volume. For this purpose, two-dimensional synthetic projections are determined from the raw data, which depict the three-dimensional volume of the object under investigation, by selecting the data point or pixel with the maximum intensity along a viewing direction (projection direction of the synthetic projection) during the reconstruction of the synthetic projections.

[0035] In addition to the rotating display described above, the operator's spatial perception can be further improved if a slice dataset of the examination subject is also provided. Therefore, a tomosynthesis scan is preferably acquired before the examination instrument is inserted into the examination subject. This advantageously avoids the examination instrument as a source of artifacts during the acquisition of the tomosynthesis scan. The tomosynthesis scan is preferably output in addition to the image sequence so that both datasets can be compared to locate the region of interest.

[0036] The raw data are preferably acquired before or after the examination instrument is activated. The raw data can therefore be acquired before or after the examination instrument is activated, as required. The activation of the examination instrument preferably involves the process of taking a sample during a biopsy using a biopsy needle, the so-called "fire." The raw data acquired before activation is accordingly referred to as "pre-fire" data, while the raw data acquired after activation is referred to as "post-fire" data. Since the biopsy needle is already inserted into the patient's breast both before and after the fire, it would cause artifacts in conventional imaging, making visualization difficult or even impossible. In contrast, the method according to the invention can determine the position of the biopsy needle in relation to the area of ​​interest, e.g., the area of ​​interest.Microcalcification can be well visualized spatially even under these conditions, enabling improved control of the position of the biopsy needle and better documentation of the procedure.

[0037] The invention is explained in more detail below with reference to the accompanying figures using exemplary embodiments. In the various figures, identical components are provided with identical reference numerals. The figures are generally not to scale. They show: FIG 1 a roughly schematic representation of an embodiment of a tomosynthesis system according to the invention, FIG 2 a schematic block diagram of an embodiment of an image reconstruction device according to the invention, FIG 3 a schematic representation of the arrangement of the areas of the acquisition angles in an embodiment of a method according to the invention for displaying an area of ​​interest, FIG 4 a block diagram of an embodiment of a method according to the invention for displaying a region of interest and FIG 5 a block diagram of a further embodiment of a method according to the invention for displaying a region of interest.

[0038] In FIG 1 A tomosynthesis system 1 according to the invention is shown by way of example and in a roughly schematic manner. Relative directional information such as "top" and "bottom," etc., refers to a tomosynthesis system 1 set up as intended for operation. The tomosynthesis system 1 comprises a tomosynthesis device 2 and a computer system 20. The tomosynthesis device 2 has a support column 17 and a source-detector assembly 3, which in turn comprises an X-ray source 4 (hereinafter also referred to as X-ray source 4) and a detector 5 with a detection surface 5.1. During operation, the support column 17 rests on the ground. The source-detector assembly 3 is movably connected to it, so that the height of the detector surface 5.1, i.e., the distance from the ground, can be adjusted to a patient's breast height.

[0039] A patient's breast O (shown schematically here) rests as the examination object O for an examination on top of the detector surface 5.1. A plate 6 is arranged above the breast O and the detector surface 5.1 and is movably connected to the source-detector arrangement 3. For the examination, the breast O is compressed and simultaneously fixed by lowering the plate 6 onto it, so that pressure is exerted on the breast O between the plate 6 and the detector surface 5.1. The plate 6 has a circular recess 7 in the center, through which the breast O is accessible for the examination.

[0040] The X-ray source 4 is arranged and configured opposite the detector 5 in such a way that the detector 5 detects X-rays emitted by it after at least a portion of the X-rays have penetrated the patient's breast O. Thus, projections of the breast O are recorded as raw data RD. The X-ray source 4 is pivotable relative to the detector 5 by means of a rotary arm 18 in a range of, for example, ± 25° about a basic position, i.e., about a central axis MA, in which it is positioned vertically above the detection surface 5.1 (see also FIG 3 ).

[0041] In addition, the tomosynthesis device 2 comprises a biopsy device 8 as the examination instrument 8 and a robot arm 9 as the positioning device 9. The robot arm 9 is connected to the source-detector assembly 3 at a fixed end. It has joints and motor elements for positioning the biopsy device 8, which is connected to its free end. The biopsy device 8 comprises a needle holder and a biopsy needle held therein (not shown here). To visualize a biopsy, i.e., a tissue sample taken for histological examination, using the tomosynthesis system 1, the method according to the invention is carried out, as described further below.

[0042] The computer system 20 comprises a computer unit 12 and, connected to it, a mouse 13, a keyboard 14, and a screen 15. The screen 15 serves as the display unit 15, while the mouse 13 and keyboard 14 each serve as input devices. The computer unit 12 comprises an image reconstruction device 10 and a control device 11 (shown schematically here as blocks), as well as a drive 16 for reading CDs or DVDs. The image reconstruction device 10 and the control device 11 can jointly use components of the computer unit 12, such as memory, processors, and the like. The computer system 20 can be arranged in the same room as the tomosynthesis device 2, but it can also be located in an adjacent control room or at a greater distance.

[0043] FIG 2 shows an embodiment of an image reconstruction device 10 according to the invention schematically as a block diagram. The image reconstruction device 10 comprises an input data interface 24, a detection unit 21, a determination unit 22, an output unit 23, and an output interface 25. The individual components of the image reconstruction device 10 are connected to one another via a common bus 26, so that data can be freely exchanged between the individual components as required. The input data interface 24 can, for example, be connected via a network to further storage devices or to a tomosynthesis device (see FIG 1 ) and can receive data transmitted therefrom. The output interface 25 can also be connected to further storage devices via a network or can transmit the output data directly to a screen, a projector, a touchscreen or the like. The interaction of the individual components of the control device is described below with reference to FIG 4 und FIG 5 described.

[0044] In FIG 3 1 shows an exemplary and schematic illustration of a lateral arrangement of the acquisition angles A1, A2, ..., A6 according to the invention. For illustration purposes, the X-ray source 4 is shown schematically in several positions, so that a central X-ray beam emitted by it strikes the detector 5 at a defined acquisition angle A1, A2, ..., A6 depending on its position. A central axis MA extends perpendicular to the detector. The biopsy device 8 and its robot arm 9 (indicated here in small letters) are arranged in the region of the central axis MA. If the X-ray source were positioned in the region of the central axis MA, the biopsy device 8 and the robot arm 9 would block the beam path or lead to artifacts during imaging. Therefore, no data is acquired in the region of the central axis MA. Accordingly, according to the invention, only raw data RD acquired from the lateral acquisition angles A1, A2, ..., A6 is recorded.The lateral acquisition angles A1, A2, ..., A6 are arranged obliquely on either side of the central axis MA and, at the same time, obliquely to detector 5. They form angles of A3, A4 = ±15°; A2, A5 = ±20°; and A1, A6 = ±25° to the central axis MA. Preferably, additional raw data RD are acquired or recorded at intermediate positions (not shown here) as needed.

[0045] FIG 4 shows an example of a block diagram of a method according to the invention. In a first step ACQ, raw data RD is acquired. For this purpose, the projection images detected with lateral acquisition angles A1, A2, ..., A6 are received by the reconstruction unit 10 via the input interface 24 and forwarded to the acquisition unit 21 via the bus 26. The acquisition, which is not included in the method according to the invention, can take place immediately before the method, but it can also be performed at a later time.

[0046] The projection images are acquired with a low radiation dose, so that suitable synthetic projections SP are first determined from the raw data RD in a second step CAL for assessment by an observer. This is preferably done in the determination unit 22 by directly reconstructing the synthetic projections SP from the raw data RD, the result of which can be a maximum intensity projection or a rotating mammogram, as required. Therefore, no intermediate step is explicitly performed in which a volume data set is reconstructed as an aid.

[0047] In a third step DIS, the synthetic projections SP are output by means of the output unit 23 via the output interface 25 as output data AD, which represent the examination object O rotating in an image sequence. The individually determined synthetic projections SP are thus combined to form an image sequence AD ​​which is ordered in such a way that when the image sequence AD ​​is run through or played back, a viewer has the impression that the displayed examination object O is rotating. When DIS is output on a screen 15, the viewer can speed up, slow down or pause the image sequence AD ​​at any time using an input device such as the mouse 13 or the keyboard 14. The image sequence AD ​​can also be output, for example, to a memory of the computer unit 12 or via a network.

[0048] FIG 5 shows a block diagram of another embodiment of a method according to the invention for displaying a region of interest. First, in a step SCA, a complete tomosynthesis scan is generated using a known method. This scan is used to plan the subsequent procedure, i.e., preferably for target planning and particularly preferably also for path planning for a subsequent biopsy using a biopsy device 8 with a biopsy needle. In accordance with this planning, in a subsequent step INS, which is not included in the method according to the invention (shown in dashed lines), the biopsy needle is inserted into the examination subject O.

[0049] In order to visually check the position of the biopsy needle, the following is the FIG 4 The method described is carried out twice. For this purpose, the region of interest is displayed from a right-hand angular range in a step Pr-R and from a left-hand angular range in a step Pr-L. The resulting output data AD (pre-fire data) can, on the one hand, be temporarily stored as a complete output at the end of the method, as shown here. On the other hand, they can also be output immediately, for example, on a screen 15, for immediate monitoring of the successful insertion INS of the biopsy needle. For this purpose, the pre-fire data can also be displayed in combination with tomographic images obtained from the tomosynthesis scan in order to provide the viewer with an even better spatial impression.

[0050] In a subsequent step BIO (shown in dashed lines), which is not included in the method according to the invention, the sample BIO is taken from the area of ​​interest using the biopsy needle.

[0051] Afterwards, the FIG 4 The described inventive method is carried out twice. For this purpose, the region of interest is represented from a right-hand angular range in a step Po-R, and from a left-hand angular range in a step Po-L. The resulting output data AD (post-fire data) can be output, as already described for the pre-fire data. This allows, on the one hand, the success of the BIO sampling to be monitored, and, on the other hand, the data can be temporarily stored for the overall output DIS' described below.

[0052] In a further step, DIS', the complete output data AD' is generated. The complete output data AD' represents documentation of the entire procedure. It includes the data from the tomosynthesis scan (SCA), stored as a layer stack, the right-sided pre-fire data, the left-sided pre-fire data, the right-sided post-fire data, and the left-sided post-fire data. By compiling all of this data, the viewer can be provided with the most comprehensive impression possible of the entire procedure.

[0053] The different views interact by synergistically complementing the advantages of the spatial perception of the individual data sets—that is, the slice data and the rotating image sequences. This allows the area of ​​interest and, if applicable, the position of the biopsy needle to be localized and assessed more accurately than would be possible with individual data sets. According to the invention, imaging artifacts caused by the biopsy needle are also avoided.

[0054] Finally, it should be noted once again that the devices and methods described in detail above are merely exemplary embodiments that can be modified in a variety of ways by those skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not exclude the possibility that the respective features may be present in multiple instances. Likewise, the terms "device," "unit," and "system" do not exclude the possibility that the respective component consists of several interacting subcomponents, which may also be spatially distributed. List of reference symbols

[0055] 1 Tomosynthesis system 2 Tomosynthesis device 3 Source-detector arrangement 4 X-ray source 5 Detector 5.1 Detection surface 6 Plate 7 Circular recess 8 Examination instrument, biopsy device 9 Robot arm 10 Image reconstruction device 11 Control device 12 Computer unit 13 Mouse 14 Keyboard 15 Screen 16 Drive 17 Stand column 18 Rotating arm 20 Computer system 21 Acquisition unit 22 Determination unit 23 Output unit 24 Input data interface 25 Output interface 26 Bus A1, A2, ..., A6 Acquisition angle SP Synthetic projections AD Output data AD` Total output data MA Central axis O Examination object, breast RD Raw data ACQ, CAL, DIS Process steps BIO, DIS`, INS, Po-L, Po-R, Pr-L, Pr-R Process steps

Claims

1. Method for visualising a region of interest inside an examination object (O) into which an examination instrument (8) has been introduced, the method being performed by means of a tomosynthesis system (2), wherein the introduction is not included by the method according to the invention, wherein the method comprises at least the following steps: - acquiring (ACQ) raw datasets (RD) from a number of lateral acquisition angles (A1, A2, A3, ..., A6), wherein acquisition angles in a range around a central axis are omitted and the examination instrument is arranged in the vicinity of the central axis, whereby a blocking of a beam path by the examination instrument is avoided, wherein the raw datasets (RD) are acquired at acquisition angles (A1, A2, A3, ..., A6) of at least 10°, preferably at least 15°, to a central axis (MA), - calculating (CAL) a number of synthetic projections (SP) from the raw datasets (RD), wherein the synthetic projections (SP) are reconstructed directly from the raw data (RD), or wherein the calculating (CAL) comprises a reconstruction of a volume dataset or individual thin slices from the raw data and a forward projection of the volume dataset or the thin slices on a virtual detector, and - outputting (DIS) the synthetic projections (SP) in the form of an image sequence (AD) which represents the examination object (O) in a rotating visualisation, wherein the synthetic projections (SP) are merged in the image sequence (AD) in such a manner that, when the image sequence (AD) is run or played back, the impression is created in an observer that the visualised examination object (O) is rotating.

2. Method according to claim 1, wherein the raw datasets (RD) are acquired at acquisition angles (A1, A2, A3, ..., A6) of at most 60°, preferably at most 45°, particularly preferably at most 25°, to a central axis (MA).

3. Method according to one of the preceding claims, wherein the number of lateral acquisition angles (A1, A2, A3, ..., A6) amounts to at least 10, preferably 20.

4. Method according to one of the preceding claims, wherein two raw datasets (RD) are acquired in each case from acquisition angles (A1, A2, A3, ..., A6) which, referred to a central axis, are arranged opposite each other.

5. Method according to one of the preceding claims, wherein the output (DIS) of the synthetic projections (SP) comprises a maximum intensity projection.

6. Method according to one of the preceding claims, wherein the raw data (RD) is acquired before and / or after an actuation of the examination instrument (8), wherein the actuation entails the sample-taking process during a biopsy with the aid of a biopsy needle, wherein the sample-taking is not included by the method according to the invention.

7. Image reconstruction device (10) for visualising a region of interest inside an examination object (O) into which an examination instrument (8) has been introduced, comprising - an acquisition unit (21) which is embodied in such a way that it acquires raw datasets (RD) from a number of lateral acquisition angles (A1, A2, A3, ..., A6), wherein acquisition angles in a range around a central axis are omitted and the examination instrument is arranged in the vicinity of the central axis, wherein the raw datasets (RD) are acquired at acquisition angles (A1, A2, A3, ..., A6) of at least 10°, preferably at least 15°, to a central axis (MA), whereby a blocking of a beam path by the examination instrument is avoided, - a calculation unit (22) which is embodied in such a way that it calculates a number of synthetic projections (SP) from the raw datasets (RD), wherein the synthetic projections (SP) are reconstructed directly from the raw data (RD), or wherein the calculating (CAL) comprises a reconstruction of a volume dataset or individual thin slices from the raw data and a forward projection of the volume dataset or the thin slices on a virtual detector, and - an output unit (23) which is embodied in such a way that it outputs the synthetic projections (SP) in the form of an image sequence (AD) which represents the examination object (O) in a rotating visualisation, wherein the synthetic projections (SP) are merged in the image sequence (AD) in such a manner that, when the image sequence (AD) is run or played back, the impression is created in an observer that the visualised examination object (O) is rotating.

8. Tomosynthesis system (1) comprising a tomosynthesis device (2) having a source-detector arrangement (3) which is embodied for acquiring raw data (RD) of an examination object (O) from defined acquisition angles (A1, A2, A3, ..., A6), and an image reconstruction device (10) according to claim 7.

9. Computer program product having a computer program which can be loaded directly into a memory device of an image reconstruction device (10) of a tomosynthesis system (1), and having program sections for the purpose of performing all steps of a method according to one of claims 1 to 6 when the computer program is executed in the image reconstruction device (10) of the tomosynthesis system (1).

10. Computer-readable medium on which are stored program sections that can be read in and executed by a computer unit in order to perform all steps of a method according to one of claims 1 to 6 when the program sections are executed by the computer unit.