Transfer of a desired image impression between different magnetic resonance imaging systems

Abstract

A method for transmitting an image impression between different magnetic resonance imaging systems (MR1, MR2) is described. In the method, reference image data (RBD) are generated from a phantom for a plurality of different pulse sequence protocols (P) with different parameter settings using a first magnetic resonance imaging system (MR1). New image data (NBD) are also generated from the phantom for the plurality of different pulse sequence protocols (P) with different parameter settings using a second magnetic resonance imaging system (MR2) that differs from the first magnetic resonance imaging system (MR1).Adapted parameter values ​​(PPM) for the different parameter settings of the second magnetic resonance imaging system (MR2) are determined based on a result of a cost function (K) that quantifies the similarity between the image impression of the new image data (NBD) and the image impression of the reference image data (RBD). Finally, the parameter settings in the second magnetic resonance imaging system (MR2) are adjusted using the adapted parameter values ​​(PPM). A transmission device (20) is also described. Furthermore, a magnetic resonance imaging system (MR2) is described.

Description

[0001] The invention relates to a method for transmitting an image impression between different magnetic resonance imaging systems. The invention also relates to a transmission device. Furthermore, the invention relates to a magnetic resonance imaging system.

[0002] In diagnostic imaging, achieving consistent image impressions across different scanner models and software remains a challenge. This can be due to different available acquisition and / or reconstruction technologies, and in particular, different acceleration technologies, different hardware configurations, hardware differences, and hardware tolerances.

[0003] These differences lead to workflow problems, as both radiographers (MTRA is an abbreviation for "medical technical assistant") and radiologists are trained in specific image impressions. In particular, technicians may not be able to carry out their quality assurance work as planned, and radiologists may have difficulty annotating and interpreting images when the image impressions change. This is particularly important in cases where longitudinal patient observations are required to determine the evolution of certain diseases, such as multiple sclerosis or tumor follow-ups (for tracking former cancer patients or monitoring the course of treatment, particularly regarding chemotherapy and / or radiation therapy).

[0004] This makes it very difficult to introduce new technologies in this field, as customers and users want to avoid the aforementioned problems and save themselves the effort of adapting a newly available technology to their usual image impressions. This customer reluctance leads to lower market penetration with new technology than would be possible. As a result, patients are often not scanned with the optimal programs, and the efficiency of the new system for customers and users does not reach its full potential.

[0005] Until now, attempts to solve the above problem involved a very cumbersome process, whereby an application specialist familiar with both the old and new technologies attempted to achieve the same image impression with the new technologies as achieved with the old technology, while optimizing the scan time and / or resolution.

[0006] Such a process is based on a mixture of trial and error and educated guesswork, requiring considerable experience from application specialists. This leads to a number of problems, some of which are listed below.

[0007] To find a comparable starting point for configuring a computer program for imaging requires a deep understanding. However, it is becoming increasingly difficult to find qualified personnel to take on this task. Furthermore, as the technology portfolio grows over time, the amount of knowledge required for this task increases each year.

[0008] Since there is no objective definition of image impression and this is a trial-and-error approach, numerous experiments and evaluations with customers are required to achieve the desired results. Furthermore, this cannot usually be achieved with pure phantom tests; patients are also required, and application specialists often require multiple trials and customer visits.

[0009] Since this approach depends solely on the person performing it, there is very limited ability to maintain and ensure consistent quality so that an optimal setting is achieved.

[0010] If an automatic or semi-automatic process were possible that would at least provide a starting point for program settings, this would greatly improve the current approach.

[0011] The object is therefore to develop a method and a device for transmitting an image impression between different magnetic resonance imaging systems or magnetic resonance imaging systems with different states with improved reliability and independence from the skills of a specialist.

[0012] This object is achieved by a method for transmitting an image impression between different magnetic resonance imaging systems according to patent claim 1, a transmission device according to patent claim 12 and a magnetic resonance imaging system according to patent claim 13.

[0013] In the method according to the invention for transmitting an image impression between different magnetic resonance imaging systems, reference image data is generated from a phantom for a plurality of different pulse sequence protocols with different parameter settings using a first magnetic resonance imaging system. "Different magnetic resonance imaging systems" should be understood not only to mean magnetic resonance imaging systems with different technical properties, in particular different hardware, but also to include magnetic resonance imaging systems with the same or identical hardware running different software or, in particular, different versions of a software.The reference image data is acquired by a phantom, which is preferably reproducibly positionable and is particularly preferably arranged at a predetermined position with a predetermined pose in a coordinate system of the scanning unit of the magnetic resonance imaging system. The coordinate system is preferably made recognizable by means of markers in the reference image data that are visible through magnetic resonance imaging.

[0014] In addition, new image data is generated from the phantom for the plurality of different pulse sequence protocols with different parameter settings using a second magnetic resonance imaging system. The second magnetic resonance imaging system differs from the first magnetic resonance imaging system in terms of its hardware and / or software, and therefore, it is expected that if the pulse sequence protocols for one and the same pulse sequence protocol with the same parameter settings were adopted unchanged on different magnetic resonance imaging systems, differences in the image impression would also occur.

[0015] In order to compensate for these differences in the image impression, adapted parameter values ​​for the different parameter settings of the pulse sequence protocols of the second magnetic resonance imaging system are subsequently generated based on the result of a cost function that quantifies the similarity between the image impression of the new image data and the image impression of the reference image data. A cost function is a function that can be used to adapt two systems. In this case, the parameterization of the system of the second magnetic resonance imaging system is adjusted in such a way that the output images appear as similar as possible to the images of the first magnetic resonance imaging system in terms of their image impression. The cost function indicates a type of “error” orIt calculates the "deviation" between the image impressions of the two systems and can be used to determine an optimum using well-known methods such as regression or gradient descent. The cost function includes as many sets of image data as possible, preferably all sets of image data (reference image data and new image data) generated with different pulse sequence protocols.

[0016] Finally, the adapted parameter values ​​are used to adjust the parameter settings of the different pulse sequence protocols in the second magnetic resonance imaging system in order to adapt the image impression on the second magnetic resonance imaging system to the image impression of the first magnetic resonance imaging system.

[0017] Advantageously, the adaptation of pulse sequence protocol parameter settings can be automated. The use of the cost function eliminates the need for adaptation by a specialist or the user of the old and new magnetic resonance imaging systems. If, in addition to the image impression, other image properties or optimization focuses, particularly resolution or speed, are to be adjusted, their desired features can also be included in the cost function. This relieves the user of a particularly complex task, greatly facilitating migration between different systems.

[0018] The transmission device according to the invention comprises a reference data receiving unit. The reference data receiving unit is configured to receive reference image data from a phantom for a plurality of different pulse sequence protocols with different parameter settings from a first magnetic resonance imaging system.

[0019] The transmission device according to the invention also has an image data generation unit for generating new image data from the phantom for the plurality of different pulse sequence protocols with the different parameter settings using a second magnetic resonance imaging system. To generate the new image data, pulse sequences based on the different pulse sequence protocols are transmitted to a scanning unit of the second magnetic resonance imaging system. The phantom already used to generate the reference image data is arranged in the second magnetic resonance imaging system. Raw data from the phantom is then acquired using the pulse sequences, and the new image data is reconstructed based on the acquired raw data. A reconstruction unit already present in a control device of the second magnetic resonance imaging system can also be used for this purpose.

[0020] Furthermore, the transmission device according to the invention comprises a determination unit for determining adapted parameter values ​​for the different parameter settings of the pulse sequence protocols of the second magnetic resonance imaging system based on the result of a cost function that quantifies the similarity between the image impression of the new image data and the image impression of the reference image data. Such a cost function is preferably designed such that its result approaches the value zero when the image impressions of the compared image data are identical, and its result assumes a value significantly different from zero when the image impressions of the compared image data differ significantly.

[0021] The transmission device according to the invention also includes an adaptation unit for adapting the parameter settings in the second magnetic resonance imaging system to the adapted parameter values. For this purpose, the adapted parameter values ​​are stored in a data storage unit of the second magnetic resonance imaging system. The transmission device according to the invention shares the advantages of the method according to the invention for transmitting an image impression between different magnetic resonance imaging systems.

[0022] The magnetic resonance imaging system according to the invention comprises the transmission device according to the invention, a scanning unit and a control device for controlling the scanning unit on the basis of parameter values ​​of pulse sequence protocols adapted by the transmission device.

[0023] A large portion of the aforementioned components of the transmission device according to the invention can be implemented entirely or partially in the form of software modules in a processor of a corresponding computing system, e.g., a control device of a magnetic resonance imaging system or a computer used to control such a system. A largely software-based implementation has the advantage that even previously used computing systems can be easily upgraded to operate in the manner according to the invention via a software update.

[0024] 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 computer system, with program sections for executing the steps of the inventive method for transmitting an image impression between different magnetic resonance imaging systems when the program is executed in the computer system. Such a computer program product may, 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.

[0025] A computer-readable medium, e.g., a memory stick, a hard disk, or another portable or permanently installed data storage device, on which the program sections of the computer program that can be read and executed by a computer system are stored, can be used for transport to the computer system and / or for storage on or in the computer system. For this purpose, the computer system can, for example, have one or more cooperating microprocessors or the like.

[0026] The dependent claims and the following description each contain particularly advantageous embodiments and developments of the invention. In particular, the claims of one claim category can also be developed analogously to the dependent claims of another claim category. Furthermore, within the scope of the invention, the various features of different embodiments and claims can also be combined to form new embodiments.

[0027] In a preferred variant of the method according to the invention, the first magnetic resonance imaging system and the second magnetic resonance imaging system differ with respect to at least one of the following features: - the hardware of the respective system, - the software used for imaging of the respective system.

[0028] Advantageously, both hardware and software migrations can be compensated by the method according to the invention, so that a user can always retain the familiar image impression in the event of any change to a magnetic resonance imaging system.

[0029] Preferably, a different imaging program and / or a different pulse sequence protocol is assigned to each of the different parameter settings. This means that the imaging is performed with different objectives and / or different pulse sequences. Advantageously, a magnetic resonance imaging system can be used for very different applications, and migration between different magnetic resonance imaging systems and / or different software variants or versions is also carried out in such a way that these different applications are possible with the same image impression or at least a comparable image impression on the new system.

[0030] Particularly preferably, the parameter settings are adjusted in such a way that the result of the cost function is iteratively optimized to represent optimal similarity between the reference image data and the new image data. This advantageously achieves optimal similarity between the image impressions from different imaging systems.

[0031] In a preferred embodiment of the method according to the invention, the cost function comprises, in addition to the similarity of the image impressions depending on the parameter settings of the pulse sequences, also additional criteria with which additional goals are pursued in addition to the similarity of the image impression and / or additional constraints are taken into account in addition to the similarity of the image impression.

[0032] Preferably, the additional objectives include one of the following objectives: - the acquisition time, - the activation of a special acceleration technique as a specific way to influence the acquisition time, - Functionalities to improve image quality.

[0033] Advantageously, additional optimization goals can be included in the adaptation process and can also be tracked automatically. Reducing acquisition time can contribute to improving image quality for moving objects.

[0034] The similarity between the reference image data and the newly generated image data is preferably characterized by at least one of the following metrics: - the numerical values ​​and derived values, in particular grey values, of the voxels of the image data, - the contrast, - the signal-to-noise ratio, - the image resolution.

[0035] "Numerical values" here refer to the intensity values ​​assigned to the voxels, which are generated during the reconstruction of image data based on raw data. Contrast, signal-to-noise ratio, and image resolution are influenced by the gray values ​​of the voxels. The comparison of the similarity of image data can therefore be performed based on the gray values ​​of voxels, which are fully known after the image data has been acquired.

[0036] Preferably, the different parameter settings of the pulse sequence protocols include parameters that influence and / or change the image impression. Advantageously, the image impression of the new image data can be adapted to the image impression of the reference image data by parameter adaptation, i.e., changing and adjusting the parameter values ​​of the pulse sequence protocols of the new magnetic resonance imaging system.

[0037] Preferably, the different parameter settings include at least one of the following parameters: - filter parameters, - the repetition time, - the echo time, - the contrast, - the acceleration factor.

[0038] The aforementioned parameters influence the image impression in different ways.

[0039] In particular, an image filter to which filter parameters are assigned influences the noise reduction in the image data and thus also the image impression.

[0040] The repetition time is an important parameter for contrast adjustment. In particular, the repetition time can be used to adjust the type of weighting, such as T1 weighting. Furthermore, the repetition time is one of the most important factors for image acquisition time. The repetition time also plays a role in saturation effects, which are particularly important with very short repetition times, such as those that occur with fast sequences.

[0041] Similarly, the echo time or the inversion time are also relevant for contrast formation.

[0042] The acceleration factor plays a decisive role in the image quality and thus also in the image impression.

[0043] Preferably, the different parameter settings do not include the following parameters: - the layer resolution, - the number of voxels, - the image geometry, - the positioning of an object or phantom under investigation, - Navigator parameters, - the coil setting.

[0044] The slice resolution refers specifically to the number of slices to be imaged. This should not be changed.

[0045] The number of voxels indicates the base resolution and should also not be changed in order not to change the image composition.

[0046] The image geometry includes, in particular, the dimensions of the field of view (or the dimensions of the image representations) and the dimensions of the voxels, and is related to the number of voxels. It should also remain constant.

[0047] The positioning of the phantom in the isocenter should also remain unchanged to enable voxel-wise comparison.

[0048] The navigator setting should also remain unchanged to avoid changing the image geometry.

[0049] Coil setting concerns the use of local receiving coils and their arrangement, which should also remain the same for a specific type of imaging.

[0050] In a preferred variant of the method according to the invention, the reference image data comprise a representative sub-area of ​​the entire examination area. Particularly preferably, the reference image data comprise a single image slice. Advantageously, the acquisition time for acquiring reference image data can be kept short or even minimal. Furthermore, the memory requirements and the resources required for processing the reference image data can be kept short or even minimal.

[0051] Automated adjustment of the pulse sequence protocol parameters on the second magnetic resonance imaging system is also preferred. This adjustment can advantageously be performed independently of the expertise of individual specialists.

[0052] A semi-automated adjustment of the pulse sequence protocol parameters is also preferred. In this case, an expert is automatically presented with a suggestion for adjusting the pulse sequence protocol parameters for the second magnetic resonance imaging system. The expert then has the option of modifying or confirming the pulse sequence protocols. In an additional step, the expert has his or her modifications automatically reviewed and receives a review result. Based on the result, the expert decides whether his or her modifications should be adopted or whether the original automated suggestion should be saved in the second magnetic resonance imaging system. Advantageously, the expert can influence the final result of the parameter adaptation while simultaneously relying on automatically determined results as a basis for decision-making, which greatly reduces the effort required by the expert.

[0053] The invention is explained in more detail below with reference to exemplary embodiments in the accompanying figures. They show: Fig. 1 is a flowchart illustrating a method for transmitting an image impression between different magnetic resonance imaging systems according to an embodiment of the invention, Fig. 2 a schematic representation of a transmission device according to an embodiment of the invention, Fig. 3 a schematic representation of a magnetic resonance imaging system according to an embodiment of the invention.

[0054] In Fig. 1 shows a flowchart 100 illustrating a method for transferring an image impression between different magnetic resonance imaging systems.

[0055] In step 1.I, reference image data RBD is acquired from a phantom for a plurality of different protocols P for pulse sequences with different parameter settings on a first magnetic resonance imaging system MR1. The parameter settings correspond to settings that produce an image impression optimized for the respective imaging purpose of the respective protocol. The image impression can also be adapted to the individual preferences of a specific user.

[0056] In step 1.II, new image data NBD are acquired from the phantom on a second magnetic resonance imaging system MR2 for the plurality of different protocols P for pulse sequences with the different parameter settings of the second magnetic resonance imaging system MR2. It is initially advisable to select the same parameter settings for the acquisition of the new image data NBD as for the acquisition of the reference image data RBD with the first magnetic resonance imaging system MR1.

[0057] In step 1.III, a cost function K is generated which quantifies the similarity between the image impression of the new image data NBD and the image impression of the reference image data RBD.

[0058] In step 1.IV, an adjustment process of the parameter settings on the second magnetic resonance imaging system MR2 takes place depending on a result of the cost function K, wherein adjusted protocol parameters PPM for the pulse sequence protocols of the second magnetic resonance imaging system MR2 are determined.

[0059] In Fig. 2 is a schematic representation of a transmission device 20 according to an embodiment of the invention.

[0060] The transmission device 20 comprises a reference data receiving unit 21 for receiving reference image data RBD from a phantom for a plurality of different protocols for pulse sequences with different parameter settings with a first magnetic resonance imaging system MR1.

[0061] The transmission device 20 also has an image data receiving unit 22 for receiving new image data NBD from the phantom for the plurality of different protocols for pulse sequences with the different parameter settings from a second magnetic resonance imaging system MR2.

[0062] Furthermore, the transmission device 20 comprises a determination unit 23 for generating a cost function K, which quantifies the similarity between the image impression of the new image data NBD and the image impression of the reference image data RBD.

[0063] Part of the transmission device 20 is also an adaptation unit 24 for adapting the parameter settings in the second magnetic resonance imaging system as a function of a result of the cost function K, wherein adapted parameter values ​​PPM are determined.

[0064] In Fig. Figure 3 is a schematic representation of an ensemble 30 comprising a first magnetic resonance imaging system MR1 and a second magnetic resonance imaging system MR2 according to an embodiment of the invention. The magnetic resonance imaging system MR2 comprises a scanning unit 31 and a control device 32. The control device 32 comprises a transmission device 20 for generating adjusted parameter values ​​PPM, which Fig. 2. The second magnetic resonance imaging system MR2 receives reference image data RBD from the first magnetic resonance imaging system MR1, which reference image data are used to adapt the image impression of the second magnetic resonance imaging system MR2 to the image impression of the first magnetic resonance imaging system MR1.

[0065] Finally, it is pointed out once again that the methods and devices described above are merely preferred embodiments of the invention and that the invention can be varied by a person skilled in the art without departing from the scope of the invention, insofar as it is defined by the claims. For the sake of completeness, it is also pointed out that the use of the indefinite articles “a” or “an” does not exclude the possibility that the features in question may be present in multiple units. Likewise, the term “unit” does not exclude the possibility that it consists of several components, which may also be spatially distributed. Regardless of the grammatical gender of a particular term, persons with male, female or other gender identity are included.

Claims

[1] Method for transmitting an image impression between different magnetic resonance imaging systems (MR1, MR2), comprising the steps: - generating reference image data (RBD) from a phantom for a plurality of different pulse sequence protocols (P) with different parameter settings using a first magnetic resonance imaging system (MR1), - generating new image data (NBD) from the phantom for the plurality of different pulse sequence protocols (P) with different parameter settings using a second magnetic resonance imaging system (MR2) different from the first magnetic resonance imaging system (MR1), - Determining adapted parameter values ​​(PPM) for the different parameter settings of the second magnetic resonance imaging system (MR2) based on a result of a cost function (K) which quantifies the similarity between the image impression of the new image data (NBD) and the image impression of the reference image data (RBD), - Adjusting the parameter settings in the second magnetic resonance imaging system with the adapted parameter values ​​(PPM). [2] The method of claim 1, wherein the first magnetic resonance imaging system (MR1) and the second magnetic resonance imaging system (MR2) differ with respect to at least one of the following features: - the hardware, - the software used for imaging. [3] Method according to claim 1 or 2, wherein a different imaging program and / or a different pulse sequence protocol (P) is assigned to the different parameter settings. [4] Method according to one of the preceding claims, wherein the adjustment of the parameter settings is carried out in such a way that the result of the cost function (K) is optimized such that it represents an optimal similarity between the reference image data (RBD) and the new image data (NBD). [5] Method according to one of the preceding claims, wherein the cost function (K) comprises, in addition to the similarity of the image impression, additional criteria with which additional objectives are pursued in addition to the similarity of the image impression. [6] The method of claim 5, wherein the additional objectives comprise one of the following objectives: - the acquisition time, - the activation of a special acceleration technique as a specific way to influence the acquisition time, - energy consumption, - Functionalities to improve image quality. [7] Method according to one of the preceding claims, wherein the similarity between the image impression of the new image data (NBD) and the image impression of the reference image data (RBD) is characterized by at least one of the following measured variables: - the gray values ​​of the voxels of the image data, - the contrast, - the signal-to-noise ratio, - the image resolution. [8] Method according to one of the preceding claims, wherein the different parameter settings comprise parameters which influence and / or change the image impression. [9] Method according to one of the preceding claims, wherein the different parameter settings which influence and / or change the image impression comprise one of the following parameters: - a filter parameter, - the repetition time, - the echo time, - the contrast, - an acceleration factor. [10] Method according to claim 9, wherein the different parameter settings do not include the following parameters: - the layer resolution, - the number of pixels, - the image geometry, - the positioning of the phantom, - Navigator parameters, - the coil setting. [11] Method according to one of the preceding claims, wherein an automated adaptation of the parameters of the protocols takes place in the second magnetic resonance imaging system (MR2). [12] Transmission device (20), comprising: - a reference data receiving unit (21) for receiving reference image data (RBD) from a phantom for a plurality of different pulse sequence protocols (P) with different parameter settings from a first magnetic resonance imaging system (MR1), - an image data receiving unit (22) for receiving new image data (NBD) from the phantom for the plurality of different pulse sequence protocols (P) with the different parameter settings from a second magnetic resonance imaging system (MR2), - a determination unit (23) for determining adapted parameter values ​​(PPM) for the different parameter settings of the second magnetic resonance imaging system (MR2) on the basis of a result of a cost function (K) which quantifies the similarity between the image impression of the new image data (NBD) and the image impression of the reference image data (RBD), - an adaptation unit (24) for adapting the parameter settings in the second magnetic resonance imaging system (MR2) with the adapted parameter values ​​(PPM). [13] Magnetic resonance imaging system (MR2), comprising: - a transmission device (20) according to claim 12, - a scanning unit (31), - a control device (32) for controlling the scanning unit (31) on the basis of parameter values ​​(PPM) of pulse sequence protocols (P) adapted by the transmission unit (20). [14] A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to any one of claims 1 to 11. [15] A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to claims 1 to 11.

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