Determination method of heart motion field and CT (Computed Tomography) equipment

Abstract

The invention discloses a cardiac motion field determination method and CT equipment, and relates to the technical field of medical image reconstruction. According to the method, an initial whole heart motion field of a heart can be obtained based on heart images of a plurality of target periods and heart images of a reference period, and a target object motion field of a target object in the heart is obtained based on the initial whole heart motion field; the initial whole heart motion field and the target motion field can then be fused to obtain a target heart motion field. Therefore, when the method is used for estimating the motion of the heart, the complexity of the motion of different tissues (namely the heart and the target object) can be fully considered, so that the overall motion of the heart and the local motion of the target object in the heart can be considered, and the determined target heart motion field can accurately reflect the position change of the heart. Therefore, it can be ensured that the compensation precision of motion compensation based on the target heart motion field is high.

Description

Technical Field

[0001] This application relates to the technical field of medical image reconstruction, and particularly to a method for determining a cardiac motion field and a CT device. Background Art

[0002] In the scanning and imaging of the heart, due to the movement of the heart during the scanning process, there are many motion artifacts in the reconstructed heart image, which affects the quality of the heart image.

[0003] Currently, it is possible to first calculate the cardiac motion field (which can also be called the cardiac displacement field) generated by the movement of the heart. This cardiac motion field can characterize the position change of the heart. After that, when reconstructing the heart image, motion compensation can be performed according to this cardiac motion field to reduce the motion artifacts in the reconstructed heart image. Summary of the Invention

[0004] This application provides a method for determining a cardiac motion field and a CT device, and the technical solutions are as follows:

[0005] On the one hand, a method for determining a cardiac motion field is provided, and the method includes:

[0006] Based on the cardiac images of multiple target phases and the cardiac image of the reference phase, obtain the initial full cardiac motion field of the heart;

[0007] Based on the initial full cardiac motion field, obtain the motion field of the target object in the heart;

[0008] Fuse the initial full cardiac motion field and the motion field of the target object to obtain the target cardiac motion field of the heart.

[0009] Optionally, based on the cardiac images of multiple target phases and the cardiac image of the reference phase, obtaining the initial full cardiac motion field of the heart includes:

[0010] Based on the reference phase, obtain multiple target phases, and the multiple target phases are distributed on both sides of the reference phase on the time axis;

[0011] Register the cardiac images of each target phase to the cardiac image of the reference phase to determine the first full cardiac deformation field of the heart from each target phase to the reference phase;

[0012] Based on multiple first full cardiac deformation fields, determine the initial full cardiac motion field of the heart.

[0013] Optionally, obtaining multiple target phases based on the reference phase includes:

[0014] Determine the acquisition time of the first view in multiple views corresponding to the reference period and the acquisition time of the last view in the multiple views corresponding to the reference period;

[0015] Based on the acquisition time of the first view, determine the first target phase among multiple target phases, where the acquisition time of the first view is the acquisition time of the central view in multiple views corresponding to the first target phase;

[0016] Based on the acquisition time of the last view, determine the last target phase among multiple target phases, where the acquisition time of the last view is the acquisition time of the central view in multiple views corresponding to the last target phase.

[0017] Optionally, multiple target phases are symmetric about the reference period on the time axis.

[0018] Optionally, based on multiple first whole-heart deformation fields, obtain the initial whole-heart motion field of the heart, including:

[0019] Based on multiple first whole-heart deformation fields, use interpolation to obtain the second whole-heart deformation field from the target time to the reference period;

[0020] Based on multiple first whole-heart deformation fields and the second whole-heart deformation field, obtain the initial whole-heart motion field of the heart.

[0021] Optionally, based on multiple first whole-heart deformation fields, use interpolation to obtain the second whole-heart deformation field from the target time to the reference period, including:

[0022] Based on the target time to be interpolated, determine at least two reference phases from multiple target phases, and the at least two reference times are distributed on both sides of the target time on the time axis;

[0023] Based on the distances between the target time and each reference phase on the time axis, and the first whole-heart deformation fields from each reference phase to the reference period, determine the second whole-heart deformation field from the target time to the reference period.

[0024] Optionally, based on the initial whole-heart motion field, obtain the motion field of the target object in the heart, including:

[0025] Perform motion compensation on the heart image of the reference period based on the initial whole-heart motion field to obtain an initial heart image;

[0026] Based on the initial heart image, obtain the region where the target object is located;

[0027] For any target moment, based on the region where the target object is located, obtain a sub-image of the target object, and iterate with the initial full-heart motion field as the initial value of the motion field increment of the target object, and transform the sub-image based on the iterated motion field increment to obtain the target motion field increment of the target object, where the target motion field increment refers to: during the successive transformation of the sub-image based on the iterated motion field increment, the motion field increment when the motion artifacts in the transformed sub-image no longer decrease;

[0028] Based on multiple target motion field increments and the initial full-heart motion field, determine the target object motion field of the target object.

[0029] Optionally, fusing the initial full-heart motion field and the target object motion field to obtain the target heart motion field of the heart includes:

[0030] Perform weighted summation on the initial full-heart motion field and the target object motion field to obtain the target heart motion field of the heart.

[0031] Optionally, before performing weighted summation on the initial full-heart motion field and the target object motion field to obtain the target heart motion field of the heart, the method further includes:

[0032] Determine a first weight vector of the target object motion field, where the first weight vector includes: the first weights of each position in the heart, and the first weight of each position is proportional to the distance from the position to the target object;

[0033] Based on the first weight vector, determine a second weight vector of the initial full-heart motion field, where the second weight vector includes the second weights of each position in the heart, and the second weight is negatively correlated with the first weight.

[0034] On the other hand, a CT device is provided, and the CT device includes: a processor; the processor is configured to:

[0035] Based on the heart images of multiple target phases and the heart image of the reference phase, obtain the initial full-heart motion field of the heart;

[0036] Based on the initial full-heart motion field, obtain the target object motion field of the target object in the heart;

[0037] Fuse the initial full-heart motion field and the target object motion field to obtain the target heart motion field of the heart.

[0038] In another aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method for determining a cardiac motion field as described in the above aspect is implemented.

[0039] In yet another aspect, a computer program product is provided, which includes a computer program or computer instructions. When the computer program or the computer instructions are executed by a processor, the method for determining a cardiac motion field as described in the above aspect is implemented.

[0040] The beneficial effects brought by the technical solution provided in this application at least include:

[0041] This application provides a method for determining a cardiac motion field and a CT device. This method can obtain an initial full cardiac motion field of the heart based on cardiac images of multiple target phases and a cardiac image of a reference phase, and obtain a target motion field of a target object in the heart based on the initial full cardiac motion field. Then, it can fuse the initial full cardiac motion field and the target motion field to obtain a target cardiac motion field. Thus, it can be seen that when estimating cardiac motion, this method can fully consider the complexity of the motion of different tissues (i.e., the heart and the target object) to take into account both the overall motion and the local motion of the heart, so as to ensure that the determined target cardiac motion field can more accurately reflect the position change of the heart. Furthermore, it can ensure a higher compensation accuracy for motion compensation based on this target cardiac motion field.

[0042] The additional aspects and advantages of this application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of this application. Description of the Drawings

[0043] Figure 1 is a flowchart of a method for determining a cardiac motion field provided by an embodiment of this application;

[0044] Figure 2 is a flowchart of another method for determining a cardiac motion field provided by an embodiment of this application;

[0045] Figure 3 is a schematic diagram of the relative position between a target phase and a reference phase provided by an embodiment of this application;

[0046] Figure 4 is a flowchart of a method for obtaining a second full cardiac deformation field from a target moment to a reference phase by using an interpolation method based on multiple first full cardiac deformation fields provided by an embodiment of this application;

[0047] Figure 5 is a flowchart of a method for obtaining a target motion field of a target object provided by an embodiment of this application;

[0048] Figure 6 It is a schematic structural diagram of a CT device provided by an embodiment of the present application. Detailed implementation manners

[0049] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application and should not be construed as a limitation to the present application.

[0050] The embodiment of the present application provides a method for determining a cardiac motion field. This method is applied to a computed tomography (CT) device, for example, it can be applied to the workstation of the CT device. Refer to Figure 1 and this method includes:

[0051] Step 101, based on the cardiac image of the target phase and the cardiac image of the reference phase, obtain the initial full cardiac motion field of the heart.

[0052] Among them, this initial full cardiac motion field can be used to characterize the position change of the heart of the scanned object at each time point (i.e., moment) in the cardiac cycle relative to the reference phase, and it is a vector field that continuously changes with time. The reference phase can be any one of multiple phases of the heart.

[0053] In the embodiment of the present application, the CT device can register the cardiac image of each target phase among multiple target phases to the cardiac image of the reference phase to determine the first full cardiac deformation field of the heart from each target phase to the reference phase. Then, the CT device can determine the initial full cardiac motion field of the heart based on these multiple first full cardiac deformation fields. For example, the CT device can determine the motion field composed of these multiple first full cardiac deformation fields as the initial full cardiac motion field of the heart.

[0054] Step 102, based on the initial full cardiac motion field of the heart, obtain the target object motion field of the target object in the heart.

[0055] Among them, this target object motion field can be used to characterize the position change of the target object at each time point in the cardiac cycle relative to the reference phase, and this target object motion field is also a vector field that continuously changes with time. The target object can be the tissue of the heart of the scanned object (such as coronary arteries), or it can be an object transplanted into this heart (such as a stent or an artificial valve, etc.).

[0056] In the embodiment of the present application, the computing device can determine the target object motion field of the target object in the heart based on the initial full cardiac motion field of the heart, and can send this target object motion field to the CT device. Correspondingly, this CT device can obtain this target object motion field.

[0057] Step 103: Fuse the initial full heart motion field and the target object motion field to obtain the target heart motion field of the heart.

[0058] In the embodiment of the present application, the CT device can fuse the heart deformation fields representing the position changes of the heart at each time point among multiple time points with the target object deformation fields representing the position changes of the target object, so as to realize the fusion of the initial full heart motion field and the target object motion field, and obtain the target heart motion field of the heart. That is to say, when fusing the initial full heart motion field and the target object motion field, the heart deformation field in the initial full heart motion field needs to be aligned with the target object deformation field in the target object motion field in terms of time.

[0059] In summary, the embodiment of the present application provides a method for determining a heart motion field. This method can obtain the initial full heart motion field of the heart based on the heart images of multiple target phases and the heart image of the reference phase, and obtain the target object motion field of the target object in the heart based on this initial full heart motion field. Then, it can fuse the initial full heart motion field and the target object motion field to obtain the target heart motion field. Thus, when estimating the heart motion, the complexity of the motion of different tissues (i.e., the heart and the target object) can be fully considered to take into account both the overall motion of the heart and the local motion of the target object in the heart, so as to ensure that the determined target heart motion field can more accurately reflect the position change of the heart. Furthermore, it can ensure that the compensation accuracy for motion compensation based on this target heart motion field is relatively high.

[0060] Figure 2 Another method for determining a heart motion field provided by the embodiment of the present application, which can be applied to a CT device. Refer to Figure 2 , this method may include:

[0061] Step 201: Obtain multiple target phases based on the reference phase.

[0062] Among them, the multiple target phases are distributed on both sides of the reference phase on the time axis. Optionally, the multiple target phases are symmetric about the reference phase on the time axis. That is to say, the scanning device can reconstruct N target phases on both sides of the reference phase with the reference phase as the center, where N is an integer greater than or equal to 1. Thus, a total of 2N + 1 phases are reconstructed. The phase intervals between any two adjacent phases among the 2N + 1 phases are equal. Each phase among the 2N + 1 phases is represented by a moment.

[0063] In an embodiment of the present application, each of the reference phase and multiple target phases corresponds to multiple frames of projection (view) data, simply referred to as view. The multiple frames of view corresponding to each phase refer to the views required to reconstruct the cardiac image of that phase, that is, the multiple frames of view corresponding to each phase are used to reconstruct the cardiac image of that phase. The range of the views corresponding to the 2N target phases includes: all the views required to reconstruct the reference phase.

[0064] Exemplarily, assume N is 1, that is, the scanning device determines two target phases based on the reference phase. Refer to Figure 3 As shown in, one of the two target phases is earlier than the reference phase, and the other target phase is later than the reference phase. And it can be seen from Figure 3 that the multiple frames of view corresponding to the two target phases include the multiple frames of view corresponding to the reference phase.

[0065] Optionally, the process of the CT device obtaining multiple target phases based on the reference phase may include: determining the acquisition time of the first frame view and the acquisition time of the last frame view in the multiple frames of view corresponding to the reference phase; determining the first target phase of the multiple target phases based on the acquisition time of the first frame view, and determining the last target phase of the multiple target phases based on the acquisition time of the last frame view. Wherein, the acquisition time of the first frame view is the acquisition time of the central view in the multiple frames of view corresponding to the first target phase. The acquisition time of the last frame view is the acquisition time of the central view in the multiple frames of view corresponding to the last target phase.

[0066] That is to say, the two outermost target phases among the multiple target phases are exactly the sampling times of the starting frame and the ending frame in the multiple frames of view corresponding to the reference phase, respectively.

[0067] Step 202: For each target phase, register the cardiac image of the target phase to the cardiac image of the reference phase to determine the first whole-heart deformation field of the heart from the target phase to the reference phase.

[0068] For each target phase among the multiple target phases, the CT device can perform image registration on the cardiac image of the target phase and the cardiac image of the reference phase, so as to obtain the first whole-heart deformation field of the heart of the scanned object from the target phase to the reference phase. Wherein, the first whole-heart deformation field can be used to characterize the position change of the entire heart of the scanned object from the target phase to the reference phase. The cardiac image of each target phase is reconstructed based on the multiple frames of view corresponding to that target phase, and the cardiac image of the reference phase is reconstructed based on the multiple frames of view corresponding to that reference phase.

[0069] Optionally, the CT device may perform image registration on the cardiac image of the target phase and the cardiac image of the reference phase by using an elastic registration method, a B-spline registration method, or a deep learning-based registration algorithm.

[0070] Step 203: Obtain an initial full cardiac motion field of the heart based on multiple first full cardiac deformation fields.

[0071] The initial full cardiac motion field is used to characterize the position change of the heart of the scanned object at each time point (i.e., moment) in the cardiac cycle relative to the reference phase, and is a vector field that continuously changes with time.

[0072] In an optional implementation manner, the CT device may determine the motion field of the heart composed of multiple first full cardiac deformation fields as the initial full cardiac motion field of the heart. That is, the initial full cardiac motion field is a continuous representation of multiple first full cardiac deformation fields in time.

[0073] In another optional implementation manner, the CT device may, based on multiple first full cardiac deformation fields, use an interpolation method to obtain a second full cardiac deformation field from the target moment to the reference phase. Then, the CT device may, based on the multiple first full cardiac deformation fields and the second full cardiac deformation field, obtain the initial full cardiac motion field of the heart. For example, the CT device may determine the motion field of the heart composed of the multiple first full cardiac deformation fields and the second full cardiac deformation field as the initial full cardiac motion field of the heart. The target moment is not any of the multiple target phases.

[0074] Since the second full cardiac deformation field from the target moment to the reference phase of the heart can be obtained, and the initial full cardiac motion field of the heart is obtained based on the second full cardiac deformation field and the multiple first full cardiac deformation fields, it can be ensured that the obtained initial full cardiac motion field is smoother as a whole. Moreover, since the computational amount of obtaining the second full cardiac deformation field by interpolating the first full cardiac deformation field is less than that of obtaining the second full cardiac deformation field by increasing the phases, the efficiency of obtaining the second full cardiac deformation field by using the interpolation method is high, thereby improving the efficiency of obtaining the initial full cardiac motion field of the heart.

[0075] In the embodiment of the present application, the process of the CT device using an interpolation method to obtain a second full cardiac deformation field from the target moment to the reference phase based on multiple first full cardiac deformation fields may include: The CT device first determines at least two reference phases from multiple target phases based on the target moment to be interpolated. The at least two reference phases are distributed on both sides of the target moment on the time axis. Then, the CT determines the second full cardiac deformation field from the target moment to the reference phase based on the distance between the target moment and each reference phase on the time axis and the first full cardiac deformation field from each reference phase to the reference phase.

[0076] Optionally, the number of the target times may be multiple, that is, the CT device may obtain multiple second whole-heart deformation fields based on multiple first whole-heart deformation fields. The interpolation method may be a linear interpolation method, a spline interpolation method, a cubic interpolation method, or the like.

[0077] Taking the linear interpolation method as an example, an exemplary description is given of the process in which the CT device obtains the second whole-heart deformation field from the target time to the reference phase by using the interpolation method based on multiple first whole-heart deformation fields. Refer to Figure 4 and the process may include:

[0078] Step 2031: Determine two reference phases from multiple target phases based on the target time to be interpolated.

[0079] In the embodiment of the present application, if the time interval between the target time and the reference phase is greater than the phase interval, the two reference phases include: two target phases adjacent to the target time. If the time interval between the target time and the reference phase is less than or equal to the phase interval, the two reference phases include: the reference phase and a target phase adjacent to the reference phase. Specifically, if the target time is earlier than the reference phase, the target phase adjacent to the reference phase is: the target phase adjacent to the reference phase and earlier than the reference phase. If the target time is later than the reference phase, the target phase adjacent to the reference phase is: the target phase adjacent to the reference phase and later than the reference phase.

[0080] Step 2032: Perform linear interpolation processing on the first whole-heart deformation field from each reference phase to the target phase by using the linear interpolation method to obtain the second whole-heart deformation field of the heart from the target time to the reference phase.

[0081] Wherein, the second whole-heart deformation field is positively correlated with the first whole-heart deformation field from each reference phase to the target phase. It should be understood that the heart deformation field of the heart from the reference phase to the reference phase is 0. That is to say, in the case where the two reference phases include the reference phase, it can be considered that the second whole-heart deformation field from the target time to the reference phase is directly obtained based on the first whole-heart deformation field from the target phase other than the reference phase to the reference phase in the two reference phases.

[0082] For example, the second whole-heart deformation field D of the heart determined by the CT device from the target time to the reference phase t wh may satisfy:

[0083]

[0084] where v t is the target time, v i is the i-th target phase among multiple target phases, v i+1is the (i + 1)-th target phase among multiple target phases. D i wh is the first full-heart deformation field of the heart from the i-th target phase to the reference phase, is the first full-heart deformation field of the heart from the (i + 1)-th target phase to the reference phase. v ref is the reference phase. i is an integer greater than or equal to 1 and less than or equal to the total number of multiple target phases. And it can be seen therefrom that the interpolation method can obtain the second full-heart deformation field based on the distance from the target time to the reference phase on the time axis and the first full-heart deformation fields of each reference phase to the reference phase.

[0085] Step 204: Obtain the initial full-heart motion field of the heart and obtain the target motion field of the target object in the heart.

[0086] For the target object in the heart, the initial full-heart motion field may not accurately reflect the local motion of the target object. Therefore, it is necessary to additionally calculate the target object motion field that can accurately reflect the position change of the target object based on the initial full-heart motion field of the heart. It can be seen that the method provided in the embodiments of the present application can estimate the motion of the heart from rough to fine.

[0087] Among them, the target object motion field can be used to characterize the position change of the target object at each time point in the cardiac cycle relative to the reference phase, and the target object motion field is also a vector field that continuously changes with time. The target object can be the tissue of the heart of the scanned object (such as coronary arteries), or can be an object transplanted into the heart (such as a stent or an artificial valve, etc.).

[0088] In the embodiments of the present application, referring to Figure 5 , the process of the CT device executing step 204 may include the following steps:

[0089] Step 2041: Perform motion compensation on the heart image of the reference phase based on the initial full-heart motion field to obtain an initial heart image.

[0090] The initial full-heart motion field includes multiple full-heart deformation fields. After the CT device obtains the initial full-heart motion field of the heart of the scanned object, it can perform image transformation on the heart image of the reference phase based on each full-heart deformation field in the multiple full-heart deformation fields to perform motion compensation on the reference phase, so as to obtain the corresponding initial heart image of the reference phase. The initial heart image is a three-dimensional image.

[0091] Step 2042: Based on the initial heart image, obtain the region where the target object is located.

[0092] For the initial full-heart image, the CT device can perform object recognition and segmentation processing on the initial heart image to obtain the location area of the object from the initial heart image. The location area of the object can be represented in the form of coordinates.

[0093] It can be understood that if the object is the coronary artery of the heart, the location area of the coronary artery segmented from the initial heart image includes a certain range of heart tissue around the coronary artery.

[0094] Step 2043: For any target moment, based on the location area of the object, obtain a sub-image of the object, and use the initial full-heart motion field as the initial value of the motion field increment of the object for iteration, and transform the sub-image of the object based on the iterated motion field increment to obtain the target motion field increment of the object.

[0095] Among them, the target motion field increment refers to: in the process of sequentially transforming the sub-image based on the iterated motion field increment, the motion field increment when the motion artifacts in the transformed sub-image no longer decrease.

[0096] In the embodiments of the present application, for each target moment, the CT device can use the full-heart deformation field corresponding to the target moment in the initial full-heart motion field as the initial value of the motion field increment, iteratively adjust the motion field increment within a certain range, and determine the intermediate deformation field of the object based on the motion field increment after each iteration and the full-heart deformation field. Each adjustment of the motion field increment is based on the previous one. Then, the CT device can perform image transformation on the sub-image based on the intermediate deformation field to obtain the transformed sub-image; and judge whether the motion artifacts in the transformed sub-image after this transformation are reduced based on the sub-image after the previous transformation. After that, if the CT device determines that the motion artifacts no longer decrease, it can determine the motion field increment when the motion artifacts no longer decrease as the target motion field increment of the object from the moment corresponding to the full-heart deformation field to the reference phase. Among them, the intermediate deformation field can be obtained by fusing the iterated motion field increment and the full-heart deformation field. The process of iterative adjustment can refer to CN114202509A.

[0097] Optionally, if the object is the coronary artery, the CT device can use the initial full-heart motion field as the initial value of the motion field increment, and iteratively solve the objective function that minimizes the coronary artery motion artifact metric (MAM) based on the sub-image, so as to obtain the target motion field increment of the coronary artery.

[0098] Step 2044: Based on multiple target motion field increments and the initial full-heart motion field, determine the target object motion field of the object.

[0099] The CT device can fuse each whole - heart deformation field in the initial whole - heart motion field with the corresponding incremental target motion field for each target to obtain the target motion field of the target object. For example, the CT device can fuse the partial motion field of the area where the target object is located in each whole - heart deformation field with the corresponding incremental target motion field to obtain the deformation field of the target object, and then obtain the target motion field of the target object based on multiple deformation fields of the target object. Among them, the incremental target motion field corresponding to each whole - heart deformation field is obtained from the sub - image in the initial heart image compensated based on this whole - heart deformation field.

[0100] In the embodiment of the present application, the CT device can sum the partial motion field and the incremental target motion field to achieve the fusion of the partial motion field and the incremental target motion field. For example, the CT device can directly add the partial motion field and the incremental target motion field to achieve the fusion of the partial motion field and the incremental target motion field. Or, the CT device can first add the partial motion field and the incremental target motion field and then multiply by a preset coefficient to achieve the fusion of the partial motion field and the incremental target motion field. Among them, the preset coefficient can be pre - stored in the CT device, for example, it can be 0.9999.

[0101] Step 205: Fuse the initial whole - heart motion field and the target motion field of the target object to obtain the target heart motion field of the heart.

[0102] After the CT device obtains the initial whole - heart motion field and the target motion field of the target object, it can fuse the initial whole - heart motion field and the target motion field of the target object to integrate the more accurate local motion information of the target object into the global initial whole - heart motion field, so as to obtain the target heart motion field that can accurately reflect the heart motion.

[0103] It can be understood that the CT device can fuse the heart deformation fields representing the heart position changes at each time point among multiple time points with the target object deformation fields representing the position changes of the target object, so as to achieve the fusion of the initial whole - heart motion field and the target motion field of the target object and obtain the target heart motion field of the heart. That is to say, when fusing the initial whole - heart motion field and the target motion field of the target object, the heart deformation field in the initial whole - heart motion field and the target object deformation field in the target motion field should be aligned in time.

[0104] In the embodiment of the present application, the CT device can directly replace the partial motion field of the target object in the initial whole - heart motion field with the target motion field of the target object, so as to fuse the initial whole - heart motion field and the target motion field to obtain the target heart motion field.

[0105] Alternatively, the CT device may perform a weighted summation of the initial full-heart motion field and the target object motion field to obtain the target heart motion field of the heart. Specifically, the CT device may first obtain an auxiliary full-heart motion field based on the target object motion field, and then perform a weighted summation of the initial full-heart motion field and the auxiliary full-heart motion field, or perform a weighted summation of the initial full-heart motion field and the target object motion field, to obtain the target heart motion field of the heart.

[0106] Wherein, both the auxiliary full-heart motion field and the initial full-heart motion field may include: vectors for characterizing the displacements of various positions in the heart, that is, the size of the auxiliary full-heart motion field is the same as the size of the initial full-heart motion field. For example, in the auxiliary full-heart motion field, the vector for characterizing the displacement of any position in the target object is the vector of that any position in the target object motion field, and the vectors for characterizing the displacements of various positions in other tissues are all 0.

[0107] It can be understood that before performing the weighted summation of the initial full-heart motion field and the target object motion field, the CT device may first determine the first weight vector of the target object motion field, and based on the first weight vector, determine the second weight vector of the initial full-heart motion field.

[0108] Wherein, the first weight vector includes the first weights of various positions in the heart, and the first weight of each position is proportional to the distance from that position to the target object. The second weight vector also includes the second weights of various positions in the heart, and the second weight is negatively correlated with the first weight. In addition, the sum of the first weight and the second weight of each position may be 1. In this way, it can be ensured that the motion field at the junction of the coronary artery region and the non-coronary artery region in the obtained target heart motion field is relatively smooth.

[0109] It can be understood that if the target object is the coronary artery, the distance from each position to the target object may refer to: the distance from that position to the center line of the coronary artery.

[0110] Step 206: Based on the target heart motion field, perform motion compensation on the heart image in the reference phase to obtain the target heart image.

[0111] The CT device may perform a transformation on the heart image in the reference phase based on the target heart motion field to perform motion compensation on the reference phase and obtain the target heart image. Compared with the heart image without motion compensation, the motion artifacts in the target heart image are less.

[0112] According to the above description, it can be known that the method provided by the embodiment of the present application fully considers the complexity of the motion of different tissues when estimating the full-heart motion, and can perform motion estimation from the global to the local and from the rough to the fine, so as to simultaneously take into account the overall motion of the heart and the local motion of the target object (such as the coronary artery), and improve the accuracy of the determined target heart motion field.

[0113] It is understandable that the sequence of steps of the method for determining the cardiac motion field provided by the embodiments of the present application can be appropriately adjusted, and the steps can also be increased or decreased accordingly according to the situation. For example, steps 201 to 202 can be deleted according to the situation; or step 206 can also be deleted according to the situation. Any method of change that can be easily thought of by any person skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application, and thus will not be elaborated herein.

[0114] In summary, the embodiments of the present application provide a method for determining a cardiac motion field. The method can obtain an initial full cardiac motion field of the heart based on cardiac images of multiple target phases and a cardiac image of a reference phase, and obtain a target object motion field of a target object in the heart based on the initial full cardiac motion field, and then can fuse the initial full cardiac motion field and the target object motion field to obtain a target cardiac motion field. It can be seen that when estimating the cardiac motion, the method can fully consider the complexity of the motion of different tissues (i.e., the heart and the target object) to take into account both the overall motion of the heart and the local motion of the target object in the heart, so as to ensure that the determined target cardiac motion field can more accurately reflect the position change of the heart. Furthermore, it can ensure that the compensation accuracy of motion compensation based on the target cardiac motion field is relatively high.

[0115] The embodiments of the present application provide a CT device. Refer to Figure 6 ., the CT device 300 includes: a processor 301. The processor 301 is used for:

[0116] Obtain an initial full cardiac motion field of the heart based on cardiac images of multiple target phases and a cardiac image of a reference phase;

[0117] Obtain a target object motion field of a target object in the heart based on the initial full cardiac motion field;

[0118] Fuse the initial full cardiac motion field and the target object motion field to obtain a target cardiac motion field of the heart.

[0119] Optionally, obtaining an initial full cardiac motion field of the heart based on cardiac images of multiple target phases and a cardiac image of a reference phase includes:

[0120] Obtain multiple target phases based on the reference phase, and the multiple target phases are distributed on both sides of the reference phase on the time axis;

[0121] Register the cardiac images of each target phase to the cardiac image of the reference phase to determine a first full cardiac deformation field of the heart from each target phase to the reference phase;

[0122] Based on multiple ones of the first full - heart deformation fields, determine the initial full - heart motion field of the heart.

[0123] Optionally, obtaining multiple target phases based on a reference phase includes:

[0124] Determine the acquisition time of the first view and the acquisition time of the last view in multiple views corresponding to the reference phase;

[0125] Based on the acquisition time of the first view, determine the first target phase among the multiple target phases, where the acquisition time of the first view is the acquisition time of the central view in the multiple views corresponding to the first target phase;

[0126] Based on the acquisition time of the last view, determine the last target phase among the multiple target phases, where the acquisition time of the last view is the acquisition time of the central view in the multiple views corresponding to the last target phase.

[0127] Optionally, the multiple target phases are symmetric about the reference phase on the time axis.

[0128] Optionally, obtaining the initial full - heart motion field of the heart based on multiple ones of the first full - heart deformation fields includes:

[0129] Based on multiple ones of the first full - heart deformation fields, use interpolation to obtain the second full - heart deformation field from the target time to the reference phase;

[0130] Based on multiple ones of the first full - heart deformation fields and the second full - heart deformation field, obtain the initial full - heart motion field of the heart.

[0131] Optionally, using interpolation to obtain the second full - heart deformation field from the target time to the reference phase based on multiple ones of the first full - heart deformation fields includes:

[0132] Based on the target time to be interpolated, determine at least two reference phases from the multiple target phases, and the at least two reference times are distributed on both sides of the target time on the time axis;

[0133] Based on the distances between the target time and each of the reference phases on the time axis, and the first full - heart deformation fields from each of the reference phases to the reference phase, determine the second full - heart deformation field from the target time to the reference phase.

[0134] Optionally, obtaining the target object motion field of the target object in the heart based on the initial full - heart motion field includes:

[0135] Performing motion compensation on the cardiac image of the reference phase based on the initial full cardiac motion field to obtain a plurality of initial cardiac images;

[0136] Iterating with the initial full cardiac motion field as the initial value of the motion field increment of the target object, and transforming the sub-image based on the iterated motion field increment to obtain the target motion field increment of the target object, where the target motion field increment refers to: during the successive transformation of the sub-image based on the iterated motion field increment, the motion field increment when the motion artifacts in the transformed sub-image no longer decrease;

[0137] Determining the target object motion field of the target object based on a plurality of the target motion field increments and the initial full cardiac motion field.

[0138] Optionally, fusing the initial full cardiac motion field and the target object motion field to obtain the target cardiac motion field of the heart, including:

[0139] Performing weighted summation on the initial full cardiac motion field and the target object motion field to obtain the target cardiac motion field of the heart.

[0140] Optionally, before performing weighted summation on the initial full cardiac motion field and the target object motion field to obtain the target cardiac motion field of the heart, the method further includes:

[0141] Determining a first weight vector of the target object motion field, where the first weight vector includes: the first weights of each position in the heart, and the first weight of each position is proportional to the distance from the position to the target object;

[0142] Based on the first weight vector, determining a second weight vector of the initial full cardiac motion field, where the second weight vector includes the second weights of each position in the heart, and the second weights are negatively correlated with the first weights.

[0143] In summary, the embodiments of the present application provide a CT device. The CT device can obtain the initial full cardiac motion field of the heart based on the cardiac images of multiple target phases and the cardiac image of the reference phase, and obtain the target object motion field of the target object in the heart based on the initial full cardiac motion field, and then can fuse the initial full cardiac motion field and the target object motion field to obtain the target cardiac motion field. Thus, when estimating the cardiac motion, the CT device can fully consider the complexity of the motion of different tissues (i.e., the heart and the target object) to take into account both the overall motion of the heart and the local motion of the target object in the heart, so as to ensure that the determined target cardiac motion field can more accurately reflect the position change of the heart. Furthermore, it can ensure that the compensation accuracy of motion compensation based on the target cardiac motion field is relatively high.

[0144] Please continue to refer to Figure 6 , the CT device 300 includes: a memory 303. Among them, the processor 301 is connected to the memory 303, such as connected through a bus 302. Optionally, the controller 300 may further include a transceiver 304. It should be noted that in practical applications, the transceiver 304 is not limited to one, and the structure of the controller 300 does not constitute a limitation to the embodiments of the present application.

[0145] The processor 301 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logical blocks, modules, and circuits described in connection with the disclosure of the present application. The processor 301 may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc.

[0146] The bus 302 may include a path for transmitting information between the above components. The bus 302 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The bus 302 may be divided into an address bus, a data bus, a control bus, etc. For the sake of representation, Figure 6 only a thick line is used to represent it in the figure, but it does not mean that there is only one bus or one type of bus.

[0147] The memory 303 is used to store a computer program corresponding to the method for determining the cardiac motion field in the above embodiments of the present application, and the computer program is controlled and executed by the processor 301. The processor 301 is used to execute the computer program stored in the memory 303 to implement the content shown in the foregoing method embodiments.

[0148] The embodiments of the present application provide a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the method for determining the cardiac motion field provided in the above method embodiments. For example, Figure 1 or Figure 2 the method shown.

[0149] An embodiment of the present application also provides a computer program product, which includes a computer program or computer instructions. When the computer program or computer instructions are executed by a processor, the method for determining a cardiac motion field provided in the above method embodiment is implemented. For example, Figure 1 or Figure 2 the method shown.

[0150] It should be noted that the logic and / or steps represented in the flowchart or described in other ways herein, for example, can be considered as a defined sequence list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or in combination with these instruction execution systems, apparatuses, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then stored in a computer memory.

[0151] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0152] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0153] In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0154] In this application, unless otherwise clearly specified and limited, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0155] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for determining a cardiac motion field, characterized in that: The method comprises: acquiring an initial whole heart motion field of the heart based on the heart images of the plurality of target phases and the heart images of the reference phase; Based on the initial whole heart motion field, acquiring a target object motion field of a target object in the heart; The initial whole heart motion field and the target object motion field are fused to obtain a target heart motion field of the heart.

2. The method according to claim 1, characterized in that Based on the cardiac images of multiple target phases and the cardiac images of reference phases, an initial whole heart motion field of the heart is obtained, including: Acquire multiple target phases based on a reference phase, wherein the multiple target phases are distributed on both sides of the reference phase on the time axis; registering the cardiac image of each of the target phases with the cardiac image of the reference phase to determine a first whole-heart deformation field of the heart from each of the target phases to the reference phase; Based on the plurality of first whole-heart deformation fields, an initial whole-heart motion field of the heart is acquired.

3. The method according to claim 2, characterized in that Based on the reference phase, multiple target phases are obtained, including: Determine the acquisition time of the first frame view and the acquisition time of the last frame view in the multiple frame views corresponding to the reference period; Based on the acquisition time of the first frame view, determining the first target phase of the plurality of target phases, wherein the acquisition time of the first frame view is the acquisition time of the center view in the plurality of frame views corresponding to the first target phase; Based on the acquisition time of the tail frame view, the last target phase of the multiple target phases is determined, wherein the acquisition time of the tail frame view is the acquisition time of the center view in the multiple frame views corresponding to the last target phase.

4. The method according to claim 2, characterized in that: The plurality of target periods are symmetrical with respect to the reference period on a time axis.

5. The method according to claim 2, characterized in that: Acquiring an initial whole heart motion field of the heart based on the plurality of first whole heart deformation fields comprises: Based on the plurality of the first whole heart deformation fields, using an interpolation method to acquire a second whole heart deformation field from the target time to the reference phase; An initial whole-heart motion field of the heart is acquired based on a plurality of the first whole-heart deformation fields and the second whole-heart deformation fields.

6. The method according to claim 5, characterized in that Based on the plurality of the first whole heart deformation fields, an interpolation method is used to obtain a second whole heart deformation field from the target time to the reference phase, comprising: Based on the target time to be interpolated, determining at least two reference phases from the plurality of target phases, wherein the at least two reference phases are distributed on both sides of the target time on the time axis; Based on the distance between the target time and each of the reference phases on the time axis and the first whole heart deformation field from each of the reference phases to the reference phase, a second whole heart deformation field from the target time to the reference phase is determined.

7. The method according to any one of claims 1 to 6, characterized in that: Acquiring a target object motion field of a target object in the heart based on the initial whole heart motion field includes: Performing motion compensation on the cardiac image of the reference phase based on the initial whole heart motion field to obtain an initial cardiac image; Based on the initial heart image, acquiring the area where the target object is located; For any target moment, based on the area where the target object is located, a sub-image of the target object is obtained, and the initial whole heart motion field is used as the initial value of the motion field increment of the target object for iteration, and the sub-image is transformed based on the iterated motion field increment to obtain a target motion field increment of the target object, wherein the target motion field increment refers to: in the process of successively transforming the sub-image based on the iterated motion field increment, the motion field increment at which the motion artifact in the transformed sub-image no longer decreases; A target motion field of the target object is determined based on a plurality of the target motion field increments and the initial whole heart motion field.

8. The method according to any one of claims 1 to 6, characterized in that: The initial whole heart motion field and the target object motion field are fused to obtain a target heart motion field of the heart, comprising: The initial whole heart motion field and the target object motion field are weightedly summed to obtain the target heart motion field of the heart.

9. The method according to claim 7, characterized in that: Performing a weighted summation on the initial whole heart motion field and the target object motion field to obtain a target heart motion field of the heart includes: Determine a first weight vector of the target object motion field, wherein the first weight vector includes: a first weight of each position in the heart, wherein the first weight of each position is proportional to the distance from the position to the target object; Based on the first weight vector, a second weight vector of the initial whole heart motion field is determined, wherein the second weight vector includes second weights for various positions in the heart, and the second weights are negatively correlated with the first weights.

10. A CT device, characterized in that: The CT device comprises: a processor; the processor is used for: acquiring an initial whole heart motion field of the heart based on the heart images of the plurality of target phases and the heart images of the reference phase; Based on the initial whole heart motion field, acquiring a target object motion field of a target object in the heart; The initial whole heart motion field and the target object motion field are fused to obtain a target heart motion field of the heart.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 9 is implemented.

12. A computer program product, characterized in that The computer program product comprises a computer program or a computer instruction, and when the computer program or the computer instruction is executed by a processor, the method according to any one of claims 1 to 9 is implemented.

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