Curved surface reconstruction method for heart coronary PET image

Abstract

A curved surface reconstruction method for a heart coronary PET image relates to the technical field of medical image.The method comprises the steps that the PET image of the heart of a patient is collected, an MR image of the heart of the patient adopted in the PET image process is collected, synchronous MR respiratory gating reconstruction is conducted on the PET image according to MR respiratory gating when the MR image of the heart of the patient is collected, and a PET synchronous image is constructed; and mapping the coronary artery walking curve on the MR image to the PET synchronous image so as to reconstruct the heart coronary artery curved surface of the PET image. According to the method provided by the invention, the MR curved surface image and the PET curved surface image can be registered and fused.

Description

Technical Field

[0001] The present invention relates to medical image technology, and in particular to a curved surface reconstruction method for coronary artery PET images. Background Art

[0002] During PET / MR coronary artery scanning, the coronary MR sequence requires curved surface reconstruction along the direction of the coronary artery to obtain a coronary image. However, due to its image characteristics, coronary PET images cannot display the anatomical structure, so the coronary artery shape cannot be outlined, making curved surface reconstruction difficult.

[0003] Currently, there is no method for curved reconstruction of coronary PET images. Most related technical solutions are fusion images of conventional cross-sections of PET images and MR images, as well as coronary MR curved reconstruction images, which cannot intuitively and clearly demonstrate the advantages of coronary PET / MR in disease display and diagnosis. Summary of the Invention

[0004] In view of the defects existing in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a curved surface reconstruction method of coronary PET images that can realize curved surface reconstruction of coronary PET images and enable the registration and fusion of MR curved surface images and PET images.

[0005] In order to solve the above technical problems, the present invention provides a method for surface reconstruction of coronary artery PET images, which is characterized by the following specific steps: 1) Set a time period t1, select a time period within the time period t1 to define as time period t2, acquire a PET image of the patient's heart during time period t1, and acquire an MR image of the patient's heart during time period t2; 2) Examining the PET images acquired at time t1; If the respiratory frequency and respiratory rate in the PET image acquired during the t1 period satisfy the normal distribution relationship, the PET image acquired during the t1 period is defined as the target image; otherwise, the PET image acquired during the t2 period is defined as the target image; 3) performing synchronous MR respiratory gating reconstruction on the target image according to the MR respiratory gating used when acquiring the patient's cardiac MR image. The reconstruction method comprises: acquiring an image during the MR respiratory gating triggering period from the target image according to the MR respiratory gating, and constructing a new PET image using the acquired image. The constructed new PET image is defined as the PET synchronized image. 4) Map the coronary artery curve on the MR image acquired at time t2 onto the PET synchronous image, thereby reconstructing the cardiac coronary artery surface of the PET image.

[0006] Furthermore, on the MR image collected at time t2, surface reconstruction is performed along the coronary artery curve to obtain an MR surface image; the MR surface image is then fused with the PET image reconstructing the cardiac coronary artery surface to obtain a PET / MR coronary artery surface reconstruction image.

[0007] The present invention provides a method for surface reconstruction of cardiac coronary artery PET images, which uses synchronous MR respiratory gating to perform reconstruction on PET images. In this way, the MR coronary artery sequence and the PET image are both triggered by respiratory gating, thereby ensuring the alignment of the two images. This allows the coronary artery direction and path on the MR image to be transferred to the PET image, ensuring that the coronary artery direction and path in the two images are consistent, and can achieve surface reconstruction of cardiac coronary artery PET images, so that the MR surface image and the PET image can be aligned and fused. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 1 is a schematic diagram of performing synchronous MR respiratory gating reconstruction on an image in a curved surface reconstruction method of a coronary PET image according to an embodiment of the present invention; Figure 2 is a schematic diagram of a conventional PET image of a patient's heart; Figure 3 Yes Figure 2 The conventional PET image shown is a PET synchronized image obtained by performing synchronized MR respiratory gating reconstruction; Figure 4 is a schematic diagram of the coronary artery course curve on a conventional MR image of a patient's heart; Figure 5 Yes Figure 4 The conventional MR image shown is an MR curved surface image after curved surface reconstruction along the coronary artery curve; Figure 6 It will Figure 4 The coronary artery curve shown is mapped onto the PET synchronous image to reconstruct a PET image of the coronary artery curve of the heart; Figure 7 It will Figure 5 The MR curved image shown is Figure 6 The PET / MR coronary artery curved surface reconstructed image is obtained by fusion of the PET image of the reconstructed coronary artery curved surface. DETAILED DESCRIPTION

[0009] The following is a further detailed description of an embodiment of the present invention in conjunction with the accompanying drawings, but this embodiment is not intended to limit the present invention. All similar structures and similar variations of the present invention should be included in the scope of protection of the present invention. The semicolons in the present invention represent the relationship of and, and the English letters in the present invention are case-sensitive.

[0010] An embodiment of the present invention provides a method for curved surface reconstruction of a coronary artery PET image, characterized by the following specific steps: 1) Set a time period t1, select a time period within the time period t1 to define as time period t2, acquire a PET image of the patient's heart during time period t1, and acquire an MR image of the patient's heart during time period t2; In this embodiment, the duration of the t1 period is set to 40 minutes, and the duration of the t2 period is set to 15 minutes. In other embodiments, the durations of the t1 period and the t2 period may also be set to other values; In this embodiment, PET and MR images of the patient's heart are acquired using an integrated PET / MR scanner, model uPMR790, manufactured by Shanghai United Imaging Healthcare Co., Ltd. The uPMR790 integrated PET / MR scanner is used to scan the patient's heart, thereby obtaining conventional PET and MR images of the patient. 2) Examining the PET images acquired at time t1; If the respiratory frequency and respiratory rate in the PET image acquired at time t1 satisfy the normal distribution relationship, the PET image acquired at time t1 is defined as the target image (i.e., the PET image acquired at time t1 is used for subsequent synchronous MR respiratory gating reconstruction). Otherwise, the PET image acquired at time t2 is defined as the target image (i.e., the PET image acquired at time t2 is used for subsequent synchronous MR respiratory gating reconstruction, and the PET image acquired at time t2 is a part of the PET image acquired at time t1). The method of checking whether the respiratory frequency and the number of breaths in the image satisfy the normal distribution relationship is a prior art and is described in many existing documents, so it will not be described in detail in this embodiment. This embodiment uses the Shapiro-Wilk test to test whether the respiratory rate and respiratory rate in the PET image satisfy the normal distribution relationship. Other embodiments may also use other normal distribution relationship detection methods. 3) performing synchronous MR respiratory gating reconstruction on the target image according to the MR respiratory gating used when acquiring the patient's cardiac MR image. The reconstruction method comprises: acquiring an image during the MR respiratory gating triggering period from the target image according to the MR respiratory gating, and constructing a new PET image using the acquired image. The constructed new PET image is defined as the PET synchronized image. The MR respiratory gating trigger period refers to the period during which the MR sequence (magnetic resonance sequence) is acquired. MR sequences include conventional MR sequences and coronary MR sequences. MR respiratory gating is generated by the MR scanner based on the subject's respiratory waveform (generating MR respiratory gating by MR scanners is an existing technology, and conventional MR scanners are all equipped with this function). The MR scanner detects the subject's respiratory waveform and, at the end of exhalation in each respiratory cycle, the MR respiratory gating is triggered to begin acquiring the MR sequence. The triggering duration is 1 / 2 of a respiratory cycle. Figure 1 This is a schematic diagram of synchronous MR respiratory gating reconstruction of images. Figure 1 The S1 line in the figure is the respiratory waveform of the scanned person. Point b on the respiratory waveform is the end of exhalation in the respiratory cycle (automatically detected by the MR scanning device), which is also the starting point of MR respiratory gating. Point e on the respiratory waveform is the end point of MR respiratory gating. The M1 line is a schematic diagram of the MR scanning device acquiring MR sequences according to MR respiratory gating. Among them, AC and T2 are conventional MR sequences, CMRA is a coronary MR sequence, and the P1 line is an image acquired from the target image according to MR respiratory gating. Because the coronary MR sequence is acquired by MR respiratory gating, the use of synchronous MR respiratory gating reconstruction for PET images can ensure the accuracy of the registration of MR and PET images and reduce the registration error between the two images. Figure 2 is an example of a conventional PET image of a patient's heart. Figure 3 Yes Figure 2 The conventional PET image shown is a PET synchronized image obtained by performing synchronized MR respiratory gating reconstruction; 4) Mapping the coronary artery curve on the MR image acquired at time t2 onto the synchronous PET image to reconstruct the coronary artery surface of the PET image; Since PET synchronized images are constructed based on MR respiratory gating, they have high registration accuracy with MR images. There is a one-to-one correspondence between the coordinates of MR images and PET synchronized images. The coronary artery curve is composed of several points. Therefore, the point coordinates of the coronary artery curve on the MR image can be mapped one-to-one to the PET synchronized image, thereby outlining the coronary artery curve on the PET synchronized image and realizing the reconstruction of the coronary artery surface on the PET image. On the MR image acquired at time t2, curved surface reconstruction is performed along the coronary artery curve to obtain an MR curved surface image; The method of performing curved surface reconstruction along the coronary artery curve on the MR image to obtain an MR curved surface image is an existing mature technology, widely used in clinical practice, and also recorded in many documents, and will not be described in detail in this embodiment; Figure 4 yes Figure 2Schematic diagram of the coronary artery course curve on a conventional MR image of a patient's heart on a conventional PET image shown. Figure 4 The curve composed of red dots is the coronary artery course curve; Figure 5 Yes Figure 4 The conventional MR image shown is an MR curved surface image after curved surface reconstruction along the coronary artery curve; Figure 6 It will Figure 4 The coronary artery curve shown is mapped onto the PET synchronous image to reconstruct a PET image of the coronary artery curve of the heart; 5) Because PET images cannot display anatomical structures, the small registration error between MR curved images and PET images reconstructed from the coronary artery curved surface can be exploited to fuse the MR curved images with the PET images reconstructed from the coronary artery curved surface to obtain a PET / MR coronary artery curved surface reconstructed image. Figure 7 It will Figure 5 The MR curved image shown is Figure 6 The PET / MR coronary artery curved surface reconstructed image is obtained by fusion of the PET image of the reconstructed coronary artery curved surface.

[0011] The embodiment of the present invention adopts a method of synchronous MR respiratory gating to reconstruct PET synchronous images, which can cut abnormal data so that the respiratory frequency and respiratory rate satisfy the normal distribution relationship. Since the coronary MR sequence is also acquired by MR respiratory gating triggering, the registration accuracy of the MR image and the PET image can be guaranteed, and the registration error of the two images can be reduced. By utilizing the relationship between the fusion registration of MR images and PET images, the coronary artery course curve on the MR image is mapped to the PET image, which can ensure the consistency of the coronary artery course curves of the two images and can intuitively display whether there is radioactive drug uptake in the coronary artery course area on the MR image and the PET image.

Claims

1. A method for surface reconstruction of coronary artery PET images, characterized in that: The specific steps are as follows: 1) Set a time period t1, select a time period within the time period t1 to define as time period t2, acquire a PET image of the patient's heart during time period t1, and acquire an MR image of the patient's heart during time period t2; 2) Examining the PET images acquired at time t1; If the respiratory frequency and respiratory rate in the PET image acquired during the t1 period satisfy the normal distribution relationship, the PET image acquired during the t1 period is defined as the target image; otherwise, the PET image acquired during the t2 period is defined as the target image; 3) performing synchronous MR respiratory gating reconstruction on the target image according to the MR respiratory gating used when acquiring the patient's cardiac MR image. The reconstruction method comprises: acquiring an image during the MR respiratory gating triggering period from the target image according to the MR respiratory gating, and constructing a new PET image using the acquired image. The constructed new PET image is defined as the PET synchronized image. 4) Map the coronary artery curve on the MR image acquired at time t2 onto the PET synchronous image, thereby reconstructing the cardiac coronary artery surface of the PET image.

2. The method for curved surface reconstruction of coronary artery PET images according to claim 1, characterized in that: On the MR image acquired at time t2, surface reconstruction is performed along the coronary artery curve to obtain an MR surface image; then the MR surface image is fused with the PET image reconstructed from the coronary artery surface to obtain a PET / MR coronary artery surface reconstruction image.

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