JPH06327650A - Image diagnosis apparatus - Google Patents

Abstract

PURPOSE:To provide an image diagnosis apparatus with which it is possible to display the changing position of images picked up with time clearly simultaneously with data taking. CONSTITUTION:The subtracted images of two images are calculated simultaneously with data taking and displayed. The phases of two sets of data that are the basis of two images used for calculating the subtracted images, are made the same, and the images are recomposed from the revised data and the subtracted images are calculated. Thus, subtracted images that shows the change of position of image-picking up with time clearly can be displayed simultaneously with data taking. Even if there is a position gap, the subtracted images are obtained showing correct change with time without the influence of the gap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image diagnostic apparatus, and more particularly to an image diagnostic apparatus capable of clearly displaying a temporal change of an imaged region.

[0002]

2. Description of the Related Art FIG. 10 shows an example of timing of image pickup and image display in a conventional image diagnostic apparatus. Data collection is continuously performed on the same imaging target site, and a plurality of sets of data R (1), R (2), R (3), and R (4) are obtained. Reconstruction is performed every time the data R (1), R (2), R (3), and R (4) are obtained, and the images I (1), I (2), I (3), and I ( 4) is obtained. The images are displayed on the images I (1), I (2), I (3), I
Do this every time (4) is obtained.

[0003]

In recent years, there has been an increasing demand for observing temporal changes in the same site by contrast dynamic scanning, functional imaging and the like. This temporal change is caused by the images I (1), I as described above.
It is easier to see the subtracted images I (2) -I (1), ... As shown in FIG. However, in the conventional image diagnostic apparatus, the images I (1), I (2), ...
Is displayed in parallel with the data acquisition, the subtraction image I
(2) -I (1), ... cannot be displayed in parallel with data collection,
There is a problem that the subtracted images I (2) -I (1), ... Must be calculated and displayed after completion of a series of imaging.

In the conventional image diagnostic apparatus, the image I
(1), I (2), ... It was premised that the displacement of the imaged region does not occur. However, if the displacement occurs due to patient movement, etc., the correct temporal change amount will appear in the subtracted image. However, there is a problem in that an incorrect change appears in the edge portion of the imaged region as shown in FIG.

Therefore, a first object of the present invention is to provide an image diagnostic apparatus capable of displaying subtracted images I (2) -I (1), ... In parallel with data acquisition. A second object of the present invention is an image in which a correct temporal change appears in the subtracted image even if the position of the imaging region is displaced between the images I (1), I (2), .... To provide a diagnostic device.

[0006]

In order to achieve the first object, the present invention continuously collects data for the same imaging target region to obtain a plurality of sets of data, and the plurality of sets of data are collected. In an image diagnostic apparatus that obtains a plurality of time-series images of the same imaging target region from data, subtraction image calculation means for calculating a subtraction image of two images among the images acquired up to that time in parallel with data collection And a subtraction image display means for displaying the subtraction image. In order to achieve the above-mentioned second object, the present invention continuously collects data for the same imaging target site to obtain a plurality of sets of data, and from the plurality of sets of data, a plurality of data of the same imaging target site is acquired. Calculating a subtraction image in an image diagnostic apparatus that obtains one time-series image 2
A phase correction unit that corrects the phase between two sets of data that are the basis of one image, and a subtraction image calculation unit that calculates a subtraction image of an image reconstructed from the corrected data are provided. The present invention provides a diagnostic imaging device.

Specific examples of the image diagnostic apparatus of the present invention include an MRI apparatus and a CT apparatus.

[0008]

In the image diagnostic apparatus for achieving the first object, the subtraction image calculation means is provided, and the subtraction image calculation means calculates the subtraction image of the two images in parallel with the data collection. Then, the subtracted image is displayed by the subtracted image display means. Therefore, it becomes possible to clearly display the temporal change of the imaging region in parallel with the data collection.

An image diagnostic apparatus for achieving the above-mentioned second object is provided with a phase correction means, and the phase between the two sets of data which is the source of the two images for which subtraction images are calculated by the phase correction means. Align. Since the positional deviation appears in the data as a change in the primary phase, the positional deviation can be corrected by aligning the phases between the data. Therefore, when an image is reconstructed from the data after this correction and the subtraction image is calculated by the subtraction image calculation means, a subtraction image that is not affected by the positional deviation can be obtained. That is, a subtracted image showing the correct amount of temporal change can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail based on the embodiments shown in the drawings. The present invention is not limited to this. FIG. 1 is a block diagram of an MRI apparatus 1 which is an embodiment of the image diagnostic apparatus of the present invention. The computer 2 controls the overall operation based on the instruction from the console 13. The sequence controller 3 operates the gradient magnetic field driving circuit 4 based on the stored sequence, and causes the gradient magnetic field coil of the magnet assembly 5 to generate a gradient magnetic field. Also, by controlling the gate modulation circuit 7, R
The RF pulse generated by the F oscillation circuit 6 is modulated into a predetermined waveform and applied from the RF power amplifier 8 to the transmission coil of the magnet assembly 5.

The NMR signal obtained by the receiving coil of the magnet assembly 5 is input to the phase detector 10 via the preamplifier 9 and further to the computer 2 via the AD converter 11. The computer 2 reconstructs an image based on the NMR signal data obtained from the AD converter 11, and displays the image on the display device 12. The computer 2 functions as a subtraction image calculation means, a subtraction image display means, and a phase correction means.

FIG. 2 shows that the MRI apparatus 1 continuously collects data R (1), R (2), ... With respect to the same imaging target region, and a plurality of sets of these data R (1), R (R).
(2), ... Is executed in parallel with the operation of obtaining a plurality of time-series images I (1), I (2), ... Of the same imaging target region, and subtracted images I (2) -I (1), Is calculated and the time series image I is calculated.
(1), I (2), ... Together with FIG. In step P1, the number of images (for example, "4") is set to the number of repetitions N, and the counter i is set to "1". In step P2, it is checked whether the count value of the counter i exceeds the number of iterations N. If it does not exceed, the process proceeds to step P3, and if it does, the process ends. At step P3, it is checked whether the count value of the counter i is "1". If it is "1", the process proceeds to step P4, and if it is not "1", the process proceeds to step P6. Step P
At 4, the image I (i) is displayed on the display device 12. In step P5, the count value of the counter i is incremented, and the process returns to step P2. In Step P6, the image (1) is subtracted from the image I (i), and the subtracted image I (i) -I
(1) is obtained and displayed on the display device 12. Then, the process proceeds to step P4.

FIG. 3 shows the timing of image pickup and image display in the operation of FIG. Data collection is performed continuously for the same imaging target region, and multiple sets of data R (1), R
(2), R (3) and R (4) are obtained. Reconstruction is for each data R
(1), R (2), R (3), R (4) is performed every time it is obtained, and images I (1), I (2), I (3), and I (4) are obtained. When the image I (1) is obtained, it is displayed, and the images I (2), I
(3), I (4) each time the subtracted image I (2) -I (1),
I (3) -I (1) and I (4) -I (1) are calculated, and the images I (2), I (3) and I (4) are displayed. From the above,
In parallel with the data collection, it is possible to clearly display the temporal change of the imaging region.

FIGS. 4A and 4B show data R (1),
It represents the absolute value of R (2). Even if there is a displacement of the imaged region between the data R (1) and R (2), the absolute value is not affected. 5A and 5B show data R (1) and R (2).
Represents the phase on the orthogonal axes x and y. Data R (1),
If there is a positional deviation of the imaged region between R (2), it affects the data as a change in the primary phase. Therefore, it is possible to correct the positional deviation by aligning the phases of the data. Therefore, next, an operation of correcting the positional deviation will be described.

FIG. 6 shows that the MRI apparatus 1 continuously collects data R (1), R (2), ... For the same imaging target region, and sets a plurality of sets of data R (1), R (R).
(2), ... Is performed in parallel with the operation of obtaining a plurality of time-series images I (1), I (2), ... Of the same imaging target region, and image I (1), I (2) ,. ), The subtraction images I ′ (2) −I (1), ... Are calculated from the corrected images I ′ (2) ,. 1), I (2), ... Together with FIG. In step S1, the number of images (for example, "4") is set to the number of repetitions N, and the counter i is set to "1". In step S2, it is checked whether the count value of the counter i exceeds the number of iterations N. If not exceeded, the process proceeds to step S3, and if exceeded, the process ends. In step S3, the image I (i) is two-dimensional inverse Fourier transformed to obtain the original data R (i) of the image I (i). In step S4, the phase φ {R (i)} of the data R (i) is obtained. In step S5, it is checked whether the count value of the counter i is "1". If it is "1", the process proceeds to step S6, and if it is not "1", the process proceeds to step S8. Step S
At 6, the image I (i) is displayed on the display device 12. In step S7, the count value of the counter i is incremented, and the process returns to step S2.

In step S8, the phase φ of the data R (i)
The phase difference Δφ {R (i)} is obtained by subtracting the phase φ {R (1)} of the data R (1) from {R (i)}. In step S9, the average value of the phase difference Δφ {R (i)} in the vicinity of the orthogonal axes x and y is calculated, and the average phase difference Δφ ′ {R (i)} is obtained by curve fitting to the average value. Step S
In 10, the average phase difference Δφ ′ {R (i)} is subtracted from the phase φ {R (i)} of the data R (i), and this is taken as the phase φ {R (i)} of the data R (i). To do. In step S11, the data R (i) is two-dimensionally Fourier transformed to obtain an image I ′ (i). In step S12, the image (1) is subtracted from the image I '(i) to obtain the subtracted image I' (i) -I (1), and the display device 12
And the process proceeds to step S6.

FIG. 7 shows the timing of image pickup and image display in the operation of FIG. Data collection is performed continuously for the same imaging target region, and multiple sets of data R (1), R
(2), R (3) and R (4) are obtained. Reconstruction is for each data R
(1), R (2), R (3), R (4) is performed every time it is obtained, and images I (1), I (2), I (3), and I (4) are obtained. The corrected images I ′ (2), I ′ (3), I ′ (4) are the images I (2), I
Obtain each time (3) and I (4) are obtained. And image I (1)
When it is obtained, it is displayed and corrected images I ′ (2), I ′
(3), I '(4) each time subtraction image I' (2) -I
(1), I '(3) -I (1), I' (4) -I (1) are calculated and the images I (2), I (3) and I (4) are displayed. As described above, in parallel with the data collection, it is possible to clearly display the temporal change of the imaged region without being affected by the positional deviation.

When the noise is small, the steps S8, S9 and S10 are omitted, and instead, the phase φ of the data R (1) is replaced with the phase φ of the data R (i). {R
A step of substituting (i)} may be provided.

The positional deviation correction method of the above embodiment is based on the image I
(i) is inverse-Fourier-transformed to calculate data R (i), and phase φ {R (i)} is calculated to correct the phase. it can. Therefore, the present invention is not limited to the case where the data acquisition is performed in parallel, and there is an advantage that the subtraction image can be obtained even after the series of data is acquired. On the other hand, if it is limited to performing the positional deviation correction in parallel with the data collection, the positional deviation correction can be performed using the raw data R (i) actually collected.
Therefore, next, an operation of correcting the positional deviation using the raw data R (i) actually collected will be described.

FIG. 8 shows that the MRI apparatus 1 continuously collects data R (1), R (2), ... For the same imaging target region, and obtains an image I (1) from the data R (1). Is calculated and displayed, the positional deviation of the data R (2), ... Is corrected, and then the image I is obtained from the data R (2) ,.
(2), ... And subtracted image I (2) -I (1) ,.
FIG. 7 is a flowchart of an operation for calculating and displaying both images on the display device 12. In step R1, the number of images (for example, "4") is set to the number of repetitions N, and the counter i is set to "1". In step R2, it is checked whether the count value of the counter i exceeds the number of iterations N. If not exceeded, the process proceeds to step R3, and if exceeded, the process is terminated. In step R3, the data R (i) is collected and its phase φ {R (i)} is obtained. At step R4, it is checked whether the count value of the counter i is "1". If it is "1", proceed to step R5. If it is not "1", step R8.
Proceed to. In step R5, the data R (1) is two-dimensionally Fourier transformed to obtain the image I (1). In step R6,
The image I (i) is displayed on the display device 12. In step R7, the count value of the counter i is incremented, and the process returns to step R2.

In step R8, the phase φ of the data R (i)
The phase difference Δφ {R (i)} is obtained by subtracting the phase φ {R (1)} of the data R (1) from {R (i)}. In step R9, the average value of the phase difference Δφ {R (i)} in the vicinity of the orthogonal axes x and y is calculated, and the average phase difference Δφ ′ {R (i)} is obtained by curve fitting to the average value. Step R
In 10, the average phase difference Δφ ′ {R (i)} is subtracted from the phase φ {R (i)} of the data R (i), and this is taken as the phase φ {R (i)} of the data R (i). To do. In step R11, the data R (i) is two-dimensionally Fourier transformed to obtain the image I (i).
In step R12, the image (1) is subtracted from the image I (i) to obtain the subtracted image I (i) -I (1), which is displayed on the display device 12, and the process proceeds to step R6.

FIG. 9 shows the timing of image pickup and image display in the operation of FIG. Data collection is performed continuously for the same imaging target region, and multiple sets of data R (1), R
(2), R (3) and R (4) are obtained. Phase calculation is for each data R
(1), R (2), R (3), R (4) are performed every time they are obtained, and the phases φ {R (1)}, φ {R (2)}, φ {R (3)}, φ {R
(4)} is obtained. Reconstruction is performed for each phase φ {R (1)}, φ
Each time {R (2)}, φ {R (3)}, φ {R (4)} is obtained, the image I (1), I (2), I (3), I (4) is obtained. obtain.
When the image I (1) is obtained, it is displayed, and the image I (1) is displayed.
Every time (2), I (3), and I (4) are obtained, the subtraction image I (2)-
I (1), I (3) -I (1), I (4) -I (1) are calculated, and the images I (2), I (3) and I (4) are displayed. As described above, in parallel with the data collection, it is possible to clearly display the temporal change of the imaged region without being affected by the positional deviation.

[0023]

According to the MRI apparatus of the present invention, it is possible to display a subtraction image in which the temporal change of the imaged region can be clearly understood in parallel with the data acquisition. Further, according to the MRI apparatus of the present invention, even if there is a positional shift, it is not affected and a subtracted image showing a correct temporal change can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an MRI apparatus of the present invention.

FIG. 2 is a flowchart of a processing operation of displaying a subtraction image in parallel with data collection.

FIG. 3 is a timing diagram of data collection and display in the operation of FIG.

FIG. 4 is a conceptual diagram showing the absolute value of data.

FIG. 5 is a conceptual diagram showing a phase of data.

FIG. 6 is a flowchart of a processing operation of performing positional deviation correction and displaying a subtraction image in parallel with data collection.

7 is a timing diagram of data collection and display in the operation of FIG.

FIG. 8 is a flow chart of a processing operation of performing positional deviation correction using raw data and displaying a subtraction image in parallel with data collection.

9 is a timing diagram of data collection and display in the operation of FIG.

FIG. 10 is a timing diagram of conventional data collection and display.

FIG. 11 is an explanatory diagram of a subtraction image.

FIG. 12 is an explanatory diagram of a subtraction image when there is a position shift.

[Explanation of symbols]

 1 MRI device 2 calculator 12 display device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location 9219-2J G01N 24/02 J

Claims (3)

[Claims] 1. An image diagnostic in which data is continuously collected for the same imaging target region to obtain a plurality of sets of data, and a plurality of time-series images of the same imaging target region are obtained from the plurality of sets of data. 2 of the images acquired by then in parallel with the data acquisition
An image diagnostic apparatus comprising: a subtraction image calculation means for calculating a subtraction image of a single image; and a subtraction image display means for displaying the subtraction image. 2. The image diagnostic apparatus according to claim 1, further comprising a phase correction unit that corrects a phase between two sets of data that are the bases of the two images for calculating the subtracted image, and The subtraction image calculation means calculates a subtraction image of an image reconstructed from the corrected data, the image diagnostic apparatus. 3. An image diagnostic for obtaining data of a plurality of sets by continuously collecting data for the same image-capturing target site and obtaining a plurality of time-series images of the same image-capturing target site from the plurality of sets of data. In the apparatus, a phase correction unit that corrects a phase between two sets of data that are the bases of two images for which a subtraction image is calculated, and a subtraction image that calculates a subtraction image of an image reconstructed from the corrected data An image diagnostic apparatus comprising: a calculating unit.