Method, apparatus, and storage medium for reconstructing cardiac image

1. A method for reconstructing a cardiac image, comprising:

collecting projection data and recording electrocardiogram data when computed tomographic scanning is performed on a patient;

selecting, based on the electrocardiogram data, first projection data related to each cardiac pixel with a same phase from the projection data, and then obtaining a cardiac image by reconstructing an image of the related cardiac pixel based on the first projection data;

determining a reconstruction phase of each reconstruction pixel in a first reconstruction region based on the electrocardiogram data, wherein the first reconstruction region is an image region selected along the patient's head-to-foot direction from the cardiac image; and

selecting, based on the reconstruction phase of each reconstruction pixel, second projection data related to the reconstruction pixel with the reconstruction phase from the projection data, and then reconstructing an image of the reconstruction pixel based on the second projection data; wherein

the determining a reconstruction phase of each reconstruction pixel in a first reconstruction region based on the electrocardiogram data, comprises:

acquiring intervals of the first reconstruction region, wherein the intervals comprise a first number of first reconstruction intervals not next to each other, and a second number of first transition intervals between the adjacent first reconstruction intervals:

acquiring reconstruction phases of the first reconstruction intervals determined based on the electrocardiogram data;

determining, based on the reconstruction phases of the first reconstruction intervals and a reconstruction position of the first transition interval, a reconstruction phase of each reconstruction pixel in the first transition interval; and wherein

in the case that the first number of the first reconstruction intervals are divided along a direction from the head to the feet of the patient, the reconstruction phase I V1W1X1 of each reconstruction pixel in the first transition interval is determined by using the following interpolation formula:

I

V

⁢

⁢

1

⁢

W

⁢

⁢

1

⁢

X

⁢

⁢

1

=

V

⁢

⁢

1

+

(

Lx

⁢

⁢

1

-

Lv

⁢

⁢

1

)

×

V

⁢

⁢

1

-

W

⁢

⁢

1

Lv

⁢

⁢

1

-

Lw

⁢

⁢

1

,

wherein V1 is a reconstruction phase of a first reconstruction interval that is next to the first transition interval and in the direction towards the head of the patient; W1 is a reconstruction phase of a first reconstruction interval that is next to the first transition interval and in the direction towards the foot of the patient; Lv1 is a critical position, closer to the head of the patient, of the first transition interval containing a current reconstruction pixel; Lw1 is a critical position, closer to the feet of the patient, of the first transition interval containing the current reconstruction pixel; and Lx1 is a reconstruction position of the current reconstruction pixel.

2. The method according to claim 1 , after the determining a reconstruction phase of each reconstruction pixel in a first reconstruction region based on the electrocardiogram data, further comprising:

determining, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a second reconstruction region, wherein the second reconstruction region is an image region selected from a same sectional image and said sectional image is in the cardiac image and perpendicular to the patient's head-to-foot direction.

3. The method according to claim 2 , wherein the determining a reconstruction phase of each reconstruction pixel in a second reconstruction region based on the electrocardiogram data, comprises:

acquiring intervals of the second reconstruction region, wherein the intervals comprise a second reconstruction interval and a second transition interval surrounding the second reconstruction interval;

acquiring a reconstruction phase of the second reconstruction interval determined based on the electrocardiogram data; and

determining, based on the reconstruction phase of the second reconstruction interval, a phase of the sectional image and a reconstruction position of the second transition interval, a reconstruction phase of each reconstruction pixel in the second transition interval.

4. The method according to claim 3 , wherein in the case that the second reconstruction region and the second reconstruction interval are concentric circles, the reconstruction phase I V2W2X2 of each reconstruction pixel in the second transition interval is determined by using the following interpolation formula:

I

V

⁢

⁢

2

⁢

W

⁢

⁢

2

⁢

X

⁢

⁢

2

=

V

⁢

⁢

2

+

(

Rx

⁢

⁢

2

-

R

V

⁢

⁢

2

)

×

V

⁢

⁢

2

-

W

⁢

⁢

2

R

V

⁢

⁢

2

-

R

W

⁢

⁢

2

,

wherein V2 is the reconstruction phase of the second reconstruction interval, W2 is the phase of the tomographic image, R V2 is a radius of the second reconstruction interval, R W2 is a radius of the second reconstruction region, and Rx2 is a distance from the reconstruction pixel to the center of the concentric circles.

5. The method according to claim 1 , wherein the selecting, based on the reconstruction phase of each reconstruction pixel and from the projection data, second projection data related to the reconstruction pixel in the reconstruction phase, comprises:

selecting a projection data range related to the reconstruction pixel from the projection data; and

selecting, from the projection data range, second projection data temporally corresponding to the reconstruction phase of the reconstruction pixel.

6. The method according to claim 5 , wherein a projection angle for the computed tomographic scanning meets the following condition:

Maxβ−Minβ≧π+γ FanAngle ,

wherein Maxβ represents a maximum value of a projection angle when the second projection data is acquired, Minβ represents a minimum value of the projection angle when the second projection data is acquired, and γ FanAngle is a fan angle of a fan-shaped X-ray beam.

7. An apparatus for reconstructing a cardiac image comprising a processor and a non-transitory computer readable storage medium storing instructions, wherein when executed by the processor, the instructions cause the apparatus to:

collect projection data and record electrocardiogram data when computed tomographic scanning is performed on a patient;

select, from the projection data and based on the electrocardiogram data, first projection data related to each cardiac pixel and in a same phase, and reconstruct, based on the first projection data, an image of the related cardiac pixel, to obtain a cardiac image;

determine, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a first reconstruction region, wherein the first reconstruction region is an image region selected along the patient's head-to-foot direction from the cardiac image; and

select, based on the reconstruction phase of each reconstruction pixel and from the projection data, second projection data related to the reconstruction pixel in the reconstruction phase, and reconstruct, based on the second projection data, an image of the reconstruction pixel; wherein

the determine, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a first reconstruction region, comprises:

acquire intervals of the first reconstruction region, wherein the intervals comprise a first number of first reconstruction intervals not next to each other, and a second number of first transition intervals between the adjacent first reconstruction intervals:

acquire reconstruction phases of the first reconstruction intervals determined based on the electrocardiogram data;

determine, based on the reconstruction phases of the first reconstruction intervals and a reconstruction position of the first transition interval, a reconstruction phase of each reconstruction pixel in the first transition interval; wherein

in a case that the first number of the first reconstruction intervals are divided in a direction along the head to the feet of the patient, the reconstruction phase I V1W1X1 of each reconstruction pixel in the first transition interval is determined by using the following interpolation formula:

I

V

⁢

⁢

1

⁢

W

⁢

⁢

1

⁢

X

⁢

⁢

1

=

V

⁢

⁢

1

+

(

Lx

⁢

⁢

1

-

Lv

⁢

⁢

1

)

×

V

⁢

⁢

1

-

W

⁢

⁢

1

Lv

⁢

⁢

1

-

Lw

⁢

⁢

1

,

wherein V1 is a reconstruction phase of a first reconstruction interval that is next to the first transition interval and in the direction towards the head of the patient; W1 is a reconstruction phase of a first reconstruction interval that is next to the first transition interval and in the direction towards the foot of the patient; Lv1 is a critical position, closer to the head of the patient, of the first transition interval containing a current reconstruction pixel; Lw1 is a critical position, closer to the feet of the patient, of the first transition interval containing the current reconstruction pixel; and Lx1 is a reconstruction position of the current reconstruction pixel.

8. The apparatus according to claim 7 , after the determine, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a first reconstruction region, the apparatus being further configured to:

determine, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a second reconstruction region, wherein the second reconstruction region is an image region selected from a same sectional image, wherein the sectional image is in the cardiac image and perpendicular to the patient's head-to-foot direction.

9. The apparatus according to claim 8 , wherein the determine, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a second reconstruction region, comprises:

acquire intervals of the second reconstruction region, wherein the intervals comprise a second reconstruction interval and a second transition interval surrounding the second reconstruction interval;

acquire a reconstruction phase of the second reconstruction interval determined based on the electrocardiogram data; and

determine, based on the reconstruction phase of the second reconstruction interval, a phase of the sectional image and a reconstruction position of the second transition interval, a reconstruction phase of each reconstruction pixel in the second transition interval.

10. The apparatus according to claim 9 , wherein in a case that the second reconstruction region and the second reconstruction interval are concentric circles, the reconstruction phase I V2W2X2 of each reconstruction pixel in the second transition interval is determined by using the following interpolation formula:

I

V

⁢

⁢

2

⁢

W

⁢

⁢

2

⁢

X

⁢

⁢

2

=

V

⁢

⁢

2

+

(

Rx

⁢

⁢

2

-

R

V

⁢

⁢

2

)

×

V

⁢

⁢

2

-

W

⁢

⁢

2

R

V

⁢

⁢

2

-

R

W

⁢

⁢

2

,

wherein V2 is the reconstruction phase of the second reconstruction interval, W2 is the phase of the tomographic image, R V2 is a radius of the second reconstruction interval, R W2 is a radius of the second reconstruction region, and Rx2 is a distance from the reconstruction pixel to the center of the concentric circles.

11. The apparatus according to claim 7 wherein the select, based on the reconstruction phase of each reconstruction pixel and from the projection data, second projection data related to the reconstruction pixel in the reconstruction phase, comprises,

select a projection data range related to the reconstruction pixel from the projection data; and

select, from the projection data range, second projection data temporally corresponding to the reconstruction phase of the reconstruction pixel, and reconstruct, based on the second projection data, an image of the reconstruction pixels.

12. A non-transitory computer readable storage medium storing instructions, wherein when executed by a processor, the instructions cause the processor to:

collect projection data and record electrocardiogram data when computed tomographic scanning is performed on a patient;

select, from the projection data and based on the electrocardiogram data, first projection data related to each cardiac pixel and in a same phase, and reconstruct, based on the first projection data, an image of the related cardiac pixel, to obtain a cardiac image;

determine, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a first reconstruction region, wherein the first reconstruction region is an image region selected along the patient's head-to-foot direction from the cardiac image; and

select, based on the reconstruction phase of each reconstruction pixel and from the projection data, second projection data related to the reconstruction pixel in the reconstruction phase, and reconstruct, based on the second projection data, an image of the reconstruction pixel; wherein

the determine, based on the electrocardiogram data, a reconstruction phase of each reconstruction pixel in a first reconstruction region, comprises:

acquire intervals of the first reconstruction region, wherein the intervals comprise a first number of first reconstruction intervals not next to each other, and a second number of first transition intervals between the adjacent first reconstruction intervals;

acquire reconstruction phases of the first reconstruction intervals determined based on the electrocardiogram data;

determine, based on the reconstruction phases of the first reconstruction intervals and a reconstruction position of the first transition interval, a reconstruction phase of each reconstruction pixel in the first transition interval; wherein

in a case that the first number of the first reconstruction intervals are divided in a direction along the head to the feet of the patient, the reconstruction phase I V1W1X1 of each reconstruction pixel in the first transition interval is determined by using the following interpolation formula:

I

V

⁢

1

⁢

W

⁢

1

⁢

X

⁢

1

=

V

⁢

⁢

1

+

(

Lx

⁢

⁢

1

-

Lv

⁢

⁢

1

)

×

V

⁢

⁢

1

-

W

⁢

⁢

1

Lv

⁢

⁢

1

-

Lw

⁢

⁢

1

,

wherein V1 is a reconstruction phase of a first reconstruction interval that is next to the first transition interval and in the direction towards the head of the patient; W1 is a reconstruction phase of a first reconstruction interval that is next to the first transition interval and in the direction towards the foot of the patient; Lv1 is a critical position, closer to the head of the patient, of the first transition interval containing a current reconstruction pixel; Lw1 is a critical position, closer to the feet of the patient, of the first transition interval containing the current reconstruction pixel; and Lx1 is a reconstruction position of the current reconstruction pixel.