Evaluation method and system for corrosion degree of absorbable stent
An evaluation method and system for the corrosion degree of an absorbable stent. The method includes the following steps: obtaining the total number S 0 of stent bars of the absorbable stent at the time zero of implantation (S 10 ); separately obtaining n frames of optical coherence tomography (OCT) images of the absorbable stent at the time x of implantation, wherein x is greater than 0, and n is a natural number greater than 1 (S 20 ); determining, according to the n frames of OCT images, the total number Ni of the stent bars corresponding to each frame of OCT image, wherein i is a natural number greater than or equal to 1 and less than or equal to n; and calculating the total number S x of the stent bars corresponding to the n frames of OCT images at the time x of implantation (I) (S 30 ); determining a corrosion degree Cij of a jth stent bar in an ith frame of OCT image at the time x of implantation, wherein j is a natural number greater than or equal to 1 and less than or equal to Ni (S 40 ); and calculating an overall corrosion degree Cx of the absorbable stent at the time x of implantation according to the following formula: (II) (S 50 ). The evaluation method can be applied to clinical treatment.
1. An evaluation method for the corrosion degree of an absorbable stent, comprising the following steps:
obtaining the total number S 0 of stent bars of the absorbable stent at the time zero of implantation;
separately obtaining n frames of optical coherence tomography (OCT) images of the absorbable stent at the time x of implantation, wherein x is greater than 0, and n is a natural number greater than 1;
determining, according to the n frames of OCT images, the total number Ni of the stent bars corresponding to each frame of OCT image, wherein i is a natural number greater than or equal to 1 and less than or equal to n; and calculating the total number Sx of the stent bars corresponding to the n frames of OCT images at the time x of implantation,
S
x
=
∑
i
=
1
n
Ni
;
determining a corrosion degree Cij of a jth stent bar in an ith frame of OCT image at the time x of implantation, wherein j is a natural number greater than or equal to 1 and less than or equal to Ni; and
calculating an overall corrosion degree Cx of the absorbable stent at the time x of implantation according to the following formula:
Cx
=
(
∑
i
=
1
n
∑
j
=
1
Ni
C
i
j
S
0
+
S
0
-
S
x
S
0
)
×
100
%
.
2. The evaluation method for the corrosion degree of the absorbable stent according to claim 1 , wherein each frame of OCT image refers to an OCT image of each section of the absorbable stent that is perpendicular to an axial central axis.
3. The evaluation method for the corrosion degree of the absorbable stent according to claim 2 , wherein the absorbable stent comprises h wave loops arranged along an axial direction, with n≥h.
4. The evaluation method for the corrosion degree of the absorbable stent according to claim 2 , wherein the axial distance between sections corresponding to any two adjacent frames is equal.
5. The evaluation method for the corrosion degree of the absorbable stent according to claim 1 , wherein the corrosion degree Cij at least comprises no corrosion, partial corrosion and full corrosion; Cij corresponding to no corrosion is 0%; Cij corresponding to partial corrosion is 50%; and Cij corresponding to full corrosion is 100%.
6. The evaluation method for the corrosion degree of the absorbable stent according to claim 1 , wherein the total number Ni of the stent bars refers to a sum of the numbers of stent bars that simultaneously satisfy the following two conditions:
(1) in an OCT image, the brightness of a stent bar is higher than that of a surrounding tissue; and
(2) in an OCT image, a stent bar has a black tail shadow.
7. The evaluation method for the corrosion degree of the absorbable stent according to claim 1 , wherein the corrosion degree Cij at least comprises no corrosion, preliminary corrosion, partial corrosion and full corrosion; Cij corresponding to no corrosion is 0%; Cij corresponding to preliminary corrosion is 20%; Cij corresponding to partial corrosion is 50%; and Cij corresponding to full corrosion is 100%.
8. The evaluation method for the corrosion degree of the absorbable stent according to claim 7 , wherein at the time zero of implantation, a contour thickness of each stent bar is T 0 or in a natural state, a thickness of each stent bar is T 0 ; and when the contour thickness of the stent bar is T 1 , if T 1 is approximately equal to T 0 , it is determined that the corrosion degree Cij is 0%.
9. The evaluation method for the corrosion degree of the absorbable stent according to claim 7 , wherein at the time zero of implantation, a contour thickness of each stent bar is T 0 or in a natural state, a thickness of each stent bar is T 0 ; and when the contour of the stent bar is an arch which has a radial height of T 2 , if T 2 is approximately equal to 2T 0 , it is determined that the corrosion degree Cij is 20%.
10. The evaluation method for the corrosion degree of the absorbable stent according to claim 7 , wherein at the time zero of implantation, a contour thickness of each stent bar is T 0 or in a natural state, a thickness of each stent bar is T 0 ; and when the contour of the stent bar is an arch which has a radial height of T 2 , if T 2 is approximately equal to 3T 0 , it is determined that the corrosion degree Cij is 50%.
11. The evaluation method for the corrosion degree of the absorbable stent according to claim 7 , wherein at the time zero of implantation, a contour thickness of each stent bar is T 0 or in a natural state, a thickness of each stent bar is T 0 ; and when the contour of the stent bar is an arch which has a radial height of T 2 , if T 2 is greater than or equal to 4T 0 , it is determined that the corrosion degree Cij is 100%; or, when the stent bars are irregularly connected into one piece, it is determined that the corrosion degree Cij is 100%.
12. The evaluation method for the corrosion degree of the absorbable stent according to claim 1 , wherein for the absorbable stents of the same specification or for the same absorbable stent, the total number S 0 of the stent bars of the absorbable stent at the time zero of implantation is a constant; and the method for obtaining S 0 includes: obtaining n frames of OCT images of the absorbable stent at the time zero of implantation, and determining the total number S 0 of stent bars of the absorbable stent at the time zero of implantation according to the n frames of OCT images of the absorbable stent at the time zero of implantation.
13. An evaluation system for determining the corrosion degree of an absorbable stent, comprising:
an OCT image obtaining module, configured to obtain n frames of OCT images of the absorbable stent;
an OCT image identification module, configured to identify stent bars in each frame of the OCT image, and calculate the total number Ni of the stent bars corresponding to each frame of the OCT image and the total number Sx of the stent bars corresponding to the n frames of OCT images,
S
x
=
∑
i
=
1
n
Ni
;
an OCT image analysis module, configured to analyze a corrosion degree Cij of the stent bars in each frame of OCT image; and
a calculation module, configured to calculate an overall corrosion degree Cx of the absorbable stent according to a formula
Cx
=
(
∑
i
=
1
n
∑
j
=
1
Ni
C
i
j
S
0
+
S
0
-
S
x
S
0
)
×
100
%
.