Computer-implemented method and apparatus for characterizing a flexible tube

1 . A process for characterizing a flexible tube, said process including at least the following further steps:

a) obtaining with a camera a first dataset of image data relating to spatiotemporal deformations of the tube, on a given period of time;

b) detecting a wall inner surface of the tube and its diameter and storing the corresponding data in a memory, in the form of a second dataset;

c) identifying a number of transverse sections of the tube in the dataset;

d) computing, for each section of the tube and at a given instant during the given period of time, an average particle velocity over this section;

e) based on the average particle velocity computed at step d), computing a wave propagation speed of an antisymmetric wave generated in the tube by the liquid flowing within the tube;

f) based on the wave propagation speed computed at step e) and on the diameter detected at step b), assessing a shear elasticity modulus of the flexible tube.

2 . The process according to claim 1 , wherein step b) is implemented by detecting a zone of maximum gradient of intensity in images of the set of image.

3 . The process according to claim 1 , wherein step e) is implemented by correlating some variations of the average particle velocity over a length of the tube or over time.

4 . The process according to claim 3 , wherein step e) includes at least the following sub-steps:

e1) based on a spatial correlation scheme, determining at least one wavelength of the antisymmetric wave;

e2) based on a temporal correlation scheme, determining at least one period of the antisymmetric wave;

e3) based on the wavelength and period determined in sub-steps e1) and e2), computing the wave propagation speed.

5 . The process according to claim 4 , wherein the spatial correlation scheme of sub-step e1) has a succession of peaks and the wavelength is determined in sub-step e1) as a distance between two adjacent peaks.

6 . The process according to claim 1 , wherein step e) is implemented by detecting, at two different given instants, a transverse section where the average particle velocity has a maximum value and computing the wave propagation speed on the basis of the distance between the two detected transverse sections and a time difference between the two instants.

7 . The process according to claim 1 , wherein step f) consists in computing the shear elasticity modulus based on of the following equation:

μ

=

76

×

C

⁢

2

4

×

f

⁢

2

-

2

/

D

2

where: C 2 is the wave propagation speed of the antisymmetric wave W 2 ;

f 2 is a representative frequency of the antisymmetric wave; and

D is the diameter of the tube T.

8 . The process according to claim 1 , wherein step f) comprises computing the shear elasticity modulus based on of the following equation:

C

⁢

2

2

=

2

⁢

π

3

⁢

μ

ρ

⁢

(

1

-

μ

α

)

1

2

⁢

f

⁢

2

×

D

where: C 2 is the wave propagation speed of the antisymmetric wave W 2 ;

f 2 is a representative frequency of the antisymmetric wave;

α is a compression elasticity modulus of the tube;

ρ is the volume mass of the tube; and

D is the diameter of the tube T.

9 . The process according to claim 1 , wherein the data set obtained at the first step relates to a pulsatile flow of liquid flowing within the tube and is preferably implemented by laser Doppler holography or Doppler ultrasound.

10 . The process according to claim 1 , wherein the tube is a blood vessel and the liquid flowing within the tube is blood.

11 . The process according to claim 10 , wherein the blood vessel is located in the fundus of the eye and the step of obtaining the first dataset occurs through the lens of the eye.

12 . The process according to claim 1 , wherein the tube is a manufactured flexible pipe, configured to be implanted in a patient body for replacing a blood vessel.

13 . The process according to claim 1 , wherein the tube is a volcano chimney and the liquid flowing within the tube is lava.

14 . An apparatus for implementing a method for characterizing a flexible tube, comprising:

a laser source emitting a laser beam;

a beam divider configured for dividing the laser beam between an illumination beam and a reference beam;

a set of converging lenses;

a polarizing beam splitter configured for illuminating a region where the flexible tube is located;

a beam splitter configured for combining a light backscattered by the flexible tube with the reference beam and forming a combined beam;

at least a camera configured for recording images formed in the combined beam and representative of spatiotemporal deformations of the flexible tube; and

a processing unit configured for implementing a method including at least the following steps:

a) recording with the camera a first dataset of images relating to spatiotemporal deformations of the tube, on a given period of time;

b) detecting a wall inner surface of the tube and its diameter and storing the corresponding data in a second dataset;

c) identifying a number of transverse sections of the tube in the dataset;

d) computing, for each section of the tube and at a given instant during the given period of time, an average particle velocity over this section;

e) based on the average particle velocity computed at step d), computing a wave propagation speed of an antisymmetric wave generated in the tube by the liquid flowing within the tube; and

f) based on the wave propagation speed computed at step e) and on the diameter detected at step b), assessing a shear elasticity modulus of the flexible tube.

15 . The apparatus of claim 14 , further comprising a memory configured for storing at least the first and second datasets.

16 . A non-transitory computer-readable medium including a program comprising software instructions which, when executed by a computer, implement the process of claim 1 .