Method for automatically measuring a fetal artery and in particular the abdominal aorta and device for the echographic measurement of a fetal artery

Patent metadata

Field	Value
Publication number	US-9629614-B2
Application number	US-201314376440-A
Country	US
Kind code	B2
Filing date	Feb 1, 2013
Priority date	Feb 3, 2012
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

Method for automatically measuring a fetal artery, and in particular the abdominal aorta, which comprises a step for acquiring and storing a sequence cineloop of B-mode images of the fetal abdomen by means of an ultrasonographic device; a step for the approximate identification of the abdominal aorta, by means of a bank of directional filters obtaining an approximate image; a step for the fine identification for each image of said sequence, of the walls of the abdominal aorta, starting from the aforesaid approximate image by means of a calculation model based on the active contours obtaining sequences of segmented images; a step for measuring the diameter and/or the corresponding intima-media thickness of the fetal artery and in particular of the abdominal aorta, conducted at one or more segmented images.

First claim

The invention claimed is:

1. Method for automatically measuring a fetal artery, and in particular the abdominal aorta, characterized in that it comprises; a step for acquiring and storing at least one sequence of images of the fetal abdomen by means of an ultrasonographic device; a step for a approximate identification of the fetal artery, and in particular of the abdominal aorta, by means of a bank of directional filters, obtaining an approximate image of the fetal artery and in particular of the abdominal aorta; a step for a fine identification of the walls of the fetal artery and in particular of the abdominal aorta, starting from said approximate image of the fetal artery and in particular of the abdominal aorta, in each image of said sequence of images by means of a calculation model based on a active contours, obtaining sequences of segmented images; a step for measuring a diameter or a corresponding intima-media thickness of the fetal artery and in particular of the abdominal aorta, conducted at one or more segmented images.

2. Method for automatically measuring a fetal artery according to claim 1 , characterized in that it comprises a step for selecting one or more measurement sections of the fetal artery, and in particular of the abdominal aorta, by means of analysis on each segmented image of said sequence of segmented images of a light intensity gradient of the image, in particular in gray scale, measured along lines orthogonal to a axis of the lumen of the fetal artery and in particular of the abdominal aorta; said measurement step being carried out at one or more segmented images of one or more of said measurement sections.

3. Method for automatically measuring a fetal artery according to claim 2 , characterized in that said step for selecting said measurement sections provides for: calculating a set of points on a axis of the fetal artery and in particular of the abdominal aorta, for each segmented image AC.sub.i,final, and extracting a light intensity values of the segmented image AC.sub.i,final for each point P(s) of such axis, along a radial line passing through P(s) and perpendicular to the axis; selecting a sections at a lumen-intima interface, in which the gradient of gray levels from dark in a lumen to light in the wall, calculated along the aforesaid radial lines, is greater than a threshold value.

4. Method for automatically measuring a fetal artery according to claim 1 , characterized in that said measurement step comprises: a calculation of a measurement variations of the aortic diameter or of a aIMT in segmented images placed in sequence, with a consequent determination of the course of a cardiac cycle and the determination of the segmented images corresponding to a same phase; a grouping of the measurements of the diameter and the aIMT in corresponding phases of the cardiac cycle, in particular during the systolic phases of the heart.

5. Method for automatically measuring a fetal artery according to claim 1 , characterized in that said acquisition and storage step is attained by means of an ultrasonographic device for acquiring cineloop sequences of B-mode images or volumes.

6. Method for automatically measuring a fetal artery according to claim 1 , characterized in that said step for the approximate identification of; a position of the abdominal aorta of the fetus is obtained with multiscale Gabor filters.

7. Method for automatically measuring a fetal artery according to claim 1 , characterized in that said step for the approximate identification of; a position of the abdominal aorta of the fetus is obtained by determining; boundaries between the lumen and the vascular wall of the abdominal aorta, through: a step for filtering at least one image of said sequence of images, obtaining a filtered image through; a use of the following three Gaussian functions for a defined number of scales and orientations: a step for calculating the maximum output of the bank of filters for each pixel by means of the equation; k (x, y; .sigma.)=−−0.5 [x, y] lumen−1 [x, y] T+−0.5 [x−1.5 .sigma., y] wall−1 [x−1.5 .sigma., y] T+−0.5 [x+1.5 .sigma., y] wall−1 [x+1.5 .sigma., y] T ##EQU00006## lumen−1=[1/.sigma. 2 0 0 1/(3 .sigma.) 2] ##EQU00006.2## wall−1=[1/(0.25 .sigma.) 2 0 0 1/(3 .sigma.) 2] ##EQU00006.3## I m ax (x, y)=m a .sigma., x 1 (x, y)*k(x, y; .sigma.,) ##EQU0006.4## where k(x, y; .sigma., .theta.) is the filter at the scale .sigma. rotated by an angle .theta., a step of binarization of the image that is obtained I.sub.max(x, y) by means of: I.sub.max(x,y).gtoreq.t using a statistical threshold t=.mu..sub.I.sub.max+.sigma..sub.I.sub.max, where .mu..sub.I.sub.max and .sigma..sub.I.sub.max represent the mean and the standard deviation of the image, respectively; said step of binarization of the image by means of a threshold producing image parts intended to be the aorta having a higher response to the filter hank.

8. Method for automatically measuring a fetal artery according to claim 7 , characterized in that said step for the approximate identification of the position of the abdominal aorta of the fetus comprises a step for selecting an aorta from said intended image parts by means of a selection of; image parts with area not less than a value A.sub.min, and with a marked eccentricity.

9. Method for automatically measuring a fetal artery according to claim 1 , characterized in that said step for the fine identification of the walls of the aorta, attained by means of; a active contour calculation method, provides for; a deformation of parametric curves .nu.(s)=[x(s), y(s)]s .epsilon.[0,1] in the domain of the obtained image, by minimizing the energy functional E.sub.xy=.intg..sub.0.sup.1[½(.alpha.|.nu.′(s)|.sup.2+.beta.|.nu.″(s)|.sup.2)+E.sub.ext(.nu. (s),f(I))]ds where .alpha. and .beta. are numeric parameters with which it is possible to establish a relative weight respectively of the smoothness and of the rigidity of the contour, whereas, v′(s) and .nu.″(s) are the first and second derivative of .nu.(s) with respect to s and E.sub.ext represents the external energy which pushes the contour to desired features of the image f(I); such energy being calculated on the basis of static forces deriving from the gradient of the image and on the basis of dynamic forces perpendicular to the active contour and whose direction is modulated by the local difference between the gray levels inside and outside the curve at every point thereof.

10. Method for automatically measuring a fetal artery according to claim 9 , characterized in that said dynamic force is calculated, for each point P(s) of the AC, by comparing; gray levels of the image in a region around P(s) outside the AC and along its normal direction n(s), with those of a region inside the AC (towards −n(s)), consequently defining a dynamic force that has direction given by the vector −n(s) and direction oriented towards the AC exterior or interior depending on whether the external region of the window is darker or lighter than the internal region, respectively.

11. Method for automatically measuring a fetal artery according to claim 9 , characterized in that said step for the fine identification of the walls of the aorta attained by moans of the active contour calculation method provides for an evolution stage in which, the ith frame of the image sequence has a contour that, starting from the initial approximate image of the position and shape of the aorta AC.sub.i,1 obtained by means of said preceding step for the approximate identification, evolves under the thrust of the internal and external forces related to the corresponding energies AC.sub.i,t+1=AC.sub.i,t+(F.sub.int,t+F.sub.ext,t).DELTA.t in which an index t represents the iteration and .DELTA.t the integrati

Assignees

• Università Degli Studi Di Padova
• Univ Degli Studi Padova

Inventors

• Grisan Enrico
• Veronese Elisa
• Cosmi Erich

Classifications

• G06T2207/30101

  Blood vessel; Artery; Vein; Vascular · CPC title

• G06T7/62

  of area, perimeter, diameter or volume · CPC title

• G06T7/11

  Region-based segmentation · CPC title

• G06T7/0012 Primary

  Biomedical image inspection · CPC title

• A61B8/0891

  for diagnosis of blood vessels · CPC title