FR2733142A1 - Method for creating ultrasonic breast image - Google Patents

Abstract

A number of compression's, at set pressure levels, are made of the patients breast (28). The breast occupies a fixed position on a support (2), above which is an adjustable compression unit (4). For each compression of the breast an ultrasonic image is formed, through the compression unit (4), for the same section of the breast. The compression unit (4) is designed so that the ultrasonic waves pass through it, and the images of the same breast section, which are associated with a number of compression's, are processed so as to form an ultrasonic elastograph relative to the section. A linear ultrasonic probe (6), which transmits and receives ultrasonic waves, is maintained perpendicular to a set direction F2 and is displaced along this direction so as to form the ultrasonic images.

Description

ELASTOGRAPHY IMAN METHOD AND DEVICE
ULTRASONIC AND MAMMOGRAPHY APPARATUS INCLUDING THE SAME
DEVICE
DESCRIPTION
TECHNICAL AREA
The present invention relates to an ultrasound elastography imaging method and device as well as a mammography apparatus comprising this device.

PRIOR STATE OF THE ART
It is known that images of a patient's breast are obtained, essentially, by means of a mammographic examination.

 It is then projection imaging which uses an X-ray source as a radiation source.

 In addition to such a mammographic examination, it is known to carry out an ultrasound examination of the breast.

 In this case, it is sectional imagery which uses a source of ultrasonic waves as a source of radiation.

 A radiologist uses mammography to try to diagnose a breast lesion.

 If the radiological signs observed on the mammographic image are not sufficient to make a sure diagnosis, the radiologist often resorts to an ultrasound examination also called "ultrasound examination".

 The analysis of ultrasound images sometimes makes it possible to make a diagnosis (malignant or benign) by providing information different from that which is available thanks to mammography images.

 An image obtained by mammographic examination is the superposition of all the structures contained in the breast along the X-ray path.

 The images obtained constitute a map of the linear attenuation of X-rays by the breast tissues along the path of these X-rays coming from the X-ray source.

 An image obtained by an ultrasound examination is a cross-sectional view of the volume of the object examined, in this case the breast.

 The images obtained form a map of ultrasound echoes which the structures constituting the breast send back to the ultrasound emission-detection probe in a plane determined by the configuration of this probe.

 The technique of ultrasonic elastography imaging is also known.

 It is a new technique allowing to build, from two ultrasound images of the same breast section, acquired at two different compression levels, and thanks to an appropriate computer processing, an image which corresponds to a card. of a size characteristic of the elasticity of breast tissue.

 It is known that the two levels of compression which are necessary to form such an image are obtained by the exercise of a more or less strong pressure of the ultrasound probe on the breast by the radiologist who holds the probe.

 When we consider, for the same patient, several cutting planes for which we want to obtain an image of ultrasound elastography, or when we seek to compare the images relating to several patients, the reproducibility of the compression levels and therefore the reproducibility of the quality of the images obtained is not guaranteed.

 The inclination of the probe relative to the breast can also vary between the two data acquisitions, carried out at different pressures, and can thus lead to erroneous ultrasound elastography images.

STATEMENT OF THE INVENTION
The object of the present invention is to remedy the above drawbacks.

 Its subject is an ultrasound elastography imaging method and device making it possible to ensure the reproducibility of the acquisitions at the different compression levels necessary for the construction of ultrasound electrography images.

 Specifically, the present invention firstly relates to an ultrasound elastography imaging method, characterized in that a plurality of compressions is carried out at determined pressure levels, of a patient's breast , this breast occupying a fixed position on a support, by means of a compression member whose distance from the support is adjustable, in that an ultrasound image of at least one same cut is formed for each compression from this breast, through the compression member, this compression member being able to let ultrasonic waves pass, and in that the images of this same section are processed, which are respectively associated with the plurality of compressions, so as to form an ultrasonic elastography image relating to this same section.

 It is possible to use a linear probe for transmitting and receiving ultrasonic waves which is held perpendicular to a determined direction and which is moved along this direction to form the ultrasonic images.

 As a variant, an annular probe for transmitting and receiving ultrasonic waves is used which is movable relative to a support in a first determined direction, the probe is moved in this first direction and this support is moved in a second determined direction , perpendicular to the first direction, to form the ultrasound images.

 According to a particular mode of implementation of the method which is the subject of the invention, more than two compression are carried out.

 This allows better tissue differentiation.

The present invention also relates to an ultrasonic elastography imaging device, characterized in that it comprises
a support intended to support a breast of a
patient,
a compression member whose distance by
support ratio is adjustable and that is
for performing a plurality of compressions
of the breast, at determined pressure levels, this
breast occupying a fixed position on the support,
training means, for each compression,
an ultrasonic image of at least one cut
of this breast, through the compression member,
this compression member being able to leave
pass ultrasonic waves, and
electronic medium wave image processing
of this same cut, which are respectively
associated with the plurality of compressions, these
electronic processing means being intended
to form an ultrasonic elastography image
relating to this same section, from the images
corresponding ultrasound.

 According to a particular embodiment of the device which is the subject of the invention, the means for forming an ultrasound image comprise a probe for transmitting and receiving ultrasonic waves and the device also comprises means for moving this probe over the compression organ.

 According to a first particular embodiment of the invention, the probe is an annular ultrasonic probe.

 According to a second particular embodiment of the invention, the probe is a linear ultrasonic probe.

 In the case of the use of such a linear ultrasonic probe, it will be noted that translations of this probe in a single direction are sufficient to form several successive images whereas, in the case of an annular probe, this requires translations according to two perpendicular directions.

The present invention also relates to a mammography apparatus comprising
an x-ray source,
a patient support comprising means for
X-ray detection, and
a compression ball capable of letting through
X-rays and placed between the ray source
X and the patient support, this apparatus being characterized in that it further comprises the device which is also the subject of the invention, said patient support also constituting said support intended to support a patient's breast and said ball of compression further being able to let the ultrasonic waves pass and also constituting said compression member.

The present invention has three advantages over the known technique of ultrasound elastography imaging.
the present invention allows reproducibility
different compression levels thanks to the
standard compression provided by the
compression whose distance is adjustable by
relation to the support, this compression member
being, in the particular case considered more
top, the compression ball of a
mammography,
thanks to the present invention, it is possible to
form a set of ultrasound images to
different compression levels according to a
reproducible configuration which ensures
perfect spatial correspondence of the different
ultrasonic sections, and
the present invention allows, thanks to
the acquisition of sets of parallel cuts
to each other, to access images
ultrasound breast volume and make
elastography imagery, very
simplified due to the simple configuration
acquisition of ultrasonic sections.

BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be better understood on reading the description of exemplary embodiments given below, by way of purely indicative and in no way limiting, with reference to the appended drawings in which
Figure 1 is a schematic view of a
first particular embodiment of the
device object of the invention, using
a linear ultrasonic probe,
Figure 2 schematically illustrates a
astrography imaging process
ultrasonic according to the invention and implemented
work using the device of FIG. 1, and
Figure 3 is a schematic view of a
second particular embodiment of the
device object of the invention, using
an annular ultrasonic probe.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
The ultrasonic astrography imaging device according to the invention, which is schematically represented in FIG. 1, comprises
a patient support 2, this support being intended
to support a patient's breast (not
represented),
a breast compression organ 4, organ of which
the distance from the support is adjustable
to be able to carry out a plurality of
cuts, and
a wave emission and reception probe
ultrasonic 6.

 The patient support 2 is fixed to a vertical support 8, itself fixed to a column 9 resting on a base not shown.

 The compression member 4, which is located above the support 2, can be displaced in translation vertically in the direction F1 shown in FIG. 1.

 The support 8 is provided with a means 10 for guiding the member 4 during a translation in the direction F1.

 The device of FIG. 1 is also provided with means 12 for controlling the translation of the compression member 4.

 The probe 6 is a linear ultrasonic probe.

 This probe is placed on the upper surface of the member 4 and displaceable in translation in a direction F2 as seen in FIG. 1.

 The upper surface of the member 4 includes means 14 for guiding in translation this probe 6.

 The direction F2 is perpendicular to the direction F1.

 FIG. 1 also shows a motor 15 allowing the translation of the probe 6 on the compression member 4.

 This motor 15 is a stepping motor allowing the probe 6 to occupy positions regularly spaced from each other in the direction F2.

 The device of FIG. 1 also comprises means 16 for controlling the motor 15.

 The device of FIG. 1 further comprises control and imaging means 18 which are intended to excite the ultrasonic probe 6 by electrical signals so that this probe emits ultrasound and to form ultrasonic images from the electrical signals supplied. by this probe when it detects ultrasound.

 The device of FIG. 1 also comprises means 20 for processing the images formed by the means 18 as well as means 22 for displaying the information supplied by the processing means 20.

 In the example shown diagrammatically in FIG. 1, the device according to the invention is integrated into a mammography device.

 This mammography device comprises a source 24 of X-rays which is fixed to the upper part of the support 8 and controlled by means not shown.

 Patient support 2 is of the type conventionally used in mammography devices and contains means 26 for detecting X-rays which pass through the patient's breast placed on this support 2.

 It will be recalled that these detection means 26 may comprise a screen which is capable of emitting visible light under the impact of X-rays and which is associated with a film sensitive to this visible light.

 As a variant, these detection means comprise a charge transfer device associated with a scintillating layer.

In the example of Figure 1, the compression member 4, which is placed between the ray source
X and the patient support 2, also constitutes the compression pad of the mammography device.

 Of course, a device according to the invention is not necessarily integrated into a mammography device.

 In this case, it suffices that the compression member, above which the ultrasonic probe is located, be made of a material capable of allowing ultrasound to pass.

 In the case where this device is integrated into the mammography device shown in FIG. 1, this material must be able to let pass not only ultrasound but also X-rays.

 One can use a compression member 4 made of a plastic material such as Lexan (registered trademark).

 Of course, when the X-ray source is operated to carry out a mammography with the apparatus shown in FIG. 1, it is necessary to retract the ultrasonic probe 6.

 An explanation is given below, with reference to FIG. 2, of an ultrasonic elastography imaging method according to the invention, using the device of FIG. 1.

 According to this method, a breast scan 28 is carried out through the compression ball 4, by means of the linear ultrasonic probe 6, in the same geometrical configuration as that which is used to form an image of mammography by X-rays.

 The ultrasonic section plane P obtained for a determined position of the probe 6 on the upper face of the compression pad 4 has been shown in dotted lines in FIG. 1.

 To carry out ultrasound elastography imaging, the breast 28 (FIG. 2) is compressed to a first determined pressure level.

 At this determined pressure, a number N of ultrasound images is formed, corresponding respectively to N sections of the breast, through the compression pad 4.

 In the example shown in Figure 2, the number N is equal to 7.

 The N ultrasonic images respectively bear the references Cl1, C12 ... CîN for the first determined pressure.

 These images Cîl ... CîN are respectively associated with determined positions A1, A2 ... AN of the ultrasonic probe 6 on the compression pad 4.

 A second compression of the breast 28 is then carried out at a determined pressure, different from the first.

 N other images of ultrasound sections of the breast are then formed.

 These other images are denoted C21, C22 ...

C2N and the ultrasonic probe 6 successively occupies the same positions A1, A2, ..., AN as previously to form these images C21, C22 ... C2N.

 There are thus two sets of N ultrasonic sections for two different pressure levels and for the same successive positions of the probe in the direction F2.

 The processing means 20 combine these two sets to form a set of N elastography sections E1, E2 ... EN making it possible to obtain a three-dimensional image of the breast 28.

 To combine these two sets, an algorithm identical to that used for ultrasound elastography imagery which can be used when the ultrasound probe is held in the hand by a radiologist is used.

 In a particular simpler embodiment, only one ultrasonic cut is made for the two pressure levels (these of course corresponding to the same position of the probe), which leads to a single image of elastography formed from these two sections.

 Instead of making two successive breast compressions and N successive ultrasound cuts for each compression (N21), one can successively perform more than two breast compressions with another N successive ultrasound cuts for each compression (N21), the same series of positions of the probe, counted in the direction F2, being used for all compressions.

 The algorithm is then adapted to take into account the fact that there are more than two compressions to provide the ultrasound elastography images.

 In a device not shown, less elaborate than that of FIG. 1, the means of displacement of the linear ultrasonic probe 6 on the compression ball 4 are eliminated and this displacement, instead of being automatic, is done by hand in taking care of course to place the probe in the same successive positions for each of the successive pressure levels.

 I1 should then be provided with marks on the top of the compression ball 4 as shown in FIG. 2.

 In Figure 3, there is shown schematically another device according to the invention.

 This device of FIG. 3 is identical to that of FIG. 1 except that an annular ultrasonic probe 30 is used instead of a linear ultrasonic probe.

This probe 30 is mounted on a carriage 32 which takes the place of the probe 6 of FIG. 1 and which is therefore movable in translation in the direction
F2 thanks to the stepping motor 15 controlled by the means 16.

 In addition, the annular probe 30 is itself movable in translation along the carriage 32, in the direction F3 (which is perpendicular to F2).

 FIG. 3 shows a motor 33 enabling the probe 30 to move along the carriage 32 as well as means 34 for controlling this motor 33.

 In this case, for a given position of the carriage 32 on the compression pad 4, an ultrasonic cutting axis X is obtained for a given position of the probe 30 on this carriage.

 To obtain a cutting plane P, it is then necessary for the probe to be moved from one end to the other of the carriage 32.

 Of course, the control and imaging means 18 are then adapted to the probe 30.

 It is understood that it is still possible to obtain several successive cutting planes corresponding to successive positions of the carriage.

 We are still able to obtain ultrasound elastography images as previously using at least two different compression levels leading to at least two sets of N ultrasonic breast sections.

Claims (9)

RESELL I CAT IONS  1. Ultrasonic elastography imaging method, characterized in that a plurality of compressions is carried out, at determined pressure levels, of a breast (28) of a patient, this breast occupying a fixed position on a support (2), by means of a compression member (4) whose distance from the support is adjustable, so that, for each compression, an ultrasound image of at least one same section of this breast is formed , through the compression member, this compression member being able to let ultrasonic waves pass, and in that the images of this same section are processed, which are respectively associated with the plurality of compressions, so as to form an ultrasonic elastography image relating to this same section.  2. Method according to claim 1, characterized in that a linear probe (6) for transmitting and receiving ultrasonic waves is used which is held perpendicular to a determined direction F2 and which is moved in this direction for form the ultrasound images.  3. Method according to claim 1, characterized in that an annular probe (30) for transmitting and receiving ultrasonic waves is used which is movable relative to a support (32) in a first determined direction (F3) , in that the probe is moved in this first direction and in that this support is moved in a second determined direction (F2), perpendicular to the first direction, to form the ultrasonic images.  4. Method according to any one of claims 1 to 3, characterized in that more than two compressions are carried out.  5. Ultrasonic elastography imaging device, characterized in that it comprises  a support (2) intended to support a breast (28)  of a patient,  a compression member (4) whose distance by  support ratio is adjustable and that is  for performing a plurality of compressions  of the breast, at determined pressure levels, this  breast occupying a fixed position on the support,  training means (6 or 30, 18), for  each compression, of an ultrasonic image of at least  minus one cut of this breast, across  the compression organ, this organ of  compression being able to let waves pass  ultrasonic, and  electronic means (20) for processing  images of this same cut, which are  respectively associated with the plurality of  compressions, these electronic means of  processing being intended to form an image  ultrasonic elastography relating to the same  section, from ultrasound images  corresponding.  6. Device according to claim 5, characterized in that the means for forming an ultrasound image comprise a probe (6, 30) for transmitting and receiving ultrasonic waves and in that the device also comprises means (15 , 33) for movement of this probe on the compression member (4).  7. Device according to claim 6, characterized in that the probe is an annular ultrasonic probe (30).  8. Device according to claim 6, characterized in that the probe is a linear ultrasonic probe (6).  9. Mammography apparatus comprising  a source (24) of X-rays,  a patient support (2) comprising means  (26) X-ray detection, and  a compression ball (4) suitable for leaving  pass the x-rays and placed between the source of  X-rays and the patient support, this apparatus being characterized in that it further comprises the device according to any one of Claims 5 to 8, said patient support also constituting said support intended to support a patient's breast and said compression pad also being able to let the ultrasonic waves pass and also constituting said compression member.