U.S. patent application number 12/501415 was filed with the patent office on 2010-07-22 for methods for measuring mechanical stimulus.
Invention is credited to Jonathan Ophir, Raffaella Righetti.
Application Number | 20100180684 12/501415 |
Document ID | / |
Family ID | 38919907 |
Filed Date | 2010-07-22 |
United States Patent
Application |
20100180684 |
Kind Code |
A1 |
Righetti; Raffaella ; et
al. |
July 22, 2010 |
Methods For Measuring Mechanical Stimulus
Abstract
The invention is directed toward a new method for estimating and
imaging the spatial and temporal mechanical behavior of materials
in responses to a mechanical stimulus. This method is designed to
work in inherently noisy applications, such as the imaging of the
time-dependent mechanical behavior of biological tissues in vivo
and using a preferred hand-held configuration of scanning.
Inventors: |
Righetti; Raffaella;
(Houston, TX) ; Ophir; Jonathan; (Austin,
TX) |
Correspondence
Address: |
DUANE MORRIS LLP - Houston
3200 SOUTHWEST FREEWAY, SUITE 3150
HOUSTON
TX
77027
US
|
Family ID: |
38919907 |
Appl. No.: |
12/501415 |
Filed: |
July 11, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11436129 |
May 17, 2006 |
|
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|
12501415 |
|
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Current U.S.
Class: |
73/620 |
Current CPC
Class: |
A61B 8/485 20130101;
A61B 5/442 20130101; A61B 8/08 20130101; A61B 8/488 20130101 |
Class at
Publication: |
73/620 |
International
Class: |
G01N 29/04 20060101
G01N029/04 |
Goverment Interests
GOVERNMENT RIGHTS
[0002] This invention was made with United States Government
support under Grant No. NIH/NIBIB P01 EB 02105, awarded by the
National Institutes of Health and National Institute of Biomedical
Imaging and Bioengineering. The United States Government has
certain rights in the invention.
Claims
1. A method for measuring the mechanical stimulus applied to a
target body during hand-held scanning, comprising: a. coupling a
transducer to the target body; b. emitting a first pulse of
ultrasound energy from the transducer into the target body; c.
receiving with the transducer at least one ultrasound echo sequence
from the first pulse; d. estimating the first distance between the
transducer and a non-moving reference point in the vicinity of the
target body from the first received echo sequence; e. emitting a
second pulse of ultrasound energy from the transducer into the
target body; f. receiving with the transducer at least one
ultrasound echo sequence from the second pulse; and g. estimating
the second distance between the transducer and the same non-moving
reference point used in step (d) from the second received echo
sequence.
2. The method of claim 2, further comprising computing the
displacement between the first distance and the second
distance.
3. The method of claim 1, wherein the target body is
viscoelastic.
4. The method of claim 1, wherein the target body is
poroelastic.
5. The method of claim 1, wherein the target body possesses time
dependent mechanical properties.
6. A method for measuring the mechanical stimulus applied to a
target body during hand-held scanning, comprising: a. coupling a
transducer to the target body; b. emitting a first pulse of
ultrasound energy from the transducer into the target body; c.
receiving with the transducer at least one ultrasound echo sequence
from the first pulse; d. estimating the distance between a
reference point in the vicinity of the transducer and a non-moving
reference point in the vicinity of the target body from the first
received echo sequence; e. emitting a second pulse of ultrasound
energy from the transducer into the target body; f. receiving with
the transducer at least one ultrasound echo sequence from the
second pulse; and g. estimating the distance between the reference
point in the vicinity of the transducer used in step (d) and the
same non-moving reference point used in step (d) from the second
received echo sequence.
7. The method of claim 1, wherein the target body is
viscoelastic.
8. The method of claim 1, wherein the target body is
poroelastic.
9. The method of claim 1, wherein the target body possesses time
dependent mechanical properties.
Description
PRIORITY INFORMATION
[0001] This application is a divisional application which claims
priority from U.S. patent application Ser. No. 11/436,129, filed on
May 17, 2006.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The invention is directed toward new methods for estimating
and imaging the spatial and temporal mechanical behavior of
materials in response to a mechanical stimulus. These methods are
designed to work in inherently noisy applications, such as the
imaging of the time-dependent mechanical behavior of biological
tissues in vivo and using a preferred hand-held configuration of
scanning.
[0005] Embodiments of the invention overcome the limitation of
current elastographic methods for imaging local strains and
displacements in inherently noisy environments, which are primarily
due to echo decorrelation problems generated by uncontrollable
motion. Embodiments of the invention minimize the decorrelation
noise between the ultrasonic frames used for the generation of the
elastograms since the reference pre-compression frame is
continuously moved in time and the inter-frame time interval is
maintained sufficiently short during the entire acquisition. This
allows the generation of good quality elastograms for short
(sub-second) as well as long (multi-second) acquisition times. In
addition, from the time-dependent behavior of the local strains or
displacements occurring in the material, images of local strain
time constants and local displacement time constants can be
generated using curve-fitting techniques.
[0006] 2. Description of the Prior Art
[0007] Prior art techniques for making time-dependent elastographic
measurements require the use of a fixed pre-compression RF frame
that is acquired immediately before compression and
post-compression frames that are acquired sequentially at
increasing time-intervals with respect to the fixed pre-compression
frame. Elastograms are then generated by applying elastographic
techniques between the same pre-compression frame and the
successive post-compression frames. This methodology has been
proven to be not adequate for imaging the temporal behavior of
materials in inherently noisy environments because of the echo
decorrelation problems that are encountered due to uncontrolled
motion, which may be significant shortly after compression.
Embodiments of the present invention overcomes the limitations of
the aforementioned techniques because the elastograms are generated
using frames that are sufficiently close in time to avoid
decorrelation due to uncontrollable motion.
[0008] Prior art elastographic methods used to generate axial
elastograms in vivo are focused on the determination of tissue's
axial displacements and strains after the application of a
compression. These displacements or strains are computed by using a
frame that is acquired immediately before the application of the
compression and a frame that is acquired immediately after the
application of the compression. To minimize noise, usually the
compression is divided in a multiplicity of small compression steps
and at the end of each step an echo sequence is acquired. Axial
displacements or strain are generated using the various
echo-sequences acquired during the compression. In general, the
axial displacement or strains are then averaged to reduce
noise.
[0009] These prior art methods may allow obtaining axial
displacement and strain of adequate quality, in vivo, but they may
not allow estimating the time-dependent mechanical changes
occurring in such displacements and strains in materials that
exhibit mechanical properties that vary with time. Indeed the usual
assumption of these prior art methods is that the target body can
be modeled as a purely linearly elastic material, so that no
significant time-dependent mechanical changes occur during the
acquisition of the echo-sequences.
[0010] The present invention differs from the aforementioned prior
art techniques because the mechanical stimulus is first applied to
the target body and thereafter the echo-sequences used for
determining the displacements or strains are acquired. In the
present invention the time-dependent mechanical behavior of a
material after the application of a mechanical stimulus is imaged
by means of post-stimulus echo-sequences only. As such, the method
of this invention is directed toward materials that exhibit a time
dependent mechanical behavior in response to the applied mechanical
stimulus. In addition, the present invention differs from the
aforementioned prior art methods since embodiments of the invention
are applicable not only to axial displacements and strains but also
displacements and strains in all directions, displacement ratios,
strain ratios and the time-dependent behavior of the aforementioned
parameters can be determined and imaged.
SUMMARY OF THE INVENTION
[0011] Embodiments of this invention overcome the limitations of
the current elastographic compression/acquisition methods in
inherently noisy applications as for example those of clinical
interest. Embodiments of this invention minimize the decorrelation
noise between the frames used for the generation of the elastograms
since the reference frame is continuously moved in time and the
inter-frame time interval is maintained sufficiently short during
the entire acquisition. This allows the generation of good quality
elastograms in noisy environments for short (sub-second) as well as
long (multi-second) acquisition times.
[0012] Embodiments of the invention may be practiced using the
preferred hand-held configuration of scanning.
[0013] Embodiments of the invention utilize the application of a
mechanical stimulus to a material that exhibits a time-dependent
mechanical behavior and acquisition of ultrasonic data from the
target body after the application of the mechanical stimulus.
Time-dependent axial strain, lateral strain and strain ratio
elastograms can be generated by using a continuously moving
reference frame and post-compression frames spaced at sub-second
intervals with respect to the pre-compression frame. The invention
is also applicable for evaluating the time dependent changes
occurring in lateral and axial displacements as well as in the
slopes of these displacements and in transverse strains.
[0014] Embodiments of the invention also generate images of local
strain time constants and displacement time constants that are
representative of the time-dependent mechanical behavior of the
material under the application of a mechanical stimulus. This is
accomplished by using curve-fitting techniques to the
time-dependent evolution of the local strains or local
displacements and displaying the coefficients of the fitting curve
as images. These images may also be of value for differentiation of
materials based on the time required for the interstitial fluid to
flow out of the area of interest. This may also allow the
generation of new contrast mechanism, which can be helpful for
detecting the presence of regions that have the same elastic
properties of the surrounding background (and therefore they are
not visible in the corresponding drained and undrained
elastograms), but have different permeability properties.
[0015] Embodiments of the invention may allow application of the
elastographic techniques for diagnosis of some pathological
conditions, such as lymphedema, decubitus ulcers, and the detection
of cancers and their differentiation from normal tissues via fluid
transport characterization.
[0016] Several terms are used herein to describe various
embodiments of the invention. The term "displacement", as used
herein, refers to local time-delays estimated between two echo
signals. The term "strain", as used herein, refers to the gradient
of local displacements. The strain in each direction may be
computed as the derivative of the displacement along that given
direction.
[0017] The term "strain ratio", as used herein, refers to the ratio
between the strains computed along two directions. The term "slope
of the displacement", as used herein, refers to the derivative of
the displacements along all possible directions.
[0018] By considering as a transverse plane any plane that is
perpendicular to the transducer's beam axis and transverse
displacement the displacement between any two points lying in any
transverse plane, the term "transverse strain", as used herein, is
the derivative of the transverse displacement.
DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 provides an example of the estimation of the strain
ratio from a sequence of strain ratios computed between different
post compression frames.
[0020] FIG. 2 provides a comparison between a poroelastogram
generated using the traditional method and two elastograms obtained
using the proposed method in vitro.
[0021] FIGS. 3A-3C provide a simulation comparison of the
performances of the traditional method (solid curve) and the
present invention (dashed curve) in inherently noisy
applications.
[0022] FIG. 4 is an example of the application of the new proposed
method in vivo in a patient with stage 2 lymphedema in the arm. For
comparison, the normal arm is shown as well.
[0023] FIG. 5 is an example of the application of the new proposed
method in vivo in a patient with stage 1 lymphedema in both
legs.
[0024] FIG. 6 shows three examples of Strain ratio time constant
elastograms (right) as estimated from the corresponding
poroelastograms (left) by applying curve fitting techniques.
[0025] FIG. 7 is a side view of a first apparatus suitable for
practicing various embodiments of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] An apparatus that can be used to practice the various method
embodiments of the invention is depicted in FIG. 7. FIG. 7 shows
multiple transducers 10 sonically coupled to a target body 15. An
ultrasonic pulse 18 is shown propagating within beam 20 toward an
echo source 25 on beam axis 12. As the pulse 18 propagates through
the target 15, corresponding echoes are generated and arrival items
noted at the transducer aperture 11.
[0027] The transducers 10 are operatively coupled to a pulse
generation and signal receiving unit 13. Unit 13 further comprises
a display 17 capable of visually displaying strains, strain ratios,
displacements, and slopes that are determined and/or estimated
using various embodiments of the present invention, described
herein. Unit 13 comprises the circuitry known to those of ordinary
skill in the elastography arts to generate ultrasound pulses,
receive echo signals, process echo signals, store echo signals, and
display data based upon the received and processed signals.
[0028] FIGS. 3A-3C show the superior performance of the proposed
method, due to the ability of this method to maintain high
cross-correlation values in time.
[0029] Several embodiments of the invention are directed toward
methods for determining the strain of a target body. One such
embodiment comprises the step of coupling a transducer array
comprising at least three transducers to the target body. In one
preferred embodiment, the three transducers are positioned along a
common line segment. In another preferred embodiment, one
transducer is equidistantly spaced with respect to the other two
transducers. In another preferred embodiment, the three transducers
are positioned such that the pulses of ultrasound energy they emit
travel along non-parallel paths in the target body.
[0030] The next step of this embodiment is applying a mechanical
stimulus to a target body. In a preferred embodiment, the applied
mechanical stimulus is selected from the group consisting of
stress-relaxation, creep, constant load, constant strain, constant
strain rate, constant displacement, sinusoidal load, sinusoidal
strain, sinusoidal strain, increasing load, increasing strain,
increasing displacement, decreasing load, decreasing strain, and
decreasing displacement.
[0031] In one preferred embodiment, the applied mechanical stimulus
is strain. In another preferred embodiment, the strain is applied
at a constant level. In another preferred embodiment, the strain is
applied at a non-constant level.
[0032] In one preferred embodiment, the mechanical stimulus is
applied in the target body. In another preferred embodiment, the
mechanical stimulus is applied by the target body.
[0033] In one preferred embodiment, the mechanical stimulus is
generated by a change of temperature in the target body. In another
preferred embodiment, the mechanical stimulus is generated by a
change of temperature in the vicinity of the target body. In
another preferred embodiment, the mechanical stimulus is generated
by fluid flow in the target body. In another preferred embodiment,
the mechanical stimulus is generated by fluid flow in the vicinity
of the target body.
[0034] In one preferred embodiment, the applied mechanical stimulus
is a load. In another preferred embodiment, the load is applied at
a constant level. In another preferred embodiment, the load is
applied at a non-constant level.
[0035] In one preferred embodiment, the applied mechanical stimulus
is a displacement. In another preferred embodiment, the
displacement is applied at a constant level. In another preferred
embodiment, the displacement is applied at a non-constant
level.
[0036] The next step of this embodiment is emitting a first pulse
of ultrasound energy from each of the transducers into the target
body. The next step of this embodiment is receiving with each of
the transducers at least one ultrasound echo sequence from each
first pulse. The next step of this embodiment is emitting a second
pulse of ultrasound energy from each of the transducers into the
target body. The next step of this embodiment is receiving with
each of the transducers at least one ultrasound echo sequence from
each second pulse. The next step of this embodiment is emitting a
third pulse of ultrasound energy from each of the transducers into
the target body. The next step of this embodiment is receiving with
each of the transducers at least one ultrasound echo sequence from
each third pulse. In a preferred embodiment, the second pulse is
emitted at a first predetermined time after the first pulse and the
third pulse is emitted at a second predetermined time after the
second pulse.
[0037] The next step of this embodiment is estimating the strain
along two directions in the target body between members of a first
pair of ultrasound sequences comprising the first ultrasound echo
sequence and another of the ultrasound echo sequences.
[0038] The next step of this embodiment is estimating the strain
along two different directions in the target body between members
of a second pair of ultrasound echo sequences comprising two
ultrasound echo sequences that are not identical to the two
ultrasound sequences that are comprised by the first pair. In one
preferred embodiment, the two directions are orthogonal to each
other. In another preferred embodiment, the two directions are
orthogonal to the paths of the pulses emitted from the three
transducers. In another preferred embodiment, the strain is
estimated using a technique selected from the group consisting of a
cross correlation technique, a Doppler technique, a phase estimator
technique, a frequency estimator technique, a pattern matching
technique, a sum-absolute difference technique, a least squares
technique, and a zero crossing estimator technique.
[0039] In one preferred embodiment, the target body is
viscoelastic. In another preferred embodiment, the target body is
poroelastic. In another preferred embodiment, the target body
possesses time dependent mechanical properties.
[0040] A preferred embodiment of the invention further comprises
displaying the estimated strain. In another preferred embodiment,
the invention comprises computing the strain ratios between the
echo sequences in the first pair and between the echo sequences in
the second pair. In a preferred embodiment, the invention further
comprises storing the computed strain ratios in a retrievable
medium.
[0041] Another embodiment of the invention for determining the
strain in a target body comprises the step of applying a mechanical
stimulus to a target body. The next step of this embodiment
comprises coupling a transducer to the target body. The next step
of this embodiment comprises emitting a first pulse of ultrasound
energy from the transducer into the target body. The next step of
this embodiment comprises receiving with the transducer at least
one ultrasound echo sequence from the first pulse. The next step of
this embodiment comprises emitting a second pulse of ultrasound
energy from the transducer into the target body. The next step of
this embodiment comprises receiving with the transducer at least
one ultrasound echo sequence from the second pulse. The next step
of this embodiment comprises emitting a third pulse of ultrasound
energy from the transducer into the target body. The next step of
this embodiment comprises receiving with the transducer at least
one ultrasound echo sequence from the third pulse.
[0042] The next step of this embodiment comprises estimating the
strain in the target body between the first ultrasound echo
sequence and a subsequent ultrasound echo sequence. The next step
of this embodiment comprises estimating the strain in the target
body between two ultrasound echo sequences other than the two
ultrasound echo sequences for which the strain was estimated in the
preceding step.
[0043] In another preferred embodiment, this method further
comprises displaying the estimated strain.
[0044] Another embodiment of the present invention for determining
the strain of a target body comprises the step of applying a
mechanical stimulus to a target body during time interval T. In one
preferred embodiment, the mechanical stimulus is increasing. In
another preferred embodiment, the increasing mechanical stimulus is
linearly increasing. In another preferred embodiment, the
mechanical stimulus is decreasing. In another preferred embodiment,
the decreasing mechanical stimulus is linearly decreasing.
[0045] The next step of this embodiment comprises coupling a
transducer to the target body during time interval T. The next step
of this embodiment comprises emitting a first pulse of ultrasound
energy from the transducer into the target body during time
interval T. The next step of this embodiment comprises receiving
with the transducer at least one ultrasound echo sequence from the
first pulse during time interval T. The next step of this
embodiment comprises emitting a second pulse of ultrasound energy
from the transducer into the target body during time interval T.
The next step of this embodiment comprises receiving with the
transducer at least one ultrasound echo sequence from the second
pulse during time interval T. The next step of this embodiment
comprises emitting a third pulse of ultrasound energy from the
transducer into the target body during time interval T. The next
step of this embodiment comprises receiving with the transducer at
least one ultrasound echo sequence from the third pulse during time
interval T.
[0046] The next step of this embodiment comprises estimating the
strain in the target body between the first ultrasound echo
sequence and a subsequent ultrasound echo sequence. The next step
of this embodiment comprises estimating the strain in the target
body between two ultrasound echo sequences other than the two
ultrasound echo sequences for which the strain was estimated in the
preceding step.
[0047] Other embodiments of the present invention are directed
toward determining the displacement of the target body. One such
embodiment comprises the step of applying a mechanical stimulus to
a target body. This embodiment further comprises coupling a
transducer array comprising at least three transducers to the
target body. This embodiment further comprises emitting a first
pulse of ultrasound energy from each of the transducers into the
target body. This embodiment further comprises receiving with each
of the transducers at least one ultrasound echo sequence from each
first pulse. This embodiment further comprises emitting a second
pulse of ultrasound energy from each of the transducers into the
target body. This embodiment further comprises receiving with each
of the transducers at least one ultrasound echo sequence from each
second pulse. This embodiment further comprises emitting a third
pulse of ultrasound energy from each of the transducers into the
target body. This embodiment further comprises receiving with each
of the transducers at least one ultrasound echo sequence from each
third pulse.
[0048] This embodiment further comprises estimating a first pair of
displacements in two directions in the target body between a first
pair of ultrasound sequences comprising the first ultrasound echo
sequence and another of said ultrasound echo sequence. This
embodiment further comprises estimating a second pair of
displacements in two directions in the target body between a second
pair of ultrasound echo sequences comprising two ultrasound echo
sequences that are not identical to the two ultrasound sequences
that are comprised by said first pair. In a preferred embodiment,
this method further comprises displaying the estimated
displacements.
[0049] In another preferred embodiment, this method further
comprises estimating the slopes of the first pair of displacements
in any direction to estimate the first pair of strains in the
target body in two directions. This preferred embodiment further
comprises estimating the slopes of the second pair of displacements
in any direction to estimate the second pair of strains in the
target body in two directions. In another preferred embodiment,
this method further comprises computing the first strain ratio
between the first pair of strains and computing the second strain
ratio between the second pair of strains. In another preferred
embodiment, this method further comprises adding the first and
second strain ratios. In another preferred embodiment, this method
further comprises determining the difference between the first
strain ratio and the second strain ratio. This method may be
practiced by subtracting the first strain ratio from the second
strain ratio, or by subtracting the second strain ratio from the
first strain ratio.
[0050] In another preferred embodiment, this method further
comprises estimating the slopes of the first pair of displacements
in any direction to estimate the transverse strains in the target
body, and estimating the slope of the second pair of displacements
in any direction to estimate the transverse strains in the target
body.
[0051] Another embodiment to of the present invention directed to
determining the displacement of a target body comprises the step of
applying a mechanical stimulus to a target body. The next step in
this embodiment comprises coupling a transducer to the target body.
The next step in this embodiment comprises emitting a first pulse
of ultrasound energy from the transducer into the target body. The
next step in this embodiment comprises receiving with the
transducer at least one ultrasound echo sequence from the first
pulse. The next step in this embodiment comprises emitting a second
pulse of ultrasound energy from the transducer into the target
body. The next step in this embodiment comprises receiving with the
transducer at least one ultrasound echo sequence from the second
pulse. The next step in this embodiment comprises emitting a third
pulse of ultrasound energy from the transducer into the target
body. The next step in this embodiment comprises receiving with the
transducer at least one ultrasound echo sequence from the third
pulse.
[0052] The next step in this embodiment comprises estimating the
first displacement in the target body between the first ultrasound
echo sequence and a subsequent ultrasound echo sequence. The next
step in this embodiment comprises estimating the second
displacement in the target body between two ultrasound echo
sequences other than the two ultrasound echo sequences for which
the displacement was estimated in the preceding step. In another
preferred embodiment, this method further comprises displaying the
estimated first and second displacements.
[0053] In a preferred embodiment, this method further comprises
estimating the slope of the first displacement in any direction to
estimate the first strain in the target body and estimating the
slope of the second displacement in any direction to estimate the
second strain in the target body. In another preferred embodiment,
this method further comprises estimating the slope of the first
displacement in any direction to estimate the first transverse
strain in the target body and estimating the slope of second
displacement in any direction to estimate the second transverse
strain in the target body. In another preferred embodiment, this
method further comprises computing the strains from the estimated
first and second displacements. In another preferred embodiment,
the invention further comprises displaying the computed strains. In
another preferred embodiment, the invention further comprises
computing the sum of the first and second displacements and
estimating the strain from some of the displacements previously
computed. In a preferred embodiment, the sum of the first and
second displacements can be computed by adding the magnitudes of
the first and second displacements. In another preferred
embodiment, the invention further comprises displaying the sum of
the first and second displacements. In a preferred embodiment, this
invention further comprises displaying the estimated strain.
[0054] In a preferred embodiment, this method further comprises
determining the difference between the first and second
displacements and estimating the strain from the computed
difference between the first and second displacements. In a
preferred embodiment, the difference between the first and second
displacements may be determined by subtracting the first
displacement from the second displacement or by subtracting the
second displacement from the first displacement. In another
preferred embodiment, the invention further comprises displaying
the difference between the first and second displacements. In
another preferred embodiment, the invention further comprises
displaying the difference between the first and second
displacements. In another preferred embodiment, the invention
further comprises displaying the estimated strain. In another
preferred embodiment, the invention further comprises determining
the sum of the first and second displacements and estimating the
slope of the sum of the first and second displacements in any
direction to estimate transverse strains. In a preferred
embodiment, the invention further comprises determining the
difference between the first and second displacements and
estimating the slope of the difference between the first and second
displacements in any direction to estimate transverse strain.
[0055] Another embodiment to the present invention directed toward
determining the displacement of a target body comprises applying a
mechanical stimulus to a target body during time interval T. This
embodiment further comprises coupling a transducer to the target
body during time interval T. This embodiment further comprises
emitting a first pulse of ultrasound energy from the transducer
into the target body during time interval T. This embodiment
further comprises receiving with the transducer at least one
ultrasound echo sequence from the first pulse during time interval
T. This embodiment further comprises emitting a second pulse of
ultrasound energy from the transducer into the target body during
time interval T. This embodiment further comprises receiving with
the transducer at least one ultrasound echo sequence from the
second pulse during time interval T. This embodiment further
comprises emitting a third pulse of ultrasound energy from the
transducer into the target body during time interval T. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the third pulse during time
interval T.
[0056] This embodiment further comprises estimating the first
displacement in the target body in between the first ultrasound
echo sequence and a subsequent ultrasound echo sequence. This
embodiment further comprises estimating the second displacement in
the target body between two ultrasound echo sequences other than
the two ultrasound echo sequences for which the displacement was
estimated in the preceding step. In a preferred embodiment, the
invention further comprises displaying the estimated displacement.
In another preferred embodiment, the invention further comprises
computing the strain from the first displacement and computing the
strain from the second displacement. In another preferred
embodiment, the invention further comprises computing the
transverse strain from the first displacement and computing the
transverse strain from the second displacement.
[0057] Another embodiment to the present invention directed toward
determining the displacement of a target body comprises applying a
mechanical stimulus to a target body. This embodiment further
comprises coupling a transducer array comprising at least three
transducers to the target body. This embodiment further comprises
emitting a first pulse of ultrasound energy from each of the
transducers into the target body. This embodiment further comprises
receiving with each of the transducers at least one ultrasound echo
sequence from each first pulse. This embodiment further comprises
emitting a second pulse of ultrasound energy from each of the
transducers into the target body. This embodiment further comprises
receiving with each of the transducers at least one ultrasound echo
sequence from each second pulse. This embodiment further comprises
emitting a third pulse of ultrasound energy from each of the
transducers into the target body. This embodiment further comprises
receiving with each of the transducers at least one ultrasound echo
sequence from each third pulse. This embodiment further comprises
estimating the strain in two directions in the target body between
a first pair of ultrasound sequences comprising the first
ultrasound echo sequence and another of said ultrasound echo
sequences. This embodiment further comprises estimating the strain
in two directions in the target body between a second pair of
ultrasound echo sequences comprising two ultrasound echo sequences
that are not identical to the two ultrasound sequences that are
comprised by said first pair.
[0058] Another embodiment to the present invention directed toward
determining the displacement of a target body comprises coupling a
transducer to the target body. This embodiment further comprises
applying a mechanical stimulus to a target body. This embodiment
further comprises emitting a first pulse of ultrasound energy from
the transducer into the target body. This embodiment further
comprises receiving with the transducers at least one ultrasound
echo sequence from the first pulse. This embodiment further
comprises emitting a second pulse of ultrasound energy from the
transducer into the target body. This embodiment further comprises
receiving with the transducer at least one ultrasound echo sequence
from the second pulse. This embodiment further comprises emitting a
third pulse of ultrasound energy from the transducer into the
target body. This embodiment further comprises receiving with the
transducer at least one ultrasound echo sequence from the third
pulse. This embodiment further comprises estimating the strain in
the target body between the first ultrasound echo sequence and a
subsequent ultrasound echo sequence. This embodiment further
comprises estimating the strain in the target body between two
ultrasound echo sequences other than the two ultrasound echo
sequences for which the strain was estimated in the preceding
step.
[0059] Another embodiment to the present invention directed toward
determining the displacement of a target body comprises coupling a
transducer to the target. This embodiment further comprises
applying a mechanical stimulus to a target body during time
interval T. This embodiment further comprises emitting a first
pulse of ultrasound energy from the transducer into the target body
during time interval T. This embodiment further comprises receiving
with the transducer at least one ultrasound echo sequence from the
first pulse during time interval T. This embodiment further
comprises emitting a second pulse of ultrasound energy from the
transducer into the target body during time interval T. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the second pulse during time
interval T. This embodiment further comprises emitting a third
pulse of ultrasound energy from the transducer into the target body
during time interval T. This embodiment further comprises receiving
with the transducer at least one ultrasound echo sequence from the
third pulse during time interval T. This embodiment further
comprises estimating the strain in the target body in between the
first ultrasound echo sequence and a subsequent ultrasound echo
sequence. This embodiment further comprises estimating the strain
in the target body between two ultrasound echo sequences other than
the two ultrasound echo sequences for which the strain was
estimated in the preceding step.
[0060] Another embodiment to the present invention directed toward
determining the displacement of a target body comprises coupling a
transducer array comprising at least three transducers to the
target body. This embodiment further comprises applying a
mechanical stimulus to a target body. This embodiment further
comprises emitting a first pulse of ultrasound energy from each of
the transducers into the target body. This embodiment further
comprises receiving with the transducer at least one ultrasound
echo sequence from each first pulse. This embodiment further
comprises emitting a second pulse of ultrasound energy from each of
the transducers into the target body. This embodiment further
comprises receiving with the transducer at least one ultrasound
echo sequence from each second pulse. This embodiment further
comprises emitting a third pulse of ultrasound energy from each of
the transducers into the target body. This embodiment further
comprises receiving with the transducer at least one ultrasound
echo sequence from each third pulse. This embodiment further
comprises estimating the first pair of displacement in two
directions in the target body between a first pair of ultrasound
sequences comprising the first ultrasound echo sequence and another
of said ultrasound echo sequences. This embodiment further
comprises estimating the second pair of displacement in two
directions in the target body between a second pair of ultrasound
echo sequences comprising two ultrasound echo sequences that are
not identical to the two ultrasound sequences that are comprised by
said first pair.
[0061] Another embodiment to the present invention directed toward
determining the displacement of a target body comprises coupling a
transducer to the target body. This embodiment further comprises
applying a mechanical stimulus to a target body. This embodiment
further comprises emitting a first pulse of ultrasound energy from
the transducer into the target body. This embodiment further
comprises receiving with the transducer at least one ultrasound
echo sequence from the first pulse. This embodiment further
comprises emitting a second pulse of ultrasound energy from the
transducer into the target body. This embodiment further comprises
receiving with the transducer at least one ultrasound echo sequence
from the second pulse. This embodiment further comprises emitting a
third pulse of ultrasound energy from the transducer into the
target body. This embodiment further comprises receiving with the
transducer at least one ultrasound echo sequence from the third
pulse. This embodiment further comprises estimating the
displacement in the target body between the first ultrasound echo
sequence and a subsequent ultrasound echo sequence. This embodiment
further comprises estimating the displacement in the target body
between two ultrasound echo sequences other than the two ultrasound
echo sequences for which the strain was estimated in the preceding
step.
[0062] Another embodiment to the present invention directed toward
determining the displacement of a target body comprises coupling a
transducer to the target body. This embodiment further comprises
applying a mechanical stimulus to a target body during time
interval T. This embodiment further comprises emitting a first
pulse of ultrasound energy from the transducer into the target body
during time interval T. This embodiment further comprises receiving
with the transducer at least one ultrasound echo sequence from the
first pulse during time interval T. This embodiment further
comprises emitting a second pulse of ultrasound energy from the
transducer into the target body during time interval T. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the second pulse during time
interval T. This embodiment further comprises emitting a third
pulse of ultrasound energy from the transducer into the target body
during time interval T. This embodiment further comprises receiving
with the transducer at least one ultrasound echo sequence from the
third pulse during time interval T. This embodiment further
comprises estimating the displacement in the target body in between
the first ultrasound echo sequence and a subsequent ultrasound echo
sequence. This embodiment further comprises estimating the
displacement in the target body between two ultrasound echo
sequences other than the two ultrasound echo sequences for which
the strain was estimated in the preceding step.
[0063] An embodiment of the invention for imaging the strain in a
target body comprises applying a mechanical stimulus to a target
body, wherein said application commences at a time T0. This
embodiment further comprises coupling a transducer to the target
body. This embodiment further comprises emitting a first pulse of
ultrasound energy from the transducer into the target body. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the first pulse at time interval
T1 after T0. This embodiment further comprises emitting a second
pulse of ultrasound energy from the transducer into the target
body. This embodiment further comprises receiving with the
transducer at least one ultrasound echo sequence from the second
pulse at time interval T2 after T0. This embodiment further
comprises emitting a third pulse of ultrasound energy from the
transducer into the target body. This embodiment further comprises
receiving with the transducer at least one ultrasound echo sequence
from the third pulse at time interval T3 after T0. This embodiment
further comprises emitting a fourth pulse of ultrasound energy from
the transducer into the target body. This embodiment further
comprises receiving with the transducer at least one ultrasound
echo sequence from the fourth pulse at time interval T4 after T0.
This embodiment further comprises estimating the strain ratio, SR1,
between the first ultrasound echo sequence and the second
ultrasound sequence. This embodiment further comprises estimating
the strain ratio, SR2, between the second ultrasound echo sequence
and the third ultrasound sequence. This embodiment further
comprises estimating the strain ratio, SR3, between the third
ultrasound echo sequence and the fourth ultrasound sequence. This
embodiment further comprises deriving a polynomial comprising at
least one coefficient defining a functional relationship between
time and SR1, SR2, and SR3. This embodiment further comprises
imaging the coefficients of the polynomial derived in the preceding
step.
[0064] An embodiment of the invention for imaging the strain in a
target body comprises coupling a transducer to the target body.
This embodiment further comprises applying a mechanical stimulus to
a target body, wherein said application commences at a time T0.
This embodiment further comprises emitting a first pulse of
ultrasound energy from the transducer into the target body. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the first pulse at time interval
T1 after T0. This embodiment further comprises emitting a second
pulse of ultrasound energy from the transducer into the target
body. This embodiment further comprises receiving with the
transducer at least one ultrasound echo sequence from the second
pulse at time interval T2 after T0. This embodiment further
comprises emitting a third pulse of ultrasound energy from the
transducer into the target body. This embodiment further comprises
receiving with the transducer at least one ultrasound echo sequence
from the third pulse at time interval T3 after T0. This embodiment
further comprises emitting a fourth pulse of ultrasound energy from
the transducer into the target body. This embodiment further
comprises receiving with the transducer at least one ultrasound
echo sequence from the fourth pulse at time interval T4 after T0.
This embodiment further comprises estimating the strain, S1,
between the first ultrasound echo sequence and the second
ultrasound sequence. This embodiment further comprises estimating
the strain, S2, between the second ultrasound echo sequence and the
third ultrasound sequence. This embodiment further comprises
estimating the strain, S3, between the third ultrasound echo
sequence and the fourth ultrasound sequence. This embodiment
further comprises deriving a polynomial comprising at least one
coefficient defining a functional relationship between time and S1,
S2, and S3. This embodiment further comprises imaging the
coefficients of the polynomial derived in the preceding step.
[0065] An embodiment of the invention for imaging the displacement
in a target body comprises coupling a transducer to the target
body. This embodiment further comprises applying a mechanical
stimulus to a target body, wherein said application commences at a
time T0. This embodiment further comprises emitting a first pulse
of ultrasound energy from the transducer into the target body. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the first pulse at time interval
T1 after T0. This embodiment further comprises emitting a second
pulse of ultrasound energy from the transducer into the target
body. This embodiment further comprises receiving with the
transducer at least one ultrasound echo sequence from the second
pulse at time interval T2 after T0. This embodiment further
comprises emitting a third pulse of ultrasound energy from the
transducer into the target body. This embodiment further comprises
receiving with the transducer at least one ultrasound echo sequence
from the third pulse at time interval T3 after T0. This embodiment
further comprises emitting a fourth pulse of ultrasound energy from
the transducer into the target body. This embodiment further
comprises receiving with the transducer at least one ultrasound
echo sequence from the fourth pulse at time interval T4 after T0.
This embodiment further comprises estimating the displacement, D1,
between the first ultrasound echo sequence and the second
ultrasound sequence. This embodiment further comprises estimating
the displacement, D2, between the second ultrasound echo sequence
and the third ultrasound sequence. This embodiment further
comprises estimating the displacement, D3, between the third
ultrasound echo sequence and the fourth ultrasound sequence. This
embodiment further comprises deriving a polynomial comprising at
least 1 coefficient defining a functional relationship between time
and D1, D2, and D3. This embodiment further comprises imaging the
coefficients of the polynomial derived in the preceding step.
[0066] An embodiment to the present invention directed toward
measuring the mechanical stimulus applied to a target body during
hand-held scanning, comprises coupling a transducer to the target
body. This embodiment further comprises emitting a first pulse of
ultrasound energy from the transducer into the target body. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the first pulse. This embodiment
further comprises estimating the first distance between the
transducer and a non-moving reference point in the vicinity of the
target body from the first received echo sequence. This embodiment
further comprises emitting a second pulse of ultrasound energy from
the transducer into the target body.
[0067] This embodiment further comprises receiving with the
transducer at least one ultrasound echo sequence from the second
pulse. This embodiment further comprises estimating the second
distance between the transducer and the same non-moving reference
point used in step (d) from the second received echo sequence. In a
preferred embodiment, this method further comprises computing the
displacement between the first distance and the second
distance.
[0068] Another embodiment to the present invention directed toward
measuring the mechanical stimulus applied to a target body during
hand-held scanning comprises coupling a transducer to the target
body. This embodiment further comprises emitting a first pulse of
ultrasound energy from the transducer into the target body. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the first pulse. This embodiment
further comprises estimating the distance between a reference point
in the vicinity of the transducer and a non-moving reference point
in the vicinity of the target body from the first received echo
sequence. This embodiment further comprises emitting a second pulse
of ultrasound energy from the transducer into the target body. This
embodiment further comprises receiving with the transducer at least
one ultrasound echo sequence from the second pulse. This embodiment
further comprises estimating the distance between the reference
point in the vicinity of the transducer used in step (d) and the
same non-moving reference point used in step (d) from the second
received echo sequence.
[0069] It will be understood that various changes in detail,
parameters, and arrangements of the steps which have been described
and illustrated above in order to explain the nature of this
invention may be made by those skilled in the art without departing
from the principle and scope of the invention.
* * * * *