Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Ultrasound Probe
FIELD OF THE INVENTION
The present invention relates to an ultrasound imaging probe for use in
ultrasound guided interventional procedures including regional anaesthesia.
BACKGROUND OF THE INVENTION
Current techniques in ultrasound guided regional anaesthesia (UGRA)
require an anaesthetist to position a needle tip adjacent to a nerve bundle
and
inject anaesthetic agent under the guidance of medical ultrasound imaging. In
order to maintain a clearer image of the needle tip position the needle may be
inserted 'in-plane' with the array.
In order to insert a needle in-plane, as directly to target as possible and
avoiding passing the needle along and under the length of the array; previous
inventions have involved taking a linear array and removing elements from the
central section to create a gap for needle insertion.
This technique may create an unwanted gap in the ultrasound image over
the area of greatest interest.
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It also does not aid the visibility of the needle shaft or tip due to the
angle
of attack between the length of needle and acoustic beam.
Because of a necessity to minimise the gap in the acoustic image, the
physical gap for the needle to pass though must also be kept to a minimum, and
this reduces possible articulation in the gap with the probe in place.
Curved arrays may allow a more direct entry of the needle but are not
generally available in a suitable frequency and for other reasons may not
offer
optimum imaging or other features.
Previous proposals such as those described in the publication by S.
Cochran, G. a Corner, K.J. Kirk, al. a Lines, and M.J. Watson, "P5C-5 Design
and Validation of an Ultrasound Array Optimised for Epidural Needle Guidance,"
2007 IEEE Ultrasonics Symposium Proceedings, vol. 1, Oct. 2007, pp. 2255-
2258; in US Patent 4408611 by S.Enjoji entitled "Probe for ultrasonic imaging
apparatus"; and in US Patent 4029084 by R. Soldner entitled "Ultrasound
applicator with guide slot for puncturing cannula" are essentially flat linear
arrays
with missing elements over the gap where the needle passes through.
Each probe functions as a normal linear (1D) array with a corresponding
gap in the image. There is minimal overlap in the acoustic image from the two
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blocks of elements as all elements exist on the same linear plane. The
direction/plane of propagation of each block of elements is identical.
Other inventions (US Patent 4,475,553 by Yamaguchi et al.) have
addressed the issues associated with the gap with extra laterally displaced
imaging components; however this adds complication to the probe design and
image reconstruction and still allows only minimal articulation in the gap.
US Patent 6423002 by J.A. Hossack, entitled "Intra-operative diagnostic
ultrasound multiple-array transducer probe and optional surgical tool" and US
Patent 7214191 by B. Stringer and G. Simmons entitled "Multiplanar ultrasonic
vascular imaging device, system incorporating same, method of use and
protective sheath," are probes where at least two individual blocks of
elements
are arranged onto the same 2D plane and lie perpendicular to each, i.e. in a T-
shape. Each block of elements produces an individual image which can be
viewed adjacent to each other or in pseudo (wrap-around) 3D, on-screen.
Again there is no significant overlap in imaging area. The direction of
propagation of each block of elements is the same, while the two acoustic
imaging fields lie on perpendicular planes.
A related US Patent 2005020919A by B.J. Stringer, G.A. Simmons, D.A.
Christensen, S. Messerly, C.P. Ford, and R.W. Evensen entitled "Multiplanar
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ultrasonic vascular sensor assembly, system and methods employing same,
apparatus for movably affixing a sensor assembly to a body and associated
methods," is the same as above, except that it has the addition of a
single/double
element angled towards the imaging field for doppler analysis.
The angled element is not an array. Although it is defined as comprising of
at least one element, it has only one element in cross section along the plane
of
the adjacent array.
A publication by M. Delaide and G. Maes entitled "Design and Application
of Low-Frequency Twin Side-by-Side Phased Array Transducers for Improved
UT Capability on Cast Stainless Steel Components,"Proc. 2nd mt. Conf. on NDE
in Relation to Structural Integrity for Nuclear and Pressurized Components,
New
Orleans May 2000, describes the use of 2 x 2D arrays consisting of 4 x 2
elements positioned directly next to each other and angled inwards.
The main differences are:
1/ The arrays described are 2 dimensional, i.e. each is arranged in a grid of
elements, in this case 2 x 4 elements with only 2 elements in lateral section.
2/ There is no gap between the edges of the adjacent arrays
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3/ The probe is connected to a shaped waveguide for mounting to steel.
4/ The intended aim is to improve beam focusing rather than provide an
overlapping visual image area.
5
It is an object of at least one aspect of the present invention to obviate or
mitigate at least one or more of the aforementioned problems.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided an
ultrasound probe comprising a pair of transducer modules arranged in-line and
spaced apart from each other to form a shallow "V" shape in a defined range of
angles which correspond to ergonomic conformity to a patient's body surface at
procedure specific locations such as to allow a full ultrasound image of a
target
depth through an ultrasound scan engine.
Preferably the ultrasound probe is shaped to conform to the body surface of
the
majority of patients over the areas of the neck, axilla, forearm, lower leg,
chest
wall, knee and other joints.
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Preferably also the angle between each front plane of the twin arrays is
angled
between 1100 and 1400, conforming to the respective part of the body being
imaged.
The ultrasound probe preferably provides a gap for needle manipulation through
the center of the two arrays of between 2mm and 15mm.
Preferably the ultrasound image is created through a recombination of waveform
data obtained from the separate arrays by treating the twin angled arrays as
one
virtual array, using respective delays and angular realignment of the
individual
transmit and receive channels to create one continuous visual image.
More preferably the ultrasound image creation includes the application of beam
steering and RF signal compounding to the arrays to produce an improved visual
image.
Alternatively the recombination of waveform data is obtained from the separate
arrays by capturing standard B-mode images from each array individually,
rotating and positioning said images, using weighted pixel selection and
overlapping visual gain mixing to create one cohesive image.
The arrays may be straight linear arrays or curved.
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The ultrasound probe may be shaped to allow ergonomic manipulation
possibilities for an operator.
A third array may be provided arranged perpendicular to the plane of the first
pair, at a similar angle thereto and also in-plane with a needle entry area,
which
adds a concurrent 2D image to the combined image.
According to a second aspect of the present invention there is provided a
method of carrying out ultrasound guided regional anaesthesia using an
ultrasound probe in accordance with a first aspect of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described, by way of
example only, with reference to the accompanying drawings in which:
Figure 1 is a representation of the layout and operating range of an
ultrasound
probe according to an embodiment of the present invention having flat arrays;
Figure 2 is a front view of an ultrasound probe similar to that of Fig 1
arranged to
provide an expanded field of view;
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Figure 3 is a corresponding view to Fig 1 illustrating the layout and
operating
range of an ultrasound probe having curved arrays;
Figure 4 is a perspective view from below of an ultrasound probe in accordance
with the present invention;
Figure 5 is a front perspective view from above of the ultrasound probe of Fig
4;
Figure 6 is a perspective view from below of an alternative embodiment of an
ultrasound probe in accordance with the present invention;
Figure 7 is a representation of the visual display resulting from use of an
ultrasound probe as exemplified in Figs 1-5; and
Figure 8 is a representation of the visual display resulting from an
ultrasound
probe as exemplified in Figure 6.
BRIEF DESCRIPTION
Referring to the drawings an ultrasound probe 10 of the present invention
comprises a pair of one dimensional transducer modules 1, 2, arranged in-line
but set apart from each other in a shallow "V" shape.
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This allows a wide gap for needle manipulation while maintaining the
ability to compute a good acoustic image of the target area 4 on the
ultrasound
scan engine.
The ultrasound image is a product of data from both the arrays.
The concept can be applied to linear arrays as shown in Fig 1, or for a
wider field of view 5, using expanded field of view algorithms as in Fig 2 or
a pair
of curved linear arrays la, 2a as in Fig3.
The probe 10 is shaped to allow ergonomic manipulation possibilities for
the anaesthetist. The probe can be held in a 'pencil-type' grip anywhere on
the
main body, or by pushing directly on the back of arrays.
The shape of the probe, which can best be seen in Figs 2, 4 & 5 means it
sits in position better on a patient than a conventional probe.
A further option is the addition of a third array 11 arranged perpendicular
to the plane of the twin pair and in-plane with the needle entry 20 as shown
in Fig
6; this gives a secondary in-plane view of the target area and needle point .
The
third array is set at a similar angle to the others.
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In the case of the twin array, a visual display will be constructed using the
data from both array modules, combined with scan engine processing to form
one cohesive image 21 covering the extent of the acoustic beam width of the
probe as can be seen in Fig 7.
5
With the triple array probe, a third array image 22 will be displayed side by
side with the combined image 21 from the twin arrays as can be seen in Fig 8.
The image reconstruction for the combined view can be performed either
10 through visual mixing of the independent images from each array or
by forming
one visual image through the interpretation of transmit and receive signals to
represent one virtual curved or linear array.
The ultrasound probe of the current invention has a number of
advantages.
In particular a pair of arrays are set apart and angled in a shallow 'V'
shape with overlapping beam area providing an ultrasound image.
The conformal shape of the device provides a more stable 'platform' for an
anaesthetist.
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The probe does not provide a 'needle guide' as such and the anaesthetist
is free to work within an extended gap.
Optionally the inclusion of a perpendicular third array, also angled
enhances the probe.
The probe may incorporate 'sparse' array beam forming to utilise the full
width of all available array elements despite the limitations of the maximum
number of independent channels that current circuitry can handle.
Whilst specific embodiments of the present invention have been described
above, it will be appreciated that departures from the described embodiments
may still fall within the scope of the present invention.
Throughout the description and claims of this specification, the words
"comprise"
and "contain" and variations of them mean "including but not limited to", and
they
are not intended to (and do not) exclude other components, integers or steps.
Throughout the description and claims of this specification, the singular
encompasses the plural unless the context otherwise requires. In particular,
where the indefinite article is used, the specification is to be understood as
contemplating plurality as well as singularity, unless the context requires
otherwise.
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Features, integers and characteristics described in conjunction with a
particular aspect, embodiment or example of the invention are to be understood
to be applicable to any other aspect, embodiment or example described herein
unless incompatible therewith.
All of the features disclosed in this specification (including any
accompanying claims, abstract and drawings), and/or all of the steps of any
method or process so disclosed, may be combined in any combination, except
combinations where at least some of such features and/or steps are mutually
exclusive.
The invention is not restricted to the details of any foregoing embodiments.
The invention extends to any novel one, or any novel combination, of the
features disclosed in this specification (including any accompanying claims,
abstract and drawings), or to any novel one, or any novel combination, of the
steps of any method or process so disclosed.
