CA2612611A1 - Concave phased array imaging catheter - Google Patents
Concave phased array imaging catheter Download PDFInfo
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- CA2612611A1 CA2612611A1 CA002612611A CA2612611A CA2612611A1 CA 2612611 A1 CA2612611 A1 CA 2612611A1 CA 002612611 A CA002612611 A CA 002612611A CA 2612611 A CA2612611 A CA 2612611A CA 2612611 A1 CA2612611 A1 CA 2612611A1
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- phased array
- elements
- imaging
- intravascular device
- imaging system
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- 238000003384 imaging method Methods 0.000 title claims abstract description 38
- 238000002059 diagnostic imaging Methods 0.000 claims description 9
- 238000012285 ultrasound imaging Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims 4
- 238000000034 method Methods 0.000 description 7
- 238000012014 optical coherence tomography Methods 0.000 description 5
- 238000002604 ultrasonography Methods 0.000 description 4
- 230000001934 delay Effects 0.000 description 3
- 238000011282 treatment Methods 0.000 description 2
- 230000002792 vascular Effects 0.000 description 2
- 239000004696 Poly ether ether ketone Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000012814 acoustic material Substances 0.000 description 1
- 210000001367 artery Anatomy 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- JUPQTSLXMOCDHR-UHFFFAOYSA-N benzene-1,4-diol;bis(4-fluorophenyl)methanone Chemical compound OC1=CC=C(O)C=C1.C1=CC(F)=CC=C1C(=O)C1=CC=C(F)C=C1 JUPQTSLXMOCDHR-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 210000001105 femoral artery Anatomy 0.000 description 1
- 238000002608 intravascular ultrasound Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000002324 minimally invasive surgery Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- HLXZNVUGXRDIFK-UHFFFAOYSA-N nickel titanium Chemical compound [Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ti].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni].[Ni] HLXZNVUGXRDIFK-UHFFFAOYSA-N 0.000 description 1
- 229910001000 nickel titanium Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 210000000056 organ Anatomy 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920002530 polyetherether ketone Polymers 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
- A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
- A61B8/4488—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer the transducer being a phased array
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/12—Diagnosis using ultrasonic, sonic or infrasonic waves in body cavities or body tracts, e.g. by using catheters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
- B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
- B06B1/0622—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface
- B06B1/0633—Cylindrical array
Abstract
The present invention generally relates to medical devices, and more particularly to an improved intravascular device. In one embodiment, an intravascular device includes a catheter having proximal and distal portions, and a phased array of imaging elements, having edge elements each having angles of emission, located in the distal portion of the catheter, wherein the phased array is concaved having a radius of curvature such that when the phased array is steered in a maximal azimuthal direction, the angles of emission of the edge elements are substantially similar.
Description
CONCAVE PHASED ARRAY IMAGING CATHETER
FIELD OF THE INVENTION
The field of the invention relates to medical devices, and more particularly to phased array imaging catheters.
BACKGROUND OF THE INVENTION
Intraluminal, intracavity, intravascular, and intracardiac treatments and diagnosis of medical conditions utilizing minimally invasive procedures are effective tools in many areas of medical practice. These procedures are typically performed using imaging and treatment catheters that are inserted percutaneously into the body and into an accessible vessel of the vascular system at a site remote from the vessel or organ to be diagnosed and/or treated, such as the femoral artery. The catheter is then advanced tlirough the vessels of the vascular system to the region of the body to be treated. The catheter may be equipped with an imaging device, typically an ultrasound imaging device, which is used to locate and diagnose a diseased portion of the body, such as a stenosed region of an artery. For example, U.S. Pat.
No. 5,368,035, issued to Hamm et al., the disclosure of which is incorporated herein by reference, describes a catheter having an intravascular ultrasound imaging transducer.
An imaging transducer generally includes an imaging element configured to emit energy pulses. During operation, the imaging element is electrically excited, thus causing an energy pulse to be emitted. The pulse is directed to a surface where iniaging is desired and reflected back to the transducer. Two desirable features of the emitted energy pulse are that the energy pulse be focused and steerable. One known approach known in the art to obtain these features is to utilize an array of imaging elements instead of just one element. Fig. 1 shows an array 10 of two imaging elements, A and B, side-by-side. As is known in the art, if both elements, A and B, are excited simultaneously, then the energy pulses are combined to form a beam that is parallel to the direction that the elements, A and B, are facing, so that the beam travels directly away from the array 10. However, if a linear timing excitation gradient (a time delay based on a coherence theory) is used across the array 10, the beam can be steered in the azimuthal direction. By sending a short acoustic pulse and receiving the echo at each azimuthal direction, the array 10 may scan a sector area and construct an image. The image resolution is primarily determined by the beam 20 width in the lateral direction and the acoustic pulse length in the axial direction.
To focus the beam, i.e., adjust the beam width, time delays for each element may also be utilized. At a certain spatial location, the acoustic pulses from all elements may be coherently enlianced when they are in phase. The phase of the pulse is determined by the dilsi~~rzc'i;,l~+~ni tls~.~letiierit~-:t~h the destination location. To focus the beam at a spatial point, appropriate time delays are applied to all of the elements, A and B. These compensating delays ensure that the arrival of the acoustic pulses from different elements, A and B, are in coincidence at the desired spatial location.
The array of imaging elements configured to enable a beam to be focused and steered is known in the art as a "phased array." Though only two imaging elements, A and B, are shown in Fig. 1, a typical phased array may include as many as 256 elements. In the case of ultrasound imaging elements, each element, A and B, is generally small enough to be treated as an acoustic point source that generates a propagating wave with a spherical front. Collectively, the elements, A and B, form an acoustic field that can be enhanced when the elements, A and B, are in phase at a certain spatial location.
The elements, A and B, are typically rectangular and are typically evenly spaced across a flat plane. For ultrasound elements, each element has a pitch size equal to half a wavelength at the working ultrasound frequency. The pitch size is defined as the distance between two adjacent elenient, A and B, centers. With this typical configuration, when the beam 20 is steered and focused to a particular point F, the beams of the individual elements, A and B, are emitted at different angles, a and (3, with respect to the flat plane. This will cause the beams of the individual elements, A and B, to have different amplitudes, which can undesirably result in a widened beam 20, even if an accurate time delay compensation is used. This is particularly so when the beam 20 is steered to the maximum azimuthal direction.
Accordingly, an improved phased array imaging catheter would be desirable.
SUMMARY OF THE INVENTION
The present invention generally relates to medical devices, and more particularly to an improved intravascular device. In one embodiment, an intravascular device includes a catheter having proximal and distal portions, and a phased array of imaging elements located in the distal portion of the catheter, wherein the phased array is concaved.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to better appreciate how the above-recited and other advantages and objects of the present inventions are obtained, a more particular description of the invention briefly dVIX,Tqnttered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. It should be noted that the components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. However, like parts do not always have like reference numerals. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.
Fig. 1 is a cross-sectional side view of a phased array of imaging transducers known in the art.
Fig. 2 is a cross-sectional side view of a phased array of imaging transducers in accordance with a preferred embodiment of the present invention.
Fig. 3 is a cross-sectional view of an imaging wire in accordance with a preferred embodiment of the present invention.
Fig. 4 is a diagram of a medical imaging system in accordance with a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As described above, prior art phased array assemblies 10 consist of a series of small rectangular elements, A and B, that are evenly spaced in a flat plane. This configuration causes the elements to emit energy beams at different angles when the phased array beam 20 is steered and focused. This can undesirably cause a widened phased array beam 20.
By contrast, the improved phased array in this patent specification reduces the undesired wideness by placing a phased array in a concaved configuration, as shown in Fig. 2.
Fig. 2 shows a phased array 100 of imaging elements, A and B. The elements, A
and B, are situated along a concave 130 path having a radius R. The phased array 100 can have additional imaging elements along the concave path 130 (not shown). The phased array 100 has a length, L, and a maximum steering angle in the azimuthal direction, 0. F represents a focal point at the maximum steering angle in the azimuthal direction. The phased array 100 is shown focusing an energy beam, such as an acoustic pulse, 120 at focal point F. a and (3, represent the tangential angles for elements A and B to the focal point F respectively. al and (31, represent the flat plane angles for elements A and B to the focal point F respectively.
Point 0 represents the origin of the horizontal and vertical axis, X and Y.
In the case of a phased array 100 having a large number of imaging elements, wherein elements A and B represent the edge elements of the array 100, at focal point F, element B will hAVI d,IH'elllWIrg,6srC::Ahgld' P1,1Itt.4 the focal point F, whereas element A
will have the smallest angle a 1, to the focal point F. The concaving of the array 100 will decrease the tangential angle (3, for element B by (32, and increase the tangential angle a for element A by a2.
One of ordinary skill in the art would appreciate that by concaving the array 100, elements A
and B will have the most significant impact on the resulting beam 120 as compared to any imaging elements in between elements A and B, and the center imaging elements will be least affected.
The following is an approach to calculating the radius of curvature R of a concave phased array 100 that enables the tangential angles a and (3, to be equal at the maximum azimuthal direction 0. From Fig. 2, the following is true:
a = al +a2, (1) and R = R l - R2 (2) and because of geometric symmetry, we have:
a2= (32=a3, (3) To obtain a=(3, the following is deduced:
al+a3= (3l-a3, (4) which means:
a3= ((31 -al) /2, (5) Since:
sin (a3) = (L/2)/R (6) and:
tan (al) = OF cos (0) / (OF sin (0) + L/2) (7) and:
tan ((31) = OF cos (0) / (OF sin (0) - L/2) (8).
Combining equations (5) - (8), the radius of curvature R can be expressed as:
R = L / 2 (9) 11 tan-' OFcosB tan ' OFcos9 sin (OFsinO-L/2) (OFsinO+L/2) 111bIih:c aa9e;;nV'a,,V6E3IHz, 64 element phased array, wherein the length of the array is 5mm, if the array's maximum angle in the azimuthal direction is 45 , and the focal depth is 5mm, then the radius of curvature R is preferably approximately 7mm.
Equation (9) expresses the radius of curvature of a concave array, R, as a function of a desired focal depth if the other parameters in the array design, such as image range, have been provided. For an image range from OF 1 to OF2, an average radius of curvature Ra may be determined by:
R" F_ rF2R(ooF 10 .
Fl OF2-OFl ( ) The concave array 100 may have a uniform pitch, wherein the space from element center to element, A and B, is uniform; however, it can be non-uniform as well. An element's width can be varied to maximize the beam quality, as one of ordinary skill in the art would appreciate. For example, the element width can conform to a Gaussian, Bessel, or sinusoidal function using an element index number calculated from the array 100 center to an edge element, e.g., A or B.
For an ultrasound phased array 100, the array 100 can be fabricated by a variety of available active acoustic material, such as piezo-ceramics, piezo-films (thin or thick), 2-2 or 1-3 piezoceramic composites, 2-2 or 1-3 piezocrystal materials, or c1V1UT.
Further, other imaging devices may be used, instead of, or in addition to imaging transducers, such as light based apparatuses for obtaining images through optical coherence tomography (OCT). Image acquisition using OCT is described in Huang et al., "Optical Coherence Tomography," Science, 254, Nov. 22, 1991, pp 1178-1181, which is hereby incorporated by reference in its entirety. A
type of OCT imaging device, called an optical coherence domain reflectometer (OCDR) is disclosed in Swanson U.S. Pat. No. 5,321,501, which is incorporated herein by reference. The OCDR is capable of electronically performing two- and three-dimensional image scans over an extended longitudinal or depth range with sharp focus and high resolution and sensitivity over the range.
Such an array 100 is useful for intracardiac applications, and may be used for other applications, such as any kind of B-scanner medical applications, ophthalmic ultrasound, HIFU
and/or NDT.
Turning to Fig. 3, the phased array 100 may be used in a catheter, as described above, and can also be placed in a distal portion 520 of a guidewire 500. The guidewire 500 may comprise a guidewire body 302 in the form of a flexible, elongate tubular member, having an outer wa11301. The guidewire body 302 may be formed of any material known in the art plastics, braided polyimide, polyethylene, PEEK braids, stainless steel, other superelastic materials, or metal alloys, such as a nitinol hypertube, Turning to Fig. 4, a proximal portion 510 of the guidewire 500, shown in Fig.
3, may be adapted to connect to circuitry 600 that processes imaging signals from the phased array 100, such circuits being well known.
In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and clianges may be made thereto without departing from the broader spirit and scope of the invention. For example, the reader is to understand that the specific ordering and combination of process actions described herein is merely illustrative, and the invention can be performed using different or additional process actions, or a different coinbination or ordering of process actions. As a further example, each feature of one embodiment can be mixed and matched with other features shown in other embodiments. Additionally and obviously, features may be added or subtracted as desired. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.
FIELD OF THE INVENTION
The field of the invention relates to medical devices, and more particularly to phased array imaging catheters.
BACKGROUND OF THE INVENTION
Intraluminal, intracavity, intravascular, and intracardiac treatments and diagnosis of medical conditions utilizing minimally invasive procedures are effective tools in many areas of medical practice. These procedures are typically performed using imaging and treatment catheters that are inserted percutaneously into the body and into an accessible vessel of the vascular system at a site remote from the vessel or organ to be diagnosed and/or treated, such as the femoral artery. The catheter is then advanced tlirough the vessels of the vascular system to the region of the body to be treated. The catheter may be equipped with an imaging device, typically an ultrasound imaging device, which is used to locate and diagnose a diseased portion of the body, such as a stenosed region of an artery. For example, U.S. Pat.
No. 5,368,035, issued to Hamm et al., the disclosure of which is incorporated herein by reference, describes a catheter having an intravascular ultrasound imaging transducer.
An imaging transducer generally includes an imaging element configured to emit energy pulses. During operation, the imaging element is electrically excited, thus causing an energy pulse to be emitted. The pulse is directed to a surface where iniaging is desired and reflected back to the transducer. Two desirable features of the emitted energy pulse are that the energy pulse be focused and steerable. One known approach known in the art to obtain these features is to utilize an array of imaging elements instead of just one element. Fig. 1 shows an array 10 of two imaging elements, A and B, side-by-side. As is known in the art, if both elements, A and B, are excited simultaneously, then the energy pulses are combined to form a beam that is parallel to the direction that the elements, A and B, are facing, so that the beam travels directly away from the array 10. However, if a linear timing excitation gradient (a time delay based on a coherence theory) is used across the array 10, the beam can be steered in the azimuthal direction. By sending a short acoustic pulse and receiving the echo at each azimuthal direction, the array 10 may scan a sector area and construct an image. The image resolution is primarily determined by the beam 20 width in the lateral direction and the acoustic pulse length in the axial direction.
To focus the beam, i.e., adjust the beam width, time delays for each element may also be utilized. At a certain spatial location, the acoustic pulses from all elements may be coherently enlianced when they are in phase. The phase of the pulse is determined by the dilsi~~rzc'i;,l~+~ni tls~.~letiierit~-:t~h the destination location. To focus the beam at a spatial point, appropriate time delays are applied to all of the elements, A and B. These compensating delays ensure that the arrival of the acoustic pulses from different elements, A and B, are in coincidence at the desired spatial location.
The array of imaging elements configured to enable a beam to be focused and steered is known in the art as a "phased array." Though only two imaging elements, A and B, are shown in Fig. 1, a typical phased array may include as many as 256 elements. In the case of ultrasound imaging elements, each element, A and B, is generally small enough to be treated as an acoustic point source that generates a propagating wave with a spherical front. Collectively, the elements, A and B, form an acoustic field that can be enhanced when the elements, A and B, are in phase at a certain spatial location.
The elements, A and B, are typically rectangular and are typically evenly spaced across a flat plane. For ultrasound elements, each element has a pitch size equal to half a wavelength at the working ultrasound frequency. The pitch size is defined as the distance between two adjacent elenient, A and B, centers. With this typical configuration, when the beam 20 is steered and focused to a particular point F, the beams of the individual elements, A and B, are emitted at different angles, a and (3, with respect to the flat plane. This will cause the beams of the individual elements, A and B, to have different amplitudes, which can undesirably result in a widened beam 20, even if an accurate time delay compensation is used. This is particularly so when the beam 20 is steered to the maximum azimuthal direction.
Accordingly, an improved phased array imaging catheter would be desirable.
SUMMARY OF THE INVENTION
The present invention generally relates to medical devices, and more particularly to an improved intravascular device. In one embodiment, an intravascular device includes a catheter having proximal and distal portions, and a phased array of imaging elements located in the distal portion of the catheter, wherein the phased array is concaved.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to better appreciate how the above-recited and other advantages and objects of the present inventions are obtained, a more particular description of the invention briefly dVIX,Tqnttered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. It should be noted that the components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. However, like parts do not always have like reference numerals. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.
Fig. 1 is a cross-sectional side view of a phased array of imaging transducers known in the art.
Fig. 2 is a cross-sectional side view of a phased array of imaging transducers in accordance with a preferred embodiment of the present invention.
Fig. 3 is a cross-sectional view of an imaging wire in accordance with a preferred embodiment of the present invention.
Fig. 4 is a diagram of a medical imaging system in accordance with a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As described above, prior art phased array assemblies 10 consist of a series of small rectangular elements, A and B, that are evenly spaced in a flat plane. This configuration causes the elements to emit energy beams at different angles when the phased array beam 20 is steered and focused. This can undesirably cause a widened phased array beam 20.
By contrast, the improved phased array in this patent specification reduces the undesired wideness by placing a phased array in a concaved configuration, as shown in Fig. 2.
Fig. 2 shows a phased array 100 of imaging elements, A and B. The elements, A
and B, are situated along a concave 130 path having a radius R. The phased array 100 can have additional imaging elements along the concave path 130 (not shown). The phased array 100 has a length, L, and a maximum steering angle in the azimuthal direction, 0. F represents a focal point at the maximum steering angle in the azimuthal direction. The phased array 100 is shown focusing an energy beam, such as an acoustic pulse, 120 at focal point F. a and (3, represent the tangential angles for elements A and B to the focal point F respectively. al and (31, represent the flat plane angles for elements A and B to the focal point F respectively.
Point 0 represents the origin of the horizontal and vertical axis, X and Y.
In the case of a phased array 100 having a large number of imaging elements, wherein elements A and B represent the edge elements of the array 100, at focal point F, element B will hAVI d,IH'elllWIrg,6srC::Ahgld' P1,1Itt.4 the focal point F, whereas element A
will have the smallest angle a 1, to the focal point F. The concaving of the array 100 will decrease the tangential angle (3, for element B by (32, and increase the tangential angle a for element A by a2.
One of ordinary skill in the art would appreciate that by concaving the array 100, elements A
and B will have the most significant impact on the resulting beam 120 as compared to any imaging elements in between elements A and B, and the center imaging elements will be least affected.
The following is an approach to calculating the radius of curvature R of a concave phased array 100 that enables the tangential angles a and (3, to be equal at the maximum azimuthal direction 0. From Fig. 2, the following is true:
a = al +a2, (1) and R = R l - R2 (2) and because of geometric symmetry, we have:
a2= (32=a3, (3) To obtain a=(3, the following is deduced:
al+a3= (3l-a3, (4) which means:
a3= ((31 -al) /2, (5) Since:
sin (a3) = (L/2)/R (6) and:
tan (al) = OF cos (0) / (OF sin (0) + L/2) (7) and:
tan ((31) = OF cos (0) / (OF sin (0) - L/2) (8).
Combining equations (5) - (8), the radius of curvature R can be expressed as:
R = L / 2 (9) 11 tan-' OFcosB tan ' OFcos9 sin (OFsinO-L/2) (OFsinO+L/2) 111bIih:c aa9e;;nV'a,,V6E3IHz, 64 element phased array, wherein the length of the array is 5mm, if the array's maximum angle in the azimuthal direction is 45 , and the focal depth is 5mm, then the radius of curvature R is preferably approximately 7mm.
Equation (9) expresses the radius of curvature of a concave array, R, as a function of a desired focal depth if the other parameters in the array design, such as image range, have been provided. For an image range from OF 1 to OF2, an average radius of curvature Ra may be determined by:
R" F_ rF2R(ooF 10 .
Fl OF2-OFl ( ) The concave array 100 may have a uniform pitch, wherein the space from element center to element, A and B, is uniform; however, it can be non-uniform as well. An element's width can be varied to maximize the beam quality, as one of ordinary skill in the art would appreciate. For example, the element width can conform to a Gaussian, Bessel, or sinusoidal function using an element index number calculated from the array 100 center to an edge element, e.g., A or B.
For an ultrasound phased array 100, the array 100 can be fabricated by a variety of available active acoustic material, such as piezo-ceramics, piezo-films (thin or thick), 2-2 or 1-3 piezoceramic composites, 2-2 or 1-3 piezocrystal materials, or c1V1UT.
Further, other imaging devices may be used, instead of, or in addition to imaging transducers, such as light based apparatuses for obtaining images through optical coherence tomography (OCT). Image acquisition using OCT is described in Huang et al., "Optical Coherence Tomography," Science, 254, Nov. 22, 1991, pp 1178-1181, which is hereby incorporated by reference in its entirety. A
type of OCT imaging device, called an optical coherence domain reflectometer (OCDR) is disclosed in Swanson U.S. Pat. No. 5,321,501, which is incorporated herein by reference. The OCDR is capable of electronically performing two- and three-dimensional image scans over an extended longitudinal or depth range with sharp focus and high resolution and sensitivity over the range.
Such an array 100 is useful for intracardiac applications, and may be used for other applications, such as any kind of B-scanner medical applications, ophthalmic ultrasound, HIFU
and/or NDT.
Turning to Fig. 3, the phased array 100 may be used in a catheter, as described above, and can also be placed in a distal portion 520 of a guidewire 500. The guidewire 500 may comprise a guidewire body 302 in the form of a flexible, elongate tubular member, having an outer wa11301. The guidewire body 302 may be formed of any material known in the art plastics, braided polyimide, polyethylene, PEEK braids, stainless steel, other superelastic materials, or metal alloys, such as a nitinol hypertube, Turning to Fig. 4, a proximal portion 510 of the guidewire 500, shown in Fig.
3, may be adapted to connect to circuitry 600 that processes imaging signals from the phased array 100, such circuits being well known.
In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and clianges may be made thereto without departing from the broader spirit and scope of the invention. For example, the reader is to understand that the specific ordering and combination of process actions described herein is merely illustrative, and the invention can be performed using different or additional process actions, or a different coinbination or ordering of process actions. As a further example, each feature of one embodiment can be mixed and matched with other features shown in other embodiments. Additionally and obviously, features may be added or subtracted as desired. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.
Claims (16)
1. An intravascular device comprising:
a catheter having proximal and distal portions; and a phased array of imaging elements, including edge elements each having an angle of emission, located in the distal portion of the catheter, wherein the phased array is concaved having a radius of curvature such that when the phased array is steered in a maximal azimuthal direction, the angles of emission of the edge elements are substantially similar.
a catheter having proximal and distal portions; and a phased array of imaging elements, including edge elements each having an angle of emission, located in the distal portion of the catheter, wherein the phased array is concaved having a radius of curvature such that when the phased array is steered in a maximal azimuthal direction, the angles of emission of the edge elements are substantially similar.
2. The intravascular device of claim 1, wherein the imaging elements are ultrasound imaging transducers.
3. The intravascular device of claim 2, wherein each of the ultrasound imaging transducers comprises an acoustic lens coupled with a layer of piezoelectric crystal, the piezoelectric crystal being coupled with a backing material.
4. The intravascular device of claim 1, wherein the imaging elements are OCT
imaging elements.
imaging elements.
5. The intravascular device of claim 1, wherein the phased array has a uniform pitch.
6. The intravascular device of claim 1, wherein the phased array has a non-uniform pitch.
7. The intravascular device of claim 1, wherein the width of each imaging element conforms to one of a Gaussian function, a Bessel function, or a sinusoidal function.
8. The intravascular device of claim 1, wherein the phased array is substantially concave.
9. A medical imaging system comprising:
a guidewire having proximal and distal portions;
a concaved phased array of imaging elements located in the distal portion of the guidewire; and an image processing device coupled to the proximal portion of the guidewire.
a guidewire having proximal and distal portions;
a concaved phased array of imaging elements located in the distal portion of the guidewire; and an image processing device coupled to the proximal portion of the guidewire.
10. The medical imaging system of claim 9, wherein the imaging elements are ultrasound imaging transducers.
11. The medical imaging system of claim 10, wherein each of the ultrasound imaging transducers comprises an acoustic lens coupled with a layer of piezoelectric crystal, the piezoelectric crystal being coupled with a backing material.
12. The medical imaging system of claim 9, wherein the imaging elements are OCT
imaging elements.
imaging elements.
13. The medical imaging system of claim 9, wherein the phased array has a uniform pitch.
14. The medical imaging system of claim 9, wherein the phased array has a non-uniform pitch.
15. The medical imaging system of claim 9, wherein the width of each imaging element conforms to one of a Gaussian function, a Bessel function, or a sinusoidal function.
16. The medical imaging system of claim 9, wherein the concaved phased array is substantially concave.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11/173,550 US7625343B2 (en) | 2005-07-01 | 2005-07-01 | Concave phased array imaging catheter |
| US11/173,550 | 2005-07-01 | ||
| PCT/US2006/025770 WO2007005710A2 (en) | 2005-07-01 | 2006-06-29 | Concave phased array imaging catheter |
Publications (1)
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| CA2612611A1 true CA2612611A1 (en) | 2007-01-11 |
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ID=37605078
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002612611A Abandoned CA2612611A1 (en) | 2005-07-01 | 2006-06-29 | Concave phased array imaging catheter |
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| US (1) | US7625343B2 (en) |
| EP (1) | EP1898798A2 (en) |
| JP (1) | JP4705168B2 (en) |
| CA (1) | CA2612611A1 (en) |
| WO (1) | WO2007005710A2 (en) |
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- 2006-06-29 JP JP2008519652A patent/JP4705168B2/en not_active Expired - Fee Related
- 2006-06-29 EP EP06786086A patent/EP1898798A2/en not_active Withdrawn
Also Published As
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| WO2007005710A2 (en) | 2007-01-11 |
| US20070016055A1 (en) | 2007-01-18 |
| WO2007005710A3 (en) | 2007-07-12 |
| EP1898798A2 (en) | 2008-03-19 |
| JP2009500082A (en) | 2009-01-08 |
| JP4705168B2 (en) | 2011-06-22 |
| US7625343B2 (en) | 2009-12-01 |
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