U.S. patent application number 11/415848 was filed with the patent office on 2007-01-18 for multiple transducers for intravascular ultrasound imaging.
Invention is credited to Byong-Ho Park, Stephen M. Rudy.
Application Number | 20070016062 11/415848 |
Document ID | / |
Family ID | 36763172 |
Filed Date | 2007-01-18 |
United States Patent
Application |
20070016062 |
Kind Code |
A1 |
Park; Byong-Ho ; et
al. |
January 18, 2007 |
Multiple transducers for intravascular ultrasound imaging
Abstract
The present invention relates to a new intravascular ultrasound
imaging device with an increased field of view. By using more than
one ultrasound transducer crystal that is capable of producing an
ultrasonic signal for imaging, and preferably aligning the
individual crystals on a shared backing with at least one edge of
the crystals in contact, the field of view generated by a given
actuator mechanism is increased without substantially increasing
the overall dimensions of the device. Also disclosed are methods of
using the same.
Inventors: |
Park; Byong-Ho; (Cincinnati,
OH) ; Rudy; Stephen M.; (Palo Alto, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
36763172 |
Appl. No.: |
11/415848 |
Filed: |
May 2, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60678676 |
May 4, 2005 |
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60677944 |
May 4, 2005 |
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60710304 |
Aug 22, 2005 |
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60711653 |
Aug 25, 2005 |
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60781786 |
Mar 13, 2006 |
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Current U.S.
Class: |
600/459 |
Current CPC
Class: |
A61B 8/12 20130101; A61B
5/02007 20130101; A61M 25/0138 20130101; G01S 7/52079 20130101;
A61M 25/0158 20130101; G10K 11/004 20130101; F03G 7/065 20130101;
F16C 2202/28 20130101; A61B 2090/3784 20160201; A61B 8/145
20130101; A61B 8/4483 20130101; G01S 15/8943 20130101; A61B
2090/3614 20160201; A61B 8/445 20130101; A61B 5/0066 20130101; A61B
8/4461 20130101 |
Class at
Publication: |
600/459 |
International
Class: |
A61B 8/14 20060101
A61B008/14 |
Claims
1. An intravascular ultrasound device comprising: an ultrasound
transducer comprising; a backing; and a first ultrasound transducer
crystal and a second ultrasound transducer, each crystal having a
substantially planar surface and a first edge; wherein said first
and second transducer crystals are mounted on said backing; and
wherein said edge of said first crystal is adjacent to said edge of
said second crystal.
2. The device of claim 1, wherein said edge of said first crystal
is in physical contact with said edge of said second crystal.
3. The device of claim 1, further comprising a third ultrasound
transducer crystal having a substantially planar surface and a
first edge; wherein said second crystal has a second edge; wherein
said third crystal is mounted on said backing; and wherein said
edge of said third crystal is adjacent to said second edge of said
second crystal.
4. The device of claim 3, wherein said wherein said edge of said
third crystal is in physical contact with said second edge of said
second crystal.
5. An intravascular ultrasound device with an enhanced field of
view comprising: an ultrasound transducer comprising: a backing; a
first ultrasound transducer crystal having a substantially planar
surface and a top edge, a bottom edge, and a first and a second
side edge; and a second ultrasound transducer crystal having a
substantially planar surface and a top edge, a bottom edge, and a
first and a second side edge; wherein said planar surface of said
first crystal and said planar surface of said second crystal are
disposed on said backing; wherein a first side edge of said first
crystal is adjacent to a first side edge of said second crystal;
wherein said first crystal and said second crystal are oriented
relative to each other such that a line that is normal to the
planar surface of said first crystal and a line that is normal to
the planar surfaces of said second crystal can be substantially in
the same plane; and wherein the angle defined by a line that is
normal to the planar surface of said first crystal and a line that
is normal to the planar surfaces of said second crystal is between
about 1.degree. and about 179.degree..
6. The device of claim 5, wherein said first side edge of said
first crystal is in physical contact with said first side edge of
said second crystal.
7. The device of claim 5 wherein said first transducer crystal,
said second transducer crystal, or both said first and said second
transducer crystals together are capable of generating an
ultrasound signal for imaging.
8. The device of claim 5, further comprising: a third ultrasound
transducer crystal having a substantially planar surface and a top
edge, a bottom edge, and a first and a second side edge of said
first crystal; wherein said planar surface of said third crystal is
disposed on said backing; wherein a first side edge of said third
crystal is adjacent to a second side edge of said second crystal;
and wherein said third crystal and said second crystal are oriented
relative to each other such that a line that is normal to the
planar surface of said third crystal and a line that is normal to
the planar surfaces of said second crystal can be substantially in
the same plane; and the angle defined by a line that is normal to
the planar surface of said third crystal and a line that is normal
to the planar surfaces of said second crystal is about equal to the
angle defined by a line that is normal to the planar surface of
said first crystal and a line that is normal to the planar surface
of said second crystal.
9. The device of claim 8, wherein said first side edge of said
third crystal is in physical contact with said second side edge of
said second crystal.
10. The device of claim 5, further comprising: an actuator means
for moving said transducer in a cyclical motion around an axis of
rotation that is substantially in the same plane as the line
defined by the intersection of said substantially planar surface of
said first crystal and the substantially planar surface of said
second crystal; and wherein said transducer is rotated about said
axis of rotation through an angle that is about equal to the angle
defined by a line that is normal to the planar surface of said
first crystal and a line that is normal to the planar surface of
said second crystal.
11. The device of claim 10, further comprising an elongate member
having a longitudinal axis and a distal end; wherein said
transducer and said actuator means are disposed in said distal end
of said elongate member; wherein said axis of rotation is
substantially parallel to said longitudinal axis of said elongate
member; and wherein said ultrasound transducer is oriented to
transmit ultrasound energy substantially orthogonal to said
longitudinal axis of said elongate member.
12. The device of claim 11, wherein said angle of rotation is about
60.degree. to about 90.degree..
13. The device of claim 11, wherein said actuator means comprises a
first anchor, a second anchor, at least one movable element, a
first SMA actuator connected to said first anchor and a movable
element, and a deformable component connected to said second anchor
and at least one movable element, wherein said anchor elements are
secured relative to said elongate member.
14. The device of claim 10, further comprising an elongate member
having a longitudinal axis, and a distal tip; wherein said
transducer and said actuator means are disposed on said distal tip
of said elongate member; wherein said axis of rotation is
substantially perpendicular to said longitudinal axis of said
elongate member; and said ultrasound transducer is oriented to
transmit ultrasound energy substantially in front of the distal tip
of said elongate member.
15. The device of claim 14, wherein said angle of rotation is about
30.degree. to about 60.degree..
16. The device of claim 14, wherein said actuator means comprises
an SMA actuator and a pivot point or compliant element.
17. A method for visualizing the interior of a patient's
vasculature, said method comprising: inserting the distal end of
the apparatus of claim 11 into the vasculature of a patient;
generating an ultrasound signal from said transducer; generating a
cyclical movement of said ultrasound transducer by activation of
said actuator means; receiving an ultrasonic signal reflected from
the interior of the vasculature on said transducer; and producing
an image from said reflected signal.
18. The method of claim 17, wherein said ultrasound signal is
generated from said first transducer crystal, said second
transducer crystal, or both said first and said second transducer
crystals.
19. A method for visualizing the interior of a patient's
vasculature, said method comprising: inserting the distal tip of
the apparatus of claim 14 into the vasculature of a patient;
generating an ultrasound signal from said transducer; generating a
cyclical movement of said ultrasound transducer by activation of
said actuator means; receiving an ultrasonic signal reflected from
the interior of the vasculature on said transducer; and producing
an image from said reflected signal.
20. The method of claim 19, wherein said ultrasound signal is
generated from said first transducer crystal, said second
transducer crystal, or both said first and said second transducer
crystals.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. 119 to U.S.
Provisional Application Ser. No. 60/678,676, filed May 4, 2005,
titled "Multiple transducers for large field of view in
intravascular ultrasound imaging," U.S. Provisional Application
Ser. No. 60/677,944, filed May 4, 2005, titled "Shape memory alloy
(SMA) mechanism for side-looking intravascular imaging," U.S.
Provisional Application Ser. No. 60/710,304, filed Aug. 22, 2005,
titled "Guide wire enabled with intravascular ultrasound imaging
for interventional applications," and U.S. Provisional Application
Ser. No. 60/711,653, filed Aug. 25, 2005, titled "Miniature
mirror-based intravascular ultrasound imaging device for
interventional applications," and U.S. Provisional Application Ser.
No. 60/781,786, filed Mar. 13, 2006, titled "Electrically driven
miniature intravascular optical coherence tomography imaging
device," the entire contents of each of which are incorporated
herein by reference. This application is also related to U.S.
patent application Ser. No. ______ filed on May 2, 2006, entitled
"MINIATURE ACTUATOR MECHANISM FOR INTRAVASCULAR IMAGING" and U.S.
patent application Ser. No. ______ filed on May 2, 2006, entitled
"MINIATURE ACTUATOR MECHANISM FOR INTRAVASCULAR OPTICAL IMAGING,"
the entire contents of each of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention concerns a miniature actuator which is
useful in intravascular imaging devices including intravascular
ultrasound (IVUS), and optical coherence tomography (OCT). The
miniature actuator mechanism and ultrasound or OCT imaging device
is embedded in an elongate member such as an intravascular guide
wire or catheter to provide imaging guidance in various
interventional applications. Also disclosed is a reflector-based
ultrasound imaging device created to minimize the overall scale of
the imaging device, as well as ultrasound transducers having
multiple transducer crystals to increase the field of view of the
device while maintaining its small size.
[0004] 2. Description of the Related Art
[0005] Coronary artery disease is very serious and often requires
an emergency operation to save lives. The main cause of coronary
artery disease is the accumulation of plaques inside artery, which
eventually occludes blood vessels. Several solutions are available,
e.g., balloon angioplasty, rotational atherectomy, and
intravascular stents, to open up the clogged section, which is
called stenosis. Traditionally, during the operation, surgeons rely
on X-ray fluoroscopic images that are basically planary images
showing the external shape of the silhouette of the lumen of blood
vessels. Unfortunately, with X-ray fluoroscopic images, there is a
great deal of uncertainty about the exact extent and orientation of
the atherosclerotic lesions responsible for the occlusion, making
it difficult to find the exact location of the stenosis. In
addition, though it is known that restenosis can occur at the same
place, it is difficult to check the condition inside the vessels
after surgery. Similarly, intravascular imaging would prove
valuable during interventional procedures as an aid to navigation
and for intraoperative feedback. For example, the precise placement
and appropriate expansion of stents would benefit from concurrent
intravascular imaging. Existing intravascular imaging devices are
too large and insufficiently flexible to be placed simultaneously
with other devices.
[0006] In order to resolve these issues, an ultrasonic transducer
device has been utilized for endovascular intervention to visualize
the inside of the blood vessels. To date, the current technology is
mostly based on one or more stationary ultrasound transducers or
rotating a single transducer in parallel to the blood vessels by
means of a rotating shaft which extends through the length of the
catheter to a motor or other rotary device located outside the
patient. These devices have limitations in incorporating other
interventional devices into a combination device for therapeutic
aspects. They require a large space inside catheter such that there
is not enough room to accommodate other interventional devices.
Also due to the nature of the rotating shaft, the distal end of the
catheter is very stiff and it is hard to go through tortuous
arteries. The high speed rotating shaft also contributes to
distorted non-uniform images when imaging a tortuous path in the
vasculature. OCT has also been utilized to visualize the
intravascular space based on differential reflectance, but like the
existing ultrasound devices, most rely on a rotating fiber optic
which extends along the length of the device. This approach also
has problems, including for example the manipulation, spinning and
scanning motion required with respect to a delicate glass or
polycarbonate optical fiber; the actuator mechanism located outside
the patient and tip located inside the patient are significantly
distant from one another, leading to inefficiencies and control
issues arising from the torque created by a long, spinning member;
and remote mechanical manipulation and a long spinning element
distort the image due to non-uniform rotational distortion. Given
the numerous difficulties with current intravascular imaging
devices, there is a need for improved intravascular imaging
devices.
SUMMARY OF THE INVENTION
[0007] An embodiment of the invention is an intravascular
ultrasound device comprising an ultrasound transducer comprising a
backing and a first ultrasound transducer crystal and a second
ultrasound transducer, each crystal having a substantially planar
surface and a first edge; where the first and second transducer
crystals are mounted on the backing; and where the edge of the
first crystal is adjacent to the edge of the second crystal. In
another embodiment, the edge of the first crystal is in physical
contact with the edge of the second crystal. In another embodiment,
the device further comprises a third ultrasound transducer crystal
having a substantially planar surface and a first edge; where the
second crystal has a second edge; where the third crystal is
mounted on the backing; and where the edge of the third crystal is
adjacent to the second edge of the second crystal. In another
embodiment, the first edge of the third crystal is in physical
contact with the second edge of the second crystal.
[0008] Another embodiment is an intravascular ultrasound device
with an enhanced field of view comprising an ultrasound transducer
comprising a backing; a first ultrasound transducer crystal having
a substantially planar surface and a top edge, a bottom edge, and a
first and a second side edge; and a second ultrasound transducer
crystal having a substantially planar surface and a top edge, a
bottom edge, and a first and a second side edge; where the planar
surface of the first crystal and the planar surface of the second
crystal are disposed on the backing; where a first side edge of the
first crystal is adjacent to a first side edge of the second
crystal; where the first crystal and the second crystal are
oriented relative to each other such that a line that is normal to
the planar surface of the first crystal and a line that is normal
to the planar surfaces of the second crystal can be substantially
in the same plane; and where the angle defined by a line that is
normal to the planar surface of the first crystal and a line that
is normal to the planar surfaces of the second crystal is between
about 1.degree. and about 179.degree.. In another embodiment, the
first side edge of the first crystal is in physical contact with
the first side edge of the second crystal. In another embodiment,
the first transducer crystal, the second transducer crystal, or
both the first and the second transducer crystals together are
capable of generating an ultrasound signal for imaging.
[0009] Another embodiment further comprises a third ultrasound
transducer crystal having a substantially planar surface and a top
edge, a bottom edge, and a first and a second side edge of the
first crystal; where the planar surface of the third crystal is
disposed on the backing; where a first side edge of the third
crystal is adjacent to a second side edge of the second crystal;
and where the third crystal and the second crystal are oriented
relative to each other such that a line that is normal to the
planar surface of the third crystal and a line that is normal to
the planar surfaces of the second crystal can be substantially in
the same plane; and the angle defined by a line that is normal to
the planar surface of the third crystal and a line that is normal
to the planar surfaces of the second crystal is about equal to the
angle defined by a line that is normal to the planar surface of the
first crystal and a line that is normal to the planar surface of
the second crystal. In another embodiment, the first side edge of
the third crystal is in physical contact with the second side edge
of the second crystal.
[0010] Another embodiment further comprises an actuator means for
moving the transducer in a cyclical motion around an axis of
rotation that is substantially in the same plane as the line
defined by the intersection of the substantially planar surface of
the first crystal and the substantially planar surface of the
second crystal; and where the transducer is rotated about the axis
of rotation through an angle that is about equal to the angle
defined by a line that is normal to the planar surface of the first
crystal and a line that is normal to the planar surface of the
second crystal.
[0011] Another embodiment of the device further comprises an
elongate member having a longitudinal axis and a distal end; where
the transducer and the actuator means are disposed in the distal
end of the elongate member; where the axis of rotation is
substantially parallel to the longitudinal axis of the elongate
member; and where the ultrasound transducer is oriented to transmit
ultrasound energy substantially orthogonal to the longitudinal axis
of the elongate member. In some embodiments the angle of rotation
is about 60.degree. to about 90.degree..
[0012] In some embodiments the actuator means comprises a first
anchor, a second anchor, at least one movable element, a first SMA
actuator connected to the first anchor and a movable element, and a
deformable component connected to the second anchor and at least
one movable element, where the anchor elements are secured relative
to the elongate member.
[0013] Another embodiment further comprises an elongate member
having a longitudinal axis, and a distal tip; where the transducer
and the actuator means are disposed on the distal tip of the
elongate member; and where the axis of rotation is substantially
perpendicular to the longitudinal axis of the elongate member; and
the ultrasound transducer is oriented to transmit ultrasound energy
substantially in front of the distal tip of the elongate member. In
some embodiments the angle of rotation is about 30.degree. to about
60.degree.. In some embodiments the actuator means comprises an SMA
actuator and a pivot point or compliant element.
[0014] Another embodiment is a method for visualizing the interior
of a patient's vasculature, the method comprising inserting the
distal end of an apparatus described herein into the vasculature of
a patient; generating an ultrasound signal from the transducer;
generating a cyclical movement of the ultrasound transducer by
activation of the actuator means; receiving an ultrasonic signal
reflected from the interior of the vasculature on the transducer;
and producing an image from the reflected signal. In some
embodiments the ultrasound signal is generated from the first
transducer crystal, the second transducer crystal, or both the
first and the second transducer crystals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a partial cut-away perspective view showing an
embodiment of the actuator mechanism of the present invention and
an ultrasound transducer disposed in the distal end of an elongate
member.
[0016] FIGS. 2a and 2b are perspective views illustrating
rotational motion of the actuator mechanism shown in FIG. 1, while
FIGS. 2c and 2d illustrate longitudinal motion of the actuator
mechanism shown in FIG. 1.
[0017] FIG. 3 is a perspective view showing an embodiment of the
actuator mechanism of the present invention connected to an
ultrasound transducer by a connecting arm.
[0018] FIG. 4 is a perspective view of the device of FIG. 3
disposed in the distal end of an elongate member having an
ultrasound transparent window.
[0019] FIG. 5 is a perspective view of the distal end of an
elongate member with an actuator mechanism and ultrasound
transducer structure disposed therein.
[0020] FIG. 6 is a perspective view of the distal end of an
elongate member with an actuator mechanism and two ultrasound
support structures stacked orthogonally.
[0021] FIG. 7 is a perspective view showing an actuator mechanism
with an ultrasound reflector connected by a connecting arm, with an
ultrasound transducer aligned with the reflector.
[0022] FIG. 8 is a partial cut-away perspective view showing the
device of FIG. 7 housed in the distal end of an elongate member
with an ultrasound transparent window.
[0023] FIG. 9 is a schematic drawing of an optical coherence
tomography device with an actuator mechanism, a reflector and an
optical fiber disposed in an elongate member having a transparent
window.
[0024] FIG. 10 is a schematic drawing of another embodiment of an
optical coherence tomography device with an actuator mechanism
connected to an optical fiber with a reflector on its distal end,
disposed in an elongate member having an transparent window.
[0025] FIG. 11 is a schematic drawing of another embodiment of an
optical coherence tomography device with an actuator mechanism, a
reflector and an optical fiber disposed in an elongate member
having a transparent window.
[0026] FIGS. 12a, 12b, and 12c are schematic drawings illustrating
ultrasound transducers having one, two, or three individual
transducer crystals, respectively. FIGS. 12d, 12e, and 12f
illustrate the field of view obtained by rotating the transducers
of FIGS. 12a, 12b, and 12c, respectively.
[0027] FIGS. 13a and 13b are perspective views showing two tubular
structures each with a built-in compliant mechanism in different
design configuration.
[0028] FIG. 14 is a perspective view showing an ultrasound
transducer coupled to a micromanipulator having the compliant
structure of FIG. 13a and two SMA actuators configured to actuate
the compliant mechanism thereof.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] The present invention relates to imaging devices for
intravascular imaging, although the present invention is not
limited to this preferred application. Imaging of the intravascular
space, particularly the interior walls of the vasculature can be
accomplished by a number of different means. Two of the most common
are the use of ultrasound energy, commonly known as intravascular
ultrasound (IVUS) and optical coherence tomography (OCT). Both of
these methods are optimized when the instruments (IVUS or OCT) used
for imaging a particular portion of the vasculature are repeatedly
swept over the area being imaged.
[0030] To address the limitations in current devices, a new
intravascular imaging device is described based on a Shape Memory
Alloy (SMA) actuator mechanism embedded inside an elongate member
such as a guide wire or catheter. The present invention utilizes a
novel SMA mechanism to provide side-looking imaging by providing
movement for an ultrasound transducer or OCT element. Since this
novel SMA actuator mechanism can be easily fabricated in
micro-scale using laser machining or other fabrication techniques,
it provides an advantage over existing imaging devices because it
offers the ability to miniaturize the overall size of the device,
while the use of multiple transducer crystals maximizes field of
view. The small dimensions of the actuator mechanism of the
invention allows for the diameter of the elongate member in which
it is housed to be very small. The outside diameter of the elongate
member, such as a guide wire or catheter containing an imaging
device described herein can be as small as from about 0.0050'' to
about 0.060'' outside diameter. The outside diameter for elongate
members can be larger when the imaging device is combined with
other interventional devices, although the outside diameter of
these devices can be as small as 0.060'' or smaller. Current
catheters containing IVUS range from 0.70 mm to 3 mm in outside
diameter.
[0031] Because the device does not require a rotating shaft or
fiber optic along the length of the catheter, it also allows for a
more flexible catheter or guide wire, and provides room for other
interventional devices. In addition, it eliminates the problems
mentioned above with current OCT technology because it does not
require rotating the entire length of the optical fiber. This
invention simplifies the manufacture and operation of OCT by
allowing a straight fiber optic directed by an independent,
oscillating reflector or prism controlled by the actuator mechanism
located only in the distal tip of the device. A variation uses the
actuator mechanism to rotate only the distal end of the optical
fiber, eliminating the need to spin the entire fiber via a remote
mechanism.
[0032] In a preferred embodiment, an ultrasound reflector can be
implemented together with the SMA actuator mechanism. This has an
advantage over the prior art because it eliminates the rotational
load required to rotate a transducer and accompanying electrical
wiring, further reducing size and increasing the amount of movement
provided by the actuator, which in turn increases the field of view
provided by the device. This preferred embodiment also increases
imaging quality by allowing for a thicker backing layer for the
ultrasound transducer, since the backing layer does not affect the
diameter of the device. This in turn improves the signal-to-noise
characteristics of the device and thus improves image quality. In
addition, because the transducer does not need to be rotated, this
also removes a constraint on the size of the backing layer.
[0033] As used herein, elongate member includes any thin, long,
flexible structure which can be inserted into the vasculature of a
patient. Elongate members include, for example, intravascular
catheters and guide wires. The actuator mechanism is disposed in
the distal end of the elongate member. As used herein, "distal end"
of the elongate member includes any portion of the elongate member
from the mid-point to the distal tip. As elongate members can be
solid, some will include a housing portion at the distal end for
receiving the actuator mechanism. Such housing portions can be
tubular structures attached to the side of the distal end or
attached to the distal end of the elongate member. Other elongate
members are tubular and have one or more lumens in which the
actuator mechanism can be housed at the distal end.
[0034] "Connected" and variations thereof as used herein includes
direct connections, such as being glued or otherwise fastened
directly to, on, within, etc. another element, as well as indirect
connections where one or more elements are disposed between the
connected elements.
[0035] "Secured" and variations thereof as used includes methods by
which an element is directly secured to another element, such as
being glued or otherwise fastened directly to, on, within, etc.
another element, as well as indirect means of securing two elements
together where one or more elements are disposed between the
secured elements.
[0036] Movements which are counter are movements in the opposite
direction. For example, if the movable element is rotated
clockwise, rotation in a counterclockwise direction is a movement
which is counter to the clockwise rotation Similarly, if the
movable element is moved substantially parallel to the longitudinal
axis of the elongate member in a distal direction, movement
substantially parallel to the longitudinal axis in a proximal
direction is a counter movement.
[0037] As used herein, "light" or "light energy" encompasses
electromagnetic radiation in the wavelength range including
infrared, visible, ultraviolet, and X rays. The preferred range of
wavelengths for OCT is from about 400 nm to about 1400 nm. For
intravascular applications, the preferred wavelength is about 1200
to about 1400 nm. Optical fibers include fibers of any material
which can be used to transmit light energy from one end of the
fiber to the other.
[0038] "Reflector" as used herein encompasses any material which
reflects or refracts a substantial portion of the ultrasound or
light energy directed at it. In some embodiments of the OCT device
the reflector is a mirror. In others, it is a prism. This allows
refractive optical coherence tomography (as opposed to reflective
tomography using a mirror.) The prism can also be designed to
replace the lens typically required at the distal tip of the
optical fiber.
[0039] Embodiments of the invention will now be described with
reference to the accompanying Figures, wherein like numerals refer
to like elements throughout. The terminology used in the
description presented herein is not intended to be interpreted in
any limited or restrictive manner, simply because it is being
utilized in conjunction with a detailed description of certain
specific embodiments of the invention. Furthermore, embodiments of
the invention can include several novel features, no single one of
which is solely responsible for its desirable attributes or which
is essential to practicing the inventions herein described.
[0040] FIG. 1 illustrates a novel actuator mechanism 10 for
achieving the sweeping or scanning motion used for IVUS or OCT
imaging. FIG. 1 shows an actuator mechanism 10, which is housed in
the distal end of an elongate member 11, with the longitudinal axis
of the actuator mechanism 10 oriented substantially parallel to the
longitudinal axis of the elongate member 11. The elongate member 11
will be described in greater detail below with reference to FIG. 4.
The actuator mechanism 10 includes a first anchor 12 and a second
anchor 14 which are secured relative to the interior of the
elongate member 11 to anchor the actuator mechanism 10 to the
distal end of elongate member 11 such that the anchors 12 and 14
cannot move relative to elongate member 11. The actuator mechanism
10 also has a movable element 16 which is not secured relative to
the elongate member 11, and which is free to move in at least one
range of motion relative to the anchors 12 and 14 and elongate
member 11.
[0041] The first anchor 12 is connected to the movable element 16
by a shape memory alloy (SMA) actuator 20 which moves movable
element 16 when activated as described in more detail below. The
SMA actuator 20 can be fabricated from any known material with
shape memory characteristics, the preferred material being nitinol.
In an alternative embodiment the actuator mechanism 10 can be
fabricated without from a single tubing using any material with
shape memory characteristics, incorporating the first anchor 12,
second anchor 14, moveable element 16, SMA actuator 20 and
deformable component 22 (described below). As known by those of
skill in the art, SMAs can be fabricated to take on a predetermined
shape when activated. Activation of an SMA actuator consists of
heating the SMA such that it adopts its trained shape. Typically,
this is accomplished by applying an electric current across the SMA
element. Deactivation of an SMA actuator includes turning off
current to SMA, such that it returns to its pliable state as it
cools. Activation of the SMA to its trained shape results in a
force which can be utilized as an actuator. As one of skill in the
art will recognize, the disclosed SMA actuator 20 can take numerous
shapes and configurations in addition to the helical shape shown in
FIG. 1. For example it could be linear, or more than one (e.g. 2,
3, 4 or more) SMA elements could be used to make the SMA actuator
20.
[0042] The second anchor 14 is connected to the movable element 16
by a deformable component 22. The deformable component 22 is made
from materials which are not rigid, including elastic and
superelastic, and non-elastic materials. Deformable materials
include trained and untrained SMAs. Elastic alloys include, but are
not limited to, stainless steel and titanium alloy, and
superelastic alloys include but are not limited to, nitinol,
Cu--Al--Ni, Cu--Al, Cu--Zn--Al, Ti--V and Ti--Nb alloy.
[0043] In an alternative embodiment, one or both of the anchors 12
and 14 are eliminated, and one end the SMA actuator 20 and/or the
deformable component 22 are secured directly to the elongate member
11. Also one or both of the anchors 12 and 14 are secured
indirectly to the elongate member 11 through additional elements
such as an intermediate housing for the actuator mechanism 10. In
addition, the SMA actuator 20 and/or deformable component 22 can be
connected to either of, or both the anchor 12 or 14 and the movable
element 16 through additional elements--they need not be directly
connected to the anchor or movable element as shown. Alternatively,
the moveable element 16 can include, or have an additional
element(s) connected thereto, that extend over or within the
anchors 12 and/or 14 with enough clearance such that the additional
element(s) supports the movement of the moveable element 16 and
help to align it relative to the anchors 12 and 14--this alignment
provides precise and uniform motion in the elongate member 11.
[0044] In the embodiment illustrated in FIG. 1, an ultrasound
transducer 24 is connected to the movable element of the actuator
mechanism by being disposed on the moveable element.
[0045] In addition, while FIG. 1 shows only a single moveable
element, multiple moveable elements are possible. For example, the
SMA actuator 20 could be connected to a first moveable element, and
the deformable component 22 could be connected to a second moveable
element, with the transducer 24 disposed between the two moveable
elements. Alternatively, the moveable element(s) can be eliminated
and the SMA actuator 20 and the deformable component 22 can be
attached directly to the ultrasound transducer 24.
[0046] In the embodiment shown in FIG. 1, the ultrasound transducer
24 is oriented such that it transmits ultrasound energy at an angle
of about 90.degree. relative to the longitudinal axes of the
actuator mechanism 10 and elongate member 11. The angle of
orientation of the ultrasound transducer 24 relative to the
longitudinal axes can be any angle between about 15.degree. and
about 165.degree., with the preferred angle for side-looking
ultrasound being between about 80.degree. and about 110.degree..
Angles contemplated include about 15, 20, 25, 30, 35, 40, 45, 50,
55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125,
130, 135, 140, 145, 150, 155, 160, and about 165 degrees, or can
fall within a range between any two of these values. For example,
15 (or 165, depending on orientation) degrees are preferred for
forward-looking ultrasound imaging applications.
[0047] Housed in the elongate member 11, the actuator 10 shown in
FIG. 1 can be used to generate movement of the moveable element 16
as shown in FIG. 2. By activating the SMA actuator 20, a force is
generated which displaces the moveable element 16 and transducer 24
in a first direction since the anchor 12 is secured relative to the
elongate member (not shown). FIG. 2a illustrates movement in a
first direction, indicated by the arrow, which is rotational about
the longitudinal axis of the actuator mechanism 10. FIG. 2c
illustrates a movement in a first direction, indicated by the
arrow, which is substantially parallel to the longitudinal axis of
the actuator mechanism 10. The direction of movement generated by
activation of the SMA actuator 20 will depend on configuration of
the SMA actuator 20 relative to the anchor 12 and moveable element
16, as well as the shape which is trained into the SMA actuator 20.
For example, the SMA actuator 20 shown in FIG. 2a is trained to
twist when activated, while the SMA actuator 20' shown in FIG. 2c
is trained to contract. A combination of rotational and
longitudinal movements is possible as well, for example by using an
SMA actuator trained to twist and extend or contract, or by using a
combination of SMA elements or actuators. For example, two or more
SMA actuators could be linked in series.
[0048] FIGS. 2b and 2d illustrate counter movements in a second
direction, indicated by the arrows, which provides an oscillating
movement to the moveable element 16 and transducer 24. This counter
movement is provided by the deformable component 22 or 22',
preferably when the SMA actuator 20 or 20' is deactivated. The
deformable component 22 can be any elastic or superelastic
material, or a second SMA actuator. The deformable component is in
a relaxed state when the SMA actuator 20 or 20' is in the
deactivated state. When the first SMA actuator 20 or 20' is
activated, as shown in FIGS. 2a and 2c, the deformable component 22
or 22' is deformed by the movement of the moveable element 16 since
the second anchor 14 is secured relative to the elongate member
(not shown).
[0049] In an embodiment where the deformable component 22 or 22' is
an elastic or superelastic material, the energy stored in the
deformable component 22 or 22' when it is in its deformed state
shown in FIGS. 2a and 2c moves the moveable element 16 and
transducer 24 to the position shown in FIGS. 2b and 2d when the
first SMA 20 or 20' is deactivated. This movement in the second
direction, indicated by the arrow, is counter to the movement in
the first direction. By alternately activating and deactivating the
first SMA 20 or 20', a cyclical movement of the moveable element 16
and transducer 24 will result. This cyclical movement can be
rotational about the longitudinal axis of the of the actuator
mechanism 10 as shown in FIGS. 2a and 2b, or approximately parallel
to the longitudinal axis of the actuator mechanism 10 as shown in
FIGS. 2c and 2d, or a combination of rotational and longitudinal
movement (not shown).
[0050] In a preferred embodiment, the deformable component 22 or
22' is a second SMA actuator that is trained to move the moveable
element 16 and transducer 24 in a second direction which is counter
the movement in the first direction caused by activation of the
first SMA actuator 20 or 20'. In this embodiment, the cyclical
motion is generated by the alternating activation of the first SMA
actuator 20 or 20' and the second SMA actuator 22 or 22'. The
activation of the first SMA actuator 20 or 20' deforms the second
SMA actuator 22 or 22' which is in its inactive state, as
illustrated in FIGS. 2a and 2c. The first SMA actuator 20 or 20' is
deactivated and the second actuator SMA 22 or 22' is activated,
causing the deformation of the first SMA actuator 20 or 20' and the
movement of the moveable element 16 and transducer 24 as
illustrated in FIGS. 2b and 2d.
[0051] FIG. 3 shows another embodiment of the invention including
the actuator mechanism 10 illustrated in FIGS. 1 and 2. As in FIG.
1, the actuator mechanism 10 in FIG. 3 includes a first anchor 12,
a second anchor 14, a movable element 16. The first anchor 12 is
connected to the movable element 16 by a SMA actuator 20. The
second anchor 14 is connected to the movable element 16 by a
deformable component 22. In the embodiment illustrated in FIG. 3,
the ultrasound transducer 24 is connected to the moveable element
16 by a connecting arm 26, such that movement of the moveable
element 16 results in movement of the ultrasound transducer 24 and
connecting arm 26. The movement of the moveable element 16 is
generated as described above and illustrated in FIG. 2. In an
alternate embodiment, the portion of the connecting arm 26 that is
shown extending past the moveable element 16 and passing through
the second anchor 14 is removed. The connecting arm 26 can have a
lumen (not shown), and optionally wires can pass through the lumen
to connect the transducer 24 to an ultrasound signal generator and
processor located at the proximal end of the elongate member in
which the actuator mechanism and transducer are housed. While the
actuator mechanism 10 is illustrated as having the SMA actuator 20
in closer proximity to the transducer 24 than the deformable
component 22, one of skill in the art will readily appreciate that
the actuator mechanism 10 can be oriented such that the location of
the SMA actuator 20 and the deformable component 22 are
reversed.
[0052] In several embodiments disclosed herein, the connecting arm
26 is shown passing through the center of the anchor 12 and 14 and
moveable element 16. One of skill in the art will recognize that it
is not necessary to locate the connecting arm 26 along the
longitudinal axis of the actuator mechanism 10. For example, the
connecting arm 26 could be located on an exterior surface of the
moveable element 16, and the anchor 12 could have a cut-out to
allow the movement of the connecting arm 26 over the anchor 12. In
addition, it can be desirable to provide structural supports for
the moveable element 16 to stabilize its movement within the
elongate member.
[0053] FIG. 4 illustrates an elongate member 30 which has a distal
end 32 in which the actuator mechanism and ultrasound transducer 34
are housed. The distal end 32 of the elongate member 30 has at
least a portion 36 of the elongate member which is transparent to
ultrasound energy. The ultrasound transducer 34 is oriented to
transmit and receive ultrasound energy through this portion 36. The
ultrasound transparent portion 36 can be a window made of an
ultrasound transparent material, a material which is partially or
substantially transparent to ultrasound energy, or the window can
be a cut-out such that there is no material between the transducer
and the outside environment. The portion 36 is desirable where the
distal end 32 of the elongate member 30 is made of a substance that
absorbs ultrasound energy. In an alternative embodiment, the entire
distal end 32 or elongate member 30 is transparent to ultrasound
energy.
[0054] FIG. 5 illustrates the distal end 40 of an elongate member,
where all but the distal tip 41 of the elongate member is
transparent so that the actuator mechanism 42 housed in the distal
end 40 is visible. The actuator mechanism 42 is similar to the one
illustrated in FIG. 3, with the addition of support members 44
disposed within the anchors 46. The support members 44 support the
connecting arm 50, which connects the moveable element 52 and
ultrasound transducer structure 54, acting to stabilize the
movements of the connecting arm 50 and moveable element 52. The
connecting arm 50 is free to rotate or slide within the support
members 44, but not the moveable element 52. The support members 44
can be separate elements as shown in FIG. 5, or the anchors 46 can
be fabricated to perform the function of the support members 44.
The actuator mechanism 42 is used to generate movement of the
moveable element 52, connecting arm 50 and ultrasound transducer
structure 54 in the manner described above in reference to FIG. 2.
The connecting arm 50 and moveable element 52 can be a single
piece. In another embodiment, the moveable element 52 is
eliminated, and the SMA actuator 62 and deformable component 64 are
attached directly to the connecting arm 50.
[0055] In the embodiment shown in FIG. 5, the ultrasound transducer
structure 54 has two ultrasound transducer crystals 56 and 56' for
sending and receiving the ultrasound signal, which share a common
backing 60. The backing 60 provides support for the transducer
crystals 56 and 56', as well as a barrier to absorb the ultrasound
energy emitted by the back face of the transducer crystals 56 and
56'. By using two transducer crystals 56 and 56', more of the
interior wall of the vasculature or other structure can be imaged
by a device of approximately the same size.
[0056] FIG. 6 shows another embodiment wherein there are two
ultrasound support structures 70 and 70' stacked orthogonally, with
each transducer support structure 70 and 70' having two transducer
crystals 72 and 72' sharing a common backing 74 and 74'. This
configuration allows for an even larger field of view, as each
transducer crystal 72 and 72' generates a signal oriented in a
different direction. One of skill in the art will recognize that
the ultrasound support structures 70 and 70' can be oriented to
each other at any desirable angle. Additionally, the transducer
crystals 72 and 72' can be oriented on the support structures 70
and 70' and with respect to each other in alternate configurations.
Preferred embodiments of ultrasound transducers having more than
one transducer crystal are described in more detail below and in
reference to FIG. 12.
[0057] FIG. 7 illustrates a preferred embodiment of the current
invention. Shown in FIG. 7 is an actuator mechanism 80 which has
two anchors 82 and 82', a moveable element 84 connected to the
anchor 82 and 82' by an SMA actuator 86 and a deformable component
90. A connecting arm 92 connects the moveable element 84 to an
ultrasound energy reflector 94. The reflector 94 has a surface 96
which is oriented to reflect ultrasound energy to and from an
ultrasound transducer 100. Movement of the moveable element 84,
connecting arm 92 and reflector 94 can be achieved as described
above, with reference to FIG. 2. In another embodiment, the
actuator mechanism 80 is configured to move the reflector 94
substantially parallel to the longitudinal axis of the actuator
mechanism 80, as described above. One of skill in the art will
recognize that to maximize longitudinal movement, a space can be
introduced between the anchor 82' and the ultrasound energy
reflector 94 to allow the reflector 94 to move in a proximal and
distal direction. As discussed above, the orientation of the
actuator mechanism 80 could be reversed such that SMA actuator 86
is closer to the reflector 94, and the deformable component 86 is
more distant.
[0058] In the embodiment shown in FIG. 7, the transducer 100 and
reflector 94 are oriented such that ultrasound energy is reflected
from the transducer away from the device at an orthogonal angle,
about 90.degree., relative to the longitudinal axes of the actuator
mechanism 80 and elongate member (not shown). The angle of the
reflector can be changed so that the ultrasound energy transmitted
to and from the ultrasound transducer is at an angle between about
between about 15.degree. and about 165.degree., with the preferred
angle for side-looking ultrasound being between about 80.degree.
and about 110.degree.. Angles contemplated include about 15, 20,
25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100,
105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, and
about 165 degrees, or can fall within a range between any two of
these values. By decreasing the angle between the surface of the
reflector and the surface of the transducer, the ultrasound energy
will be reflected in a more forward-looking direction, that is
toward the distal tip of the device. This can be useful in some
applications where it is desirable to image the area in front of
the device, such as when navigating a tortuous path through a
blockage in the vasculature.
[0059] In the embodiment shown in FIG. 7, the reflector 94 can be
shaped for specific purposes. For example, the surface 96 can be
concave to focus the ultrasound beam into a smaller beam for
certain imaging requirements. In other embodiments the surface is
convex. In other embodiments, the reflector 94 has more than one
reflective surface.
[0060] FIG. 8 is a partial cut-away view which illustrates the
device of FIG. 7 housed in the distal end 102 of an elongate
member. A portion of the distal end housing the actuator mechanism
80 is cut away to show the actuator mechanism 80. The portion of
the distal end adjacent to the reflector 94 is a window 104 which
is transparent to ultrasound energy. This permits ultrasound energy
to be transmitted to and from the ultrasound transducer 100 through
the distal end 102 of the elongate member. Alternatively, the
configuration of the actuator mechanism 80 and the transducer 100
can be reversed--the actuator mechanism 80 is housed in the distal
end of the elongate member and the transducer is located closer to
the proximal end of the device.
[0061] FIG. 9 is a schematic diagram of another embodiment of the
current invention, where the imaging apparatus uses optical
coherence tomography. OCT relies on light emitted from a fiber
optic which is directed to the surface of the vasculature being
imaged. The imaged surface reflects light back to the device where
the same or another fiber optic transmits the signal to a processor
outside the patient. Based on differential reflectance of the
surface, and image is formed from the signal. FIG. 9 illustrates an
actuator mechanism 110 similar to the ones disclosed in the
previous figures, which has two anchors 112 and 112', a moveable
element 114 connected to the anchors 112 and 112' by an SMA
actuator 116 and a deformable component 120. A connecting arm 122
connects the moveable element 114 to a reflector 124. The reflector
has a surface 126 which is oriented to reflect light energy to and
from an optical fiber 130. The actuator mechanism 110, connecting
arm 122, reflector 124 and fiber optic 130 are advantageously
housed in the distal end of an elongate member 132. The apparatus
further includes a window 134 that is transparent to light energy,
located at the distal end of the elongate member 132.
[0062] While the connecting arm 122 is free to move relative to the
anchors 112 and 112', it is secured to the moveable element 114.
Movement of the moveable element 114, connecting arm 122 and
reflector 124 can be achieved as described above with reference to
FIG. 2. Rotational movement of the reflector 124 about the
longitudinal axes of the actuator mechanism 110 and elongate member
132 is illustrated by the arrow in FIG. 9. In another embodiment,
the actuator mechanism 110 is configured to move the reflector 124
substantially parallel to the longitudinal axes, as previously
described. Also as discussed above, the connecting arm 122 can be
supported by the anchors 112 and 112' or support elements disposed
in the anchors. One of skill in the art will recognize that the
connecting arm 122 and moveable element 114 can be fabricated from
a single piece of material, or be separate pieces secured together,
for example by glue, welding, snap-fit, or frictional forces due to
a tight fit. These are examples only, and are not limiting. In an
alternative embodiment, the SMA actuator 116 and deformable
component 120 are attached directly to the connecting arm 122.
[0063] Since the optical fiber 130 is stationary and not mounted on
the actuator mechanism 110, it eliminates the rotational load
associated with conventional OCT devices which require rotating the
entire length of the optical fiber. As a result, the actuator
mechanism can potentially generate a wider range of motion due to
the smaller load associated with the connecting arm 122 and
reflector 124. Since the OCT imaging device is based on a sweeping
reflector, the fiber optic is can remain motionless, reducing or
eliminating image distortion and issues associated with the torque
generated by the spinning optical fiber.
[0064] The reflector 124 can be shaped for specific purposes. For
example, the surface 126 can be concave to focus the coherent light
into a smaller beam for certain imaging requirements. In other
embodiments the surface is convex. The surface 126 can be designed
to replace the lens typically attached to the end of a fiber optic
when used for OCT. In this case the reflector 124 is used to focus
the coherent light at the distance needed to image the vasculature,
and the lens is not necessary. In some embodiments the reflector
124 is a mirror, in others, it is a prism. A prism allows
refractive optical coherence tomography (as opposed to reflective
tomography using a mirror.) The prism can also be designed to
replace the lens typically required at the distal tip of the
optical fiber. In other embodiments, the reflector 124 has more
than one reflective surface. In another embodiment, one or more
additional optical fibers and/or reflectors are provided to
increase the field of view, or to provide different wavelengths of
light.
[0065] FIG. 10 is a schematic of another embodiment of the
invention where the actuator mechanism 140 rotates the distal end
of the fiber optic used for OCT. FIG. 10 illustrates an actuator
mechanism 140 which has two anchors 142 and 142', a moveable
element 144 connected to the anchors 142 and 142' by an SMA
actuator 146 and a deformable component 150. The moveable element
144 is secured to the distal end of a fiber optic 154 by, for
example but not limited to, crimping, glue, welding, snap-fit, set
screw, or frictional forces due to a tight fit. The optical fiber
154 which has a prism 156 or other reflective surface mounted on
its distal tip. The prism 156 has a surface oriented to refract
light energy to and from the optical fiber 154 as illustrated by
the arrows. The actuator mechanism 140, fiber optic 154 and prism
156 are shown housed in the distal end of an elongate member 160.
In the embodiment shown in FIG. 10, a portion of the distal end of
the elongate member is a window 162 that is transparent to light
energy.
[0066] While the optical fiber 154 is free to move relative to the
anchors 142 and 142', it is secured to the moveable element 144.
Movement of the moveable element 144 can be achieved as described
above, and as illustrated in FIG. 2. Because the moveable element
144 is secured to the fiber optic 154, rotational movement of the
moveable element as illustrated by the arrow in FIG. 10 results in
rotational movement of the distal end of the fiber optic 154 and
prism 156 about the longitudinal axis of the elongate member.
[0067] The sweeping motion of the actuator mechanism 140 creates a
scanning pattern and can achieve a field of views in a range of
angles, depending upon the strain characteristics of the optical
fiber 154. This produces the required scanning motion for OCT
imaging without requiring the rotation of the entire fiber optic
and the high-speed mechanical rotator in the proximal end of the
device. In another embodiment, one or more additional actuator
mechanisms are spaced along the fiber optic from the distal end
toward the proximal end, increasing the rotational displacement of
the distal end or the entire length of the optical fiber, and
distributing the rotational load generated along the length of the
optical fiber.
[0068] FIG. 11 is a schematic illustration of an actuator mechanism
170, which has two anchors 172 and 172', a moveable element 174
connected to the anchors 172 and 172' by an SMA actuator 176 and a
deformable component 180. A reflector 182 is mounted on the
moveable element 174. The reflector has a surface 184 which is
oriented to reflect light energy to and from an optical fiber 186.
An optional support structure 190 stabilizes the moveable element
174. The actuator mechanism 170, reflector 182 and fiber optic 186
are shown housed in the distal end of an elongate member 192 as
shown in FIG. 9. The actuator mechanism provides cyclical movement
of the moveable element 174 and reflector 182 as described
previously.
[0069] FIGS. 9, 10 and 11 illustrate a reflector or prism oriented
such that light energy is reflected from the fiber optic away from
the device at an orthogonal angle, about 90.degree., relative to
the longitudinal axes of the actuator mechanism and elongate
member. The angle of the reflector can be changed so that the light
energy transmitted to and from the fiber optic is at an angle
between about 15.degree. and about 165.degree. relative to the
longitudinal axis of the device, with the preferred angle being
between about 80.degree. and about 110.degree.. Angles contemplated
include about 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,
80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145,
150, 155, 160, and about 165 degrees, or can fall within a range
between any two of these values. By adjusting the angle between the
reflective surface of the reflector or prism and the end of the
fiber optic, the light can be reflected in a more forward-looking
direction, that is toward the distal tip of the device. This can be
useful in some applications where it is desirable to image the area
in front of the device, such as when navigating a tortuous path
through a blockage in the vasculature.
[0070] As described herein, at least a portion of the elongate
member is transparent to ultrasound energy or light energy. This
includes a window made of an ultrasound or light energy transparent
material, a material which is partially or substantially
transparent to ultrasound or light energy, or the window can be a
cut-out such that there is no material between the transducer,
reflector or prism and the outside environment. In other
embodiments the entire distal end or elongate member is
transparent.
[0071] The actuator described herein can be made very small, such
that the actuator has a diameter/width between about 5 .mu.m and
about 1000 .mu.m, with the preferred size being between about 5
.mu.m and about 100 .mu.m. The actuator preferably has a diameter
or width of, or of about, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90,
100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 .mu.m, or is
at least about, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200,
300, 400, 500, 600, 700, 800, 900, or 1000 .mu.m, or is no more
than about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300,
400, 500, 600, 700, 800, 900, or 1000 .mu.m, or can fall within a
range between any two of these values. The range of lengths
preferred for the actuator is quite broad, and depends on the
application. For rotational motion, the length of the actuator
mechanism can be from about 20 .mu.m to about 10 mm, with the
preferred size being from about 200 .mu.m to about 10 mm. For
longitudinal motion, the length of the actuator can be from about
100 .mu.m to about 20 mm, with the preferred length being from
about 1 mm to about 20 mm. The actuator preferably has a length of,
or of about, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400,
500, 600, 700, 800, 900 .mu.m, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, or 20 mm, or is at least about, 20,
30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800,
900 .mu.m, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, or 20 mm, or is no more than about 20, 30, 40, 50, 60,
70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900 .mu.m, 1,
2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or
20 mm, or can fall within a range between any two of these
values.
[0072] The outside diameter of the elongate member, such as a guide
wire or catheter containing an imaging device described herein can
be as small as from about 0.005'' to about 0.100'' outside
diameter. Preferably, the outside diameter of the elongate member
is, or is about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,
80, 85, 90, 95, or 100 hundredths of an inch, or is at least about,
0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,
or 100 hundredths of an inch, or is no more than about 0.5, 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100
hundredths of an inch, or can fall within a range between any two
of these values.
[0073] The range of motion generated by the actuator mechanism
described herein will vary depending of the application. Rotational
motion can be in a range from about 1 or 2 degrees up to about 400
degrees, depending on the area of interest. Angles of rotational
displacement generated by the actuator mechanism are, or are about,
1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,
80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145,
150, 155, 160, 165, 170, 175, 180, 190, 195, 200, 205, 210, 215,
220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280,
285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345,
350, 355, 360, 365, 370, 375, 380, 385, 390, 395, or 400 degrees,
or at least about 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55,
60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130,
135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 190, 195, 200,
205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265,
270, 275, 280, 285, 290, 295, 300, 305, 310, 315, 320, 325, 330,
335, 340, 345, 350, 355, 360, 365, 370, 375, 380, 385, 390, 395, or
400 degrees, or no more than 1, 2, 5, 10, 15, 20, 25, 30, 35, 40,
45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115,
120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180,
190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250,
255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315,
320, 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, 380,
385, 390, 395, or 400 degrees, or can fall within a range between
any two of these values. By adjusting the power and/or duration of
the activation signal to one or more of the SMA actuators, the
degree of rotation or length of longitudinal displacement can be
adjusted while the device is in the patient, allowing the operator
to adjustably define a specific image field of view. The preferred
range of rotational displacement generated by the actuator device
is from about 25 to 360 degrees. In addition, it is possible to use
the device of the invention for singe point interrogation for
optical coherence reflectometry or Doppler effect measurements.
[0074] The amount of longitudinal displacement generated by the
actuator mechanism is also dependent on the length of the area of
interest. The length of longitudinal displacement can be from about
100 .mu.m to about 30 mm or more. The length of longitudinal
displacement generated by the actuator mechanism preferably is, or
is about 100, 200, 300, 400, 500, 600, 700, 800, 900 .mu.m, 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
25, or 30 mm, or is at least about, 100, 200, 300, 400, 500, 600,
700, 800, 900 .mu.m, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 25, or 30 mm, or is no more than about 100,
200, 300, 400, 500, 600, 700, 800, 900 .mu.m, 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, or 30 mm, or
can fall within a range between any two of these values.
[0075] The frequency of the motion generated by the actuator
mechanism can range from about 1 Hz to about 100 Hz. The preferred
frequency of motion is between about 8 Hz and 30 Hz. The frequency
of movement generated by the actuator mechanism is, or is about, 1,
2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100
Hz, or at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70,
75, 80, 85, 90, 95, or 100 Hz, or no more than about 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35,
40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 Hz, or can
fall within a range between any two of these values.
[0076] In some embodiments, the actuator mechanism disclosed herein
is made without any mechanical joints.
[0077] When the actuator described above is used to generate
movement of an ultrasound transducer, the area imaged by a single
transducer is limited by the range of movement the actuator can
generate. One way to achieve a larger field of view is to use
multiple transducer crystals. The prior art discloses phased array
devices where individual crystal transducers are used in
combination to generate an ultrasound wave for imaging. In these
prior art devices, the individual crystals are mounted on separate
backings and are not capable of individually producing an
ultrasound signal for imaging. In contrast, the individual
transducer crystals used in the transducers of the instant are
preferably mounted on a shared backing and are preferably capable
of individually producing an ultrasound signal for imaging.
[0078] As used herein, transducer crystal or crystal transducer
refers to the material used to produce and/or receive the
ultrasound signal. Materials used for making the transducer crystal
are known in the art and include quartz and ceramics such as barium
titanate or lead zirconate titanate. Ultrasound transducer crystals
for IVUS utilize frequencies from about 5 MHz to about 60 MHz, with
the preferred range being from about 20 MHz to about 45 MHz.
[0079] Ultrasound crystals are preferably substantially
rectangular, square, elliptical, or circular, although any shape
that produces a functional ultrasound transducer is contemplated.
As used herein, the top and bottom edge of a transducer crystal are
defined by substantially parallel lines bounding the transducer, a
first and second side edge are defined by a second set of
substantially parallel lines bounding the transducer, where the
lines defining the top and bottom edges are substantially
perpendicular to the lines defining the first and second side
edges. As defined herein, ellipses, circles, irregular shapes, etc.
can have top, bottom, first and second edges.
[0080] FIG. 12 illustrates a schematic of ultrasound transducers
having one, two or three crystal transducers. The dashed lines
shown in FIG. 12 represent the direction the ultrasound energy is
transmitted and received from the transducer crystals. FIG. 12a
shows an ultrasound transducer 200 having one crystal transducer
202 on a backing structure 204. The backing material can be any
material known to those in the art which absorbs ultrasound energy
radiated from the transducer crystals back face. FIG. 12b shows an
ultrasound transducer 210 having two crystal transducers 212 and
214 on a single backing structure 216. FIG. 12c shows an ultrasound
transducer 220 having three crystal transducers 222, 224 and 226 on
a single backing structure 228.
[0081] FIGS. 12d, 12e, and 12f show the range of fields of view
with the different configurations of transducers shown in FIGS.
12a, 12b and 12c, respectively. As an example, assume that the
actuator mechanism (not shown) used to move the transducer can
generate 60.degree. rotational motion. With a single transducer as
shown in FIG. 12a, rotation of the ultrasound transducer 200
through 60.degree. will provide a 60.degree. field of view as shown
in FIG. 12d, where the crystal transducer 202 is shown at the two
extremes of the range of motion (the backing 204 is excluded for
clarity.) If two transducers 212 and 214 are arranged with a
60.degree. angle between their respective fields of view as shown
in FIG. 12b, rotating the transducer structure 210 through
60.degree. as shown by the two positions illustrated in FIG. 12e
will provide a field of view totaling 120.degree. with the same
actuator. Similarly, three-transducers configured with a 60.degree.
angle between each crystal transducer 222, 224 and 226 as shown in
FIG. 12c will have a field of view equivalent to 180.degree. if the
transducer is rotated through 60.degree. as shown in FIG. 12f.
[0082] Although a 60.degree. angle between the beams of the
transducer crystals is shown in FIG. 12, any angle between
0.degree. (equivalent to the field of view provided by a large
crystal) and 180.degree. is encompassed by the present invention.
Angles encompassed by the invention include about 5, 10, 15, 20,
25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100,
105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165,
170, 175, and about 180 degrees, or can fall within a range between
any two of these values. In some embodiments, the angles defined by
the adjacent pairs of crystals are not equal. For example, where
three crystals are used, the angle defined by the third crystal and
the second crystal can be different than the angle defined by the
first crystal and the second crystal. The angle between the faces
of the transducer crystals is preferably about the same as the
degrees of deflection which can be achieved by the actuator
mechanism. This maximizes field of view without significant overlap
or gaps between the individual fields of view for each transducer
crystal. For example, if two crystal transducers 212 and 214 are
aligned at 60.degree. as illustrated in FIG. 12b, but the actuator
can only rotate the transducer structure by 30.degree., there will
be a gap of approximately 30.degree. between the fields of view
generated by each transducer crystal. Similarly, if the actuator
can rotate through 90.degree., there will be a 30.degree. field of
view overlap between the two fields of view generated by each
transducer crystal. While an overlap or gap in the fields of view
can be desirable in some applications, the preferred embodiment
provides for minimal gaps or overlaps. Importantly, the individual
transducer crystals are placed with their edges adjacent or
touching, such that the size of any gap between the fields of view
of the individual crystal transducers is minimized and
significantly reduced. In a preferred embodiment, the individual
transducer crystals are configured such that any gap between the
individual fields of view are substantially eliminated. This
provides an improved image quality.
[0083] While FIG. 12 illustrates an ultrasound transducer with 1,
2, or 3 crystals, more crystals can be used. Also contemplated are
ultrasound transducers with 4, 5, 6, 7, 8, 9, or 10 transducer
crystals. The crystals can be arranged on a single backing device,
or on multiple backing devices as illustrated in FIG. 6. For single
crystal transducers the diameter of the crystal if circular shaped,
or width if rectangular shaped, is preferably from about 10 .mu.m
to about 10 mm, and more preferably from about 100 .mu.m to about 1
mm. For transducers with multiple crystals, the combined diameter
or width of the individual crystals is preferably from about 10
.mu.m to about 10 mm, and more preferably from about 100 .mu.m to
about 1 mm. Preferably, the diameter or width of the individual
crystals on a given transducer is approximately equal, although
crystals of different diameters or widths can be combined. The
individual transducer crystals preferably have a diameter or width
of, or of about, 100, 200, 300, 400, 500, 600, 700, 800, 900, or
1000 .mu.m, or are at least about, 100, 200, 300, 400, 500, 600,
700, 800, 900, or 1000 .mu.m, or are no more than about 100, 200,
300, 400, 500, 600, 700, 800, 900, or 1000 .mu.m, or can fall
within a range between any two of these values.
[0084] In another embodiment, the multiple transducer
configurations disclosed herein are utilized in a device in which
the actuator is configured to provide longitudinal, rather than
rotational motion, for example as shown in FIGS. 2c and 2d. As with
the rotational movement illustrated in FIG. 12, combining multiple
transducers with longitudinal motion can also provide a larger
field of view with the same actuator.
[0085] The multiple transducer configuration disclosed herein can
also be used for forward looking ultrasound devices. Providing a
180.degree. field of view allows ultrasound imaging with the
capability of side-looking as well as forward-looking in a single
device. A preferred forward looking device is disclosed in U.S.
Patent Publication No. US-2004-0056751-A1, which is herein
incorporated by reference in its entirety. Other forward looking
devices include those disclosed in U.S. Pat. Nos. 5,379,772 and
5,377,685, which are herein incorporated by reference. As used
herein, a pivot point is a point around which the transducer is
rotated, and includes mechanical joints, for example those
disclosed in U.S. Pat. No. 5,379,772, FIGS. 2, 5, and 6. While the
aforementioned forward looking devices disclose a single crystal
transducer, applicants have discovered that transducers having
multiple crystals dramatically increase the field of view. As was
described with reference to side-looking devices, the multiple
crystal transducers are disposed on the actuator mechanism.
[0086] U.S. Patent Publication No. US-2004-0056751-A1 discloses an
elastic or superelastic material utilized as a structural material
for a micromanipulator. In principle, when a compliant mechanism is
deformed with an actuator, strain energy is stored inside the
underlying structure during deformation (elastic and plastic). The
stored energy is then directly utilized to produce a bias force to
return the structure to its original shape. However, an elastic
material such as stainless steel can also be utilized as a
structural material for compliant mechanisms
[0087] According to an aspect of the disclosure, a Nd:YAG laser is
implemented in the fabrication of the compliant structure out of a
tube. A tubular nitinol structure with compliant mechanism was
successfully fabricated using laser machining with a laser beam
size of about 30 .mu.m. The outer diameter of the tube is about 800
.mu.m and the wall thickness is about 75 .mu.m. Actual feature size
is about 25 .mu.m, which is mostly limited by the size of the laser
beam. Thus, by reducing the beam size, resolution of the laser
machining can be enhanced.
[0088] To shape a nitinol structure, there are three fabrication
processes currently commercially available: chemical etching, laser
machining and micro-mechanical cutting. However, these two
processes are not able to precisely control etching depth. Thus, it
is very difficult to have a variation in thickness and,
consequently, the thickness of the mechanism determines the
substrate thickness. This presents another issue in design, which
is structural rigidity. For instance, if the substrate thickness is
on the order of tens of microns, the supporting structure also
starts deflecting as the mechanism moves. This deflection at the
supporting structure, which is supposed to be fixed, directly
contributes to loss of output displacement. Structural rigidity is
mostly a shape factor, which is related to flexural modulus, EI.
Considering the structural rigidity, a tube shape is more
attractive than a plate form.
[0089] FIG. 13a illustrates an exemplary tubular structure 1200a
with a built-in compliant mechanism 1201a. FIG. 13b illustrates
another exemplary tubular structure 1200b with a built-in compliant
mechanism 1201b in a helical configuration having helix 1291 and
helix 1292 intertwined in a "double helix"-like fashion. The
mechanism design can be any shape and/or configuration as long as
it utilizes structural compliance (elasticity and/or
superelasticity) as a main design parameter. Similarly, as one
skilled in the art would appreciate, the rest of the tubular
structure can be in any suitable configuration, size, and length,
etc., optimized for a particular application and thus is not
limited to what is shown here. Moreover, in addition to nitinol,
other flexible, resilient biocompatible metal or polymer materials
can also be utilized as long as they have reversible structural
behaviors, i.e., have elastic and/or superelastic behaviors while
actuated.
[0090] As illustrated in FIG. 13b, compliant mechanisms can be in a
"double helix" configuration. U.S. Patent Publication No.
US-2004-0056751-A1 teaches that it is desirable with the disclosed
invention that any bending strain of the compliant mechanisms is
distributed substantially evenly along their entire lengths. This
reduces peak strain, which in various embodiments, can be, 4% or
less, 3% or less, 2% or less and 1% or less. The "double helix"
configuration provides greater symmetry in motion and provides a
more even bending It is desired that the stiffness of compliant
mechanisms in different directions be substantially the same.
[0091] In various embodiments, the elastic bending strength of the
compliant mechanisms is customized in order to match with that of
the actuators. In some embodiments, the actuators have slightly
stiffer elastic bending strengths than those of the compliant
mechanisms. In one embodiment, the compliant mechanisms are stiffer
than the actuators when the actuators are relaxed, and the
compliant mechanisms are softer than the actuators when the
actuators are active. It is desirable to provide compliant
mechanisms in configurations, such as those of the "double helix"
configurations, that have as little stress concentration as
possible.
[0092] According to the invention disclosed in U.S. Patent
Publication No. US-2004-0056751-A1, the strain of a compliant
mechanism is distributed, while minimizing the occurrence of strain
location. The mechanical characterization of a compliant mechanism
can be tuned by modifications in, (i) stiffness, (ii) peak strain
(maximum strain), (iii) size, (iv) fatigue life, and the like. In
one embodiment, the upper limit of strain is no more than 4%. The
bending stiffness depends on actual application. By way of
illustration, and without limitation, the bending stiffness of a
compliant mechanism can be at least 0.5 N-mm and no more than 10
N-mm. In various embodiments, compliant mechanisms are stiffer than
the imaging device. The associated actuators are also stiffer than
the imaging device. The actuators need a longer thermal time
constant than the imagining device.
[0093] FIG. 14 schematically shows, according to an aspect of the
invention disclosed in U.S. Patent Publication No.
US-2004-0056751-A1, a micromanipulator 1300 tightly coupled with an
ultrasound transducer 1310 for image scanning. Micromanipulator
1300, as well as the other embodiments of micromanipulators
disclosed herein, provide for steering, viewing and treatment at
sites within vessels of the body, as well as for industrial
applications.
[0094] The micromanipulator 1300 enables the ultrasound transducer
1310 to be directly coupled to the compliant mechanisms 1301. In
this fashion, the rotational center of the transducer 1310 for the
scanning motion is substantially closer to the rotational axis of
the mechanism 1301. In an embodiment, SMAs are implemented as main
actuators 1320 for the micromanipulator 1300. To allow the SMAs
1320 be attached thereto, the micromanipulator 1300 might have one
or more attachment points or built-in micro structures such as
welding-enabling structures 1302 as shown in a cross-sectional view
A-A and clamping-enabling structures 1302' as shown in another
cross-sectional view A'-A'. In some embodiments, the SMAs 1320 are
attached to the compliant apparatus via the one or more attachment
points or welding-enabling structure 1302 using a laser having a
laser beam size of about 200 .mu.m or less. In some embodiments,
the SMAs 1320 are fastened to the compliant apparatus via the
built-in clamping-enabling structures 1302'.
[0095] The compliant mechanisms 1301 are actuated with SMA 1320
actuators based on shape memory effects including contraction as
well as rotation motion to maximize output displacement. As one
skilled in the art can appreciate, the SMA actuators can be in any
shape such as wire, spring, coil, etc. and thus is not limited to
what is shown.
[0096] Another aspect of the current invention is a method for
visualizing the interior of a patient's vasculature, or other
structure with a lumen. The method comprises inserting the
inserting the distal end of the elongate member of any of the
apparatuses disclosed herein into the vasculature of a patient. The
distal end is advanced through the vasculature, optionally under
the guidance of x-ray fluoroscopic imaging to the location of the
blockage, legion, or other area to be imaged. Alternatively, the
imaging device can be used instead of or in addition to the x-ray
fluoroscopic imaging to guide the device through the
vasculature.
[0097] To generate an image, an ultrasound signal
generator/processor located outside the patient is activated,
generating an ultrasound signal from the ultrasound transducer. The
actuator mechanism described herein is used to generate a cyclical
movement of the ultrasound transducer or reflector as described
above. In the case of OCT, the fiber optic is used to transmit a
light signal from a signal processor unit outside the patient to
the distal tip of the optical fiber. The reflector, prism, or
distal end of the optical fiber is moved in a cyclical motion by
the actuator mechanism as described herein. The cyclical movement
sweeps the ultrasound or light energy over the area being imaged.
The ultrasound or light energy is reflected back to the ultrasound
transducer or fiber optic, respectively. The signal is then
transmitted to the proximal end of the device where it is processed
to produce an image.
[0098] In some embodiments of the current invention, the elongate
member has one or more lumens along the longitudinal axis of the
elongate member. The lumen(s) can be used to house the actuator
mechanism, compliant mechanism, optical fiber and other devices
described herein. The lumen(s) can also be used to house wiring
which connects the ultrasound transducer(s) and SMA actuator(s)
disposed in the distal end of the elongate member to devices
located adjacent to the proximal end of the elongate member. These
devices include, for example, other components of an ultrasound or
OCT imaging system, such as an ultrasound or light source
generator, receiver and computer located near the proximal end of
the elongate member. In some embodiments, the imaging device of the
invention is connected wirelessly to one or more components of the
imaging system. The ultrasound imaging device of the invention is
optionally configured to provide real-time imaging of the
environment at the distal end of the elongate member. Other devices
include a signal generator for controlling the activation of the
SMA actuators.
[0099] The lumen(s) can also be used to flush the distal end of the
ultrasound device with fluid. This fluid can improve the ultrasound
signal, can be used to flush the area around the IVUS imaging
device to ensure that the area is free of debris or bubbles which
would interfere with the performance of the ultrasound device, and
cool the ultrasound transducer and/or the SMA actuators. In an
embodiment with using one or more lumens to flush the distal end of
any of the devices described herein, it is desirable to provide a
means for the fluid to circulate through the area around the
ultrasound transducer, such as another lumen to return the fluid to
the proximal end of the elongate member, or an opening in the
distal end of the elongate member so that the fluid can escape.
Optionally, a fluid pump can be attached to the proximal end of the
elongate member to facilitate fluid circulation through the
lumen(s). In another embodiment, the distal end of the elongate
member contains fluid which is sealed or injected in the distal end
and/or a lumen of the elongate member.
[0100] In another embodiment, SMA actuators can be used to bend or
steer the distal end of the elongate members disclosed herein to
allow the user to reduce the distance between the distal end of the
device and image target. In the case of intravascular OCT this
reduces the artifact caused by blood between the image acquisition
device and the vessel wall by bringing the imaging portion of the
device closer to the wall itself. Similar to current intravascular
ultrasound system (IVUS), local actuators can provide the pull-back
motion of the imaging tip, so it can control precisely the
pull-back of the distal imaging tip and generate three-dimensional
images of the blood vessel.
[0101] As discussed above, the angle or orientation of the
ultrasound transducer or reflector, or the OCT reflector or prism
can determine where the imaging energy is directed. For some
applications, these elements direct the energy generally
orthogonally from the longitudinal axis of the device. For other
applications, these elements can be oriented to direct the imaging
energy toward the distal tip of the device, resembling forward
looking devices, or toward the proximal end of the device. In
another embodiment of the invention, an additional SMA actuator is
incorporated into the device to actively move the transducer,
reflector or prism and change the imaging plane adaptively. This
active angle control can provide side-looking and forward-looking
as needed with a single imaging device.
[0102] In another embodiment, the IVUS system described herein and
the OCT device described herein are combined in a single elongate
member to provide both IVUS and OCT imaging in a single, compact
device.
[0103] Although the embodiments described herein have the imaging
devices located in the distal end of the elongate member, one of
skill in the art will recognize that the imaging devices can be
placed anywhere along the length of the elongate member.
[0104] In another embodiment, the imaging devices disclosed herein
are integrated into the distal end of a guide wire's rigid section,
but proximal to the coil structure that defines the distal tip of a
guidewire.
[0105] In another embodiment, the imaging devices described herein
are combined with one or more therapeutic or interventional
devices, for example, but not limited to, devices for stent
placement and deployment, balloon angioplasty, directional
atherectomy, cardiac ablation, PFO (patent foramen ovule) closure,
transvascular re-entry, trans-septal punch, and CTO (chronic total
occlusion) crossing.
[0106] The foregoing description details certain embodiments of the
invention. It will be appreciated, however, that no matter how
detailed the foregoing appears in text, the invention can be
practiced in many ways. As is also stated above, it should be noted
that the use of particular terminology when describing certain
features or aspects of the invention should not be taken to imply
that the terminology is being re-defined herein to be restricted to
including any specific characteristics of the features or aspects
of the invention with which that terminology is associated. The
scope of the invention should therefore be construed in accordance
with the appended claims and any equivalents thereof.
* * * * *