U.S. patent application number 10/759045 was filed with the patent office on 2004-07-29 for intra vascular imaging method and apparatus.
Invention is credited to Adler, Doron.
Application Number | 20040147806 10/759045 |
Document ID | / |
Family ID | 26977739 |
Filed Date | 2004-07-29 |
United States Patent
Application |
20040147806 |
Kind Code |
A1 |
Adler, Doron |
July 29, 2004 |
Intra vascular imaging method and apparatus
Abstract
An invasive imaging apparatus comprising: a flexible catheter
with a proximal end and a distal end, the distal end being shaped
for insertion into a blood vessel along a guide wire thereby to
reach remote places in the vasculature or other organs, an optical
assembly positioned at the distal end of the catheter comprising an
image sensor positioned non-perpendicularly to the longitudinal
axis of the catheter, at least one illumination source for
illuminating an immediate region beyond the distal end of the
catheter, and at least one working channel running from the
proximal to the distal end of the catheter.
Inventors: |
Adler, Doron; (Nesher,
IL) |
Correspondence
Address: |
SOL SHEINBEIN
c/o ANTHONY CASTORINA
SUITE 207
2001 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Family ID: |
26977739 |
Appl. No.: |
10/759045 |
Filed: |
January 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10759045 |
Jan 20, 2004 |
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09973181 |
Oct 10, 2001 |
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6692430 |
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60311093 |
Aug 10, 2001 |
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Current U.S.
Class: |
600/109 ;
600/160; 977/878; 977/952 |
Current CPC
Class: |
A61B 1/00091 20130101;
Y10S 977/869 20130101; A61B 1/00193 20130101; A61B 1/015 20130101;
A61B 1/0638 20130101; A61B 5/02007 20130101; A61B 1/00082 20130101;
A61B 5/0275 20130101; A61B 1/3137 20130101; A61B 5/0084 20130101;
A61B 1/05 20130101; Y10S 977/876 20130101; A61B 1/0655
20220201 |
Class at
Publication: |
600/109 ;
600/160 |
International
Class: |
A61B 001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2000 |
IL |
135571 |
Claims
1.-40. (Canceled).
41. (Original) A method for performing biopsies and other
diagnostic or therapeutic procedures comprising placing an invasive
optical assembly apparatus on the distal end of a needle, inserting
said optical assembly and needle into vasculature or other organs,
and using said optical assembly to provide visual feedback of said
biopsies and diagnostic or therapeutic procedures.
42. (Original) A method for viewing through blood in Situ
comprising injecting a controlled amount of fluid into blood in the
immediate region in front of an invasive optical assembly,
temporarily changing the optical characteristics of the blood in
said immediate region, and thereby improving visibility through
said blood.
43. (Original) A method for viewing through blood in Situ
comprising injecting a controlled amount of fluid into blood in the
immediate region in front of an invasive optical assembly,
temporarily changing the reflectance of the liquid portion of said
blood, and improving visibility through said blood.
44. (Original) A method fir viewing through blood in Situ according
claim 42 wherein said fluid is used to change the optical
characteristics of blood in Situ to facilitate imaging through said
blood, said fluid being a physiological fluid, such as saline, or a
hypoosmolar fluid, such as 0.45% saline or 1/6 saline.
45. (Original) A method for viewing through blood in Situ according
to claim 42 wherein said fluid for use in changing the optical
properties of blood in Situ to facilitate imaging through said
blood, said fluid being a blood substitute which does not contain
red blood cells and has homogenous optical characteristics.
46. (Original) A method for viewing through blood in Situ according
to claim 42 wherein said fluid is chosen to enable illumination to
facilitate imaging through said blood and the environment in Situ
with an IR illumination source, enabling a frequency shift so that
a visible light sensor can be effectively used.
47. (Original) A method for viewing through blood in Situ according
to claim 42 wherein said fluid is chosen to be oxygen carrying,
such as a blood substitute, to reduce the risk of hypoxia to the
heart muscle.
48. (Original) An invasive imaging control apparatus comprising: i.
A flexible catheter with a proximal end and a distal end, said
distal end being shaped for insertion into a blood vessel along a
guide wire thereby to reach remote places in the vasculature or
other organs. ii. An optical assembly positioned at the distal end
of said catheter. iii. At least one working channel running from
the proximal to the distal end of said catheter. iv. A control unit
for regulating the opacity level of blood in said blood vessel
around said distal end of said catheter, controllably injecting
quantities of fluid into said blood vessel in the vicinity of said
optical assembly, thereby enhancing visibility.
49. (Original) Apparatus according to claim 48 wherein said optical
assembly comprises an illumination sensor operable to sense at
least one wavelength taken from within a range from visible light
to infra-red light.
50. (Original) Apparatus according to claim 48 wherein said working
channel is usable for controllably passing through fluid to said
distal end of catheter.
51. (Original) Apparatus according to claim 48 wherein said control
unit is connectable to the proximal end of said catheter from
outside of the patient's body.
52. (Original) Apparatus according to claim 48 wherein said control
unit is operable to control the timing and amount of injection of
said fluid.
53. (Original) Apparatus according to claim 52 wherein the
injection of said fluid is synchronized with the operation of said
optical assembly, synchronizing said operation and said injection
with the cycle of patient physiological conditions.
54. (Original) Apparatus according to claim 48 wherein said fluid
is insertable into the immediate region of said distal end of said
catheter to change the optical characteristics of blood in said
immediate region.
55. (Original) Apparatus according to claim 48 wherein said fluid
comprises one or more fluids selected to modify the optical
characteristics of blood plasma to render said optical
characteristics to be as close as possible to those of red blood
cells.
56. (Original) Apparatus according to claim 53 wherein said
physiological condition is heart beat sensible using a heart rate
sensor connectable to a patient's body from outside of said
patient's body or insertable into said blood vessel through said
catheter.
57. (Original) Apparatus according to claim 56, wherein said heart
rate sensor comprises a plethysmograph.
58. (Original) Apparatus according to claim 56 wherein information
from said heart rate sensor is transferred to said central control
unit enabling synchronization with said physiological
conditions.
59. (Original) An invasive imaging control apparatus comprising: i.
A flexible catheter with a proximal end and a distal end, said
distal end being shaped for insertion into a blood vessel along a
guide wire thereby to reach remote places in the vasculature or
other organs. ii. An optical assembly positioned at the distal end
of said catheter. iii. At least one working channel running from
the proximal to the distal end of said catheter iv. A
semi-permeable membrane positioned at said distal end of said
catheter, surrounding said optical assembly extendable to displace
blood from around the optical assembly allowing clear
visibility.
60. (Original) Apparatus according to claim 59 wherein said
membrane is rigid.
61. (Original) Apparatus according to claim 59 wherein said
membrane is flexible.
62. (Original) Apparatus according to claim 59 wherein said
membrane is inflated and deflated by means of controllably passing
a fluid through said working channel to said distal end of
catheter.
63. (Original) apparatus according to claim 59 comprising a control
unit connectable to the proximal end of said catheter from outside
of the patient's body.
64. (Original) An apparatus according to claim 62 wherein the
injection of said fluid is synchronized with the operation of said
optical assembly, synchronizing said operation and said injection
with the cycle of patient physiological conditions.
65. (Original) Apparatus according to claim 64 wherein one of said
physiological conditions is heart beat sensible using a heart rate
sensor connectable to a patient's body from outside of said
patient's body or insertable into said blood vessel through said
catheter.
66. (Original) Apparatus according to claim 65 wherein information
from said heart rate sensor is transferred to said central control
unit enabling synchronization with said physiological
conditions.
67. (Original) A method for reconstructing images by interpolating
image data along at least one of the longitudinal and axial axes of
a flexible catheter with a distal end inserted into a blood vessel
and thereby reaching remote places in the vasculature or other
organs, based on image data from both said longitudinal and axial
axes, comprising: i. off-line image training initialization, and;
ii. real-time image data interpolation.
68. (Original) A method of reconstructing images according to claim
67 wherein said off-line image training initialization comprises:
i. training image construction; ii. reconstruction of a lower
resolution mew image from said training image; iii. finding edge
directions of said lower resolution image, and; iv. training a
neural network to obtain a set of filters.
69. (Original) A method of reconstructing images according to claim
68 wherein said training image is clipped and rotated to obtain
robust edges in each one of a plurality of directions.
70. (Original) A method of reconstructing images according to claim
67 comprising executing local control enhancement following said
image data interpolation.
71. (Original) A method according to claim 70 wherein said local
contrast enhancement comprises: i. calculating the average
intensity of said real time image, yielding an intensity image; ii.
generating a first image by correcting the intensity of said
intensity image; iii. calculating a local contrast image; iv.
generating a second image by enhancing said local contrast image,
and; v. summing said first image and said local contrast image to
generate an output image.
72. (Original) A method according to claim 71 comprising generating
said first image by modifying the intensity of said real time image
using a lookup table.
73. (Original) A method according to claim 71 comprising generating
said second image by modifying the local contrast of said real time
image using a lookup table.
74. (Original) A method according to claim 67 wherein said
real-time date interpolation comprises: i. finding edge directions
of each pixel, and; ii. interpolating data using an appropriate
direction filter from a set of direction filters.
75. (Original) A method according to claim 74 comprising generating
said set of direction filters in said off-line image training.
Description
RELATIONSHIP TO EXISTING APPLICATIONS
[0001] The present application claims priority from U.S.
provisional patent application No. 60,311,093 filed Aug. 10, 2001.
The application is also related to U.S. patent application Ser. No.
09/826,163, filed Apr. 5, 2001, the contents of which are hereby
incorporated by reference.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention relates to an intra vascular imaging
method and apparatus which allow the acquisition of endoscopic
images of small internal cavities of the body including methods and
apparatus for visualization through opaque liquid media.
[0003] Heart and blood vessel diseases are among the main causes
for morbidity and mortality in Western society. Therefore,
interventional procedures involving blood vessels of the heart are
among the most widely used in the medical field. The pathology that
is in the base of most acute coronary syndromes and sudden cardiac
deaths is atherosclerosis. In this process, atherosclerotic
plaques, which are an active collection of different cells, mainly
immune cells and smooth muscle cells along with deposits of fatty
substances, cholesterol, cellular waste products, calcium and other
substances, are accumulated in the inner lining of an artery.
Stable plaques, which cause the more significant narrowing of the
arterial wall, are considered the major factor in the development
of angina pectoris (chest pain). However, studies from recent years
have shown, that unstable angina, myocardial infarctions (heart
attacks) and sudden cardiac related deaths are caused mainly by
unstable plaques, otherwise known as vulnerable plaques. This type
of plaque is usually smaller and therefore less significant and
difficult to detect with currently used angiographic methods
described hereafter.
[0004] Some of the important developments were made in the field of
minimally invasive procedures. A very common diagnostic and
therapeutic procedure is cardiac catheterization. The commonly
applied method, angiography, includes imaging the heart and
coronary blood vessels using an X-ray camera as the imaging device,
and a catheter, through which a contrast substance is injected into
the heart and vessels to enable them to be viewed by the camera.
This method gives a two-dimensional monochromatic view of the heart
and blood vessels as viewed from the outside. This method detects
major occlusions by identifying places where blood flow is
disturbed and it may direct the PTCA (Percutaneous Transluminal
Coronary Angioplasty) or stent-inserting technique to the place of
the occlusion, but it does not give a direct view of the occlusion
site or the surrounding area. One of the major risks of the
techniques described above is a rupture or a disruption in the
fibrous cap covering the plaque and the release of plaque particles
into the blood stream. These particles may cause numerous small
occlusions in the coronary arteries but also may cause occlusions
in small blood vessels of other organs, such as the brain, kidney,
or lungs. A direct, clear view of the field of operation, as
provided in the current invention, could substantially decrease the
risk of disruption, as described above. Also, and perhaps more
importantly, only through intra-vascular imaging will it be
possible to detect the smaller, vulnerable plaques. The
effectiveness and precision of the plaque treatment, when assisted
with direct intra-vascular imaging, such as in the present
invention, would be enhanced when compared to current indirect
imaging methods.
[0005] Important methods that have been developed to confront the
issue of intra-vascular imaging are angioscopy and intra-luminal
ultrasound. New techniques, which are still under development,
include Optical Coherence Tomography (OCT) and infrared
endoscopy.
[0006] Angioscopy is a form of endoscopy developed for the
arteries. Because the illumination used in angioscopy is in the
visible wavelength range, in which the blood that fills the
arteries is opaque, the method requires a way of moving the blood
from the field of view prior to visualization. One way to do this
is by injecting a high-pressure physiological fluid into the vessel
to temporarily displace the blood, as disclosed in patents U.S.
Pat. No. 4,827,907, U.S. Pat. No. 4,998,972, U.S. Pat. No.
5,730,731, U.S. Pat. No. 5,010,875 and U.S. Pat. No. 4,934,339.
Another way of clearing the field of view is by inflating a
balloon, which is positioned at the distal end of the angioscope,
in front of the camera-head or optical assembly. The balloon is
made of a transparent substance, so that when it is inflated inside
the blood vessel, with either gas or a transparent liquid, it
pushes the blood away from the distal end of the angioscope and
clears a field of view of the walls of the vessel. Such an
apparatus is described in U.S. Pat. No. 4,784,133 and U.S. Pat. No.
5,411,016; the latter patent disclosing a transparent part at the
distal end of the angioscope in addition to the balloon surrounding
it. A similar apparatus is disclosed in U.S. Pat. No. 4,470,407,
except that the optical system terminates inside the balloon (also
allowing laser operation through the balloon). An apparatus that
uses two spaced and expendable balloons, that occlude and isolate
an operating area in the blood vessel between them, is disclosed in
U.S. Pat. No. 4,445,892. Most methods combine an inflatable balloon
with injection of a transparent liquid. The balloon coaxially
surrounds the sheath at the distal end of the catheter and, when
inflated, it blocks some of the blood flow. The method described
above allows the injection of less flush liquid and at a lower
pressure, which is safer and more efficient. Prior art in which the
method described above is used is U.S. Pat. No. 4,576,145, U.S.
Pat. No. 4,576,146, U.S. Pat. No. 5,263,928 and U.S. Pat. No.
5,464,394. A combination of an angioplasty balloon with
intra-vascular endoscopy is disclosed in patents EP177124A, U.S.
Pat. No. 5,116,317 and U.S. Pat. No. 4,961,738. In the latter
patent, the optical system terminates within the balloon and there
is a "working well" in the balloon to allow the insertion of
instruments into the lumen of the vessel.
[0007] Another method for intra-vascular imaging is the use of
ultrasound. The ultrasound transducer is positioned at the distal
end of a catheter inside the blood vessel and the ultrasound
transducer is used to obtain an image of the lumen and walls of the
artery. Patents referring to this kind of apparatus are U.S. Pat.
No. 6,129,672, U.S. Pat. No. 6,099,475, U.S. Pat. No. 6,039,693,
U.S. Pat. No. 6,059,731, U.S. Pat. No. 5,022,399, U.S. Pat. No.
4,587,972, U.S. Pat. No. 4,794,931, U.S. Pat. No. 4,917,097 and
U.S. Pat. No. 5,486,170. A patent that combines PTCA with
ultrasonic imaging is U.S. Pat. No. 5167233.
[0008] OCT provides a three-dimensional image by performing optical
measurements, and it can be used in intra-vascular imaging. Related
patents are U.S. Pat. No. 6,134,003, U.S. Pat. No. 6,010,449, and
U.S. Pat. No. 5,459,570.
[0009] The opaqueness of blood at visible light wavelengths poses a
specific problem when attempting to acquire an image of an
intra-vascular space. One solution to the problem noted above is to
utilize infrared (IR) light to enable visibility through the
suspended particles and cells in the blood. A patent that discloses
a method for using deep-IR light for imaging through blood is U.S.
Pat. No. 6,178,346. The use of deep-IR wavelengths to achieve
visibility in a blood medium as described in the referred patent
requires very high-energy illumination, which has risks and
disadvantages when used inside the body. The use of near-IR
radiation substantially diminishes risks. U.S. Pat. No. 4,953,539
discusses the use of an endoscopic imaging device, which is
illuminated from outside the body with infrared light. The referred
patent serves as an example of the use of infrared light in imaging
body organs. External illumination has not been used to date for
intra-vascular imaging.
[0010] A well-known property of human tissue is that it has
different absorption, scattering, and attenuation coefficients of
IR radiation. This fact allows different types of tissues to be
distinguished in general, and allows different types of plaque to
be to be distinguished in particular. Reference is made to "A
Review of the Optical Properties of Biological Tissues" Cheong,
Prahl and Welch, IEEE J. of Quantum Electronics, Vol 26 No 12
December 1990.
SUMMARY OF THE INVENTION
[0011] According to a first aspect of the present invention there
is thus provided an invasive imaging apparatus comprising;
[0012] i. A flexible catheter with a proximal end and a distal end,
said distal end being shaped for insertion into a blood vessel
along a guide wire thereby to reach remote places in the
vasculature or other organs.
[0013] ii. An optical assembly positioned at the distal end of said
catheter comprising an image sensor positioned non-perpendicularly
to the longitudinal axis of said catheter.
[0014] iii. At least one illumination source for illuminating an
immediate region beyond the distal end of said catheter.
[0015] iv. At least one working channel running from the proximal
to the distal end of said catheter.
[0016] Preferably said illumination source utilizes at least one
wavelength taken from within a range comprising visible light, near
infra-red, and infra-red light.
[0017] A preferred embodiment comprises a plurality of illumination
sources and said illumination sources are controlled together.
[0018] A preferred embodiment comprises a plurality of illumination
sources and said illumination sources are controlled
separately.
[0019] Preferably said illumination source uses at least one
wavelength preselected to improve visibility through blood.
[0020] Preferably said illumination source is comprised of an
infra-red illumination source positionable outside of said
patient's body.
[0021] Preferably said illumination source is controllable to be
aimed directly at an imaged object from the direction of said
imaging assembly.
[0022] Preferably said illumination source is controllable to be
directed in a general viewing direction.
[0023] Preferably said optical assembly comprises optical
components and an imaging assembly.
[0024] Preferably said imaging assembly comprises said image sensor
and an illumination sensor.
[0025] Preferably said optical components comprise a lens with two
optical planes, a shutter, and a light deflector.
[0026] Preferably said light deflector is one of a prism and a
mirror with a reflecting surface.
[0027] Preferably said image sensor and said illumination sensor
are operable to sense at least one wavelength taken from within a
range from visible light to infra-red light to correspond to said
illumination source.
[0028] Preferably a polarized filter is positionable before at
least one of a member of a group comprising said illumination
sensor, said image sensor, said illumination sources, and said
lens, and said polarized filter polarization direction is
controllable to enhance image quality.
[0029] A preferred embodiment comprises a central control and
display unit connectable to the proximal end of said catheter from
outside of the patient's body.
[0030] Preferably said working channel comprises a guide wire.
[0031] Preferably said working channel is usable for controllably
passing through fluid to said distal end of catheter.
[0032] Preferably said image sensor is positioned substantially
parallel to the longitudinal axis of said catheter.
[0033] Preferably said image sensor is shaped to fit within
restricted dimensions of said catheter.
[0034] Preferably said image sensor is a CMOS or CCD-based pixel
sensor.
[0035] Preferably said image sensor comprises an imaging area
shaped in a rectangular pixel array.
[0036] Preferably said rectangular pixel array measures
128.times.256 pixels.
[0037] Preferably said sensor comprises sensor control electronic
circuitry located beneath a shorter side of said imaging area, said
imaging area being arranged as a rectangular pixel array.
[0038] Preferably I/O and supply pads for said electronic circuitry
are placed along at least one of the shorter sides of said image
sensor.
[0039] A preferred embodiment with a local controller located at
the distal end of said catheter to coordinate data flow to and from
said optical assembly and to perform commands received from said
central control and display unit.
[0040] Preferably said display and control unit is operable to
control the timing and amount of injection of said fluid.
[0041] Preferably a transparent balloon-like structure is
positioned at said distal end of said catheter to displace blood
from around the optical sensor-head, allowing clear visibility.
[0042] Preferably said balloon-like structure is rigid
[0043] Preferably said balloon-like structure is flexible.
[0044] Preferably said balloon-like structure is inflated and
deflated by means of using a liquid or a gas passed through said
working channel.
[0045] Preferably said optical assembly comprises two image sensors
for obtaining a stereoscopic image.
[0046] Preferably the injection of said fluid is synchronized with
the operation of said optical assembly, synchronizing said
operation and said injection with the cycle of patient
physiological conditions.
[0047] Preferably one of said physiological conditions is heart
beat sensible using a heart rate sensor (such as a plethysmograph,
or other device) connectable to a patient's body from outside of
said patient's body or insertable into said blood vessel through
said catheter.
[0048] Preferably information from said heart rate sensor is
transferred to said central control unit enabling synchronization
with said physiological conditions.
[0049] Preferably said balloon-like structure is pressure-sensed to
provide real-time feedback when said balloon-like structure
impinges upon an obstacle, such as a blood vessel wall.
[0050] Preferably said working channel is usable for passage of
therapeutic instruments to a site of operation.
[0051] Preferably said optical assembly is used in conjunction with
a laser cutting device to enable laser operated surgery.
[0052] Preferably said laser cutting device is used to obtain
biopsy biological samples by cutting and transferring through said
working channel to the proximal end of said catheter.
[0053] Preferably said optical assembly and said laser cutting
device are used in conjunction with one of a suction and
nano-gripper mechanisms to enable visual inspection of a desired
location for biological sample retrieval.
[0054] According to a second aspect of the present invention there
is provided an invasive imaging control apparatus comprising:
[0055] i. A flexible catheter with a proximal end and a distal end,
said distal end being shaped for insertion into a blood vessel
along a guide wire thereby to reach remote places in the
vasculature or other organs.
[0056] ii. An optical assembly positioned at the distal end of said
catheter.
[0057] iii. At least one working channel running from the proximal
to the distal end of said catheter.
[0058] iv. A control unit for regulating the opacity level of blood
in said blood vessel around said distal end of said catheter,
controllably injecting quantities of fluid into said blood vessel
in the vicinity of said optical assembly, thereby enhancing
visibility.
[0059] Preferably said optical assembly comprises an illumination
sensor operable to sense at least one wavelength taken from within
a range from visible light to infra-red light.
[0060] Preferably said working channel is usable for controllably
passing through fluid to said distal end of catheter.
[0061] Preferably said control unit is connectable to the proximal
end of said catheter from outside of the patient's body.
[0062] Preferably said control unit is operable to control the
timing and amount of injection of said fluid.
[0063] Preferably the injection of said fluid is synchronized with
the operation of said optical assembly, synchronizing said
operation and said injection with the cycle of patient
physiological conditions.
[0064] Preferably said fluid is insertable into the immediate
region of said distal end of said catheter to change the optical
characteristics of blood in said immediate region.
[0065] Preferably said fluid comprises one or more fluids selected
to modify the optical characteristics of blood plasma to render
said optical characteristics to be as close as possible to those of
red blood cells.
[0066] Preferably said physiological condition is heart beat
sensible using a heart rate sensor (such as a plethysmograph, or
other device) connectable to a patient's body from outside of said
patient's body or insertable into said blood vessel through said
catheter.
[0067] Preferably information from said heart rate sensor is
transferred to said central control unit enabling synchronization
with said physiological conditions.
[0068] According to a third aspect of the present invention there
is provided an invasive imaging control apparatus comprising:
[0069] i. A flexible catheter with a proximal end and a distal end,
said distal end being shaped for insertion into a blood vessel
along a guide wire thereby to reach remote places in the
vasculature or other organs.
[0070] ii. An optical assembly positioned at the distal end of said
catheter.
[0071] iii. At least one working channel running from the proximal
to the distal end of said catheter
[0072] iv. A semi-permeable membrane positioned at said distal end
of said catheter, surrounding said optical assembly extendable to
displace blood from around the optical assembly allowing clear
visibility.
[0073] Preferably said membrane is rigid.
[0074] Alternatively, said membrane is flexible.
[0075] Preferably said membrane is inflated and deflated by means
of controllably passing a fluid through said working channel to
said distal end of catheter.
[0076] A preferred embodiment has a control unit connectable to the
proximal end of said catheter from outside of the patient's
body.
[0077] Preferably the injection of said fluid is synchronized with
the operation of said optical assembly, synchronizing said
operation and said injection with the cycle of patient
physiological conditions.
[0078] Preferably one of said physiological conditions is heart
beat sensible using a heart rate sensor (such as a plethysmograph,
or other device) connectable to a patient's body from outside of
said patient's body or insertable into said blood vessel through
said catheter.
[0079] Preferably information from said heart rate sensor is
transferred to said central control unit enabling synchronization
with said physiological conditions.
[0080] According to a fourth aspect of the present invention there
is provided a method for performing biopsies and other diagnostic
or therapeutic procedures comprising placing an invasive optical
assembly apparatus on the distal end of a needle, inserting said
optical assembly and needle into vasculature or other organs, and
using said optical assembly to provide visual feedback of said
biopsies and diagnostic or therapeutic procedures.
[0081] According to a fifth aspect of the present invention there
is provided a method for viewing through blood in Situ comprising
injecting a controlled amount of fluid into blood in the immediate
region in front of an invasive optical assembly, temporarily
changing the optical characteristics of the blood in said immediate
region, and thereby improving visibility through said blood.
[0082] According to a sixth aspect of the present invention there
is provided a method for viewing through blood in Situ comprising
injecting a controlled amount of fluid into blood in the immediate
region in front of an invasive optical assembly, temporarily
changing the reflectance of the liquid portion of said blood, and
improving visibility through said blood.
[0083] Preferably said fluid is used to change the optical
characteristics of blood in Situ to facilitate imaging through said
blood, said fluid being a physiological fluid, such as saline, or a
hypoosmolar fluid, such as 0.45% saline or 1/6 saline.
[0084] Preferably said fluid for use in changing the optical
properties of blood in Situ to facilitate imaging through said
blood, said fluid being a blood substitute which does not contain
red blood cells and has homogenous optical characteristics.
[0085] Preferably said fluid is chosen to enable illumination to
facilitate imaging through said blood and the environment in Situ
with an IR illumination source, enabling a frequency shift so that
a visible light sensor can be effectively used.
[0086] Preferably said fluid is chosen to be oxygen carrying, such
as a blood substitute, to reduce the risk of hypoxia to the heart
muscle.
[0087] According to a seventh aspect of the present invention there
is provided a method for reconstructing images by interpolating
image data along at least one of the longitudinal and axial axes of
a flexible catheter with a distal end inserted into a blood vessel
and thereby reaching remote places in the vasculature or other
organs, based on image data from both said longitudinal and axial
axes, comprising:
[0088] i. off-line image training initialization, and;
[0089] ii. real-time image data interpolation.
[0090] Preferrably said off-line image training initialization
comprises:
[0091] i. training image construction;
[0092] ii. reconstruction of a lower resolution new image from said
training image;
[0093] iii. finding edge directions of said lower resolution image,
and;
[0094] iv. training a neural network to obtain a set of
filters.
[0095] Preferably said training image is clipped and rotated to
obtain robust edges in each one of a plurality of directions.
[0096] A preferred embodiment executing local contrast enhancement
following said image data interpolation.
[0097] Preferably said local contrast enhancement comprises:
[0098] i. calculating the average intensity of said real time
image, yielding an intensity image;
[0099] ii. generating a first image by correcting the intensity of
said intensity image;
[0100] iii. calculating a local contrast image;
[0101] iv. generating a second image by enhancing said local
contrast image, and;
[0102] v. summing said first image and said local contrast image to
generate an output image.
[0103] Preferably said first image is produced by modifying the
intensity of said real time image using a lookup table.
[0104] A preferred embodiment comprises generating said second
image by modifying the local contrast of said real time image using
a lookup table.
[0105] Preferably said real-time data interpolation comprises:
[0106] i. finding edge directions of each pixel, and;
[0107] ii. interpolating data using an appropriate direction filter
from a set of direction filters.
[0108] A preferred embodiment comprises generating said set of
direction filters in said off-line image training.
BRIEF DESCRIPTION OF THE DRAWINGS
[0109] For a better understanding of the invention and to show how
the same may be carried into effect, reference will now be made,
purely by way of example, to the accompanying drawings.
[0110] With specific reference now to the drawings in detail, it is
stressed that the particulars shown are by way of example and for
purposes of illustrative discussion of the preferred embodiments of
the present invention only, and are presented in the cause of
providing what is believed to be the most useful and readily
understood description of the principles and conceptual aspects of
the invention. In this regard, no attempt is made to show
structural details of the invention in more detail than is
necessary for a fundamental understanding of the invention, the
description taken with the drawings making apparent to those
skilled in the art how the several forms of the invention may be
embodied in practice. In the accompanying drawings:
[0111] FIG. 1 is a simplified schematic of the overall patient
system.
[0112] FIG. 2A is a simplified schematic of the optical head--side
view.
[0113] FIG. 2B is a simplified schematic of the optical head--top
view.
[0114] FIG. 3 is a system block diagram.
[0115] FIG. 4A is a simplified schematic of the optical array
assembly.
[0116] FIG. 4B is a schematic example configuration of optical
design A.
[0117] FIG. 4C is a schematic example configuration of optical
design B.
[0118] FIG. 5A is a simplified diagram of a configuration with the
optical head inside of a transparent balloon distal to a PTCA/stent
balloon.
[0119] FIG. 5B is a simplified diagram of a configuration with the
optical head adjoining the PTCA/stent balloon.
[0120] FIG. 6 is a schematic representation of the image
sensor.
[0121] FIG. 7 is a block diagram of the post-processing
algorithm.
[0122] FIG. 8 is a simplified schematic of use of an external IR
source.
[0123] FIG. 9 is a simplified schematic of a biological sample
collector.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0124] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
applicable to other embodiments or of being practiced or carried
out in various ways. Also, it is to be understood that the
phraseology and terminology employed herein is for the purpose of
description and should not be regarded as limiting:
[0125] The present embodiments preferably provide a diagnostic and
operative system for use in intra-vascular procedures. They consist
of the following:
[0126] 1. A small-diameter flexible catheter, with a distal end
that can be inserted into the blood vessel or any other internal
cavity along a guide wire and reach remote places in the
vasculature or other organs; and
[0127] 2. A viewing apparatus, which is positioned at the distal
end of the catheter, and consists of a specifically designed image
sensor, a distorting optical assembly and an illumination
source.
[0128] (a) The image sensor is shaped to fit within the restricted
dimensions of the catheter. The image sensor is positioned
non-perpendicularly to the longitudinal axis of the catheter; in a
preferred embodiment parallel to the longitudinal axis of the
catheter. The small width of the imaging area makes it possible to
reduce the diameter of the catheter. The design of the sensor
allows the catheter to contain both the viewing apparatus and a
working channel without a prohibitive increase in catheter
diameter.
[0129] (b) An optical assembly. One preferred embodiment consists
of a lens with two optical planes, a shutter and a prism or mirror
with a reflecting surface. The optical assembly is designed to
distort and deflect the light received from the viewed object to
fit the sensor.
[0130] (c) The light source or sources may be visible light
sources, IR sources or any combination of the light sources in one
embodiment, according to the embodiment's uses. The lighting is
either aimed directly at the imaged object from the direction of
the optical sensor head or directed generally at the scene, i.e.
without directing the light sources straight ahead at the
object.
[0131] 3. One or more working channels, which run along the length
of the catheter, from the proximal end to the distal end, through
which therapeutic instruments can be inserted to the site of their
operation. The working channel is also used for the injection of
liquids or gas, as is described in some of the embodiments. A
channel for a guide wire is necessary, and may be provided as a
dedicated channel for the guide wire only or combined with a an
injection channel.
[0132] 4. A local controller situated at the distal head of the
catheter for coordinating data flow to and from the optical image
sensor head and carrying out commands coming from a central
processing and control unit outside the body regarding, for
example, shutter speed and changing the intensity of the light
sources. The communication between the local controller and the
central unit is conducted through a wire connection or a wireless
connection. The local controller may be an entirely separate
element situated at the distal head of the catheter as described
above, but it also may be a part of the image sensor. Another
option is that some or all of the local controller's functions are
carried out by the central control and display unit described
hereafter.
[0133] 5. A central control and display unit is typically located
on a rack in the operating/catheterization room. This unit
executes, among other tasks, basic reconstruction of the image
including color reconstruction, interface to the user, display of
the video and additional data, manual/automatic control over image
acquisition parameters, and a specific image reconstructing
algorithm for improving resolution and local contrasts based on the
specific design of the sensor.
[0134] The embodiments described are designed for use in both
diagnostic and therapeutic procedures. Therefore, they can be used
on catheters as a viewing device only or as part of a PTCA,
stenting, laser, or any other operative device. Another option for
combining intra-vascular imaging with the diagnostic and operative
devices is by mounting the viewing apparatus at the distal end of a
guide wire. The guide wire is inserted into the artery at the
beginning of a catheterization procedure, and the guide wire guides
the catheters used during the procedure to their proper location.
The positioning of the imaging apparatus on a guide wire makes it
possible to use it in very restricted spaces. Positioning of the
imaging apparatus on the guide wire also allows better navigation
inside the vessel and the replacement of the diagnostic and
operating tools while keeping an insertion path open by means of
the wire.
[0135] Reference is now made to FIG. 1, which is a simplified
schematic of the overall patient-system configuration according to
a first preferred embodiment of the present invention. The
configuration has a processing and control unit 28 comprising,
among others, three functional units: digital video unit 40;
balloon inflation unit 41; and fluid injection unit 42. The
proximal end of the catheter 30 is connected to the processing and
control unit 28. The display unit 50 (typically a monitor) is also
connected to the processing and control unit 28. The catheter 30 is
inserted into the patient 25 with the inflatable balloon 31 located
at the catheter distal end, inside the patient. A heart rate sensor
26 is connected to the patient.
[0136] The heart rate of the patient 25 is monitored either by a
heart rate sensor 26 attached to the patient or by a method
described below to determine the transparency level of the blood.
(Such a measurement can indicate blood pressure changes, and is
correlated to heart activity.) Information about the heart rate is
sent to the processing and control unit 28. The processing and
control unit receives the information, processes it and
synchronizes the system's operation with the heart rate. The
catheter 30 is connected to the processing and control unit through
three channels: digital video 40, balloon inflation 41 (for
inflating and deflating the inflatable balloon 31 located at the
distal end of the catheter 30, located inside the patient) and
fluid injection 42 (used to inject fluids to alter the optical
quality of the blood in the immediate vicinity of the inflatable
balloon 31).
[0137] Reference is now made to FIGS. 2A and 2B which are schematic
details of a side view and a top view, respectively, of the optical
head, located on the distal end of the catheter 30. The optical
head comprises a lens 2 and an optical array, comprising a prism
10, and a sensor array, comprising an illumination sensor 1 and an
image sensor 8 (for acquiring images). The illumination sensor 1
and image sensor 8 may be separate elements or they may be combined
together. One or more illumination sources 3, which may use visible
or infrared or both types of light, are positioned at the distal
end of the optical head. A pressure sensor 7 is also positioned at
the distal end of the optical head. A variable volume transparent
balloon 6 encloses all components on the distal end. A mechanical
enclosure houses the previously mentioned components and serves as
the proximal surface of the variable volume transparent balloon 6.
Working channel A 4, representing one or more such channels, runs
along the catheter 30 and terminates at the distal end inside of
the variable volume transparent balloon 6. Working channel B 9,
representing one or more such channels, runs along the catheter 30
and terminates distally outside of the variable volume transparent
balloon. A cable 5 runs along the catheter 30 and connects with the
local controller 11 and provides power and communications for the
optical head.
[0138] The illumination sources 3 in the present embodiment
illuminate the region immediately in front of the optical head. DC
power and electrical signals are fed to and from the optical head
via the cable 5 which is connected at the distal end to the local
controller 11. Working channels (in this example, two) provide
fluid feed and removal and/or other functions inside and outside of
the variable volume transparent balloon 6.
[0139] The variable volume transparent balloon 6 enables short
period imaging of a blood vessel (for example) using the visible
and/or infrared illumination sources 3. The variable volume
transparent balloon pressure is sensed and controlled by the
pressure sensor 7 to inflate/deflate the balloon via air or liquid
provided through working channel A 4. The system has a fixed
optical mechanism comprised of a lens 2 and a prism 10. The
variable volume transparent balloon 6 has known optical attributes
and it enables close contact with the blood vessel wall. Inflation
of the variable volume transparent balloon 6 enables a clear path
for the visible or infrared light directly onto the lens 2. When
deflated, the variable volume transparent balloon 6 allows an
undisturbed flow of blood until the moment before an image is
acquired, whereupon the variable volume transparent balloon 6 is
inflated again. At the time of variable volume transparent balloon
6 inflation, blood flow is momentarily disturbed to enable a clear
view. A safety mechanism, comprising a pressure sensor 7 ensures
that pressure within the balloon is maintained at acceptable
limits. The combination of the pressure sensor 7 and the momentary
pressure supply provide and indication of a possible obstacle in
the path of the catheter. A local controller 11 coordinates data
flow to and from the optical head, as is described in more detail
below.
[0140] Reference is now made to FIG. 3, which is a system block
diagram. FIG. 3 highlights the logic in and between the optical
head 20, as detailed in FIGS. 2A and 2B, with the processing and
control unit 28, as described in FIG. 1. The functions of the
optical head 20 are grouped logically in FIG. 3. The local
processor 11 serves to control the functions of the optical head 20
while coordinating signals and power with the processing and
control unit 28 located in the operating room. Functions of the
optical head 20 are the illumination source 3 (commanded by the
local processor 11), light sensor 8 (which feeds back to the local
processor 11), image sensor 1 (which feeds back to the local
processor 11), and shutter 12 (commanded by the local processor
11). The local processor 11 receives and sends commands and
receives power from the video control and command unit 40 and power
and data control command unit 13, both of which are located in the
processing and control unit 28. The video control and command unit
40 and power and data control command unit 13 together form the
core of command and control of the entire system. Additional
functions are: supply controller 14 (power supply to power and data
control 13), data acquisition and control system 15 (commanded by
power and data control unit 13), and the fluid and air pressure
controller 41 (commanded by power and data control unit 13). The
fluid and air pressure controller 41 operates through working
channel A 4, which physically passes through the optical head to
enable balloon inflation. In addition, the fluid and air pressure
control 41 commands the physiological fluid control source 42. The
suction mechanism 19 and laser source 18 all function through
working channel B 9, which runs along the catheter but parallel and
external to the optical head. The suction mechanism 19 and laser
source 18 are devices that may be employed in an embodiment
described below.
[0141] The local processor 11 controls and coordinates functioning
of components previously described on the optical head with the
system control and supply functions located in the operating room.
Specific functions of the power and data control unit 13 include,
timing control of the system fimctions such as timing of balloon
inflation, fluid infusion/injection, activation of light sources 3,
and image sensor 1 activation. The video control and command unit
40 receives digital image information from the image sensor 1.
Corrections of optical distortion created by the image sensor 1
taking into account the system overall design, are controlled by
the video control and command unit 40. Other functions controlled
by the video control and command unit 40 are:
[0142] 1. Improvement of image resolution based on redundant
information residing in the system, intended specifically for
improving image resolution.
[0143] 2. Improvement of image quality and image adjustment for the
specific medical application, for example: color, local contrasts,
and emphasis on pathologies.
[0144] 3. Evaluation of relative temperature based on video
information for spotting pathologic areas suspected as
inflamed.
[0145] 4. Evaluation of the blurring parameters of the image based
on the blurring model of the blood and the acquired image.
[0146] 5. Reconstruction of the original image according to the
blurring model and evaluated parameters.
[0147] Images processed by the video control and command unit 40
may be displayed, typically on the previously mentioned monitor, as
video images in one of two display modalities. The first modality
is a succession of separate images as received by the image sensor
1. This modality requires a minimal delay. The second modality is a
stream of video images. In order to enable a stream of video images
the processing and control unit 28 performs a time interpolation of
missing images to provide a continuous image. As a result, a delay
of up to a second between image acquisition and display is
typical.
[0148] Reference is now made to FIG. 4A, which shows a schematic of
the optical array assembly. The optical array assembly 48 is
comprised of a lens 2 which is located in front of the shutter 12,
which is in turn mounted before the prism 22. The prism is
positioned above the image sensor 1. One preferred embodiment
consists of a lens 2 with two optical planes, a shutter 12 and a
prism 22 or mirror with a reflecting surface. The optical array
assembly 48 is designed to distort and deflect light received from
the viewed object to fit the image sensor 1. The lens 2 and prism
22 are two fixed optical components whereas the shutter 12 offers
flexibility. The shutter 12, as previously mentioned, is commanded
by the processing and control unit, located outside of the patient
at the proximal end of the catheter in the operating room.
Schematic descriptions of two optical design alternatives are
depicted on FIGS. 4B and 4C. In FIG. 4B PMMA refers to a specific
plastic lens material called polymethyl methacrylate.
[0149] Reference is now made to FIGS. 5A and 5B, which show related
embodiments where a fluid is used to inflate the flexible PTCA or
stenting catheter balloon at the distal end of the catheter. FIG.
5A shows an embodiment where an optical head 47 is located distally
to the PTCA/stent balloon 50. The stent balloon 50 is located
distally to the catheter 30. The optical head 47 is located within
a second balloon 60. A regulating valve 55 is located between the
PTCA/stent balloon 50 and the second balloon 60. Inflation of the
second balloon 60 is enabled by the regulating valve 55, which
allows the second balloon 60 to be initially inflated, followed by
inflation of the stent balloon 50. Note that the optical head shown
in FIG. 5A is similar to the optical head previously shown in FIG.
2, in that the functions of on-board multiple light sources, on
board light receivers, and an on board pressure sensor are
preferably included. The regulating valve 55 is designed to close
itself under high pressure and enables the inflation of the
PTCA/stent balloon 50. Once the second balloon 60 is inflated and
the pressure inside is high enough, the valve closes and the
PTCA/stent balloon 50 inflates. The injected fluid inflates the
second balloon 60, made of a transparent membrane which is
non-permeable to red blood cells, to remove the red blood cells
from the field of view and reduce the scattering of light. The
optical characteristics of the injection fluid are discussed
hereafter. The regulating valve 55 also controls deflation of both
the PTCA/stent balloon 50 and the second balloon 60.
[0150] FIG. 5B shows an embodiment where the optical head 48 is
installed distally and exterior to the PTCA/stent balloon 50. The
optical head assembly 48 is mounted on the fluid injection channel
75, which terminates in a regulating valve 56, located at the
distal end of the fluid injection channel 75. The PTCA/stent
balloon 50 is located at the distal end of the catheter. Note that
the optical head assembly 48 shown in FIG. 5B is similar to the
optical head previously shown in FIG. 2 in that the functions of
on-board multiple light sources and on board light receiver are
preferably included. In the present embodiment, a regulating valve
56 located distally to the PTCA/stent balloon 50 controls the flow
of injected fluid distally outside of the PTCA/stent balloon 50 to
momentarily clear the field of view in front of the optical
assembly and allow images to be acquired.
[0151] The embodiments shown in FIGS. 5A and 5B operate in a
cyclical manner. Every heartbeat sensed by the previously mentioned
heart rate sensor, initiates a new device cycle. Each cycle
comprises a delay after which fluid is injected in order to inflate
the second balloon 60 as in FIG. 5A or clear the field of view as
in FIG. 5B. Inflation of the second balloon 60 and fluid injection
are synchronized and timed so that they occur after a pulse of
blood which is pushed from the heart. The regulating valve 56 is
opened and fluid is infused into the artery to improve the
visibility at the distal end of the catheter. A short period after
the start of fluid infusion, the optical head assembly 48 starts
acquiring images of the scene. The previously-mentioned light
sources are powered in synchronized pulses with the frame rate of
the optical head assembly 48 to increase the ratio between the
effective light absorbed by the optical head assembly 48 and power
dissipation of the light source. After obtaining several images and
in synchronization with the beginning of the next heart beat, the
system stops both image acquisition and infusion of fluid and
reduces the pressure inside the second balloon 60.
[0152] The embodiments shown in FIGS. 5A and 5B are not
space-consuming because one channel is used for inflating both
balloons (FIG. 5A) or for inflating and injecting fluid into the
blood vessel (FIG. 5B), thus allowing a smaller width catheter.
[0153] Reference is now made to FIG. 6, which is a simplified
diagram showing an image sensor 70. The sensor comprises an imaging
area 71 which is shaped as a rectangle pixel area, such as a
128.times.256 pixel array. The sensor may also contain additional
circuitry 72 that performs functions such as analog to digital
conversion, timing control, and local control. I/O. Supply pads 73
are indicated. The sensor 70 is located in the optical head
assembly previously noted in FIGS. 2, 3, and 4A, 4B, and 4C. The
sensor 70 serves to capture the visible or IR light from the scene
as shaped by the lenses and shutters located in front of it. As
previously noted, the sensor is positioned non-perpendicularly to
the longitudinal axis of the catheter. In a preferred embodiment it
is placed parallel to that axis. The small width of the imaging
area makes it possible to reduce the diameter of the catheter.
[0154] Reference is now made to FIG. 7. FIG. 7 is a simplified
block diagram describing a post-processing algorithm, which
reconstructs the displayed image based on a training sequence and a
real time image, once an image has been received by the central
control and display unit. The central control and display unit is
preferably located in the operating room, and it receives images
from the image sensor, preferably located at the distal end of the
catheter, preferably located in a blood vessel.
[0155] The initialization and training sequence 301 takes place as
a one-time off-line process. The aim of this sequence is to
determine the optimal set of filters for reconstructing the
real-time image. The sequence begins by construction of a training
image, followed by clipping and rotating the image to obtain robust
edges in all directions 302. For illustration purposes the training
image size may be N by N pixels. Then, pre input image conversion
303 takes place involving construction of a new image from the
training frame in order to obtain an input to a neural network. The
input image size selected for this case is N/2 by N pixels, but the
algorithm works with other image sizes. Input image conversion 303
is then performed by finding the edge direction 304 at each pixel
of the input according to neighborhood decision vote, followed by
training the neural network 305 to obtain a set of filters. The
training process is performed on the intensity image (a black and
white gray level image). The result at this point is a set of
filters (weights) to be used on the real-time sequence.
[0156] Real-time execution begins with step 306, when a new image
is received 307. If there are no more images, execution is
completed 317. If a new image is received, the next step is to find
the direction for each pixel 308 in the intensity input image
according to the neighborhood decision vote. The neural networks'
filters are then run 309, in accordance with the directions for
each color plane, which is performed separately. If contrast
enhancement is necessary 310, a series of steps are performed, as
noted below. If contrast enhancement is not necessary, a new image
is received 307.
[0157] The first step of contrast enhancement is to perform image
segmentation 311 based on local average intensity. The following
steps are performed: calculate average intensity 312, taking into
account only neighbors with relatively close values, and; correct
average intensity 313 using look up tables (LUT) which optimizes
the dynamic range of the system (camera and display device). In
parallel to the two previous steps, the following are performed:
calculate local image contrast 314 and; enhance local contrast 315.
The enhancement function is a function of the average intensity and
the local contrast and it is done by means of LUT. Generation of
the final image 316 utilizes the previous steps of contrast and
intensity enhancement, summing the local contrast and the average
intensity. At this point, a new image is received 307. This logic
continues until there are no new images and the algorithm ends
317.
Methods for Imaging in the Presence of Opaque Liquids
[0158] The following are various preferred embodiments for
different methods and applications designed to achieve visibility
through a medium of an opaque liquid, preferably, in blood. It is
important to emphasize that the various embodiments described below
can be used either separately as stand-alone systems or in any
combination with each other.
[0159] 1. Lighting with Near-IR Wavelengths:
[0160] There are three properties of light that effect the
visibility of light with a specific wavelength passing through a
medium: scattering, absorption, and attenuation. Scattering is
significant in both near-IR and visible light when passing through
blood. Absorption and attenuation, on the other hand, are minimal
in near-IR radiation. Therefore, near-IR light may be advantageous
when compared to visible light for effective illumination through
such a medium as blood. In the following text, it should be noted
that wherever IR is mentioned, near-IR (radiation with wavelengths
shorter than 1 .mu.m) is preferably used, unless specified
otherwise.
[0161] The fact that IR light absorption is minimal in a blood
medium means that IR light may be used in a viewing apparatus
designed for intra-vascular imaging in combination with other
methods mentioned in the present disclosure. The apparatus and
method in the present embodiment includes a flexible catheter with
a viewing apparatus at its distal end, a working channel running
from the proximal to the distal end, and a local controller at the
distal end. The previously mentioned imaging sensing apparatus is
applicable to the present embodiment. The apparatus consists of one
or more light sources which emit IR light, an image sensor that is
able to receive this light, and an optical assembly. The image
sensor is preferably a CMOS or CCD pixilated sensor. In order to
allow acquisition of IR images, the sensor may use filters that
have band passes at IR wavelengths. Silicon-based devices (CMOS,
CCD) exhibit a reasonably good response to IR wavelengths of up to
1 .mu.m.
[0162] The light sources may also include a combination of
wavelengths of visible and IR light, requiring appropriate sensors
to receive multiple light wavelengths. Illuminating the scene with
multiple wavelength light sources enables acquisition of several
types of pictures for diagnostic purposes.
[0163] IR light can be used in another diagnostic embodiment,
considering the fact that in general, different human tissues and
different substances have different absorption, scattering, and
attenuation coefficients in the IR region. The present embodiments
can include an analyzing apparatus for the analysis of these
coefficients. Evaluation of blood status (for example, sugar level
in the blood may be analyzed by evaluating the IR light absorption)
may be one of the applications of the present embodiment. Several
pathologies in the vessel tissue may be analyzed in the same
way.
[0164] Another embodiment uses external IR illumination. Reference
is made to FIG. 8. The optical assembly 80 is located at the distal
end of the catheter 30 within the patient's body 85, preferably in
a blood vessel. An exterior IR light source 88 exterior to the
patient's body illuminates the field of view in front of the
optical assembly. Note that the optical head assembly 80 shown in
FIG. 8 is similar to the optical head assembly 80 previously shown
in FIG. 2 in that the function of on-light receiver is preferably
included. However, in the present embodiment, the light source is
not on board the optical head assembly 80, rather it is exterior to
the patient.
[0165] 2. Changing the Optical Properties of Blood
[0166] Another method and embodiment make use of light sources
utilizing visible light or IR radiation. Blood is opaque in visible
light illumination because blood contains suspended cells. This
phenomenon is much like that encountered with water vapor drops in
fog; even though the content of the red blood cells is transparent,
when the content of red blood cells is arranged in "drops"
surrounded by a membrane, the reflectance factor of the solution
yields an opaque situation. Therefore, in order to obtain a clear
vision of the field of view, blood may be temporarily diluted at
the site of an object to be imaged.
[0167] The injection fluid is not necessarily a physiological
fluid. One possible embodiment uses a fluid with a reflectance
factor identical or similar to the reflectance rotcaf of red blood
cells, or a fluid that creates such a reflectance factor when mixed
in a certain concentration with blood. This type of fluid solves
the problem of light scattering in blood, leaving only a light
absorption problem, which is much simpler to solve. The present
embodiment includes a flexible catheter, a viewing apparatus and a
local controller at the distal end and a working channel, through
which the fluid may be injected from the proximal end into the
blood vessel or injected directly into the vessel. Another option
is to inject the fluid through the guide wire channel. The amount
of injected fluid is controlled centrally by a processing device,
and is determined according to the transparency level of the blood,
measured by the reflection of illumination from the light source
onto the light sensor as previously described, or according to a
sensor connected to the patient outside of the patient's body. Such
a light measurement may supply the timing to inject the
physiological fluid into the vessel. In another application, the
reflected light measurement may provide for analysis of blood
pressure changes by measuring the amplitude of the light reflected
into the sensor, according to the level of heart activity. There is
a correlation between the amplitude of light received by the sensor
and blood pressure.
[0168] Variations in the amount and timing of fluid injection may
be determined by a quality control algorithm, which may be able to
calculate necessary changes to lighting or fluid injection from the
received image to improve image quality.
[0169] A further embodiment of the present invention uses either a
fluid with a physiological concentration of particles or a fluid
with less than a physiological concentration of particles, such as
1/6 saline. The latter type of fluid can cause hemolysis of some of
the red blood cells, thus improving the reflectance factor of the
liquid, and reducing the above-mentioned phenomenon of light
scattering in blood. Another embodiment uses a fluid that is
capable of carrying oxygen, such as a blood substitute, thus
reducing the risk of hypoxia to the heart muscle; this compared to
injecting a fluid not capable of carrying oxygen to body tissues
into the artery.
[0170] Yet another embodiment uses a fluid that enables a frequency
conversion of light, i.e. from IR wavelengths to the visible light
spectrum, thus making it possible to use a visible light optical
sensor and nevertheless retaining the advantages of illuminating
with IR light.
[0171] 3. Transparent Structure at the Distal End
[0172] The present embodiment also makes use of light sources in
the visible light or IR wavelengths. There is a need to displace
the blood in order to clear the field of view. This embodiment uses
a transparent dome or balloon, either rigid or flexible. The
structure is positioned at the distal end of the catheter, beyond
the viewing apparatus. In one form of the embodiment previously
described and referred to in FIGS. 5A and 5B, the structure at the
distal end is a flexible balloon, which inflates by injecting a
transparent fluid or gas into it. It is positioned at the distal
end of the catheter at its deflated mode. The injection is
preferably, centrally controlled and the fluid or gas may be
injected to inflate the balloon whenever the viewing apparatus is
activated. When inflated, the balloon displaces the blood from the
field of view, as does the dome described above. In another form of
the embodiment, the structure is a rigid dome, which is positioned
around and at the edge of the distal end and extends distally to
it. The rigid structure is situated so that it removes the blood
from around the viewing apparatus, thus clearing the field of view
between the dome and the apparatus without blocking the flow of
blood in the artery. The rigid structure is either hollow (vacuum,
gas) or filled with a transparent fluid.
[0173] 4. Polarized Light Filter
[0174] Light that impinges on a surface has a component that
returns polarized. Reflected light is more polarized when the
incidence angle is closer to normal. In an intra-vascular
surrounding, light hitting the wall and/or any structures connected
to it returns mostly polarized, while the light hitting suspended
cells in the fluid filling the vessel does not return polarized.
Imaged objects are usually surfaces connected to the vessel's wall.
As a result, by situating a polarized light filter before the
optical assembly, light reaching the sensor may be only polarized
light, i.e. the light reflected from the imaged structure. This
method of using polarized light increases the image/noise ratio and
improves the quality of the received image.
Other Possible System Embodiments
[0175] In addition to the embodiments previously discussed, the
following represent four other possible embodiments, related to
previously described embodiments:
[0176] 1. An optical sensor head with two sensors for obtaining a
stereoscopic image.
[0177] 2. A distal balloon made of a transparent membrane blocking
the passage of red blood cells but allowing the passage of fluids.
In the present embodiment, the injected fluid can also be used for
the inflation of the distal balloon membrane.
[0178] 3. Laser operated surgery mechanism using service channel
and local imaging device(s). This embodiment enables an accurate
operation procedure with continuous imaging of the operation
area.
[0179] 4. Mounting the viewing apparatus close to the front end of
a needle for performing biopsies and other diagnostic or
therapeutic procedures.
[0180] 5. Another embodiment is that of biopsy and sample
retrieval.
[0181] Reference is made to FIG. 9. Working channel B 9 is used to
pass either or both the suction and nano-gripper 98 and the laser
device 98 distally, in front of the optical head 90. Biological
sample collection, using a suction/nano-gripper 99 mechanism and
the optical head 90 to enable visual inspection of the desired
location.
[0182] Samples may be transferred through the working channel B 9
outside the patient's body for analysis. The suction/nano-gripper
99 is used to hold a sample in position and the laser apparatus is
used to cut the sample from surrounding tissue. The optical head 90
is similar to the previously mentioned optical head configuration.
The suction/nano-gripper 99 and laser device 98 can alternately or
together be positioned in front of the optical head 90 to provide
visual feedback. This process enables biopsy of samples which can
be removed from the patient's body through working channel B 9.
[0183] The application in the field of cardiovascular therapy is
only one of the possible applications for the present invention.
Minimally invasive surgery is applied in many fields of medical
diagnosis and therapy, such as in other vascular, breast, urethral
and renal, and abdominal procedures, for example, and the present
invention may be applied in these fields.
[0184] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable sub
combination.
[0185] It will be appreciated by persons skilled in the art that
the present invention is not limited to what has been particularly
shown and described hereinabove. Rather the scope of the present
invention is defined by the appended claims and includes both
combinations and sub combinations of the various features described
hereinabove as well as variations and modifications thereof which
would occur to persons skilled in the art upon reading the
foregoing description.
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