U.S. patent application number 10/350897 was filed with the patent office on 2003-09-11 for parametric imaging ultrasound catheter.
Invention is credited to Seward, James B..
Application Number | 20030171667 10/350897 |
Document ID | / |
Family ID | 26825256 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030171667 |
Kind Code |
A1 |
Seward, James B. |
September 11, 2003 |
Parametric imaging ultrasound catheter
Abstract
A parametric imaging ultrasound catheter apparatus is capable of
obtaining parametric images of the surrounding insonated
environment. Parametric imaging is defined as the imaging of
quantifiable "parameters" which of visible two-, three-,
fourth-dimensional or non-visible higher-dimensional temporal
physiologic events. Visible motion is a fourth-dimensional event
and includes surrogate features of cardiac muscle contraction, wall
motion, valve leaflet motion, etc. Non-visible motion is a
higher-dimensional event and includes slow non-visible events
(i.e., remodeling, transformation, aging, healing, etc.) or fast
non-visible events (i.e., heat, electricity, strain, compliance,
perfusion, etc.). An ultrasound catheter with parametric imaging
capability can obtain dynamic digital or digitized information from
the surrounding environment and display information features or
quanta as a static or dynamic geometric figures from which discrete
or gross quantifiable information can be obtained. A quantifiable
geometric image or parametric information may have little
resemblance or dependence on the fundamental ultrasound image.
Parametric ultrasound information may be used as a surrogate for
common visible or non-visible events such as electrical
depolarization of the heart, perfusion, myocardial injury, etc.
Inventors: |
Seward, James B.;
(Rochester, MN) |
Correspondence
Address: |
Attention of Alan R. Stewart
MERCHANT & GOULD P.C.
P.O. Box 2903
Minneapolis
MN
55402-0903
US
|
Family ID: |
26825256 |
Appl. No.: |
10/350897 |
Filed: |
January 24, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10350897 |
Jan 24, 2003 |
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10092355 |
Mar 5, 2002 |
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6544187 |
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10092355 |
Mar 5, 2002 |
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09421712 |
Oct 20, 1999 |
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6398736 |
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60127017 |
Mar 31, 1999 |
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Current U.S.
Class: |
600/407 ;
600/437; 600/462; 600/467 |
Current CPC
Class: |
A61B 8/4461 20130101;
A61B 8/445 20130101; A61B 8/14 20130101; Y10S 128/916 20130101 |
Class at
Publication: |
600/407 ;
600/437; 600/462; 600/467 |
International
Class: |
A61B 005/05; A61B
008/00 |
Claims
What is claimed is as follows:
1. A method of modeling physiological phenomena comprising the
steps of: providing a body within which a biological event is
occurring collecting a dataset including a plurality of data items,
each data item including at least one measurement of a biological
feature related to the event and a time stamp; compiling a subset
of data items including measurements of the same biological feature
at substantially the same time; parameterizing the data items
within the subset; and generating a surrogate image of the event
from the parameterized data subset.
2. The method of claim 1, wherein the dataset items include a
plurality of measurements of biological features and a plurality of
data subsets are compiled relating to measurements of the
biological feature taken at substantially the same time.
3. The method of claim 1, wherein the dataset items include
measurements of the biological feature taken at a plurality of time
stamps and a plurality of data subsets are compiled relating to
measurements of the biological feature at different times.
4. The method of claim 1, wherein the measurements within data
items in a subset are of the location of the biological
feature.
5. The method of claim 1, wherein the measurements within data
items in a subset are of the velocity of the biological
feature.
6. The method of claim 1, wherein the measurements within data
items in a subset are of the electrical state of the biological
feature.
7. The method of claim 1, wherein the measurements within data
items in a subset are of the pressure acting upon the biological
feature.
8. The method of claim 1, wherein the measurements within data
items in a subset are of the contractility of the biological
feature.
9. The method of claim 1, wherein the measurements within data
items in a subset are of the metabolism of the biological
feature.
10. The method of claim 1, wherein the measurements within data
items in a subset are of the transformation of the biological
feature.
11. The method of claim 1, wherein data subsets including
measurements regarding different characteristics of the biological
feature are utilized to create a composite surrogate image of the
biological feature.
12. The method of claim 1, wherein data subsets including
measurements regarding the same characteristics of the biological
feature at different times are utilized to create a composite
surrogate image of the biological feature.
13. The method of claim 1, wherein the biological event being
modeled by the surrogate image is a blood flow velocity within a
vessel.
14. The method of claim 1, wherein the biological event being
modeled by the surrogate image is perfusion within the body.
15. The method of claim 1, wherein the biological event being
modeled by the surrogate image is an action of pressure affecting
the biological feature.
16. The method of claim 1, wherein the biological event being
modeled by the surrogate image is a flow of electricity within the
body.
17. The method of claim 1, wherein the biological event being
modeled by the surrogate image is a contraction of a muscle within
the body.
18. The method of claim 1, wherein the surrogate image is in the
form of a geometric solid.
Description
[0001] This application is a Continuation of application Ser. No.
10/092,355, filed on Mar. 5, 2002, which was a continuation of Ser.
No. 09/421,712, filed on Oct. 20, 1999 (now U.S. Pat. No.
6,398,736, issued Jun. 4, 2002), which was filed as provisional
application Serial No. 60/127,017, on Mar. 31, 1999, which
applications are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to a catheter apparatus, more
particularly to an underfluid ultrasound parametric imaging
catheter apparatus.
BACKGROUND OF THE INVENTION
[0003] Medical Ultrasound: In the field of medical ultrasound, one
acquires ever more knowledge of reality by solving problems and
finding better explanations. Medical ultrasound over the past 25
years has evolved to become one of the most commonly performed
imaging and hemodynamic examinations. Modern ultrasound machines
can replicate those features previously obtained by more invasive
means such as, cardiac catheterization. Those features attributable
to invasive technologies at least include: 1) ability to obtain
anatomic images, 2) ability to quantitatively assess function, 3)
ability to measure hemodynamics, and 4) ability to visualize blood
flow (i.e., an angiographic substitute). The advantages of using
ultrasound technology include: 1) non-invasive, 2) no ionizing
radiation (a safe repeatable energy source), 3) comparatively low
cost, 4) obtaining hemodynamics as well as images, 5) technology
capable of being fabricated into different sizes and shapes (e.g.,
ultrasound tipped catheter), 6) rapid temporal and spatial
resolution, and 7) portable, etc.
[0004] Computer Interface: With the incorporation of more
sophisticated computer interfacing, in the later part of the
twentieth century, diagnostic ultrasound has entered into the era
of information acquisition. The prerequisites for this change
include use of newer sophisticated information acquisition and
management techniques, reconstruction or assimilation of multiple
forms of information, segmentation of the pertinent or most
meaningful information, quantitation and display of the result. The
acquired information represents the physiology and structure of the
insonated environment (i.e., tissue, muscle, blood, etc.).
Information acquisition techniques include new Doppler technology,
such as tissue Doppler imaging (TDI) and strain-rate imaging (SRI),
harmonic imaging, pulse-inversion imaging, and pulsed and
intermittent imaging, etc.
[0005] Ultrasound Catheter: A recent innovation in diagnostic
medical ultrasound is the development and introduction of invasive
ultrasound tipped catheters including (U.S. Pat. Nos. 5,325,860,
5,345,940 and 5,713,363 issued to Seward et al.). These catheters
allow one to obtain high-resolution images from within the confines
of fluid filled spaces (i.e., heart, urinary bladder, blood
vessels, etc.). However, these newest catheters have the capacity
not only to obtain an image but in addition also to obtain more
unique physiologic ultrasound information which to date has not
been feasible using a rotating ultrasound element catheter. For
example, full Doppler capabilities are now possible with the
ultrasound catheter and include pulsed and continuous wave Doppler,
color flow Doppler, tissue Doppler, etc. Newer evolving acquisition
technologies include pulse inversion, harmonic imaging, strain-rate
imaging, intermittent imaging, etc.
[0006] New image paradigm: Information can be fractionated into its
small individual digital components, each unit is "parameterized"
(i.e., has quantifiable value), and groups of related units can be
expressed as a volumetric image. Parametric imaging referred herein
is the term applied to the acquisition of various types of
quantifiable events and in the case of ultrasound represents the
display surrogates information representing anatomic, functional,
hemodynamic, or physiologic events. A parameter is defined as a
mathematical quantity or constant whose value varies with the
circumstances. Examples include blood pressure, pulse rate, and an
infinite number of other visible and non-visible events which
permeate our reality. The quantifiable event can be measured and
expressed as a change over time, for example a change in pressure
over time, is most often graphed or charted as a graph (e.g. a
pressure curve) with the magnitude of pressure on the ordinate and
time on the abscissa. However, today a sophisticated imaging device
can record such events throughout a field or volume of interest
(i.e., a volumetric two- or three-dimensional image of the spatial
distribution of the event). Fields of specific individual or group
events can then be displayed as a geometric image as opposed to a
graphic or one-dimensional display of a single continuous
happening. The analogy is being capable of simultaneously measuring
numerous similar or dissimilar individual events and instead of
graphing the result, displaying the phenomena as a dynamic
geometric image (instead of looking at a single bee in a hive, the
action of the whole hive is assessed simultaneously).
[0007] The observed events can occur in a regular or irregular
manner, distribute in a predictable or unpredictable manner, or
remain constant or change randomly, etc. The events are virtually
always continuous or cyclical (repetitive) but can be broken down
into smaller and smaller components, which can be looked upon as
quanta (i.e., elemental units) and displayed in a computer
presentation as quantifiable pixels. It is the elemental unit(s),
which can be pictured as changing over time (i.e., time and
magnitude, such as pressure or temperature). However, the whole
field of units (quanta) is best presented as a distribution of
measurable units dispersed throughout a defined spatial domain (for
example, the distribution of pressure throughout a cavity of the
heart or temperature of the body). A parametric imager enables the
presentation of quantifiable, information as a geometric picture of
a continuous event. The event becomes the image while the
fundamental image or source information becomes subservient or
nonessential. At any moment in a temporal sequence, the event can
be captured as a volume with a specific quantifiable distribution.
However, when it is viewed over time, the event is displayed as a
moving surface, and or volume (i.e., a two-, three-,
fourth-dimensional or higher-dimensional image). Event information
may include point of initiation (epicenter: for example, a very hot
infected ear causing an increase in body temperature), distribution
(epicenter spreading outward), moment to moment change (evolution
or wave front distribution), decay (transient, periodicity, etc.),
and others. In topological language, the point is called a repeller
and the expanding phenomenon an attractor. An attractor, in
general, is a region of space that "attracts" all nearby points as
time passes. To the human senses, the imaged event may be a
normally visible phenomenon such as the contracting wall of the
heart, or a non-visible phenomenon (referred to as
higher-dimensional events) such as the distribution of electricity,
or in the case of ultrasound electricity can be pictured through a
display of a parametric surrogate. The manipulation and display of
data are solved by quantum mathematical concepts. The parametric
image is a geometric image of a quantifiable phenomenon but not a
mere picture of that phenomenon (for example: the motion of muscle
contraction is visible, however, a parametric surrogate of
contraction would be the display of change itself). The parametric
image often does not appear similar to the fundamental event.
[0008] Quantum Mathematics Concept: Generally, all physical
processes are quantum-mechanical. The quantum theory of computation
is an integral part of the fundamental understanding of reality.
Quantum solutions applied to information, displayed as a geometric
image, provide a revolutionary mode of explanation of physical
reality. The human does not accord equal significance to all our
sensory impressions but is known to perceive reality best when
presented as an image. Thus, given the fact that general theories
about nature are best expressed in quantifiable mathematical form
and that geometric images are the most mature expression of a
mathematical computation, it is logical that a parametric image
solution will have considerable acceptance as a pleasing as well as
quantifiable diagnostic imaging solution. As the trend towards
faster, more compact sophisticated computer hardware continues, the
technology must become even more "quantum-mechanical", simply
because quantum-mechanical effects dominate in all sufficiently
small systems. The digital pixel of an image becomes a quantifiable
unit (i.e., quanta) belonging to a family of events having related
or meaningful characteristics. The repertoire of computations
available to all existing computers is essentially the same. They
differ only in their speed, memory capacity, and input-output
devices. However, a "quantum computer" is a machine that uses
uniquely quantum-mechanical effects, especially interference, to
perform wholly new types of computation that would be impossible on
earlier generations of computers. Such computational mathematics is
a distinctively new way of looking and assessing nature. In the
twentieth century, information was added to the evolution of modem
computers, which has allowed complex information processing to be
performed outside the human brain. As one enters into the
twenty-first century, quantum computation is slowly being
introduced which is the next step in the evolution of information
presentation. Observations of ever smaller, subtler effects are
driving ever more momentous conclusions about the nature of
reality. Ever better explanations and predictions can successively
approximate visible or non-visible events, which permeate the
reality.
[0009] Physiological events can be computed as distributions of
quanta (i.e., pixels of measurable information). Today, computers
can provide integrated quantitative answers to certain otherwise
unseen or unappreciated events. Quantum events are initially given
a position and then "spread out" in a random volumetric
distribution. Because of the unpredictability of the volumetric
event, increasing computational resources must be used to measure
and present the information. Quantum solutions are often used to
make probabilistic predictions; however, many of the predictions
can be used to predict a single, definite outcome (example: a
geometric image of electricity or its surrogate, as described
herein, can be used to very accurately localize the anatomic site
of an electrical excitation of the heart muscle). Quantum solutions
of complexity show that there is a lot more happening in the
quantum-mechanical environment than that literally meets the eye.
Quantum phenomena can be highly predictable and can foster the
increasing use of computational solutions for the assessment of
physiologic events.
[0010] Accordingly, there is a need for a computer driven
acquisition device to acquire quantifiable events from today's
state-of-the-art medical ultrasound machines, such as the
ultrasound empowered catheter system as described herein, to
rapidly acquire physiologic information and provide images of
continuously changing volumetric (spatial) information.
SUMMARY OF THE INVENTION
[0011] To overcome the natural limitations in the art described
above, and to overcome other limitations that will become apparent
upon reading and understanding the present specification, the
present invention provides a catheter apparatus for parametric
imaging a visible fourth-dimensional or a non-visible
higher-dimensional events in an underfluid environment.
[0012] Why a catheter--The present invention pertains to an
ultrasound tipped catheter; however, the imaging solution described
in the present invention could apply to any complex computer
manipulation of acquired information. The ultrasound tip catheter
described in the present invention has not accommodated a
parametric solution before. The ultrasound catheters in the present
invention are those capable of rapidly acquiring finite information
presented as quantifiable pixels. The acquisition elements are in
multiples aligned and spaced in a manner to act in concert to
obtain a field of information (i.e., a symphony of events). Capable
ultrasound include linear array, curved array, vector phased array,
phased array, and multi-dimensional arrays. All of these ultrasound
transducers are characterized by having multiple piezoelectric
elements lying closely together and function to insonate a field
and acquire underlying information. The resulting image can be a
flat two-dimensional tomogram or a volumetric three-dimensional
image.
[0013] Why ultrasound--Ultrasound imaging has to date received no
appreciable parametric application. Digital solutions have been
slow to evolve in ultrasound imagery, as opposed to other image
solutions such as radioisotopes, X-ray, or magnetic resonance. The
ultrasound catheter of the present invention is unique and without
comparable technology. The unique image solution of the present
invention is thus applied to an equally unique acquisition device
(the catheter).
[0014] What is parametric imaging and why there is potential for
confusion--The term "parametric imaging" has been used for years to
apply to the general concept of using measurable information to
form an image. In this general definition, one could say that any
picture which has a numerical value to its contents is parametric
(i.e., its component parts are parameterized). This can be further
extrapolated to say that any picture which is digital, such as
computerized tomography (CT), magnetic resonance (MR), isotope
scans, Doppler ultrasound, etc., is parametric because some or all
of the acquired information is expressed as a measurable number.
The present invention herein addresses a unique parametric image
solution and one that requires a higher order computer solution and
is not merely displayed of pixelated digital information.
[0015] Firstly, the whole image is broken down into its smallest
quantifiable components (i.e., pixels, quanta, etc.). Currently,
this exists for CT, MR, isotopes, and Doppler but does not exist
for the remainder of the ultrasound image, x-rays, etc., which is
typically presented as analog pictures.
[0016] Secondly, the digital components (i.e., pixels) are
parameterized and measurable, a feature, which exists with CT, MR,
and isotope images but has only recently been possible with
experimental ultrasound Doppler. The analog components of images
have been "digitized" in an attempt to overcome this second
requirement, however "digitization" significantly narrows the
measurable features. There are numerous historical examples of
digital or digitized information pictures, which can be called
parametric. However, this is not sufficient for the present
invention herein.
[0017] Thirdly, and most importantly for the present invention, the
parameterized pixels are recognized by the computer as having
unique quantifiable features. Each pixel has a unique identifiable
quantity. Pixels with similar features are classified as families,
distributions, or probabilities. Lastly, the classified pixel
features are themselves presented as a geometric picture (i.e., the
Parametric Image Solution pertaining to the present invention).
"Para" refers to a substitute or replacement of reality; "metric"
refers to mathematical, quantifiable; and "image" refers to a
geometric picture (of a mathematically derived surrogate of
reality). The resultant picture may have little similarity to the
image described in the second requirement. A new parametric image
is formed which itself is a picture of selected information. The
selected information is normally imbedded within a fundamental
image. Such a process occurs rapidly to be clinically applied. Very
sophisticated computer solutions are required to handle these very
large digital solutions and carry out the statistical sorting of
pixel features. Such parametric solutions currently exist in some
CT, MR and isotope imaging but are essentially experimental. There
is no mention of this form of parametric solutions in ultrasound
imagery. There is absolutely no mention of such solutions applied
to an underfluid ultrasound catheter.
[0018] What makes the present invention unique--Nature and its
physiologic underpinnings are complex. Complex phenomena
continuously change in a linear or cyclical manner. Breaking such
events down into small components and then expressing complexity as
understandable geometric images are extremely informative. Such
images impart new information. Most importantly, such information
solutions are very reproducible, more accurate than conventional
measuring tools, and are quantifiable. Important prerequisites
include objectivity, reproducibility, quantitation, and
multidimensional display. Although a historically familiar term,
parametric image, is used, the concept disclosed is a new paradigm.
The solution described herein is completely new and has never been
applied to an underfluid ultrasound imaging system. Nor does the
solution of the present invention have any intuitive counterpart in
existing ultrasound or even in related comparable "imaging"
modalities such as magnetic resonance, computerized tomography, or
isotopes.
[0019] The present invention provides an imaging catheter apparatus
having an acquisition device or parametric imager to interpret and
present to the user a new geometric image of a selected parameter
of an event acquired from an ultrasound imaging catheter apparatus.
The selected parameter of an event which can be a visible
fourth-dimension or non-visible higher-dimensional event is
displayed in an image format which distinct from the conventional
fundamental ultrasound image.
[0020] In one embodiment of the present invention, an
ultrasound-based parametric imaging catheter apparatus adapted for
an underfluid environment is described by way of example.
Accordingly, parametric imaging is defined hereinwith in terms of a
unique ultrasound image presentation and quantitation technique.
Without the parametric solution, described herein, information
parameters appear imbedded in the fundamental image display having
no separable or unique image. With the described parametric
solution, quantifiable parameters such as computed velocity,
surrogate electrical phenomena, derived pressure, or other
constantly changing events are separated and presented as new
unique images which are more readily perceived and understood by a
user. Most importantly, they are objective, reproducible,
quantitative (mathematical) and multidimensional. Accordingly, an
underfluid ultrasound parametric imaging catheter apparatus of the
present invention is capable of visualizing quantitative physiology
and altered physiological states of insonated surroundings. The
parametric image is one of phenomena which are normally too fast,
too slow, or too complex to be accommodated with current imaging
solutions.
[0021] One embodiment of the underfluid ultrasound imaging catheter
apparatus in accordance with the principles of the present
invention includes: a catheter body; a transducer, disposed on the
catheter body, transmitting signals to a structure proximate the
transducer outside of the catheter body and receiving signals which
represent an event of at least one selected parameter; a parametric
image processor processing and imaging at least one selected
parameter of the event. The event can be a four-dimensional event
visible to a human user's eye or a higher than four-dimensional
event normally non-visible to the human user's eye.
[0022] Dimensions: The subject of dimensions is complex and often
confusing. Three dimensions totally explain our spatial reality,
which encompass height, length and width. A volumetric image, which
contains three spatial dimensions, is conventionally called a
three-dimensional or volumetric image. Visible motion, as described
by Einstein in 1908, is designated the fourth dimension of our
reality. A volumetric image, which visibly moves, is called a
four-dimensional image. Our reality is, however, permeated with an
infinite number of normally non-visible moving events (the term
higher-dimensional phenomenon has been applied to non-visible
events, which permeate our reality but should not be confused with
theoretical physics' use of the same descriptor, which refers to
parallel universes or dimensions). Examples of non-visible
phenomena include heat, electricity, transformation, etc. We
normally perceive these events as continuous, for example, the
changing temperature of the body. The non-visible events are
perceived as complex, unpredictable linear or cyclical variables.
In physics, complex natural events have been discussed under the
headings of chaos, fractals, fuzzy logic, quantum mechanics, etc.
All of these disciplines are based on the fact that immense
predictability of complex systems can be obtained from less than
absolute solutions. By breaking a complex event into quantifiable
(i.e., parameterized) components and then presenting the event as a
probability distribution in an image format is extremely
enlightening. The parametric image described herein presents
visible and non-visible events as geometric pictures, thus brings
an otherwise complex event into our visible reality. The technique
requires sophisticated computer management of information which
results in extremely reproducible, quantifiable information.
[0023] Other embodiments of an underfluid ultrasound imaging
catheter apparatus in accordance with the principles of the
invention may include alternative or optional additional aspects.
One such aspect of the present invention is that the transducer is
an ultrasound-based transducer. The transducer is the catheter
component which acquires information. The configuration of the
transducer can be in a variety of formats. The ultrasound
transducer configuration (format) can be of any form that can be
accommodated into a catheter as described herein and acquire
parameterized information in a two-, three-, four-, or a higher
dimensional image presentation. For example, the transducer can be
a group of transducer elements or an array of transducer elements.
Also, the type or operation type of the ultrasound-based transducer
can be in a variety of formats. For example, the transducer can be
an offset stereoscopic imaging ultrasound transducer array, a
sector array, a linear array, a linear phase array, a phase linear
array, a curved phase array, vector array, etc.
[0024] Another aspect of the present invention is that the selected
quantifiable parameter is truly an ultrasound surrogate of a
parametric phenomenon. Events such as blood flow velocity,
perfusion, pressure, contractility, image features, electricity,
metabolism, transformation, and a vast number of other constantly
changing parameters are brought into the realm of visual reality.
However, the event itself (i.e., electricity) is not visualized.
Instead, ultrasound produces a surrogate parameter which can
accurately predict an event such as electrical
depolarization/repolarization.
[0025] Parametrics is an old term, however, in the context
described herein, the application is totally different.
Historically, digital imaging systems such as magnetic resonance,
nuclear radioisotopes, x-ray, and computed tomography have been
used to acquire pixelated information. Ultrasound has not
accommodated digital solutions and in particular use of an
underfluid imaging catheter is unique. The term parametric imaging
has been applied in various manners but not to the ultrasound
solution. The unique aspect of the present invention is the
extraction of parametric information from the fundamental image and
reformatting this new information into a new geometric image (i.e.,
parametric image).
[0026] In one aspect of the present invention, the invention is
unique in that it is an underfluid catheter system with the
creation of a new geometric parametric event imager.
[0027] Using an underfluid ultrasound catheter apparatus and the
concept of quantum computation, one can describe families of
physiologic events by geometrically expressing surrogate features.
This presentation assists in explaining such events, and ultimately
describing why something happens by invoking the flow of time.
Quantum descriptions of distributions resolve events into
measurable units of simplicity and comprehensibility and can be
looked upon a high-level simplicity derived from low-level
complexity. The surrogates of physiologic phenomena can be
displayed as easily understood geometric images suited to the
human's four-dimensional comprehension of reality.
[0028] Accordingly, the present invention provides a geometric
image for an objective result of an event. Such event is
reproducible. One obtains the same result each and every time if
provided comparable parameters. The present invention provides a
capability of placing a numerical result into a measurable scheme.
Further, the present invention has a capacity to expand as a
spatial distribution in surface, area, and volume.
[0029] These and various other advantages and features of novelty
which characterize the invention are pointed out with particularity
in the claims annexed hereto and forming a part hereof. However,
for a better understanding of the invention, its advantages and
objectives obtained by its use, reference should be made to the
drawings which form a further part hereof, and to the accompanying
descriptive matter, in which there is illustrated and described a
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] A better understanding of the construction and operational
characteristics of a preferred embodiment(s) can be realized from a
reading of the following detailed description, especially in light
of the accompanying drawings in which like reference numerals in
the several views generally refer to corresponding parts.
[0031] FIG. 1 is a perspective view of one embodiment of a catheter
body of an underfluid ultrasound parametric imaging catheter
apparatus in accordance with the principles of the present
invention, in which the ultrasound catheter is an acquisition
device which acquires information from the surrounding underfluid
environment, and the information is processed and reformatted into
a unique parametric expression of an underlying event.
[0032] FIG. 2 is an enlarged cross-sectional view taken proximate a
distal end of one embodiment of catheter body showing an ultrasonic
transducer and a generic therapeutic device extending within a
field of view.
[0033] FIG. 3 is a block diagram illustrating one embodiment of the
underfluid ultrasound parametric imaging catheter apparatus in
accordance with the principles of the present invention.
[0034] FIG. 4 is a perspective view of one embodiment of the
underfluid ultrasound parametric imaging catheter apparatus in an
underfluid environment in accordance with the principles of the
present invention.
[0035] FIG. 5 is an image display of a segment of left ventricular
myocardium using a phased array ultrasound imaging catheter without
applying a parametric image solution.
[0036] FIG. 6 is an image display of a velocity mode of the segment
of left ventricular myocardial (i.e., the parameter is the velocity
and is displayed as a surrogate of electricity and the
depolarization/contractio- n of the myocardium) using a phased
array ultrasound imaging catheter applying the parametric image
solution in accordance with the principles of the present
invention.
[0037] FIG. 7 is a schematic view of one example of presentation
and display of radio frequency (RF) signals in a parametric imaging
process in accordance with the principles of the present
invention.
[0038] FIG. 8 is a schematic view of one example of acquisition of
transducer received signals and formation of the RF signals in the
parametric imaging process in accordance with the principles of the
present invention.
[0039] FIG. 9 is a schematic view of a parametric imaging catheter
apparatus in accordance with the principles of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] In the following description of the exemplary embodiment,
reference is made to the accompanying drawings which form a part
hereof, and in which is shown by way of illustration the specific
embodiment in which the invention may be practiced. It is to be
understood that other embodiments may be utilized as structural
changes may be made without departing from the scope of the present
invention.
[0041] The present invention provides an imaging catheter apparatus
having an acquisition device (transducer and ultrasound machine)
and a parametric imager which interprets and presents an acquired
event of a selected parameter. The selected parameter can be a
visible or non-visible quantifiable temporal event which is then
displayed as a unique parametric image.
[0042] In one embodiment of the present invention, an
ultrasound-based parametric imaging catheter apparatus adapted for
an underfluid environment is described by way of example.
Accordingly, parametric imaging is defined hereinwith as a type of
ultrasound image presentation and quantitation. Without the
parametric solution, parameters are presented as a part of a
fundamental image and are not separated temporally or geometrically
from the surroundings. With the parametric solution, parameterized
information such as velocity, strain, pressure, or surrogate
information representing electricity, motion, change, etc., can be
recorded as constantly changing quantifiable events (pixels to
volumes) and expressed as a new uniquely geometric image. As a
result, even normally non-visible parameters can be more readily
perceived and understood and quantified. Accordingly, an underfluid
ultrasound parametric imaging catheter apparatus of the present
invention is capable of quantitatively visualizing dynamic
physiologic events and altered states within the insonated
surroundings.
[0043] The prefix "para" of the term "parametric" refers to
something which represents some naturally occurring phenomenon
which may or may not look like the original. "Parametric" is
defined herein as a quantifiable metric expression of a naturally
occurring phenomenon. "Parametric imaging" is a geometric image of
the distribution of a quantifiable phenomenon.
[0044] In one embodiment of the present invention, catheter based
invasive ultrasound imaging systems, typically used for
intracardiac or transvascular imaging, include transducers
generally comprised of arrays of elements (e.g. linear phased
array) or a single element rotated or translated to produce a
tomographic field of view in an azimuthal plane. Typical arrays may
include: 1) a linear array (linear sequential array), usually
producing a rectangular or rhomboidal tomographic picture; 2) a
cylindrical array or rotating crystal, producing a round pie-shaped
tomographic cut; 3) a sector array (linear curved or vector phased
array), producing a triangular shaped tomographic image. Images
from these transducers are tomographic in nature and are focused
both in the azimuthal and elevation planes. These transducer
configurations produce a thin ultrasound cut of the insonated
structures, which by nature is thin and of high resolution.
[0045] A more sophisticated catheter based ultrasound imaging
solution includes transducers which obtain volumetric images. Two
general techniques are utilized to obtain three-dimensional spatial
information. The first utilizes the tomographic two-dimensional
imaging array and fuses the information obtained from multiple
spatially aligned two-dimensional images. The second technique
obtains an instantaneous volumetric image with the use of
two-dimensional piezoelectric element arrays (i.e., multiple rows
of elements). A volumetric image obtains information in all three
spatial dimensions. In summary, a parametric solution (i.e.,
distribution of quantifiable information) can be expanded from a
conventional two-dimensional spatial domain to a three-dimensional
domain. Both solutions are germane to the present invention, each
having certain applications and in certain circumstances an
advantage over the other.
[0046] FIGS. 1-3 illustrate one embodiment of a parametric imaging
catheter apparatus in accordance with the principles of the
invention. In the embodiment, an ultrasound-based catheter
apparatus is generally illustrated by reference numeral 20. As
shown, the catheter 20 includes an elongated flexible or rigid
tubular catheter body 22 having a proximal end 24 (FIG. 3) and a
distal end 26. The catheter 20 includes proximate to its
longitudinal distal end 26 a phased array ultrasonic transducer 28
which is used to transmit ultrasound and receive resultant echo
information such as Doppler Flow, Tissue Doppler, Color Doppler,
Harmonics, Pulse Inversion, Feature Extraction or characterization,
Strain, Strain Rate, Acceleration Doppler, Power Doppler, and
various features. As described, various types ultrasonic
transducers or transducer arrays can be used in the present
invention, such as mechanical and dynamic one- and two-dimensional
transducer arrays. Images can be two-dimensional or
multidimensional and present tomographic, volumetric, stereoscopic,
or virtual information. Various acquisition, image and display
solutions are suitable for underfluid operation. The information
obtained in any of these manners can be subjected to
parameterization and be processed into a parametric solution.
[0047] As shown in FIG. 2, an electrical conductor 30 is disposed
in the catheter body 22 for electrically connecting the transducer
28 to a control circuitry 32 (FIG. 3) preferably external of the
catheter body 22. The ultrasonic transducer 28 can be a
piezoelectric material such as a ceramic crystal or polymer, such
as Polyvinylidenedifloride (PVDF) 34, which is bonded by an epoxy
layer 36 to a depression 38 approximate the distal end 26. Although
some details are provided with respect to an embodiment of an
ultrasonic transducer which might be used, it will be appreciated
that various types of transducers or transducer arrays having
various configurations and orientations may be utilized to obtain
parametric information without departing from the principles of the
present invention.
[0048] In FIGS. 1-3, additional features may be added in the
catheter body 22. For example, an access port 40 may be disposed in
catheter body 22. The port 40 extends from proximate the proximal
end 24 of catheter body 22 to proximate the distal end 26 of
catheter body 22. The port 40 may be configured to receive a
therapeutic device 42, such as a catheter, medication, sensors,
etc., so as to enable the device 42 to be delivered via the port 40
to the distal end 26 of the catheter body 22 for operation within
the ultrasonic transducer field of view. The device 42 may be used
for intervention, e.g., ablation catheter, monitoring blood
pressure, and/or sampling blood, etc. Phenomena observed or so
created can be subjected to the parametric information acquisition
and display.
[0049] A guide wire access port 44 may also be disposed within the
same catheter body 22. The port 44 extends from the proximate
proximal end 24 of the catheter body 22 to proximate distal end 26
of catheter body 22 for receiving a guide wire 46 (FIG. 3).
[0050] In FIG. 3, the catheter 20 includes an appropriate control
circuitry 32 for controlling operation of the ultrasonic transducer
28. The control circuitry 32 is electrically interconnected to a
transceiver circuitry 48 (T/R) for transmitting and receiving
signals via a cable 50 to and from the ultrasonic transducer 28. In
turn, the transceiver circuitry 48 is electrically interconnected
to a Doppler circuitry 52 and an appropriate display device 54 for
displaying hemodynamics or blood flow, etc. In addition, the
transceiver circuitry 48 is electrically interconnected to a
suitable imaging circuitry 56 which is interconnected to a display
58 for displaying images.
[0051] During operation, the control circuitry 32 may be designed
to cause ultrasonic transducer 28 to vibrate. The ultrasound wave,
represented by line 60 in FIG. 2, will propagate through the fluid,
e.g. blood, fluid, or tissue surrounding the distal end 26. A
portion of the ultrasound wave so transmitted will be reflected
back from both the moving structures such as valves and red blood
cells, as well as from insonated structures to impinge on the
transducer 28. Because of the piezoelectric nature of the
transducer, an electrical signal is thereby generated and
transmitted by the cable 50 to the input of transceiver 48. A
signal may then be variably transmitted to the Doppler circuitry 52
which may use a conventional amplifying and filtering circuitry
commonly used in Doppler flow metering equipment. The Doppler
circuitry 52 analyzes the Doppler shift between the transmitted
frequency and the receive frequency to thereby derive an output
proportional to velocity or other phenomena. This output may then
be displayed at the display 54. The display 54 may be a suitable
analog or digital display terminal. Accordingly, the user will be
able to obtain a readout of velocity, blood rates hemodynamic or
physiologic information.
[0052] In order to obtain fundamental imaging information, the
control circuitry 32 triggers ultrasonic transducer 28 via the
transceiver 48 to vibrate and produce an ultrasound wave. Once
again, a portion of the wave or energy will be reflected back to
the ultrasonic transducer 28 by the body features. A corresponding
signal will then be sent by the cable 50 to the transceiver
circuitry 48. A corresponding signal is then sent to the imaging
circuitry 56 which will analyze the incoming signal to provide to
the display 58. The display 58 may be any type of suitable display
apparatus for displaying an image (fundamental or parametric) of
the underfluid features.
[0053] The imaging can occur at anytime even while a therapeutic or
surgical device is used at the distal end 26 of the catheter 20
within the field of view provided by the ultrasonic transducer 28.
Accordingly, the user will be able to monitor his/her actions and
the result thereof.
[0054] Further in FIG. 3, the catheter body 22 may include
proximate to its proximal end 24 a suitable mounting structure 62
to the access port 40. A therapeutic or surgical device access 64
may be suitably attached to the structure 62 by suitable means,
e.g., threaded, etc. As illustrated, an elongated cable-like member
66 will extend along the access port 40 and slightly beyond the
distal end 26 of the catheter body 22 wherein the device 42 may be
interconnected.
[0055] FIG. 4 shows that the parametric imaging ultrasound
transducer catheter 30 can be inserted into an underfluid
environment. The parametric images of a selected parameter or mode
representing the underfluid environment can be viewed on the
displays. In this embodiment, the therapeutic device 42 is inserted
into the catheter access port 40 and operated in the field of view
of the transducer 28. It is appreciated that the catheter 20 can
also be a merely imaging catheter which may not include the access
port 40 or guide wire port 44, or accommodate a device 42 or guide
wire 46.
[0056] Also in FIG. 3, parametric information can be obtained or
generated in numerous places in the acquisition circuitry. One can
use the Doppler information from the Doppler Circuitry 52 and
create parametric information and image via a parametric imager 68.
This can be analog or digital information but considerably far down
the image processing cascade and image circuitry. One can also
create parametric information and images via a parametric imager 70
off of the imaging circuitry 56. This would include display of
motion and gross anatomic information. A more mature parametric
solution and image via a parametric imager 72 or 84 can be obtained
from radio frequency (RF) data taken off of the beam former 76. The
parametric information and resulting images at imager 72 is created
by received data from the transducer 28 and is taken off very early
in the image processing cascade, for example, just after the beam
former 76. The digital information or data 78 is presented as
parameterized image pixels of quantifiable information. The
distribution of features (i.e., surrogate families of pixels) can
be displayed 90 as the parametric image. Similarly, parametric
information and image can be generated further along the imaging
process chain, for example, after performing a scan conversion 80
and generating a digital data set 82. The digital data set 82 is
used to generate a parametric image via a parametric imager 84.
Accordingly, parametric imaging is a particular data processing
solution that looks at distributions of parameterized events and
presents those real or mathematically derived distributions as a
quantifiable geometric image. A parametric image can be a
distribution of an image feature, a distribution of Doppler
phenomena, a distribution of parameterized digital data pixels, or
a distribution of post-scan conversion display information.
[0057] The use of an underfluid ultrasound catheter to generate
parametric images via imagers 68, 70, 72, and 84 is unique.
Parametric imaging is defined as the imaging of "parameters" which
are visible two-dimensional, three-dimensional, fourth-dimensional,
or non-visible higher-dimensional temporal events. Visible
fourth-dimensional events include features such as cardiac
contraction, valve leaflet motion, dynamic features, etc.
Non-visible motion may include slow non-visible events (i.e.,
remodeling, aging, healing, etc.) or fast non-visible events (i.e.,
contractility, electricity, strain, compliance, perfusion, etc.)
Parametric imaging requires: 1) an acquisition device (i.e.,
ultrasound machine and transducer); 2) rapidly or temporally
sequenced acquired analog, digitized, or digital information; 3) a
state-of-the-art "information" computer processor (quantum
mechanical solutions); 4) a geometric presentation of the resultant
parameterized information; and 5) a quantitative interactive
display. It is appreciated that various types of acquisition
techniques can be used. The techniques vary in sophistication
(anatomic to digital pixel parameterization), modality (image,
Doppler, phenomena etc.), information (analog, digitized, digital),
and purpose (aging which is a slow event recording; electricity
which is a very rapid nonvisible event; contractility which is a
visible motion event). Specific examples of the applications will
be discussed below.
[0058] A parametric imager selects at least one parameter of an
event and generates an image which is a quantifiable geometric
surrogate of a visible or non-visible event displayed in a
comprehensible realistic manner. Quantified distributions of
parameters represent a new and unique means for an underfluid
catheter to appreciate phenomena such as dynamic physiology.
Accordingly, a parametric imaging empowered ultrasound catheter, in
addition to conventional imaging solutions, function, dynamic flow
and hemodynamics, can obtain dynamic quantifiable feature extracted
information from the insonated environment and display this
information as a static or dynamic geometric figures from which
discrete or gross quantifiable information can be obtained.
[0059] A parametric image is an image that acquires parameterized
(i.e., mathematical variable) information either as gross features
or increasingly fractionated discrete elements (pixels). The
feature or element is parameterized (i.e., numerically weighed) and
looked upon as a quanta of the event. The parameterized features or
elements have distinguishing magnitudes. Groups of units (quanta or
pixels or characteristic elements) are visible and can be
continuously changing both in value and spatial distribution.
[0060] Any evolving or spreading phenomenon has a spatial
distribution and volume and includes a sequence of changing
geometric moments or "snapshots" of itself. The instantaneous
"snapshots" or versions of an event collectively are perceived as
continuous and moving phenomena (i.e., heat) or objects (i.e.,
contraction of the heart). Any moving or changing phenomenon is
thus capable of being depicted as a sequence of geometric moments.
Sophisticated computer acquisition devices can be configured to
rapidly acquire dynamic physiologic information. The ultimate
device is a form of quantum computation. The families of
physiologic events or features are geometrically displayed. Thus,
such events are visually and quantitatively explained, and
ultimately why something happened by invoking the flow of time is
described. Quantum descriptions of distributions resolve events
into measurable units of simplicity and comprehensibility and can
be looked upon as high-level simplicity derived from low-level
complexity.
[0061] Described below are a few general examples of parametric
images which can be obtained with the ultrasound imaging catheter.
The present invention generally pertains to the introduction of
parametric imaging to an ultrasound catheter. These examples
represent only a sampling of an infinite array of parametric
solutions. The present invention provides an ultrasound imaging
catheter empowered with parametric solutions described herein.
Parametric imagery is equated with the geometric (i.e., volumetric)
display of physiologic events which is particularly unique and
suited to the underfluid ultrasound tipped catheter. It is
appreciated that the utilization and understanding of
multidimensional quantifiable distribution of parametric events
with the confines of fluid filled spaces have important clinical
utility and implications.
[0062] Examples of multidimensional medical parametric imaging are
described below, whereby visible or non-visible motion is recorded
and quantified, and events mathematically expressed in numerous
ways, depending on the clinical purposes. Parametric solutions are
a unique introduction to ultrasound and never described in
conjunction with a catheter system.
[0063] 1) Change or Transformation: Normal and abnormal physiologic
events which occur over time can be as slow as aging and remodeling
or as rapid as the heart's myocardial contraction. Although one can
perceive the evolution of the actual event, one cannot capture
prolonged or instantaneous change as a separate phenomenon. At any
moment in time, the phenomenon's change is so minute or transient
that it cannot be separated as a distinct happening. The human
senses perceive such events only as linear or cyclical continua.
However, the computer is used to change or transform and express
this phenomenon as a sequence of geometric moments. Change or
transformation information is presented in a number of meaningful
ways. For example, the volumetric excursion of a surface is
presented as a geometric picture and measured as expression of the
magnitude of change. The phenomenon change is expressed as an image
and not the physical motion such as a wall contraction. In this
circumstance, excursion is itself and not the wall surface, and
motion is expressed as a volumetric expression of that which has
changed or transformed.
[0064] Unique to the ultrasound expression of parametric images of
the present invention is the manner in which the phenomenon is
expressed. For example, electrical events are expressed as the
instantaneous and sequential contraction of muscle fibers,
transformation as a volumetric expression of that which has
expanded or contracted or the mass which has changed, profusion as
a feature of the insonated milieu, pressure as Doppler frequency
shift, and metabolism as alterations in stiffness, etc. In each
instance, the parametric solution is very much different from that
described by CT, MR, or nuclear for that fact in any previous
science. Further, the manner of display is uniquely differentiated
in that it is the phenomenon of which is displayed in preference to
the fundamental image. The phenomenon becomes the primary visible
and quantifiable result. The resultant images, which are an
expression of the event but not the structure, may have little
resemblance to the original structure but will contain qualitative
(visual) and quantifiable (mathematical) information important to
the better understanding of the event.
[0065] 2) Flow: The continuous movement of gas or liquid is
normally invisible because of the rapidity of the event and the
invisible nature of the perfusate. Doppler ultrasound can display
blood flow as a shift in ultrasound frequency and displayed as a
distribution event. Parametric expressions of flow capture multiple
parameterized morphological and physiological phenomena, such as:
1) the space in which the event occurs, 2) the actual
three-dimensional distribution of the event within the ultrasound
space, and 3) quantifiable physiology of the fluid, such as
velocity, viscosity, turbulence, etc. Parametric imaging takes an
advantage of unique and powerful attributes of simultaneous
visualization of quantifiable features, pixels, as well as the
visualization of multiple phenomena (multi-parametric image) or
information from multiple technologies (i.e., multi-modality
parametric image).
[0066] 3) Perfusion: Ultrasound parametric image of perfusion is
expressed as a distribution of refractile feature changes caused by
the interaction of ultrasound and a blood tracer such as spheres of
gas. This is a quantifiable two- or three-dimensional surrogate
distribution of the perfusate. A multi-parametric ultrasound would
display multiple simultaneous events, such as function
(transformation) and perfusion, simultaneously. The quantitative
distribution of feature, such as flow velocity, can be utilized as
an expression of the magnitude of a perfusion/function defect or
burden.
[0067] 4) Pressure: Pressure can be perceived but not visualized
without enhancement. The multi-dimensional display of pressure
(i.e., volumetric distribution of quantifiable features or families
of parameterized pixels) processes otherwise non-visible phenomena
into a visible format. In the new imaging paradigm, instantaneous
pressure, such as recorded ultrasound Doppler velocity shift, can
be displayed as a three-dimensional distribution. An ultrasound
surrogate of a dynamic pressure map betters the highlights of
regional and global physiological dynamics. The uniqueness of the
parametric solution is the volumetric display of quantifiable
physiology. Pressure itself becomes the picture.
[0068] 5) Contractility: Distribution of velocity, force, and
traction parameters, such as fractional shortening, and
distribution of contractile phenomena, can be displayed in a
volumetric image. The parameterized phenomena, and not the normal
ultrasound signal, is itself the primary image. Ultrasound tissue
Doppler velocity imaging (TDI-velocity) and motion imaging record
the velocity and succession of muscle contraction, respectively. A
volumetric image of these events, displayed as a geometric image,
displays normal and abnormal functional activity of the heart in a
visual and quantifiable manner. The resultant parametric solution
may have little resemblance to the original fundamental
information, such as TDI-velocity, but imparts more meaning by
being presented as a quantifiable volume.
[0069] 6) Image Features: Tissue texture metrics (i.e., features)
can be assessed in many ways. The parametric imaging solution can
actually elucidate dynamic tissue histopathology. When displayed as
a higher dimensional parametric image, normal and abnormal tissue
can be separated from its surroundings. Feature extraction is a
quantum statistical technique, which can analyze the entire volume
which can be used to create a new image of the organ represented by
one or more of its embedded characteristics. This parametric image
is unique to the underfluid catheter systems.
[0070] 7) Electricity: Electrical forces are invisible events to
ultrasound. However, surrogate phenomena can be detected and
recorded using ultrasound technology (for example, tissue Doppler
imaging velocity or acceleration which parameterizes the sequence
of myocardial muscle contraction during electrical depolarization
and repolarization). When processed into a visible map and
displayed as a volumetric image, a volumetric parametric image is
created. This image is a surrogate of electrical depolarization but
unlike the actual mapping of electrical events, as conventionally
occurs, a surrogate ultrasound parametric solution is utilized.
Visualization of the sequence of polarization and depolarization
displayed as a distribution in these cases allows better
understanding of normal and abnormal electrophysiology. Such
understanding can be used to direct therapy of arrhythmias as
currently practiced in an electrophysiologic laboratory.
Quantifiable alterations of the geometry of the electrical field
have therapeutic implications. This parametric solution is unique
to the underfluid ultrasound systems.
[0071] 8) Metabolism: Metabolic activity and change of underlying
function are not visible to the normal human senses. However,
through various higher-dimensional displays of ultrasound
acquisition techniques, metabolic activity is modeled, accurately
depicted, and most importantly expressed as distributions of
variable metabolic activity, such as myocardial injury, death, or
hibernation.
[0072] 9) Others: It is appreciated that there are an infinite
number of higher-dimensional parametric ultrasound solutions.
[0073] As an example, FIG. 5 shows an image display of a segment of
left ventricular myocardium using a phased array ultrasound imaging
catheter without applying a parametric solution and represents the
fundamental image. The frequency of the transducer is 7.5 MHz and
the diameter of the catheter body is 10 French (one French divided
by Pi equals one millimeter (mm)). FIG. 6 shows the same myocardium
displayed as a parametric myocardial velocity map. Each pixel and
family of like velocity pixels appear as concentric evolving
contractual waves. Parameterized features include velocity,
distribution, volume, and variable concentric waves of velocity.
The ultrasound tipped catheter is used for parametric imaging in
accordance with the principles of the present invention. As shown
in FIG. 6, the myocardial segment is imaged with parametric tissue
Doppler (TD) at a frame rate of >=100 frames per second and
reformatted to a temporal sequence which is more familiar to the
human reality (i.e., static or visible wavelets of surrogate
electrical phenomenon). Using the velocity mode of TD, regional
myocardial contraction is parameterized to equate to an electrical
event (i.e., the ultrasound visualization of electricity using
surrogate pictures of tissue acceleration velocity). Each segment
of muscle is given a color based on recorded regional pixel
velocity. Each pixel has a specific value related to velocity, all
similar velocities have a similar color. As shown, the initial and
now slowing velocity is the epicenter of the electrical stimulus
(bright green). The contractile velocity spreads outward in
wavelets from the epicenter, velocities spread outward like waves
in a pond with each wavelet having a similar instantaneous velocity
(orange, deep red, blue). The initial point of electrical
excitation is visually and quantifiably localized to the point of
the initial muscle contraction. Propagation of the electrical
surrogate is the realistically and quantitatively assessed. Such a
parametric image is unique to underfluid ultrasound systems. As
shown in FIG. 6, the image is a two-dimensional surrogate display
designed to show an electrical epicenter. The phenomenon, however,
is multidimensional and distributes irregularly. Other
multidimensional displays of this event are intuitive and would be
designed to answer specific physiologic questions.
[0074] FIG. 7 illustrates a schematic view of one example of
presentation and display of radio frequency (RF) signals in a
parametric imaging process in accordance with the principles of the
present invention. The RF signals are parameterized and presented
as quantifiable pixels of image information. The pixels are then
summed to form a fundamental picture or image. The parameterized
pixels contain mathematical features of families of pixels which
can be separated into meaningful parametric distributions and
displayed as a new geometric image. These new images can be
presented as geometric moments or dynamic cyclical or continuous
events. The new image often does not appear like the fundamental
image or have an intuitively familiar analogy or analog. However,
the new image is a simple quantifiable geometric figure of an
otherwise complex event.
[0075] FIG. 8 is a schematic view of one example of a sophisticated
acquisition of transducer received signals and formation of the RF
signals which are parameterized in accordance with the principle of
the present invention. The RF signals are the output of the beam
former 76 (FIG. 3). The received signals from the transducer
elements are amplified (e.g. analog gain) to ensure the optimal use
of the dynamic range of the analog-to-digital (A/D) converters. The
analog gain factor varies according to the distance the received
signals travel into the insonated tissues, i.e., deep signals are
amplified more. The signals are then delayed individually to focus
the beam to account for certain depth and direction. The delayed
signals are weighed to obtain the desired apodization and beam
profile. The weighed and delayed signals are summed in phase to
result in RF signals. The RF signals are digital, thus are more
easily parameterized, and thus are most suited to the parametric
solution.
[0076] FIG. 9 illustrates a schematic view of one example of
parametric imaging catheter apparatus in accordance with the
principles of the present invention. The transmitter 48 sends
signals to the transducer 28 which transmits signals to an
underfluid structure (FIG. 4) and in turn receives echo signals
from the structure. The received signals are then sent to the
receiver 48 to be processed in the processing device 88 (FIG. 3)
and to be displayed by a display 90. It is appreciated that the
processing device 88 may also incorporate with the processing
device 86 as shown in FIG. 3 to obtain parametric imagers from the
Doppler circuitry 52 and/or imaging circuitry 56.
[0077] It is appreciated that the configuration and arrangement of
the catheter and catheter body itself can be varied within the
scope and spirit of the present invention. The present invention
deals with the use of parametric imaging in such catheters in order
to uniquely assess dynamic natural events such as physiology. The
parametric imaging catheter apparatus of the present invention is
capable of visualizing visible as well as very fast or very slow
non-visible motion events and is capable of creating measurable
geometric surrogate representations of physiology, including
transformation, blood flow velocity, perfusion, pressure,
contractility, image features, electricity, metabolism, and a vast
number of other constantly changing parameters. Parametric
solutions have not been applied to a catheter system. The present
invention allows presentation of physiologic phenomena as easily
understood geometric images temporally and realistically
reformatted to the human's two-, three-, and four-dimensional
comprehension of reality.
[0078] In one preferred embodiment, the ultrasonic transducer 28
preferably has a frequency of 5 to 30 megahertz (MHz) and more
preferably a frequency of 5 to 12 MHz, and further more preferably
a frequency of 7.5 MHz. The catheter body 22 has preferably a
diameter of 4 to 15 French (one French divided by Pi equals one
millimeter (mm)) and more preferably a diameter of 5 to 10 French,
and further more preferably a diameter of 8 to 10 French (2.6 to
3.2 mm diameter). The optional access port 40 has preferably a
diameter of 7 to 8 French, and the guide wire port 44 has
preferably a diameter of 0.025 to 0.038 inches. It is appreciated
that the ultrasound tipped catheter may or may not have other
features such as articulation capability, and may or may not have a
port (guide wire port and/or therapeutic device assess port). The
catheter is capable of performing various acquisition technologies
such as harmonic imaging, pulse inversion, intermittent imaging,
automated edge and cavity delineation, etc. The present invention
is unique firstly as it pertains to a catheter system, particularly
to an underfluid ultrasound catheter, and secondly, the present
invention pertains to a parametric image solution.
[0079] It is also appreciated that the transducer 28 may have
variable configurations and arrangements, such as longitudinal,
toroidal (longitudinal rotation), forward-and-side viewing,
volumetric (3-Dimensional viewing), mechanically rotating
element(s), etc.
[0080] It is further appreciated that the catheter 20 may have full
Doppler capabilities which includes pulsed and continuous wave
Doppler, color flow Doppler, tissue Doppler (velocity,
acceleration, and power modes), strain-rate, etc.
[0081] The present invention pertains to the incorporation of a
unique imaging solution (parametric imaging) into an ultrasound
tipped catheter. Parametric imaging is an evolving concept based on
an evolving technology empowered by increasingly sophisticated
computer management of acquired information. For the purposes of
this imaging technique, information is broken down into measurable
features or into small measurable components and likened to quanta
(i.e., elemental units). Parameterization requires a digital or
digitized image presentation (i.e., an image comprised of
mathematically measurable components). The change over time of the
elemental feature or unit can be measured (i.e., velocity,
strain-rate, etc.). Features and/or units, on a larger scale, are
envisioned as having definable meaningful characteristics, which
when presented as a group, are interpreted as a surrogate of a
physiological events, such as: (infarct, perfusion, electricity,
transformation, etc.). An event can be defined as having a
measurable distribution (i.e., volume, mass, surface), as well as a
variable mathematical value of the constant constituent pixels
(i.e., quanta). The distribution of the event is typically
unpredictable and irregular and best defined by a multi-dimensional
image presentation (i.e., more meaningful and understandable to the
observer as the dimensional presentation increases from a two- to
three- to four-dimensional presentation). The incorporation of a
parametric solution into an underfluid catheter in particular does
not exclusively foster the visualization and quantitation of
physiologic and feature characteristics of the insonated
volume.
[0082] The computer interfaced image processing may include the use
of any quantifiable acquisition technique including: harmonics,
Doppler, pulse inversion, etc., which capture motion as discrete
quantifiable local events or distributions of events. One of the
unique aspects of the present invention is the display of that
information and not the specific acquisition transducer or
information acquisition algorithm.
[0083] The computer interfaced image processing optimally includes
the capture of motion (fourth- and higher-dimensional events). The
examples of physiologic motion are as follows: fast invisible
motion (i.e., higher-dimensional information, for example,
electricity, strain, elasticity, pressure, force, perfusion, etc.);
slow invisible motion (i.e., higher-dimensional information, for
example, aging, remodeling, transformation, etc.); and visible
motion (i.e., fourth-dimension, for example, contractility,
translated motion, valve motion, etc.). One unique aspect of the
present invention is the assessment of these events by the use of
surrogate information presented as quantifiable units (pixels,
quanta) and displayed as quantifiable spatial distributions
(surface, area, volume). For example, fast invisible electrical
events are in one embodiment displayed as tissue Doppler
acceleration and the temporal and spatial distribution of that
surrogate event; slow invisible motion of remodeling is displayed
as a geometric distribution of the phenomenon of quantifiable
change while tissue itself is not displayed subservient to the
image; and the visible motion of contractility displayed as
quantifiable volumetric excursion.
[0084] The computer interfaced image processing further includes
the captured otherwise invisible features (i.e., feature
extraction). The examples are as follows: microanatomy including
fibrosis, edema, infarction, etc., and perfusion including
microcirculation (echo contrast, Doppler blood cell tracking,
target tracking, etc.). It is acknowledged that the particular
acquisition technique, expressed mathematical events, particular
phenomenon recorded are merely exemplary of the present invention.
In general, the present invention relates to a new quantifiable
image solution (i.e., parametric imaging) applied specifically to
any ultrasound catheter device used for underblood or fluid
application.
[0085] The geometric presentation of physiologic events includes:
a) Distribution of quanta: motion events are presented as
quantifiable distributions; b) Scalable dimensions:
one-dimensional, two-dimensional, three-dimensional,
four-dimensional and higher-dimensional presentations.
(Higher-dimensional events are invisible to the human senses and
are normally perceived as continuous events, e.g., temperature,
electricity, aging, etc.).
[0086] The quantum mathematics and quantum computing includes: a)
Mathematics of quanta, examples of quanta include electricity,
pressure, sound; b) Quantum math where location and velocity
typically cannot be computed simultaneously; c) Geometric
presentation of physiologic events and otherwise unseen features;
and d) The use of probability theory (fractal geometry, chaos,
fuzzy, logic . . . mathematics which presents highly accurate
predictions of natural events).
[0087] It is to be understood that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
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