U.S. patent application number 13/270471 was filed with the patent office on 2012-02-02 for method and apparatus for multi-modal imaging.
Invention is credited to Gilbert Feke, Warren M. Leevy, Douglas L. Vizard.
Application Number | 20120029346 13/270471 |
Document ID | / |
Family ID | 41447503 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120029346 |
Kind Code |
A1 |
Leevy; Warren M. ; et
al. |
February 2, 2012 |
METHOD AND APPARATUS FOR MULTI-MODAL IMAGING
Abstract
A method and apparatus for imaging a subject animal. The method
comprises the steps of treating the animal with an x-ray contrast
agent and an imaging agent; supporting the animal in an immobilized
state on a support member; acquiring an x-ray anatomical image of
the animal; acquiring an optical, dark-field image of the animal;
and registering the x-ray anatomical image and the optical image,
whereby features of the optical image can be observed in relation
to features of the anatomical image.
Inventors: |
Leevy; Warren M.; (Granger,
IN) ; Feke; Gilbert; (Durham, CT) ; Vizard;
Douglas L.; (Durham, CT) |
Family ID: |
41447503 |
Appl. No.: |
13/270471 |
Filed: |
October 11, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12460010 |
Jul 10, 2009 |
8041409 |
|
|
13270471 |
|
|
|
|
11221530 |
Sep 8, 2005 |
7734325 |
|
|
12460010 |
|
|
|
|
12354830 |
Jan 16, 2009 |
8050735 |
|
|
11221530 |
|
|
|
|
61079847 |
Jul 11, 2008 |
|
|
|
Current U.S.
Class: |
600/427 |
Current CPC
Class: |
A61B 6/00 20130101; A61B
6/508 20130101; A61D 7/04 20130101; A61B 5/0059 20130101; A01K
1/031 20130101; A61B 6/5247 20130101; A61B 5/0035 20130101 |
Class at
Publication: |
600/427 |
International
Class: |
A61B 6/00 20060101
A61B006/00 |
Claims
1. A method of imaging a subject animal, comprising: treating the
animal with an x-ray contrast agent and an optical imaging agent;
supporting the animal in an immobilized state on a support member;
providing a phosphor plate adapted to be disposed proximate the
support member when capturing a first image; with the phosphor
plate disposed proximate the support member, imaging the
immobilized animal in a first imaging mode to capture the first
image, the first imaging mode being an x-ray mode; removing the
phosphor plate from proximate the support member, after capturing
the first image and while the object remains immobilized on the
support member; and with the phosphor plate removed from proximate
the support member, imaging the immobilized animal in a second
imaging mode to capture a second image, the second imaging mode
being an optical dark-field mode.
2. The method of claim 1, further comprising the step of generating
a third image by merging the first and second images, whereby
features of the second image can be observed in relation to
features of the first image.
3. The method of claim 1, wherein the x-ray contrast agent and the
optical imaging agent are administered simultaneously to the
animal.
4. The method of claim 1, wherein the x-ray contrast agent and the
optical imaging agent are administered sequentially to the
animal.
5. The method of claim 1, wherein the optical, dark-field image is
a fluorescence image.
6. The method of claim 1, wherein the x-ray anatomical image and
the optical, dark-field image are acquired using a common, shared
focal plane.
7. The method of claim 1, wherein the x-ray contrast agent is
targeted and the optical imaging agent is non-targeted.
8. The method of claim 1, wherein the x-ray contrast agent is
non-targeted and the optical imaging agent is targeted.
9. The method of claim 1, wherein both the x-ray contrast agent and
the optical imaging agent are targeted.
10. The method of claim 1, wherein both the x-ray contrast agent
and the optical imaging agent are non-targeted.
11. A method of imaging a subject animal, comprising: treating the
animal with an x-ray contrast agent and an optical imaging agent;
supporting the animal in an immobilized state on a support member;
providing a phosphor plate movable relative to the support member,
while the object remains immobilized on the support member, between
a first position wherein the phosphor plate is in optical
registration with the support member and a second position wherein
the phosphor plate is not in optical registration with the support
member; capturing an x-ray image of the immobilized animal when the
phosphor plate in disposed in the first position; and capturing an
optical dark-field image of the immobilized animal when the
phosphor plate in disposed in the second position.
12. The method of claim 11, further comprising: generating a third
image by merging the first and second images, whereby features of
the second image can be observed in relation to features of the
first image; and displaying, transmitting, processing, or printing,
the third image.
13. The method of claim 11, wherein the x-ray anatomical image and
the optical, dark-field image are acquired using a common, shared
focal plane.
14. An apparatus for imaging a subject animal, comprising: first
imaging means for imaging such an animal in a first imaging mode to
capture a first image, the first imaging mode being selected from
the group: x-ray mode and radio isotope mode; second imaging means
for imaging such an animal in a second imaging mode that uses light
from the immobilized animal to capture a second image, the second
imaging mode being selected from the group: bright-field imaging
mode and dark-field imaging mode; a support stage, fixedly mounted
in the apparatus, for receiving such an animal in an immobilized
state such that the animal is immobilized in the apparatus during
imaging by the first and second imaging means without movement of
the animal from the support stage; and a movable phosphor plate to
transduce ionizing radiation from the first imaging means to
visible light, the phosphor plate being mounted to be moved, while
the object remains immobilized on the support member, between a
first position proximate the support stage during capture of the
first image and a second position not proximate the support stage
during capture of the second image.
15. A method for imaging a subject animal, comprising: providing a
fixed support stage; receiving the animal on the support stage in
an immobilized state; imaging the immobilized animal on the support
stage in a first imaging mode to capture a first image, the first
imaging mode being selected from the group: x-ray mode and radio
isotope mode; without moving the animal or the support stage,
imaging the animal on the support stage in a second imaging mode
that uses light from the immobilized animal to capture a second
image, the second imaging mode being selected from the group:
bright-field imaging mode and dark-field imaging mode; providing a
movable phosphor plate to transduce ionizing radiation from the
first imaging means to visible light; and moving the phosphor
plate, while the object remains immobilized on the support member,
between a first position proximate the support stage during capture
of the first image and a second position not proximate the support
stage during capture of the second image.
16. The method according to claim 15, further comprising: treating
the animal with an x-ray contrast agent and an optical imaging
agent; and registering the first image with the second image,
whereby features of the second image may be observed in relation to
features of the first image.
17. A method of imaging a subject animal, comprising: supporting
the animal in an immobilized state on a support member; providing a
phosphor plate movable relative to the support member, while the
object remains immobilized on the support member, between a first
position wherein the phosphor plate is in optical registration with
the support member and a second position wherein the phosphor plate
is not in optical registration with the support member; capturing a
first image of the immobilized animal when the phosphor plate in
disposed in the first position, the first image being captured
using an imaging mode selected from the group: x-ray mode and radio
isotope mode; and capturing a second image of the immobilized
animal when the phosphor plate in disposed in the second position,
the second image being captured using an imaging mode selected from
the group: bright-field imaging mode and dark-field imaging mode.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation of U.S. Ser. No. 12/460,010 filed
Jul. 10, 2009 by Leevy et al entitled METHOD AND APPARATUS FOR
MULTI-MODAL IMAGING, incorporated herein in its entirety, which
itself claimed priority to U.S. Provisional Patent Application Ser.
No. 61/079,847 filed Jul. 11, 2008 by Leevy et al and entitled
APPARATUS AND METHOD FOR MULTI-MODAL IMAGING, the contents of which
are incorporated by reference into this specification.
[0002] This application is a continuation-in-part of the following
commonly assigned, copending U.S. patent applications, the contents
of each of which also are incorporated by reference into this
specification:
[0003] U.S. Ser. No. 11/221,530, filed Sep. 9, 2005 by Vizard et
al, entitled APPARATUS AND METHOD FOR MULTI-MODAL IMAGING; and
[0004] U.S. Ser. No. 12/354,830 filed Jan. 6, 2009 by Feke et al,
entitled APPARATUS AND METHOD FOR MULTI-MODAL IMAGING.
FIELD OF THE INVENTION
[0005] The invention relates generally to the field of imaging
systems, and more particularly to the imaging of objects. More
specifically, the invention relates to an improved apparatus and
method that enable analytical imaging of objects (for example,
small animals and tissue) in differing modes, including
bright-field, dark-field (e.g., luminescence and fluorescence), and
x-ray and radioactive isotopes.
BACKGROUND OF THE INVENTION
[0006] Electronic imaging systems are well known for enabling
molecular imaging. An exemplary electronic imaging system 10 (shown
in FIG. 1 and diagrammatically illustrated in FIG. 2) is the Image
Station 2000MM Multimodal Imaging System formerly available from
the Eastman Kodak Company. System 10 includes a light source 12, an
optical compartment 14 which can include a mirror 16, a lens and
camera system 18, and a communication and computer control system
20 which can include a display device, for example, a computer
monitor 22. Camera and lens system 18 can include an emission
filter wheel for fluorescent imaging. Light source 12 can include
an excitation filter selector for fluorescent excitation or bright
field color imaging. In operation, an image of an object is
captured using lens and camera system 18. System 18 converts the
light image into an electronic image, which can be digitized. The
digitized image can be displayed on display device 22, stored in
memory, transmitted to a remote location, processed to enhance the
image, used to print a permanent copy of the image, or all of
these.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide an improved
method and apparatus for enabling analytical imaging of an object.
Another object of the present invention is to provide such a method
and apparatus that use differing imaging modes.
[0008] These objects are given only by way of illustrative example,
and such objects may be exemplary of one or more embodiments of the
invention. Other desirable objectives and advantages inherently
achieved by the disclosed invention may occur or become apparent to
those skilled in the art. The invention is defined by the appended
claims.
[0009] According to one aspect of the present invention, there is
provided an improved method for using an imaging system for imaging
an object. An example of such an imaging system useful in the
inventive method includes a support member adapted to receive the
object in an immobilized state. The system also includes first
means for imaging the immobilized object in a first imaging mode to
capture a first image, and second means for imaging the immobilized
object in a second imaging mode, different from the first imaging
mode, to capture a second image. The first imaging mode is selected
from the group: x-ray mode and radio isotopic mode. The second
imaging mode is selected from the group: bright-field mode and
dark-field mode. A removable phosphor screen may be employed when
the first image is captured, but not employed when the second image
is captured. The phosphor screen is adapted to transduce ionizing
radiation to visible light. The phosphor screen is adapted to be
removable without moving the immobilized object. The system can
further include means for generating a third image comprised of the
first and second image.
[0010] A first embodiment of the inventive method is useful for
imaging a subject animal. The method includes a step of treating
the animal with both an x-ray contrast agent and an optical imaging
agent, which may be targeted or non-targeted agents, or both. As
used in this specification and as understood by those skilled in
the art, the terms "targeted agent" refer in general to agents that
accumulate in specific tissues or organs of the animal's body by
molecular targeting, such as antibodies, peptides and the like
attached to the agents. Similarly, the terms "non-targeted agents"
refer in general to agents that accumulate in specific tissues or
organs by physiological processes, such as the gastrointestinal
process or the renal process. The method of the invention further
may include steps of supporting the animal in an immobilized state;
acquiring an x-ray anatomical image of the immobilized animal;
acquiring an optical dark-field image, such as a fluorescence image
or a luminescence image, of the immobilized animal; and registering
the x-ray anatomical image and the optical dark-field image,
whereby features of the optical image can be observed in relation
to features of the anatomical image. The x-ray contrast agent and
optical imaging agent may be administered simultaneously or
sequentially to the animal. In accordance with the invention, the
x-ray contrast agent may be targeted while the optical imaging
agent is non-targeted; or the x-ray contrast agent may be
non-targeted while the optical imaging agent is targeted; or both
agents may be targeted; or both agents may be non-targeted. The
x-ray image and the optical image may be acquired using a common,
shared focal plane.
[0011] A second embodiment of the inventive method may include
steps of treating the animal with an x-ray contrast agent and an
optical imaging agent, as in the first embodiment; supporting the
animal in an immobilized state on a support member; providing a
phosphor plate adapted to be disposed proximate the support member
when capturing a first image; with the phosphor plate disposed
proximate the support member, imaging the immobilized animal in a
first imaging mode to capture the first image, the first imaging
mode being an x-ray mode; removing the phosphor plate from
proximate the support member, after capturing the first image and
without moving the immobilized animal and the support member; and
with the phosphor plate removed from proximate the support member,
imaging the immobilized animal in a second imaging mode to capture
a second image, the second imaging mode being a dark-field mode.
The method may include a further step of generating a third image
by merging the first and second images, whereby features of the
second image can be observed in relation to features of the first
image. Again, the x-ray contrast agent and optical imaging agent
may be administered simultaneously or sequentially to the animal.
Also, the x-ray contrast agent may be targeted while the imaging
agent is untargeted; or the x-ray contrast agent may be
non-targeted while the imaging agent is targeted; or both agents
may be targeted; or both agents may be untargeted. The x-ray image
and the optical image may be acquired using a common, shared focal
plane.
[0012] A third embodiment of the inventive method may include steps
of treating the animal with an x-ray contrast agent and an optical
imaging agent as in the first and second embodiments; supporting
the animal in an immobilized state on a support member; providing a
phosphor plate movable relative to the support member, without
disturbing the immobilized animal and the support member, between a
first position wherein the phosphor plate is in optical
registration with the support member and a second position wherein
the phosphor plate is not in optical registration with the support
member; capturing an x-ray image of the immobilized animal when the
phosphor plate in disposed in the first position; and capturing a
dark-field image of the immobilized animal when the phosphor plate
in disposed in the second position. The method may include further
steps of generating a third image by merging the first and second
images, whereby features of the second image can be observed in
relation to features of the first image; and displaying,
transmitting, processing, or printing, the third image. As in the
first two embodiments, the x-ray contrast agent and optical imaging
agent may be administered simultaneously or sequentially to the
animal. Also, the x-ray contrast agent may be targeted while the
imaging agent is untargeted; or the x-ray contrast agent may be
non-targeted while the imaging agent is targeted; or both agents
may be targeted; or both agents may be untargeted. The x-ray image
and the optical image may be acquired using a common, shared focal
plane.
[0013] A fourth embodiment of the invention concerns an apparatus
for imaging a subject animal. This apparatus may include first
imaging means for imaging such an animal in a first imaging mode to
capture a first image, the first imaging mode being selected from
the group: x-ray mode and radio isotope mode; second imaging means
for imaging such an animal in a second imaging mode that uses light
from the immobilized animal to capture a second image, the second
imaging mode being selected from the group: bright-field imaging
mode and dark-field imaging mode; and a support stage, fixedly
mounted in the apparatus, for receiving such an animal in an
immobilized state such that the animal is immobilized in the
apparatus during imaging by the first and second imaging means
without movement of the animal from the support stage or movement
of the support stage between capture of the first and second
images.
[0014] The fourth embodiment also may include movable phosphor
plate to transduce ionizing radiation from the first imaging means
to visible light, the phosphor plate being mounted to be moved,
without moving the immobilized animal and support stage, between a
first position proximate the support stage during capture of the
first image and a second position not proximate the support stage
during capture of the second image.
[0015] A fifth embodiment of the invention concerns a method for
imaging a subject animal. This method may include steps of
providing a fixed support stage; receiving the animal on the
support stage in an immobilized state; imaging the immobilized
animal on the support stage in a first imaging mode to capture a
first image, the first imaging mode being selected from the group:
x-ray mode and radio isotope mode; and without moving the animal or
the support stage, imaging the animal on the support stage in a
second imaging mode that uses light from the immobilized animal to
capture a second image, the second imaging mode being selected from
the group: bright-field imaging mode and dark-field imaging
mode.
[0016] This fifth embodiment also may include steps of providing a
movable phosphor plate to transduce ionizing radiation from the
first imaging means to visible light; and moving the phosphor
plate, without moving the immobilized animal and support stage,
between a first position proximate the support stage during capture
of the first image and a second position not proximate the support
stage during capture of the second image. This method further may
include steps of treating the animal with an x-ray contrast agent
and an optical imaging agent; and registering the first image with
the second image, whereby features of the second image may be
observed in relation to features of the first image.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The foregoing and other objects, features, and advantages of
the invention will be apparent from the following more particular
description of the embodiments of the invention, as illustrated in
the accompanying drawings. The elements of the drawings are not
necessarily to scale relative to each other.
[0018] FIG. 1 shows a perspective view of an exemplary prior art
electronic imaging system, of a type useful in accordance with the
method of the present invention.
[0019] FIG. 2 shows a diagrammatic view of the system of FIG.
1.
[0020] FIG. 3A shows a diagrammatic side view of the imaging system
of FIGS. 1 and 2.
[0021] FIG. 3B shows a diagrammatic front view of the imaging
system of FIG. 3A.
[0022] FIG. 4 shows a perspective view of the imaging system of
FIGS. 3A and 3B.
[0023] FIG. 5A shows a diagrammatic side view of the sample object
stage, showing the relative movement of the phosphor plate relative
to the sample object stage.
[0024] FIG. 5B shows a diagrammatic side view of the sample object
stage in the first imaging position P1 wherein the phosphor plate
is disposed proximate the sample object stage.
[0025] FIG. 5C shows a diagrammatic side view of the sample object
stage in the second imaging position P2 wherein the phosphor plate
is not proximate the sample object stage.
[0026] FIG. 6 shows an enlarged, fragmentary sectional view taken
along line 6-6 of FIG. 5B.
[0027] FIG. 7 shows an enlarged, fragmentary sectional view taken
along line 7-7 of FIG. 5C.
[0028] FIG. 8 shows a work flow diagram in accordance with the mode
of operation of the system of FIGS. 1 to 7.
[0029] FIG. 9A shows a first image of an immobilized object in a
first, fluorescence imaging mode.
[0030] FIG. 9B shows a second image of the immobilized object of
FIG. 9A in a second, x-ray imaging mode.
[0031] FIG. 9C shows an image generated by thresholding the image
of FIG. 9A and then merging that image with the image of FIG.
9B.
[0032] FIG. 10A shows a first image of an immobilized object in a
first, fluorescence imaging mode.
[0033] FIG. 10B shows a second image of the immobilized object of
FIG. 10A in a second, x-ray imaging mode.
[0034] FIG. 10C shows an image generated by thresholding the image
of FIG. 10A and then merging that image with the image of FIG.
10B.
[0035] FIG. 11A shows a first image of an immobilized object in a
first, fluorescence imaging mode.
[0036] FIG. 11B shows a second image of the immobilized object of
FIG. 11A in a second, x-ray imaging mode.
[0037] FIG. 11C shows an image generated by thresholding the image
of FIG. 11A and then merging that image with the image of FIG.
11B.
[0038] FIG. 12 is a diagrammatic view of a suitable phosphor plate
for use with the apparatus suitable for practice of the method of
the present invention.
[0039] FIG. 13 is a flow diagram of a method for making a phosphor
plate of FIG. 12.
[0040] FIG. 14A shows a diagrammatic partial view of a mouse in a
sample chamber on the sample object stage of the imaging system of
FIGS. 3A and 3B when an X-ray anatomical image, with an X-ray
contrast agent providing contrast of the gastro-intestinal tract of
the subject, is acquired in accordance with the present
invention.
[0041] FIG. 14B shows an x-ray anatomical image captured using the
imaging system of FIG. 14A.
[0042] FIG. 15A shows a diagrammatic partial view of a mouse in a
sample chamber on the sample object stage of the imaging system of
FIGS. 3A and 1B when a near-infrared fluorescence image of the
gastro-intestinal tract is acquired in accordance with the present
invention.
[0043] FIG. 15B shows a near-infrared fluorescence image captured
using the imaging system of FIG. 15A.
[0044] FIGS. 16A and 16B respectively show an anatomical X-ray
image and a near-infrared fluorescence image of the
gastro-intestinal tract of a subject acquired in accordance with
the method of the present invention.
[0045] FIGS. 17A, 17B and 17C respectively show an anatomical X-ray
image with an X-ray contrast agent providing contrast of the
kidneys of the subject, a near-infrared fluorescence image of the
kidneys of the subject, and a co-registered image of the anatomical
X-ray image and the near-infrared fluorescence images of the
kidneys of the subject, acquired in accordance with the method of
the present invention.
[0046] FIG. 18 shows a workflow diagram in accordance with a method
of the present invention.
[0047] FIG. 19A shows a diagrammatic partial view of a mouse in a
sample chamber on the sample object stage of the imaging system of
FIGS. 3A and 3B when an X-ray anatomical image, with an X-ray
contrast agent providing contrast of the kidneys of the subject, is
acquired in accordance with the present invention.
[0048] FIG. 19B shows an x-ray anatomical image captured using the
system of FIG. 19A.
[0049] FIG. 20A shows a diagrammatic partial view of a mouse in a
sample chamber on the sample object stage of the imaging system of
FIGS. 3A and 1B when a near-infrared fluorescence image of the
kidneys is acquired in accordance with the present invention.
[0050] FIG. 20B shows a near-infrared fluorescence image captured
using the system of FIG. 20A.
[0051] FIG. 21 shows an anatomical X-ray image of a mouse in a
sample chamber on the sample object stage of the imaging system of
FIGS. 3A and 3B.
[0052] FIG. 22 shows a graph of the excess x-ray density in the
medullary regions of the kidneys conferred by the X-ray contrast
agent of FIG. 19 vs. the injected volume of the X-ray contrast
agent.
DETAILED DESCRIPTION OF THE INVENTION
[0053] The following is a detailed description of the preferred
embodiments of the invention, reference being made to the drawings
in which the same reference numerals identify the same elements of
structure in each of the several figures.
[0054] In the complex pharmaceutical analyses of small objects or
subjects such as small animals and tissue samples, images are
particularly enhanced by using different in-vivo imaging
modalities. Using the known or current practices of bright-field,
dark-field and radiographic imaging for the analysis of small
objects or subjects such as a mouse can be expensive and may not
provide the precision of co-registered images that is desired.
[0055] Using the method and apparatus of the present invention,
precisely co-registered images can be obtained using x-ray and
fluorescent, luminescent, or radioactive isotopic probes,
individually or in combination, within an object such as a live
animal or a tissue sample. The images can be localized and multiple
images can be accurately overlaid onto the simple bright-field
reflected image or anatomical x-ray image of the same animal within
minutes of animal immobilization.
[0056] The method and apparatus of the present invention use the
same imaging system to capture images using different modes of
imaging, thereby enabling or simplifying multi-modal imaging. In
addition, relative movement of imaging probes can be kinetically
resolved over the time period that the animal is effectively
immobilized, which can be tens of minutes. Alternatively, the same
animal may be subject to repeated complete image analysis over a
period of days or weeks required to assure completion of a
pharmaceutical study, with the assurance that the precise
anatomical frame of reference (particularly, the x-ray image) may
be readily reproduced upon repositioning the object animal. The
method of the present invention can be applied to other objects or
complex systems, or both, subject to simple planar imaging
methodologies. More particularly, using the imaging method of the
present invention, an immobilized object can be imaged in several
imaging modes without changing or moving the immobilized object.
These acquired multi-modal images can then be merged to provide a
co-registered image for analysis.
[0057] Imaging modes supported by the method of the present
invention include: x-ray imaging, bright-field imaging, dark-field
imaging (including luminescence imaging, fluorescence imaging) and
radioactive isotope imaging. Images acquired in these modes can be
merged in various combinations for analysis. For example, an x-ray
image of the object can be merged with a near-infrared fluorescence
image of the object to provide a new image for analysis.
[0058] The use of molecular imaging has engendered a need to
co-register fluorescent and luminescent, or radioactive isotope
signals with anatomical features of the animal or specimen. The
type of imaging system particularly useful for the method and
apparatus of the present invention utilizes a low energy X-ray
source and phosphor screen to supplement the optical imaging
modalities. An X-ray image provides a convenient anatomical map of
musculoskeletal features, and is an orthogonal imaging modality
that will not pollute optical signals emanating from the subject.
While the skeleton provides the framework to spatially assign
organs, X-ray contrast agents are used in the method of the
invention to provide an effective means to delineate soft tissues
that typically give poor contrast by X-ray. For example, many
optical or radioisotopic signals emanate from soft tissues like the
kidneys, liver, and gastrointestinal tract during circulation and
clearance. Thus, it is particularly important to identify and
delineate these organ structures in an X-ray to provide anatomical
co-registration of these signals.
[0059] An embodiment of the apparatus of the present invention,
useful to practice the method of the invention, is now described
with reference to FIGS. 3A, 3B, and 4. Imaging system 100 includes
light source 12, optical compartment 14, a lens and camera system
18, and communication and computer control system 20 which can
include computer monitor 22. As best shown in FIG. 3A, imaging
system 100 includes an x-ray source 102 and a sample object stage
or support member 104. An immobilized object, such as a mouse, is
received on and supported by sample object stage 104 during use of
system 100. Imaging system 100 further comprises epi-illumination,
for example, using fiber optics 106, which directs conditioned
light (of appropriate wavelength and divergence) toward sample
object stage 104 to provide bright-field or fluorescent imaging.
Sample object stage or support member 104 is disposed within a
sample environment 108, which allows access to the object being
imaged. Preferably, sample environment 108 is light-tight and
fitted with light-locked gas ports (not illustrated) for
environmental control. Such environmental control might be
desirable for controlled x-ray imaging or for support of particular
specimens. Environmental control enables practical x-ray contrast
below 8 Kev (air absorption) and aids in life support for
biological specimens. Imaging system 100 can include an access
means/member 110 to provide convenient, safe and light-tight access
to sample environment 108, such as a door, opening, labyrinth, and
the like. Additionally, sample environment 108 is preferably
adapted to provide atmospheric control for sample maintenance or
soft x-ray transmission (e.g., temperature/humidity/alternative
gases and the like). Imaging system 100 can be a unitary system.
Alternatively, imaging system 100 can be a modular unit adapted to
be used or mated with electronic imaging system such as electronic
imaging system 10.
[0060] FIGS. 5-7 more particularly illustrate elements of sample
object stage 104 and an optical interface relative with the focal
plane of camera and lens system 18. FIG. 5A shows a diagrammatic
side view of sample object stage 104 showing the relative movement
of a movable phosphor plate 125 according to the invention relative
to the sample object stage. FIG. 5B shows a diagrammatic side view
of the sample object stage in a first imaging position P1 wherein
phosphor plate 125 is disposed proximate the sample object stage
and positioned for imaging light from a phosphor layer 132, as
shown in FIG. 6. FIG. 5C shows a diagrammatic side view of the
sample object stage in the second imaging position P2 wherein
phosphor plate 125 has been withdrawn to a position that is not
proximate the sample object stage. FIG. 6 shows an enlarged,
fragmentary sectional view taken along line 6-6 of FIG. 5B, which
corresponds with the first imaging position P1. FIG. 7 shows an
enlarged, fragmentary sectional view taken along line 7-7 of FIG.
5C, which corresponds with the second imaging position P2.
[0061] Continuing with regard to FIGS. 6 and 7, sample object stage
104 includes a support member made up from an open frame 120 to
support and stretch a thin plastic support sheet 122. Support sheet
122 is selected so as to support the weight of a sample or object
to be imaged and is made from a material that is optically clear
and free of significant interfering fluorescence. Phosphor plate
125 is mounted for motion toward and away from sample object stage
104. While those skilled in the art might recognize other
configurations, in a preferred embodiment, phosphor plate 125 is
mounted for translation to provide slidable motion (in the
direction of arrow A in FIG. 5A) relative to frame 120, beneath the
sample, in intimate contact with support sheet 122. Such motion can
be accomplished using methods known to those skilled in the art,
for example, frame 100 and phosphor plate 125 can be disposed on
rails supported by a surface of an optical platen 126. As will be
more particularly described below, in first imaging position P1,
phosphor layer 130 in phosphor plate 125 is in overlapping
arrangement with sample object stage 104 (FIG. 6) when an x-ray
image of the object is captured. In second imaging position P2,
phosphor plate 125 is translated or moved away from sample object
stage 104 (FIG. 7) for capture of an image of the object such that
phosphor plate 125 is not imaged when an image of the object is
captured in second imaging position P2.
[0062] FIG. 6 provides an enlarged view of sample object stage 104
including phosphor plate 125 to more particularly show a focal
plane. Sample support sheet 122 preferably comprises Mylar or
polycarbonate and has a nominal thickness of about 0.1 mm. A
protective layer 128 (for example, reflective Mylar) of about 0.025
mm is provided on phosphor layer 130 to protect the surfaces of
layer 130 during movement of phosphor plate 125. Protective layer
128 promotes or increases the image-forming light output. In a
preferred embodiment, protective layer 128 is reflective so as to
prevent object reflection back into the image-forming screen,
reducing confusing of the ionizing radiation image.
[0063] Phosphor layer 130 functions to transduce ionizing radiation
to visible light practically managed by lens and camera system 18
(such as a CCD camera). Phosphor layer 130 can have a thickness
ranging from about 0.01 mm to about 0.1 mm, depending upon the
application (i.e., soft x-ray, gamma-ray or fast electron imaging).
On the underside of phosphor layer 130, as illustrated, an optical
layer 132 is provided for conditioning emitted light from phosphor
layer 130. Optical layer 132 can have a thickness in the range of
less than about 0.001 mm. Particular information about phosphor
layer 130 and optical layer 132 are disclosed in U.S. Pat. No.
6,444,988 (Vizard), commonly assigned and incorporated herein by
reference. A supporting glass plate 134 is provided. Glass plate
134 is spaced at a suitable mechanical clearance from optical
platen 126, for example, by an air gap or void 136. In one
embodiment, the surfaces of clear optical media (e.g., a lower
surface of glass plate 134 and both surfaces of optical platen 126)
are subject to anti-reflective coating to minimize reflections that
may confuse the image of the object. FIG. 7 provides an expanded
view of sample object stage 13 including wherein phosphor plate 125
is removed (i.e., taken along line 7-7 of FIG. 5C). Shown in FIG. 7
are frame 120, sample support sheet 122, an air gap/void 138 (since
phosphor plate 125 is removed), and optical platen 126.
[0064] Referring now to FIG. 8, in operation, in Step 200 an object
(such as a small animal) is immobilized on sample object stage 104.
An operator configures system 100 for imaging in a first mode, and
in Step 202 an image of the object is captured using lens and
camera system 18 in the first mode. System 18 converts the light
image into an electronic image which can be digitized. This
digitized image is referred to as Image1 or I1. The digitized image
can be displayed on the display device, stored in memory,
transmitted to a remote location, processed to enhance the image,
and/or used to print a permanent copy of the image. The object
remains immobilized on sample object stage 104; no change in the
position/location of the object is made. The operator configures
system 100 for imaging in Step 204 and an image of the object is
captured using lens and camera system 18 in a second mode. The
resulting digitized image is referred to as Image2 or I2. Since the
position of the object was not moved or changed during the capture
of the images, both Image1 and Image2 can readily be merged or
superimposed in Step 206, using methods known to those skilled in
the art, such that the two images are co-registered. As such, a
third image can be generated comprising Image1 and Image2. In Step
208, the animal is removed from the object stage.
[0065] As indicated above, system 100 can be configured in several
modes, including: x-ray imaging, bright-field imaging, dark-field
imaging (including luminescence imaging, fluorescence imaging) and
radioactive isotope imaging. To configure system 100 for x-ray
imaging or isotope imaging, phosphor plate 125 is moved to position
P1 in optical registration with sample object stage 104 (as shown
in FIGS. 5B and 6). For an x-ray image, x-ray source 102 is
employed when capturing the image of the immobilized object. To
configure system 100 for bright-field imaging or dark-field imaging
(including luminescence imaging and fluorescence imaging) without
moving the immobilized object and the support member or object
stage, phosphor plate 125 is moved to position P2, out of optical
registration with sample object stage 104 (as shown in FIGS. 5C and
7), and an image of the immobilized object is appropriately
captured. The object is immobilized on sample object stage 104, and
light emitted from the object (usually diffusive within the turbid
constituents of a solid object) is projected to the object surface,
which intimately bears upon the upper surface of sample support
sheet 122.
[0066] For the purpose of optical imaging, the object surface is
defined by a refractive boundary (e.g., the skin of an animal) that
delineates the interior of the object (usually a heterogeneous,
turbid media of higher index of refraction) and air. Light
emanating from within an object (e.g., luminescent or transmitted)
projects to the surface from which it scatters, defining the light
that may be productively managed to create an image of the object.
Conversely, light may be provided from beneath optical platen 126
and scattered from the object surface, thereby providing reflective
light for imaging the same object. For optical imaging, the
definition of the object boundary may be moderated by matching the
refractive index of the object boundary to support sheet 122 by
introducing an index-matching fluid (e.g., water). The depth to
which good focus can be achieved in optical imaging is dependent on
minimizing the surface scatter of the object, and methods such as
index matching and increasing wavelength (e.g., near-infrared
imaging) are well known in the art.
[0067] The emitted sample light can arise from luminescence,
fluorescence, or reflection, and the focal plane of the lens can be
adjusted to the elevation of object surface. Alternatively, the
"light" can be ionizing radiation passing through or emitted from
the object, or passing into the phosphor and forming an image. Soft
x-rays, consistent with thin objects or small animals, project an
image through the diffusive phosphor onto the optical boundary,
adding the depth of the (more than about 0.02 mm) to the depth of
focus. More significant is the focal distance contributed by the
phosphor support plate 134, which may be fractional millimeters,
depending upon the thickness and index of the glass or plastic. The
fractional-millimeter elevation of the best focal plane contributed
by the phosphor support can provide a better coincidence between
the phosphor focal plane and the focal plane used for optical
imaging. For near-infrared optical imaging, the preferred/best
focal plane may be located at millimeter depths into a nominally
turbid object. The phosphor support plate 134 can be thicker to
maximize the coincidence of the optical and phosphor imaging
planes. Those skilled in the art will recognize how to tune the
materials of the present invention to optimally co-locate the
preferred optical and phosphor imaging planes. Currently described
materials may be practically assembled to assure multi-modal focal
plane co-location to accommodate the demands of a fast lens
system.
[0068] Appropriately fast lens systems for dark-field and x-ray
imaging applications will likely have sub-millimeter focal depths,
necessitating the above considerations. Accordingly, for a
particular embodiment, it may be desirable for multiple optical
elements to enable the location of a common focal plane shared by
differing modes of imaging.
[0069] Emitted gamma rays from a thick object (such as 99Tc
emission from an animal organ) are distributed over the plane of
the phosphor, diffusing the image by millimeters, and an
appropriately thick phosphor layer (about 0.1 mm) may be preferred
for increased detection efficiency. Consequently, the location of
the focal plane at the supporting sheet is not critical to the
resolution of the radio isotopic image. Better resolution and more
precise planar projection of the emitting isotope can be achieved
by gamma-ray collimation. Collimators of millimeter-resolution are
available and capable of projecting isotopic location to millimeter
resolution at the focal plane of the phosphor in the present
invention.
[0070] Of particular relevance to the operation of the present
invention is the thickness of the layers in the focal plane of the
lens. For example, fast lenses, (which are essential elements for
the practice of imaging low-light emissions) will have a focal
depth of focus of about 0.5 mm for very fast lenses. For good
resolution of objects of interest, less than about 0.2 mm of
spatial resolution is desirable, and a megapixel CCD camera
(cooled) imaging at 100 mm field is suitable. Generally, more
resolution is desirable.
[0071] Precision registration of the multi-modal image can be
accomplished using methods known to those skilled in the art. By
placing the object on a thin, stretched optical support that allows
phosphor plate 125 to be removed without displacement of the
object, co-registered optical imaging is enabled by the same lens
and camera system using epi-illumination methodologies at a
sufficiently similar focal plane.
[0072] Examples are now provided. FIGS. 9A-9C show images captured
using the apparatus and the method of the present invention. A
mouse was immobilized on sample object stage 104 (step 200 of FIG.
8) of system 100. System 100 was first configured for near-infrared
fluorescence imaging wherein phosphor plate 125 is removed from
co-registration with frame 100. A first image was captured and is
displayed in FIG. 9A (step 202 of FIG. 8). Next, system 100 was
configured for x-ray imaging wherein phosphor plate 125 is placed
in co-registration with frame 100. A second image was captured and
is displayed in FIG. 9B (step 204 of FIG. 8). Using methods known
to those skilled in the art, the image of FIG. 9A was thresholded
to make transparent those regions with pixel intensity values less
than the threshold value and then the thresholded image was merged
with the image of FIG. 9B in step 206 of FIG. 8; and the merged
image is displayed in FIG. 9C. Note that the fluorescent signals
superimposed on the anatomical reference clarify the assignment of
signal to the bladder and an expected tumor in the neck area of
this illustrated experimental mouse. It is noted that the first
and/or second image can be enhanced using known image processing
methods/means prior to be merged together. Alternatively, the
merged image can be enhanced using known image processing
methods/means. Often, false color is used to distinguish
fluorescent signal from gray-scale x-rays in a merged image.
[0073] FIGS. 10A-10C provide a further example using an apparatus
suitable for use in accordance with the method of the present
invention. FIG. 10A is a near-infrared fluorescence image of a
mouse while FIG. 10B is an x-ray image of the same immobilized
mouse. Using methods known to those skilled in the art, the first
and second images were merged in the manner previously described
and the merged image is displayed in FIG. 10C. Prior to being
merged, the first and second images were contrasted, using methods
known to those skilled in the art. This processing allows
particular areas of the mouse to be visually enhanced for
diagnostic purposes. For example, areas 150, 152, and 156 are
potential secondary early detection sites, and area 154 shows the
primary tumor injection site at the knee.
[0074] FIGS. 11A-11C provide yet a further example using an
apparatus suitable for use in accordance with the method of the
present invention. FIG. 11A is a near-infrared fluorescence image
of a mouse wrist while FIG. 11B is an x-ray image of the same
immobilized mouse wrist. Using methods known to those skilled in
the art, the first and second images were merged in the manner
previously described and the merged image is displayed in FIG. 11C.
The merged image provides a diagnostic image for viewing a
potential secondary tumor site. Note that this image set clearly
demonstrates the precision with which the apparatus of FIGS. 1 to 8
enables the co-location of images of objects from differing imaging
modes. The maximum fluorescent signal emanating from a
pre-metastatic tumor on the radius (arm-bone) tip at the wrist is
within about 0.1 mm of the suspect lesion subsequently identified
by microscopic histology.
[0075] A phosphor plate suitable for use with the method of the
present invention is disclosed in U.S. Pat. No. 6,444,988 (Vizard),
commonly assigned and incorporated herein by reference. A phosphor
plate as described in Vizard is shown in FIG. 12. A suitable
phosphor plate 125A for use with the apparatus and the method of
the present invention includes a transparent support 210 (such as
glass) upon which is coated an interference filter 220 which is a
multicoated short-pass filter designed to transmit light at a
specified wavelength (and below) and reflect light above that
wavelength. Plate 125A also includes a thin phosphor layer 240 and
a removable thick phosphor layer 260. Thin phosphor layer 240 is
used for high resolution imaging applications of ionizing radiation
or for very low energy (self-attenuating) ionizing radiation such
as low-energy electrons or beta particles. Thick phosphor layer 260
is used for high-energy ionizing radiation that freely penetrates
the phosphor. Thick phosphor layer 260 is removable and is shown in
FIG. 12 overlaying thin phosphor layer 240. Layer 260 is removable
to the position shown in dashed lines out of contact with layer
240.
[0076] The phosphor preferably used in phosphor layers 240 and 260
is Gadolinium Oxysulfide Terbium whose strong monochromatic line
output (544-548 nanometers (NM) is ideal for co-application with
interference optics. This phosphor has technical superiority
regarding linear dynamic range of output, sufficiently "live" or
prompt emission and time reciprocity, and intrascenic dynamic range
which exceed other phosphors and capture media. This phosphor layer
preferably has a nominal thickness of 10-30 micrometers (.mu.m) at
5-20 grams/square foot (g/ft.sup.2) of phosphor coverage, optimally
absorbing 10-30 Kev x-rays. Thick phosphor layer 260 has a nominal
thickness of 100 .mu.M at 80 g/ft.sup.2 of phosphor coverage.
[0077] The duplex phosphor layers impart flexibility of usage for
which the thick phosphor layer 260 may be removed to enhance the
spatial resolution of the image. Thin phosphor layer 240 intimately
contacts filter 220, whereas thick phosphor layer 260 may be
alternatively placed on thin phosphor layer 240. Interference
filter 220 transmits light at 551 NM and below and reflects light
above that wavelength. Filter 220 comprises layers of Zinc
Sulfide-Cryolite that exhibits a large reduction in cutoff
wavelength with increasing angle of incidence. The filter has a
high transmission at 540-551 NM to assure good transmission of
540-548 NM transmission of the GOS phosphor. The filter also has a
sharp short-pass cut-off at about 553 NM, that blue shifts at about
0.6 NM per angular degree of incidence to optimize optical gain.
Glass support 210 should be reasonably flat, clear, and free of
severe defects. The thickness of support 210 can be 2 millimeters.
The opposite side 280 of glass support 210 is coated with an
anti-reflective layer (such as Magnesium Fluoride, green optimized)
to increase transmittance and reduce optical artifacts to ensure
that the large dynamic range of the phosphor emittance is
captured.
[0078] Referring now to FIG. 13, there is shown a method of
producing phosphor layer 240. In Step 300, a mixture of GOS:Tb in a
binder is coated on a polytetrafluoroethylene (PTFE) support. The
PTFE support enables release of the coated phosphor layer from the
PTFE support and subsequent use of the phosphor layer without
support, since conventional supporting materials are an optical
burden to screen performance. For the thin phosphor layer 240, in
Step 320 an ultra thin (about 0.5 g/ft.sup.2, 0.5 .mu.m thick)
layer of cellulose acetate overcoat can be applied to offer
improved handling characteristics of the thin phosphor layer and to
provide greater environmental protection to the underlying optical
filter. In Step 340, the phosphor layer is removed from the PFTE
support. The thin phosphor layer overcoated side is overlayed on
interference filter 220 in Step 360. Clean assembly of the thin
phosphor layer 240 and filter 220 assures an optical boundary that
optimizes management of screen light output into the camera of the
lens/camera system. Optical coupling of layer 240 and filter 220 is
not necessary, since performance reduction may result. In Step 380,
layer 240 can be sealed around its periphery and around the
periphery of filter 220 for mechanical stability and further
protection of the critical optical boundary against environmental
(e.g., moisture) intrusion.
[0079] Advantages of the method of the present invention include:
anatomical localization of molecular imaging agent signals in small
animals, organs, and tissues; precise co-registration of anatomical
x-ray images with optical molecular and radio isotopic images using
one system; improved understanding of imaging agent's
biodistribution through combined use of time lapse molecular
imaging with x-ray imaging; and simple switching between
multi-wavelength fluorescence, luminescence, radio-isotopic, and
x-ray imaging modalities without moving the object/sample.
[0080] Reference is made to the following commonly assigned,
copending U.S. patent applications: Ser. No. 12/381,599 filed Mar.
13, 2009 by Feke et al, entitled METHOD FOR REPRODUCING THE SPATIAL
ORIENTATION OF AN IMMOBILIZED SUBJECT IN A MULTI-MODAL IMAGING
SYSTEM; and Ser. No. 12/475,623 filed Jun. 1, 2009 by Feke et al,
entitled TORSIONAL SUPPORT APPARATUS AND METHOD FOR CRANIOCAUDAL
ROTATION OF ANIMALS, the disclosures of both of which are
incorporated by reference into this specification.
[0081] FIGS. 14A, 14B, 15A and 15B show a diagrammatic partial view
of the sample stage 104 (a transparent tube in this instance) of
the imaging system 100 of FIGS. 3A and 3B where the subject mouse
112 is positioned in a chamber 113 and administered immobilizing
anesthesia through a respiratory device 114 connected to an outside
source via a tube 115 which enters the sample environment 108 via
the light-locked gas ports. A rotational mechanism 116 may be
provided for adjusting the rotational position of the mouse about
its craniocaudal axis. A translational mechanism 117 may be
provided to adjust the axial location of the mouse relative to
source 102 and fiber optics 106. Further details of the structure
shown in these figures are disclosed in the first application of
Feke et al, mentioned in the preceding paragraph. An X-ray
anatomical image 140 and a near-infrared fluorescence image 142 are
acquired of the gastro-intestinal tract of the immobilized subject
mouse 112. Images 140, 142 are shown side by side in FIGS. 16A and
16B.
[0082] In a preferred embodiment of the present invention,
referring to FIGS. 14A and 14B, an X-ray image 140 provides a
convenient anatomical map of musculoskeletal features of the
subject mouse 112. The X-ray image 140 is an orthogonal imaging
modality that will not pollute optical signals emanating from the
subject. While the skeleton provides the framework to spatially
assign organs, X-ray contrast agents may be administered to the
mouse in accordance with the invention to provide an effective
means to delineate tissues that typically give poor contrast by
X-ray.
[0083] FIG. 21 shows an anatomical X-ray image of a mouse in the
sample chamber on the sample object stage of the imaging system of
FIGS. 3A and 1B. Labels refer to regions A: Bones/Joints, B: Heart,
C: Lungs, D: Liver, E: Kidneys, F: GI Tract, and G: Bladder. Since
bones are dense structures they absorb X-rays and appear dark. One
can immediately note the fine structure in bones that are
sub-millimeter in scale, like the rib cage and fibia bones in the
leg. Many disease models involving the skeleton may be
non-invasively studied using such images. These include bone growth
and damage in response to environmental or physical inputs.
Furthermore, subtle changes in bone density may also be measured.
While bones are dense and provide positive contrast that appears
black, air is obviously of low density and absorbs very little
X-ray radiation. Thus, locations in an animal that contain gases
give contrast toward the white end of the intensity spectrum shown
in FIG. 21. One area in which air is plentiful is in the lungs
(FIG. 21 region C). In fact, the rib cage is often considered a
cavern of air due to the presence of the lungs, which appear as a
triangular pattern on each half of the rib cage. Incidentally,
another area in which gas tends to build up and give negative
contrast on X-ray is in the bowels (FIG. 21 region F).
Nevertheless, the air cavern of the rib cage is home to another
important organ: the heart (FIG. 21 region B). Since the tissue
comprising the heart has higher density than air, it gives positive
(dark) contrast in comparison to the lungs. Indeed, since this
organ is effectively surrounded by air from the lungs, it is often
described as a "heart shadow" in the rib cage. The size of the
heart shadow may be measured as it expands into the lung area. If
its size increases too much, it is an indication of pulmonary
edema, a condition in which the heart fills with liquid and expands
to unsafe levels. Pulmonary edema has been measured and studied in
rat models of heart disease. While the heart and lungs are soft
tissue systems that are readily observed by X-ray, other organs
possess little innate contrast to permit their imaging and require
an alternate strategy. Organs like the stomach, gastrointestinal
tract, kidneys, bladder and liver give little to no contrast during
X-ray imaging. FIG. 21 regions D-F shows the lack of discernable
contrast from each of these various tissue systems in the abdomen.
However, through the use of x-ray contrast agents in accordance
with the present invention, these organs can be delineated and
studied in a non-invasive fashion using the X-ray modality.
Molecules that incorporate atoms with exceptional X-ray absorption
properties are typically utilized as contrast agents. Barium and
iodine meet this criterion and are two of the most widely used
atomic components of X-ray contrast agents. Indeed, both of these
reagents have been utilized in the clinic for decades to perform
gastric and heart perfusion imaging, among others. X-ray contrast
agents effectively absorb X-ray irradiation, thus providing
contrast in the organs in which they reside. Different X-ray
contrast agents may be chosen depending on the organ to be imaged.
For example, barium sulfate may be administered orally to the
subject to view its stomach and gastrointestinal tract as shown in
images 140 and 142 of FIGS. 14B and 16A. Iodinated contrast agents
may be used intravenously to image the kidneys of the animal under
study as shown in images 144 and 146 of FIG. 17. Other agents like
gold nanoparticles may be used to add X-ray contrast to the liver,
kidneys, or tumors.
[0084] The x-ray contrast agent may be administered at various time
points in an imaging study to assign and delineate organs using
X-ray imaging. A researcher will use that anatomical information to
determine the contribution of fluorescent or luminescent signal
emanating from that organ at that time point. For example as shown
by the images in FIGS. 17A, 17B and 17C, a researcher may
administer a fluorescent probe into an animal at time zero. At this
and subsequent time points, the X-ray contrast agent may be given
to the subject. A fluorescence image 146 is then acquired to
capture signal from the original fluorescence probe as shown in
FIG. 17B, and is immediately followed by an X-ray image 144 to view
the organs as shown in FIG. 17A. In a final step, the images are
then overlaid, or combined, to determine co-localization of the
fluorescent signal to the organ of interest as shown in image 148
of FIG. 17C. Alternatively, the fluorescence imaging probe and the
x-ray contrast agent may be administered to the mouse essentially
simultaneously.
[0085] Referring now the workflow shown in FIG. 18 and FIGS. 17, 19
and 20, in Step 400 the optical imaging agent and X-ray contrast
agent are introduced into the subject 112 as per the experimenter's
protocol. In Step 410, the subject mouse 112 is placed on the
object stage 104. The anatomical X-ray image 144 and near-infrared
fluorescence image 146 are acquired in Step 420 and a co-registered
image 148 of the anatomical X-ray image 144 and near-infrared
fluorescence image 146 shown FIG. 17 is created in Step 430.
[0086] An example of this strategy in practice is given in FIGS.
14A through 16B, previously discussed. In this case, the
experimenter is attempting to localize a fluorescent signal with
the gastrointestinal (GI) tract. Since this sizable organ yields
poor contrast in an X-ray image, an x-ray contrast agent must be
utilized. Agents such as barium sulfate have been used in the
clinic for decades to resolve GI features. Since barium salts are
generally insoluble and inert, they may be safely used in the human
GI tract, either orally or rectally, to provide contrast during
X-ray imaging. After imaging is complete, the barium is excreted
from the subject without absorption into the body. However, the use
of agents such as barium sulfate in small animal imaging has been
minimal, and they have not been used in a multimodal approach to
localize fluorescent or luminescent signals. The images shown in
FIGS. 14B, 15B, 16A and 16B illustrate how contrast agents like
barium sulfate may be utilized for the anatomical co-registration
of fluorescent or luminescent signals during optical imaging. These
figures show an example of a mouse after one hour of consumption of
40 mg of a 1:1 mixture of barium sulfate and creamy peanut butter
combined with Kodak X-Sight 761 Nanospheres, which are
near-infrared fluorescent nanoparticles (commercially available
from Carestream Health, Inc.). In this case, the contrast agent and
fluorescent nanoparticles were administered simultaneously.
Subsequent experiments could possibly use the barium sulfate/peanut
butter mix alone to determine the clearance of the original dose of
fluorophore. FIGS. 14B and 16A show the X-ray image 140 with
excellent barium sulfate contrast (Target/Non-Target=1.33) of the
GI tract. The near-infrared fluorescence image 142 of FIGS. 15B and
16B show near-infrared fluorescence from the nanoparticles. In this
case, the origin of the optical signal is coincident with barium
sulfate contrast of the X-ray image 140.
[0087] In addition to barium sulfate, iodinated contrast agents as
well as gold nanoparticles may be used as X-ray contrast agents for
various tissues. Iodine is a synthetically accessible atom with
sufficient electron density to yield X-ray contrast. Thus, it has
been incorporated into several compounds that may be synthesized as
water soluble through contrast agents. These reagents are generally
used for the purposes of intravenous injection since they are not
harmful, and will rinse out of the subject through the renal
pathway. Several iodine based contrast agents are commercially
available for use in humans for imaging of heart vasculature and
other bulk tissues. FIGS. 17A to 17C, 19A and 19B, and 20A and 20B
show the utilization one such agent, Visipaque.TM. (iodixanol)
commercially available from GE Healthcare, to localize a
fluorescent signal in the renal system of mice. The mouse was
administered an intravenous injection of 200 .mu.L of Visipaque
(iodixanol) (320 mg/ml iodine) combined with Kodak X-Sight 670
Large Stokes Shift dye, which is a near-infrared fluorescent dye
(commercially available from Carestream Health, Inc.). The contrast
agent and dye concentrated in the kidneys thereby providing clear
contrast in them.
[0088] FIG. 22 shows a graph of the excess x-ray density in the
medullary regions of the kidneys conferred by the Visipaque vs. the
injected volume of the Visipaque. Varying volumes of Visipaque were
mixed with complementarily varying volumes of phosphate buffered
saline to achieve a series of 200 .mu.L total injection volumes.
Mice were immobilized, and X-ray images were acquired both before
and 10 minutes after injection of the different Visipaque injection
volume for each mouse. The images before injection were subtracted
from the images after injection corresponding to each mouse
receiving a different Visipaque injection volume to create
difference images, and a region-of-interest analysis was performed
for the medullary regions of the kidneys in the difference images
to measure the excess x-ray density conferred by the Visipaque in
the medullary regions. The graph shows that the excess x-ray
density in the medullary regions of the kidneys, wherein the excess
x-ray density of both kidneys was averaged together for each mouse,
is directly proportional to the injected volume of the Visipaque,
with a constant of proportionality of 0.0032 as determined by a
linear fit of the data.
[0089] As indicated earlier in this specification, the x-ray
contrast agents and optical imaging agents may be targeted,
non-targeted, or both. In accordance with the invention, the x-ray
contrast agent may be targeted while the optical imaging agent is
non-targeted; or the x-ray contrast agent may be non-targeted while
the optical imaging agent is targeted; or both agents may be
targeted; or both agents may be non-targeted. The following table
lists the agents previously mentioned along with other known agents
that the inventors consider appropriate for use in any convenient
combination suited for an anatomical region of interest, without
departing from the scope of the present invention.
TABLE-US-00001 Targeted or Anatomical Agent Modality Non-targeted
Regions Comments Barium X-ray Non-targeted Gastrointestinal Example
in sulfate tract this spec Barium X-ray Non-targeted Vasculature
sulfate in gelatin (Baritop) Iodinated X-ray Non-targeted
Vasculature, Example in contrast renal this spec agents Fenestra VC
X-ray Non-targeted Vasculature, renal Fenestra LC X-ray
Non-targeted Hepatobiliary eXIA 160 X-ray Targeted Vasculature
Radiocontrast eXIA 160 X-ray Non-targeted Hepatobiliary
Radiocontrast and Splenic Gold X-ray Non-targeted Vasculature,
nanoparticles renal, tumors Corrosion X-ray Non-targeted
Vasculature casting material Batson's 17 with added lead pigment
Silicon X-ray Non-targeted Vasculature rubber; Microfil MV122
Agents X-ray Targeted Various disclosed in U.S. Pat. No. 5,141,739
Kodak X- Optical Non-targeted Gastrointestinal Example in Sight
tract this spec Nanospheres Kodak X- Optical Non-targeted
Vasculature, Example in Sight hepatobiliary this spec Nanospheres
Kodak X- Optical Non-targeted Renal Example in Sight large this
spec Stokes shift dyes Gold X-ray Non-targeted Vasculature,
nanoparticles renal, tumors Corrosion X-ray Non-targeted
Vasculature casting material Batson's 17 with added lead pigment
Silicon X-ray Non-targeted Vasculature rubber; Microfil MV122
Agents X-ray Targeted Various disclosed in U.S. Pat. No. 5,141,739
Kodak X- Optical Non-targeted Gastrointestinal Example in Sight
tract this spec Nanospheres Kodak X- Optical Non-targeted
Vasculature, Example in Sight hepatobiliary this spec Nanospheres
Kodak X- Optical Non-targeted Renal Example in Sight large this
spec Stokes shift dyes Kodak X- Optical Targeted Various Sight
Nanosphere Conjugates Kodak X- Optical Targeted Various Sight large
Stokes shift dye conjugates Qdots Optical Non-targeted Qdot Optical
Targeted Vascular, conjugates hepatobiliary Various dyes Optical
Non-targeted Various Various dye Optical Targeted Vascular
conjugates Fluorescent Optical Non-targeted Vasculature, silica
renal, hepatobiliary Fluorescent Optical Targeted Various silica
conjugates Nanoparticles Optical Non-targeted Vascular, derived
from hepatobiliary self-assembly of amphiphilic copolymers
Nanoparticles Optical Targeted Various derived from self-assembly
of amphiphilic copolymers Fluorescent Optical Targeted Various
proteins Luciferase Optical Targeted Various
[0090] The X-ray contrast agents described herein, when used as
disclosed, provide a facile methodology for the anatomical
co-registration of both targeted and non-targeted fluorescent and
luminescent signals during molecular imaging.
[0091] The invention has been described in detail with particular
reference to a presently preferred embodiment, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention. The presently disclosed
embodiments are therefore considered in all respects to be
illustrative and not restrictive. The scope of the invention is
indicated by the appended claims, and all changes that come within
the meaning and range of equivalents thereof are intended to be
embraced therein.
PARTS LIST
[0092] 10 electronic imaging system [0093] 12 light source [0094]
14 optical compartment [0095] 16 mirror [0096] 18 lens and camera
system [0097] 20 communication and computer control system [0098]
22 computer monitor [0099] 100 imaging system of the present
invention [0100] 102 x-ray source [0101] 104 sample object stage or
support member [0102] 106 epi-illumination; fiber optics [0103] 108
sample environment [0104] 110 access means/member [0105] 112
subject mouse [0106] 113 chamber for mouse 112 [0107] 114
respiratory device [0108] 115 tube [0109] 116 rotational mechanism
[0110] 117 translational mechanism [0111] 120 frame [0112] 122
support sheet [0113] 125, 125A phosphor plate [0114] 126 optical
platen [0115] 128 protective layer [0116] 130 phosphor layer [0117]
132 optical layer [0118] 134 support plate; glass [0119] 136 air
gap or void [0120] 138 air gap or void [0121] 140 x-ray image
[0122] 142 near-infrared fluorescence image [0123] 144 x-ray image
[0124] 146 near-infrared fluorescence image [0125] 148
co-registered image [0126] 150, 152, 156 potential secondary early
detection sites [0127] 154 primary tumor injection site [0128] 200
to 208 method steps [0129] 210 transparent support [0130] 220
interference filter [0131] 240 thin phosphor layer [0132] 260 thick
phosphor layer [0133] 280 opposite side [0134] 300 to 380 method
steps [0135] 400 to 430 method steps
* * * * *