clinical translation of ultrasound-guided photoacoustic...
TRANSCRIPT
1
Clinical Translation of
Ultrasound-Guided
Photoacoustic Imaging
Stanislav (Stas) Emelianov
Department of Biomedical Engineering
The University of Texas at Austin
Department of Imaging Physics The University of Texas M.D. Anderson Cancer Center
Detection of Micrometastases in
Sentinel Lymph Node (SLN)
Primary tumor metastasizes through lymphatic system Melanoma, Breast cancer, Head and neck squamous carcinoma
Lymph
nodes
Sentinel lymph node SLN is a first organ to be
reached by metastasizing
cancer cells from the
primary tumor
No single imaging
modality can • localize SLN, and
• detect metastases
(presence of cancer
cells in SLN)
Metastasis
Cancer
cells
Detection/Characterization/Treatment
of SLN using Imaging/Biopsy/Surgery A
D C
B
Lymph
nodes
Metastasis
Cancer
cells
2
• Dye and radioactive tracer are
injected near the tumor
• Contrast agent is allowed to
drain to lymph nodes
• Lymphoscintigraphy is
performed to identify the
sentinel node
• Biopsy is performed to sample
sentinel lymph node
• If positive for micrometastatic
cancer cell, sentinel and
axillary lymph nodes are
surgically removed
Detection/Characterization of SLN
using Imaging/Biopsy
• Highly effective
• Accurate prognosis
• May take up to 2 weeks
• Invasive
• Requires multiple specialists
(nuclear medicine, surgery,
pathology)
Lymph
nodes
Metastasis
Cancer
cells
Detection/Characterization/Treatment
of SLN using Imaging/Biopsy/Surgery A
D C
B
Lymph
nodes
Metastasis
Cancer
cells
We are
here Information
Dis
ease
Disease Management
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Monitoring
Treatment
Characterization
Detection
3
We are
here Information
Dis
ease
Disease Management: Problem
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Monitoring
Treatment
Characterization
Detection
Personalized
medicine
We are
here
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Monitoring
Treatment
Characterization
Detection
mm = 10-3 m nm = 10-9 m Spatial Scale
Disease Management: Challenge
Monitoring
Treatment
Characterization
Detection
Molecular Probe Augmented
Ultrasound/Photoacoustic (USPA) Imaging
Grayscale
Ultrasound
Conventional
Ultrasound
Ultrasound Combined with
Photoacoustics
Solution:
Ultrasound and Photoacoustics
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
4
Photoacoustics Imaging and Sensing:
Alexander Bell, 1980
Alexander Bell A. Bell and C. Tainter, 1880
Photoacoustics: Lightning and Thunder
Photoacoustics Imaging
Lightning and Thunder An optical absorber is irradiated with a short pulse of light (up to 5 cm deep)
Optical energy is absorbed and converted into thermal energy (0.01-0.05 ºC)
Deposition of heat leads to rapid thermal expansion of medium and generation of acoustic (pressure) transients (hundreds of Pa)
The acoustic signal can be recorded using ultrasound transducer and used to “detect” the absorber
1
2
3
4
EM Heat
Heat Pressure
5
An optical absorber is irradiated with a short pulse of light (up to 5 cm deep)
Optical energy is absorbed and converted into thermal energy (0.01-0.05 ºC)
Deposition of heat leads to rapid thermal expansion of medium and generation of acoustic (pressure) transients (hundreds of Pa)
The acoustic signal can be recorded using ultrasound transducer and used to “detect” the absorber
1
2
3
4
z
oeffeFzF
)(
DT(z) =ma (z)F(z)
r ×Cp
Incompressibility
small DT« large P
( ) ( ) ( )ap z z F z
tVz sound
Photoacoustics Imaging
Lightning and Thunder
Photoacoustic Imaging:
Optical (Imaging/Therapeutic) Window
400 500 600 700 800 900 1000 1100 1200 1300
Epidermis (a+s)
Water (a)
103
102
101
100
10-1
10-2
10-3
Fat (a)
Fat (a)
HbO2 (a)
Hb (a)
Optical wavelength (nm)
Absorp
tion (
a)
coeffic
ient (c
m-1
)
Extinction (
a+
s)
coeffic
ient
(cm
-1)
Fat (a)
Water (a)
Optical window (650-1700 nm)
Contrast in PA imaging is primarily
related to optical absorption
( ) ( ) ( )ap z z F z
Integrated USPA Imaging System
(Ultrasound and Photoacoustics)
Integrated
Imaging
Probe
6
Integrated USPA Imaging System
(Ultrasound and Photoacoustics)
Several clinical systems are
being developed and tested
Clinical Prototype of USPA Imager Ultrasound imaging system (Verasonics) Laser (Opotek) Handheld
probe
Monitoring
Treatment
Characterization
Detection
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging
7
Mouse Model of
Metastatic Oral Cancer
Lymph
node
• Primary tumor in a tongue of a mouse
• After 2-3 weeks, micrometastatic foci are
formed in sentinel lymph node(s)
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging Monitoring
Treatment
Characterization
Detection
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging Monitoring
Treatment
Characterization
Detection
?
8
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging Monitoring
Treatment
Characterization
Detection
Functional Imaging:
Hemoglobin (Hb)
400 500 600 700 800 900 1000 1100 1200 1300
Water (a)
103
102
101
100
10-1
10-2
10-3
Fat (a)
Fat (a)
HbO2 (a)
Hb (a)
Optical wavelength (nm)
Absorp
tion (
a)
coeffic
ient (c
m-1
)
Extinction (
a+
s)
coeffic
ient
(cm
-1)
Fat (a)
Water (a)
Optical window (650-1300 nm)
1
Functional Imaging:
Total Hemoglobin and Oxygen Saturation
400 500 600 700 800 900 1000 1100 1200 1300
Water (a)
103
102
101
100
10-1
10-2
10-3
Fat (a)
Fat (a)
HbO2 (a)
Hb (a)
Optical wavelength (nm)
Absorp
tion (
a)
coeffic
ient (c
m-1
)
Extinction (
a+
s)
coeffic
ient
(cm
-1)
Fat (a)
Water (a)
𝑆𝑂2𝑥, 𝑦 =
𝐶𝐻𝑏𝑂2(𝑥, 𝑦)
𝐶𝐻𝑏𝑂2𝑥, 𝑦 + 𝐶𝐻𝑏(𝑥, 𝑦)
2 1
9
Detection/Characterization of SNL
1 mm
Normal lymph
node Metastatic
lymph node
50 100 150 200 250 300 350 400 450 500
50
100
150
200
250
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Oxygen
satu
ratio
n
50%
100%
Oxygen
satu
ratio
n
0%
100%
Detection/Characterization of SNL
10-3
10-2
10-1
100
50
55
60
65
70
Metastasis Volume (mm3)
SO
2 (
%)
• SO2 varies with
metastatic invasion
• SO2 indicated
widespread functional
changes
• SO2 is inversely related
to metastasis size
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging Monitoring
Treatment
Characterization
Detection
10
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging Monitoring
Treatment
Characterization
Detection
?
500 600 700 800 0
0.25
0.50
0.75
1.00
Extin
ctio
n (
a.u
.)
Wavelength (nm)
500 600 700 800 0
0.25
0.50
0.75
1.00
Extin
ctio
n (a
.u.)
Wavelength (nm)
Cellular/Molecular Imaging (Cancer cells, Stem cells, Macrophages, etc.)
Unla
be
led
ce
lls
La
be
led
ce
lls
?
Cellular/Molecular Imaging (Cancer cells, Stem cells, Macrophages, etc.)
Dye-stained cells
Nanoparticle-labeled cells
(Clinically approved)
optical dyes
(Metallic)
nanoparticles
11
Contrast nanoAgents for
US/PA Molecular Imaging
100 nm
100 nm
100 nm
30 nm
20 nm
25 nm
Silica-coated gold nanorods
Magneto-
photo-
acoustic
liposomes
Silver/
polymer Silver
stars
Silver
nanoplates
Remotely-triggered
photo-acoustic nanodroplets
Nanoclusters
Gold
nanosphere
100 nm
200 nm
Contrast Agents for Molecular US/PA Imaging:
Plasmonic Nanoparticles and/or Optical Dyes
400 500 600 700 800 900 1000 1100 1200 1300
104
103
102
101
100
10-1
10-2
10-3
Absorp
tion (
a)
coeffic
ient (c
m-1
)
Extinction (
a+
s)
coeffic
ient
(cm
-1)
Epidermis: rat (a+s)
Media (a+s)
Adventitia (a+s) Intima (a+s)
Water (a)
Fat (a)
Fat (a)
HbO2 (a)
Hb (a)
Nanospheres Aspect Ratio Nanorods
Methylene Blue (~680 nm) Indocyanine Green (~700 mn)
Contrast Agents for Molecular US/PA Imaging:
Plasmonic Nanoparticles and/or Optical Dyes
400 500 600 700 800 900 1000 1100 1200 1300
104
103
102
101
100
10-1
10-2
10-3
Absorp
tion (
a)
coeffic
ient (c
m-1
)
Extinction (
a+
s)
coeffic
ient
(cm
-1)
Epidermis: rat (a+s)
Media (a+s)
Adventitia (a+s) Intima (a+s)
Water (a)
Fat (a)
Fat (a)
HbO2 (a)
Hb (a)
Nanospheres Aspect Ratio Nanorods
Methylene Blue (~680 nm) Indocyanine Green (~700 mn)
Plasmonic (e.g., gold, silver) nanoparticles (NPs)
are strong optical absorbers due to localized
surface plasmon resonance (LSPR or SPR):
NP/tissue ratio – 106, NP/dye ratio – 105
12
Contrast Agents for Molecular US/PA Imaging:
Plasmonic Nanoparticles and/or Optical Dyes
400 500 600 700 800 900 1000 1100 1200 1300
104
103
102
101
100
10-1
10-2
10-3
Absorp
tion (
a)
coeffic
ient (c
m-1
)
Extinction (
a+
s)
coeffic
ient
(cm
-1)
Epidermis: rat (a+s)
Media (a+s)
Adventitia (a+s) Intima (a+s)
Water (a)
Fat (a)
Fat (a)
HbO2 (a)
Hb (a)
Nanospheres Aspect Ratio Nanorods
Methylene Blue (~680 nm) Indocyanine Green (~700 mn)
Based on size, shape and composition,
peak optical absorption of gold/silver/silica NPs
can be tuned to a desired optical wavelength
within tissue optical window
Contrast Agents for Molecular US/PA Imaging:
Plasmonic Nanoparticles and/or Optical Dyes
400 500 600 700 800 900 1000 1100 1200 1300
104
103
102
101
100
10-1
10-2
10-3
Absorp
tion (
a)
coeffic
ient (c
m-1
)
Extinction (
a+
s)
coeffic
ient
(cm
-1)
Epidermis: rat (a+s)
Media (a+s)
Adventitia (a+s) Intima (a+s)
Water (a)
Fat (a)
Fat (a)
HbO2 (a)
Hb (a)
Nanospheres Aspect Ratio Nanorods
Methylene Blue (~680 nm) Indocyanine Green (~700 mn)
Due to their nanometer size and, therefore, ability
to escape vasculature and diffuse into tissue,
plasmonic nanoparticles are ideal candidates for
molecular PA imaging
Ultrasound/Photoacoustic Imaging with
Molecularly Targeted NanoAgents
Integrated
Imaging
Probe
13
Detection and Characterization of SLN
using Molecular USPA Imaging Tumor
Lymph nodes
Sentinel lymph node
• Cocktail of optical dye and
targeted gold nanospheres
are injected near the tumor
• Contrast agent is allowed to
drain to lymph nodes
• Ultrasound-guided
photoacoustic (USPA) imaging
is performed to identify
– the sentinel node
– cancer cells within the node
Gold nanosphere
PEG-SH
Linker
anti-EGFR mAb
Targeted gold
nanospheres
Detection of Micrometastases in
Sentinel Lymph Node (SLN)
• We have developed an approach based on
– Gold nanospheres targeted to phenotype of the
primary tumor (peak absorption at ~530 nm)
– Ultrasound-guided spectroscopic photoacouistics
• In this approach
– Nanoparticles are injected near the tumor and
allowed to drain to lymph node (SLN)
– US/PA imaging is performed within 680-750 nm
wavelength range to identify receptor-mediated
endosytosed nanoparticles
Molecular Photoacoustic Imaging
Ultra
sound
Drainage only,
no cells-NPs
interaction
Drainage and
cells-NPs
interaction
Ph
oto
aco
ustics
680 n
m
US/PA imaging of tissue models
using 680 nm optical wavelength
that is away from the resonance
of individual particles (530 nm)
Normal cells
mixed with NPs
Cancer cells
mixed with NPs
14
Molecular Photoacoustic Imaging
Ultra
so
un
d
Drainage only,
no cells-NPs
interaction
Drainage and
cells-NPs
interaction
Ph
oto
aco
ustics
680 n
m
500 600 700 800 0
0.25
0.50
0.75
Extin
ctio
n (a
.u.)
Wavelength (nm)
Plasmon
coupling
Molecular Photoacoustic Imaging
Ultra
sound
Drainage only,
no cells-NPs
interaction
Drainage and
cells-NPs
interaction
Ph
oto
aco
ustics
680 n
m
Targeted nanoparticles, due to
interaction with cancer cells,
change their optical properties
and act as molecularly
activated nanosensors.
Photoacoustic Detection of
Micrometastases in
Sentinel Lymph Node
Lymph
node
• Injection of molecularly active plasmonic
sensors – MAPS (targeted 40 nm gold
nanospheres)
15
In-Vivo Mouse Imaging Studies Group C Group B Group A
No tumor
(normal mouse)
EGFR targeted
nanospheres
EGFR-positive
tumor and mets
RG16 targeterd
nanospheres
EGFR-positive
tumor and mets
EGFR targeted
nanospheres
Mismatch No match Match
Metastatic Mouse Model
Ultrasound Optical (Bioluminescence)
In-Vivo Mouse Imaging Studies
Only LN is shown
LN, blood,
and NPs are shown
3-D USPA images, cut-away view
(Group A)
(Gro
up A
) (G
roup B
) (G
roup C
)
Representative comparison
between three groups
16
Statistical Analysis
Group C Group B Group A
n = 12 nodes n = 7 nodes n = 5 nodes
• Statistically significant
increase in sPA signal in
positive group
• Sensitivity = 85.7%
• Specificity = 87.5%
Before injection
2 hours after
• Molecular PA imaging
can identify metastasis
within 30 minutes after
contrast agent injection.
• Clinically, the procedure
can be performed within
2-4 hour visit to an
outpatient facility.
17
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging Monitoring
Treatment
Characterization
Detection
Detection/Characterization of SLN and
Treatment of Axillary Lymph Nodes
Lymph nodes
Cocktail of dye and small (5-nm)
targeted gold nanospheres are
injected near the tumor
• Contrast agent is allowed to
drain to lymph nodes
Ultrasound-guided
photoacoustic (USPA) imaging
is performed to identify
– the sentinel node
– cancer cells within the node
• If positive for micrometastatic
cancer cell, sentinel and axillary
lymph nodes may be removed
• Non-invasive
• Non-ionizing
• Accurate
• Cancer specific
• Immediate
Detection/Characterization of SLN and
Treatment of Axillary Lymph Nodes
Lymph nodes
• Cocktail of dye and small (5-nm)
targeted gold nanospheres are
injected near the tumor
• Contrast agent is allowed to
drain to lymph nodes
• Ultrasound-guided
photoacoustic (USPA) imaging
is performed to identify
– the sentinel node
– cancer cells within the node
• Photothermal therapy
• Non-invasive
• Non-ionizing
• Accurate
• Cancer specific
• Immediate
• Imaging Therapy
18
Integrated US/PA Imaging and
Image-Guided Therapeutic System
Role of USPA Imaging in
Photothermal Therapy
Temperature
mapping
Delivery of
Nanoparticles
Targeted
Nanoparticles
Cancer
Cell
NP-labeled
Cancer Cell
CW Laser
Light
Thermal Imaging using
Photoacoustics • The photoacoustic signal is given by
• The Gruneisen parameter is temperature-dependent
• Therefore, PA pressure p(z,T) temperature T
zFzp a
pC
TcTT
2)()()(
zFbTazFTTzp aa )()(,
T : thermal expansion coefficient
c(T) : speed of sound
Cp : heat capacity
19
Photothermal Therapy using
Plasmonic Nanoparticles 0 sec 60 sec 180 sec
0℃
ΔT
15
℃ U
S /
PA
Ther
mal
0ºC
Δ
T 0℃
1
5 ℃
0 1 2 3 4 5 0
4
8
12
16
20
Time (min) Max
imu
m Δ
T (℃
)
NP Concentration
Photothermal Therapy using
Plasmonic Nanoparticles
34 50
Temperature (°C)
Before Injection After Injection
0 sec
30 sec
Monitoring
Treatment
Characterization
Detection
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging
20
Detection/Characterization of SLN and
Treatment of Micrometastases
Lymph nodes
?
Clearance of Nanoparticles
Tumor
Liver Kidneys
Bladder
Diameter: 20 ~ 150 nm
Particles smaller than 5.5 nm in diameter are rapidly cleared
by kidney from the body! Choi, H.S. et al. Nature Biotechnology (2007)
Tumor
Liver Kidneys
Bladder
Diameter: less than 5.5 nm
Detection/Characterization of SLN and
Treatment of Axillary Lymph Nodes
Lymph nodes
~5 nm
21
Detection/Characterization of SLN and
Treatment of Micrometastases
Lymph nodes
? ?
Detection and Characterization of SLN
using Molecular USPA Imaging Tumor
Lymph nodes
Sentinel lymph node
• Molecularly sensitive dye
is injected near the tumor
– Matrix Metalloproteinases (MMP)
are associated with metastasis
• Contrast agent is allowed to
drain to lymph nodes
• Ultrasound-guided
photoacoustic (USPA) imaging
is performed to identify
– the sentinel node
– cancer cells within the node
Kufe et al. Cancer Medicine MMPSense 750 FAST (Perkin Elmer)
680
nm
750
nm
Drainage and Activation of
MMP-sensitive Dye
Front view Side view Top view (MIP)
22
Perfluorocarbon NanoDroplets
for PA and US Imaging
US contrast:
Microbubble
2.5-in-1 Contrast Mechanisms
PA contrast:
Nanoparticles
PA contrast:
PFC vaporization
100 200 300 400 500 600 700 800 900 1000 1100
100
200
300
400
500
600
700
800100 200 300 400 500 600 700 800 900 1000 1100
100
200
300
400
500
600
700
800
Vaporization
Thermal
Expansion
Width (mm)
Depth
(m
m)
0 10 20
0
5
10
15
20
25
30
35
Ultrasound
Contrast
2.5-in-1 Contrast Mechanisms PA US PA
23
50 100 150 200 250
100
200
300
400
500
600
700
800
900
50 100 150 200 250
100
200
300
400
500
600
700
800
900
Photoacoustic
contrast:
vaporization
of PFC-nDs
(laser-triggered
liquid-to-gas
phase transition)
Ultrasound
contrast:
vaporized
PFC-nDs
(remaining
gas
microbubble)
Before laser irradiation After laser irradiation
50 100 150 200 250
100
200
300
400
500
600
700
800
900
Bla
nk
na
no
Dro
ple
ts
ICG
-Lo
ad
ed
na
no
Dro
ple
ts
50 100 150 200 250
100
200
300
400
500
600
700
800
900
USPA Detection of SLN
and Micrometastases • Injection of molecularly targeted dual
contrast agent – PFC nanodroplets
24
Monitoring
Treatment
Characterization
Detection
Molecular Probe Augmented
Ultrasound/Photoacoustic (USPA) Imaging
Grayscale
Ultrasound
Conventional
Ultrasound
Ultrasound Combined with
Photoacoustics
Combined
Ultrasound and Photoacoustics
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Physiological
Biochemical
Functional
Anatomical
Morphological
Structural
Cellular
Sub-cellular
Molecular
Detection/Characterization/Therapy of
SLN using USPA Imaging Monitoring
Treatment
Characterization
Detection
Acknowledgements
Industrial partners: Visualsonics, Inc. NanoHybrids, Inc. Athera Medical, Inc. Sonosite, Inc. Verasonics, Inc. TVL, TMA, ATI
Funding: National Institutes of Health National Science Foundation Breast Cancer Research Foundation Department of Defense American Heart Association
Collaborators from: University of Texas at Austin BME, ECE, ChE, ME, Chemistry Pharmacy, Dell Medical School UT MD Anderson Cancer Center UT Health Science Center Houston University of Alabama at Birmingham
25
Clinical Translation of
Ultrasound-Guided
Photoacoustic Imaging
Stanislav (Stas) Emelianov
Department of Biomedical Engineering
The University of Texas at Austin
Department of Imaging Physics The University of Texas M.D. Anderson Cancer Center