Clinical Translation of Ultrasound-Guided Photoacoustic ...amos3.aapm.org/abstracts/pdf/90-25313-339462-108053.pdf · Clinical Translation of Ultrasound-Guided Photoacoustic Imaging

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


SLN using USPA Imaging Monitoring

Treatment

Characterization

Detection

Physiological

Biochemical

Functional

Anatomical

Morphological

Structural

Cellular

Sub-cellular

Molecular



Treatment

Characterization

Detection

?

8

Physiological

Biochemical

Functional

Anatomical

Morphological

Structural

Cellular

Sub-cellular

Molecular



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)


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)


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



Treatment

Characterization

Detection

10

Physiological

Biochemical

Functional

Anatomical

Morphological

Structural

Cellular

Sub-cellular

Molecular



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)



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)


Media (a+s)


Water (a)

Fat (a)

Fat (a)

HbO2 (a)

Hb (a)



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



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)


Media (a+s)


Water (a)

Fat (a)

Fat (a)

HbO2 (a)

Hb (a)



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



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)


Media (a+s)


Water (a)

Fat (a)

Fat (a)

HbO2 (a)

Hb (a)



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



• 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


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


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



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




Ultrasound-guided





• If positive for micrometastatic

cancer cell, sentinel and axillary

lymph nodes may be removed

• Non-invasive

• Non-ionizing

• Accurate

• Cancer specific

• Immediate



Lymph nodes

• Cocktail of dye and small (5-nm)

targeted gold nanospheres are









• 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


SLN using USPA Imaging

20


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



Lymph nodes

~5 nm

21


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








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



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

Documents

Clinical Translation of Ultrasound-Guided Photoacoustic ...amos3.aapm.org/abstracts/pdf/90-25313-339462-108053.pdf · Clinical Translation of Ultrasound-Guided Photoacoustic Imaging