Fluorescence Assisted Resection and Exploration for Surgery

Sylvain Gioux, BS, ME Research assistant to John V. Frangioni Beth Israel Deaconess Medical Center Thursday, August 11, 2005

Outline  Introduction  Near infrared light  Fluorescent agents  System design  Zoom / Focus  Results  Conclusion

Introduction  Cancer detection problem  Blind surgery  Fluorescent contrast agents with high SNR  Imaging device

Outline  Introduction  Near infrared light  Fluorescent agents  System design  Zoom / Focus  Results  Conclusion

Near-infrared light

NIR Window

Autofluorescence White Light 1 cm GB SI Bl Green Filter Set Red Filter Set NIR Filter Set

Autofluorescence 200 150 100 50 0

Near-infrared light Invisible to the human eye but:  Safe at the fluence rates used  High transmission through living tissue  Tissue has very low autofluorescence “background” => high SBR  Permits high sensitivity detection of NIR fluorescent “targets”

in vivo

Outline  Introduction  Near infrared light  Fluorescent agents  System design  Zoom / Focus  Results  Conclusion

Principle of Imaging CA CA

Introduction

Target Background SBR ≈ 1

Biodistribution

CA Target CA Background SBR ≈ 1 Time

Clearance

CA Target Background SBR High

Low-molecular weight ligands  Rapid bio-distribution into tissues/tumors  Rapid clearance  Excellent tumor penetration  Ease of preparative chemical synthesis  Potential for ”modularity”

Effect of Hydrodynamic Diameter (HD) on Biodistribution and Clearance Molecule Glucose Inulin Lysozyme ScFv Diabody M.W.

(Da) 180 5,200 14,600 20,000 40,000 Bence-Jones 44,000 Fab’ 50,000 Hemoglobin 68,000 Albumin F(ab’)2 IgG 69,000 100,000 150,000 HD (nm) 0.72

2.8

3.8

3.67

4.89

5.54

5.75

6.36

7.1

8.34

10.4

Urine /Blood Ratio 1 1 0.8

0.74

0.3

0.1

0.09

0.04

0.003

0.002

< 0.001

Blood Half-Life 8 min 30 min 6.6 hr Body Half-Life 1 hr < 4 hr 4 hr 1-2 day 2-3 day

NIR Fluorescent Contrast Agents Developed by the Laboratory Agent NIR Pamidronate NIR Albumin NIR QDs NIR Annexin IR-786 GPI-18648 Antibodies and Fragments Application Breast cancer microcalcification Vessel microcalcification Sentinel lymph node mapping Vascular mapping (long cases) Sentinel lymph node mapping Intraop myocardial damage Tumor response to therapy Optical perfusion measurements PSMA targeting Herceptin, Misc.

Human Serum Albumin HSA800

Human Serum Albumin HSA800

Quantum dots (type II)

Quantum dots (type II)

Advantages and Disadvantages of NIR Fluorescent Lymphatic Tracers

NIR Fluorescent Albumin (HSA800)

Advantages Human-derived No known toxicity Adequate fluorescent yield Disadvantages 7 nm particle, can flow through SLN Stock concentration limited to 10 µM Single wavelength, not tunable Advantages Extremely bright

NIR Fluorescent Quantum Dots

Disadvantages Potential toxicity of components 15 nm particle stops at SLN Photo- and chemically stable Tunable to any wavelength

Outline  Introduction  Near infrared light  Fluorescent agents  System design  Zoom / Focus  Results  Conclusion

System design

NIR Camera NIR Excitation Source (Typically 725-775 nm) NIR Depleted (<700 nm) White Light Source 810 ± 20 nm NIR Emission Filter 785 nm Dichroic Mirror Color Camera 400 -700 nm Band-pass Filter Zoom Lens = Visible Light Path = NIR Fluorescence Light Path

Surgical Field 15-20 cm

Prototype #1

Prototype #2

Prototype #3 M onitor #1 M onitor #2 NIR Fluorescence Optical Sub-System Rigid Post Radiolucent M ovable OR Table Coded Aperture M ask Coded Aperture Frame

Prototype #4

Prototype #4

Outline  Introduction  Near infrared light  Fluorescent agents  System design  Zoom / Focus  Results  Conclusion

Zoom/Autofocus  Goal  Zooming without using hands → footswitch  Coupling with auto focus  Parts  Stepper motors  Drive controllers  Hub

Operation  Communication  RS-232 serial connection to the Hub  two RS-232 serial to each controller  Languages  Si Command Language (SCL)  LabVIEW

Referencing Zoom/Focus wheel Pinhole (at max position) Transmission wheel Motor wheel LED Detector

Referencing

Focus index : contrast method  Image acquisition :  Color Camera  15 fps, firewire (IEEE1394)  Resizing and conversion to 8bits gray levels  Edge detection  Evaluation  Quantification

30 20 50 40 60 Focus index vs. displacement Differentiation_Variation Gradient_Variation Prew itt_Variation Roberts_Variation Sigma_Variation Sobel_Variation 10 0 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000

Quantification

Focus Index (no quantification)

3.5

3.45

3.4

3.35

3.3

3.25

3.2

3.15

3.1

3.05

3 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000

Quantification

FI * 20 + Rounded

70 69 68 67 66 65 64 63 62 61 60 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000

Focus algorithm #1 1 st point : Z1, Fi1 ∆Z>0 Z1 -> Z1 ∆Z -> - ∆Z 2 nd point : Z2, Fi2 ∆Z -> + ∆Z Z1 -> Z2 ∆Fi<0 Fi2-Fi1 ∆Fi>0 ∆Fi<0, iteration > 2 STOP

Results #1  Works great but very slow  Time to send data : t1 = 20ms  Time to move : t2 = 40ms (for 5000 steps)  Time to acquire (after move) : t3 = 67 ms  Total time per cycle : T = 127 ms (at least) => New algorithm

Focus algorithm #2 Speed : - Very Fast Fast Slow Very Fast Focus index Boundary #1 Start #1 #3 Final #2 Z Boundary #2

Results #2  Works faster  Not able to auto-focus real-time  Improvements :  Faster camera : 30 Hz  Region of interest  Gating  Frequency Domain Photon Migration

Software (surgeon’s view)

Outline  Introduction  Near infrared light  Fluorescent agents  System design  Zoom / Focus  Results  Conclusion

NIR Pamidronate (Pam78)

Skeleton Stomach Heart Color Video NIR Fluorescence Color-NIR Merge 5 mm

Intact Circulation

Color Image

Intraoperative Bleeding

Color Image NIR Fluorescence NIR Fluorescence

Sentinel Lymph Node Hypothesis

Solid Tumor

Find, Resect, and Analyze First Draining Lymph Node (i.e., the “Sentinel” Lymph Node) Malignant Cells Absent Malignant Cells Present

End of Surgery Radical Lymph Node Dissection and Associated Morbidity

Gross/Histopathological Evaluation (NIR QDs)

Color Video

1 cm S

NIR Fluorescence Color-NIR Merge

S N N

Color Video

1 cm

NIR Fluorescence 40X

50 µm

H + E NIR Fluorescence

Conclusion  Efficient tool for near-infrared fluorescence imaging => guided surgery  Modularity  Problem => depth resolution  Frequency Domain Photon Migration  X-ray imaging using coded aperture