Laser Induced Fluorescence Spectroscopy and Molecular Imaging as Tools for Tumor Detection in vivo

Transcription

1 Laser Induced Fluorescence Spectroscopy and Molecular Imaging as Tools for Tumor Detection in vivo B. Ebert Physikalisch-Techn. Bundesanstalt, Section 8.31, PTB, Berlin, Germany Outline: Spectroscopic identification of malignant regions in the gastrointestinal tract Receptor-targeted fluorescence imaging of animals Demarcation of lymph nodes by fluorescence imaging Spatial resolution in fluorescence imaging Fluorescence reference material Bayer Schering Pharma

2 Fluorescence imaging of lymph nodes Experimental setup shutter dichroic beam splitter beam dump 505 nm dichroic beam splitter excitation fiber OPO 355 nm colonoscope THG SHG power supply electr. delay HV generator Nd:YAG 50 Hz synchronisation imaging polychromator gastrointestinal tract intensified CCD camera controller

3 Heme biosynthesis Succinyl-CoA + Glycine COO Aminolevulinic acid (ALA) CH 2 2 mol ALA CH 2 C=O V M Porphobilinogen NH 3 + CH 2 M NH N V 4 mol Porphobilinogen N HN Uroporphyrinogen III Coproporphyrinogen Protoporphyrinogen IX Protoporphyrin IX (PpIX) M P P M M: CH 3 V: CH=CH 2 P: CH 2 _ CH2 _ COOH

4 Fluorescence spectroscopy of tumors endoscopic view

5 Fluorescence spectroscopy of malignant tissue Normalized fluorescence intensity I(599 nm, 0 ns) 0 ns delay 20 ns delay I(635 nm, 20 ns) nm Wavelength R= I(635 nm, 20 ns) / I(599 nm, 0ns)

6 Fluorescence spectroscopy of lymph nodes Comparison with histology (cumulative frequency) Normalized cumulative frequency connective tissue (n = 272) lymph nodes (n = 434) involved lymph nodes (n = 90) 1 10 R=I(633 nm, 20 ns) / I(595 nm, 20 ns) Cancer Research, 2001, 61,

7 Experimental setup: Gated fluorescence imaging Gate: 10 ns, 100 Hz Gate:200 ps, 20 MHz OPO SHG THG Nd:YAG. 100 Hz Excitation fiber Delay generator ICCD 200 ps Photocathode driver HV pulse generator Filter PC & Delay card ICCD- Camera Controller Programmable delay line depth Laser Laserdriver & Trigger Filter

8 Receptor targeted NIR- imaging of mouse xenografts with fluorescent ligands ITCC- Octreotid ITCC-(M 2, M 7 ) Octreotid In vivo fluorescence imaging of tumors SSTR2 Tumor, NIR38: 20nmol /kg body weight Octreotid R = dphe-cys-phe-dtrp-lys-thr-cys- Thr 6 h 6 h nature biotechnology, 2001, 19, Bayer Schering Pharma

9 Optical molecular imaging of lymph nodes using a targeted vascular contrast agent A A CH CH CH + N 3 - (CH 2 ) 4 SO 3 N O (CH 2 ) 4 SO 3 - Na + OH ITCC MECA B B Lymph nodes strong fluorescence in the liver consistent with the hepatobiliary elimination pathway Liver C C Bladder Bayer Schering Pharma J Biomed Opt. 2005, 10(4):41205

10 Optical molecular imaging of lymph nodes using a targeted vascular contrast agent 0.5 Contrast: K = (I lymph - I muscle )/I muscle High sensitivity, requiring as little as 0.25 nmol dye per animal 0.4 Contrast MECA- 79 Cyanine dye Control conjugate Time (min) Bayer Schering Pharma

11 Experimental setup: Gated fluorescence imaging Gate: 10 ns, 100 Hz Gate:200 ps, 20 MHz OPO SHG THG Nd:YAG. 100 Hz Excitation fiber Delay generator ICCD 200 ps Photocathode driver HV pulse generator Filter PC & Delay card ICCD- Camera Controller Programmable delay line depth Laser Laserdriver & Trigger Filter

12 Depth resolved fluorescence imaging Fluorescent rod at different depth in a scattering solution µ s = 14 cm -1 depth: 1 mm depth: 12 mm 1.7 ns 2.2 ns 3.3 ns 2.7 ns 3.7 ns 4.8 ns Normalized intensity response fluorescence Normalized intensity response fluorescence time / ns time / ns

13 Depth resolved fluorescence imaging Fluorescent rod at different depth in a scattering solution µ s = 14 cm-1 Rod 3 mm x Influence of geometry Depth 5 mm Depth 10 mm 6 Mean time of flight x / mm x / mm 2.2 ns 2.85 ns 4.0 ns Depth / mm

14 Fluorescence reference material and application Fluorescence excitation spectra Normalized fluorescence intensity NIR96007 in solution with spheres NIR96007 in solution covalently bound to spheres NIR96007 in solution 1µM NIR96007 in solution 100 µm Observation at 790 nm Wavelength (nm) Bayer Schering Pharma

15 Fluorescence intensity in dependence on concentration of cyanine dye molecules Fluorescence intensity (counts/sec) 4x10 7 NIR in solution NIR bound to glass spheres 3x10 7 2x10 7 1x Dyes (µmol) Bayer Schering Pharma

16 Scattering phantom with NIR96007, 2% on glass spheres 4 3 X (cm) 2 1 Normalized fluorescence intensity X (cm) Normalized fluorescence intensity Bayer Schering Pharma

17 Monitoring of inflammation of ankle joints using cyanine dyes as contrast agents Regions of interest Reference Inflamed region Inflamed region Bayer Schering Pharma

18 Increase of fluorescence intensity in the right ankle joint after i.v. application of a cyanine dye Normalized fluorescence intensity measured values corrected values (normalized to reference) J Fluoresc (3): Time (s) Bayer Schering Pharma

19 Conclusion Small malignant regions (dysplasias) in the gastrointestinal tract can be identified. Light sources with high pulse energy and low repetition rates are preferable to suppress ambient light Succesful targeting of endothelial surface-expressed molecules - leukocyte homing Determination of depth of inclusions by time resolved fluorescence imaging Fluorescent phantoms are needed, however, to match optical properties of biological tissue is difficult