fluorescence reflectance imaging (fri)

© CEA 2008. Tous droits réservés. Toute reproduction totale ou partielle sur quelque support que ce soit ou utilisation du contenu de ce document est interdite sans l’autorisation écrite préalable du CEA All rights reserved. Any reproduction in whole or in part on any medium or use of the information contained herein is prohibited without the prior written consent of CEA 200 7 www.leti .fr Fluorescence Reflectance Imaging (FRI) Abstract Fluorescence enhanced diffuse optical tomography is an emergent diagnosis tool for the localization and the quantification of fluorescent probes ; this technique comes as a supplement or sometimes replaces the classical ionizing radiation imaging techniques, and in particular if a simple , inexpensive, non invasive and accurate instrumentation is sought. For 5 years now, the CEA-LETI has built a base of knowledge in markers and instrumentation within the framework of small animal imaging. More recently, an instrumentation has been developed, the purpose of which is a specific approach to the examination of underlying structures, deeply embedded within the tissues, and in fine for human being screening. Cooled CCD camera lens Why fluorescence ? Visualization techniques widely used in vitro Non ionizing technique Cheap Principl e In vivo Fluorescence imaging limitations The excitation and emission wavelengths must be in the near infra red: higher than 650 nm and lower than 900 nm. The scattering coefficient is much higher than the absorption coefficient, therefore the outcoming photons have been highly scattered. Light propagation in biological tissues is modeled as a diffusion process. µ s >>µ a light source Strong heamoglobin attenuation Strong water attenuation haem oglobin and w aterabsorption 0,01 0,1 1 10 100 1000 250 450 650 850 1050 1250 w avelength (nm ) absorption (cm -1) H b02 cm -1 H b cm -1 H 2O cm -1 Excitation light scattering ~20cm CCD Camera Emission filter Optical fibers Laser source Halogen lamp IR filter IR filtered visible light illumination •Two optical fibred 690nm laser light 100mW for fluorescence excitation •Scattering of the illumination source with a holographic lens •Field homogeneity better than 30% •Illumination: 2,6 mW/cm² 3D imaging: Trans-illumination Diffuse Optic Tomography live r Nodules in the lungs day 10 day 12 day 14 Course of an experiment Exemple of in vivo follow up [*] National funded project Prostafluo Deep Tissue Screening: endoscopy The major challenge in deep tissues fluorescence imaging initially consists in bringing the fluorescent marker in sufficient quantity on the target. The second difficulty in deep tissue screening consists in being freed from the intrinsic fluorescence of biological tissues. To get rid of this autofluorescence, the approach considered consists in using a pulsed signal and time-resolved measurements in order to achieve a temporal discrimination between the autofluorescence signal and the fluorophores emission signal. This discrimination will be all the more efficient if the fluorescence marker lifetime is significantly different from the autofluorescence lifetime. [*] A. Koenig, L. Hervé, V. Josserand, M. Berger, J. Boutet, A. Da Silva, J.-M. Dinten, P. Peltié, J.-L. Coll, P. Rizo, “In vivo mice lungs tumors follow-up with fDOT”, to be published in Journal of Biomedical Optics 2008 Edges detection 3D Visualisation 10x10 fluorescence images acquisition -> 5 minutes Ufl 100 200 300 400 500 600 100 200 300 400 500 600 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 x 10 4 Reconstruction -> 5-10 min IAB IAB IAB 2D fluorescence reflectance image

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Cooled CCD camera. IAB. IR filter. Halogen lamp. Edges detection. 2D fluorescence reflectance image. Nodules in the lungs. Strong water attenuation. Strong heamoglobin attenuation. lens. Optical fibers. Laser source. liver. CCD Camera. Emission filter. Excitation light scattering. - PowerPoint PPT Presentation

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Page 1: Fluorescence Reflectance Imaging (FRI)

contenu de ce document est interdite sans l’autorisation écrite préalable du CEAAll rights reserved. Any reproduction in whole or in part on any medium or use of the

information contained herein is prohibited without the prior written consent of CEA

2007

www.leti.fr

Fluorescence Reflectance Imaging (FRI)

AbstractFluorescence enhanced diffuse optical tomography is an emergent diagnosis tool for the localization and the quantification of fluorescent probes ; this technique comes as a supplement or sometimes replaces the classical ionizing radiation imaging techniques, and in particular if a simple , inexpensive, non invasive and accurate instrumentation is sought. For 5 years now, the CEA-LETI has built a base of knowledge in markers and instrumentation within the framework of small animal imaging. More recently, an instrumentation has been developed, the purpose of which is a specific approach to the examination of underlying structures, deeply embedded within the tissues, and in fine for human being screening.

Cooled CCD camera

lens

Why fluorescence ?

Visualization techniques widely used in vitro Non ionizing technique Cheap

Principle

In vivo Fluorescence imaging limitations

The excitation and emission wavelengths must be in the near infra red: higher than 650 nm and lower than 900 nm.

The scattering coefficient is much higher than the absorption coefficient, therefore the outcoming photons have been highly scattered.Light propagation in biological tissues is modeled as a diffusion process.

µs>>µa

light source

Strong heamoglobin attenuation Strong water attenuation

haemoglobin and water absorption

0,01

0,1

100

1000

250 450 650 850 1050 1250

wavelength (nm)

abso

rpti

(cm

-1)

Hb02 cm-1

Hb cm-1

H2O cm-1

Excitation light scattering

~20

CCD Camera Emission filter

Optical fibers

Laser source

Halogen lamp IR filter

IR filtered visible light illumination

•Two optical fibred 690nm laser light 100mW for fluorescence excitation•Scattering of the illumination source with a holographic lens•Field homogeneity better than 30%•Illumination: 2,6 mW/cm²

3D imaging: Trans-illumination Diffuse Optical Tomography

liver

Nodules in the lungs

day 10 day 12 day 14

Course of an experiment

Exemple of in vivo follow up [*]

National funded project Prostafluo

Deep Tissue Screening: endoscopy

The major challenge in deep tissues fluorescence imaging initially consists in bringing the fluorescent marker in sufficient quantity on the target.

The second difficulty in deep tissue screening consists in being freed from the intrinsic fluorescence of biological tissues. To get rid of this autofluorescence, the approach considered consists in using a pulsed signal and time-resolved measurements in order to achieve a temporal discrimination between the autofluorescence signal and the fluorophores emission signal.

This discrimination will be all the more efficient if the fluorescence marker lifetime is significantly different from the autofluorescence lifetime.

[*] A. Koenig, L. Hervé, V. Josserand, M. Berger, J. Boutet, A. Da Silva, J.-M. Dinten, P. Peltié, J.-L. Coll, P. Rizo, “In vivo mice lungs tumors follow-up with fDOT”, to be published in Journal of Biomedical Optics 2008

Edges detection

3D Visualisation

10x10 fluorescence images acquisition -> 5 minutes

Ufl

100 200 300 400 500 600

100

200

300

400

500

600

0.2