3D Fluorescence Optical Tomography (FOT) and PET

We have designed a fluorescence optical tomography (FOT) system based on a conical mirror, in which the whole-body surface of a mouse can be imaged with no motion. A collimated laser beam is used to excite fluorescence inside the mouse body and an electron-multiplying Charge-Coupled Device (EMCCD) is used to collect fluorescence photons at different emission wavelengths through bandpass filters. Photon propagation inside the mouse body is modeled by the diffusion equation that is solved with a finite element method. A preconditioned conjugate gradient (PCG) method is used to iteratively map the fluorescence measurements on the mouse body surface to the fluorescence concentration inside the mouse. Mouse-shaped phantoms and in vivo experiments were performed to validate this imaging system.[1]

Fig. 1: Design of conical mirror (a) and schematic of 3D FOT imaging system (b). Reconstructed 3D fluorescence optical image of a mouse 24 hours after 2DG injection: (c) coronal section and transverse sections at level of the tumor and bladder.

Combined FOT and PET

We have built a prototype simultaneous PET and three-dimensional (3D) fluorescence optical tomography (FOT) system for small animals, compatible with existing small-animal PET scanners. Insertion of the conical mirror into the gantry of the PET scanner allowed simultaneous PET and 3D FOT imaging. In vivo experiments using both radionuclide and fluorescently-labeled contrast agents were conducted and proved feasibility of the prototype system. PET can be used to improve 3D FOT reconstructions and also to validate advances in 3D FOT methods.1

Fig. 2: Conical mirror inserted into gantry of microPET II scanner (left). Simultaneous 3D FOT and PET imaging system (right)

 

References:

1. Li C, Mitchell GS, Dutta J, Ahn S, Leahy RM, Cherry SR. A three-dimensional multispectral fluorescence optical tomography imaging system for small animals based on a conical mirror design. Opt. Express 2009;17(9):7571-85.
2. Li C, Wang G, Qi J, Cherry SR. Three-dimensional fluorescence optical tomography in small-animal imaging using simultaneous positron-emission-tomography priors. Opt. Lett. 2009;34(19):2933-5.

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