Fusion of [18F]FDG PET with Fluorescence Diffuse Optical Tomography to Improve Validation of Probes and Tumor Imaging

Anikitos Garofalakis,Benoît Thézé,Frédéric Ducongé,Albertine Dubois,Bertrand Czarny,Bertrand Tavitian

doi:10.1007/s11307-012-0581-z

Abstract

PurposeGiven the progress of fluorescence diffuse optical tomography (fDOT) technology, here, we study the additional benefits provided by multimodal PET/fDOT imaging by comparing the biodistribution of 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) in tumors with three fluorescent probes: a glucose analog, a protease activatable optical probe, and a ligand of αvβ3 integrin.ProceduresSequential fDOT/PET/computed tomography (CT) imaging of mice was performed with a custom multimodal mouse support that allows the subject to be transferred between the fDOT and the PET/CT scanners. Experiments were performed in xenografted tumor models derived from the human breast cancer line MDA-MB 231 and compared to ex vivo analysis.ResultsThe three-dimensional signals showed that the fluorescent glucose analog is not colocalized with [18F]FDG, raising questions about its use as a surrogate probe of the PET tracer. Fusion of [18F]FDG with the other fluorescent probes showed evidence of high variability both for the protease activity and the αvβ3 integrin expression during tumor growth.ConclusionThe added value of hybrid PET/fDOT over the two modalities was demonstrated for cross-validation of probes and for better characterization of tumor models.

Highlights

I n oncology, 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is largely used to monitor the glucose metabolism of tumors by positron-emission tomography (PET) imaging
PET imaging has been fused with different imaging modalities, mostly X-ray computed tomography [7] (CT) and, more recently, magnetic resonance imaging [8] (MRI)
As a proof of principle, we studied the additional benefits provided by the combination of fluorescence diffuse optical tomography (fDOT) with PET imaging by comparing the biodistribution of [18F]FDG with three fluorescent probes in nude mice bearing tumor xenografts of MDA-MB-231 cells. [18F]FDG is the most used PET tracer in the world [1]

Summary

Introduction

I n oncology, 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is largely used to monitor the glucose metabolism of tumors by positron-emission tomography (PET) imaging. A. Garofalakis et al.: [18F]FDG PET/fDOT for Tumor Imaging useful to study the effect of a therapy or the function of a specific oncogene to the development of tumors in small animal models. Garofalakis et al.: [18F]FDG PET/fDOT for Tumor Imaging useful to study the effect of a therapy or the function of a specific oncogene to the development of tumors in small animal models To address this issue, several PET tracers have been developed to highlight different physiological processes of tumors [2]. The coregistration of [18F]FDG with another PET tracer is limited since tracers have to be injected sequentially, waiting the decay of the previously injected isotope without moving the animal Another possibility is to fuse [18F]FDG PET with information originating from another imaging modality. CT and MRI display high-spatial resolution imaging, they lack contrast agents to perform functional imaging and are mostly used to measure tumor's morphologic features (i.e., size, shape, or blood vessel density)

Methods

Results

Conclusion