Fluorescence molecular tomography and in-vivo applications

Given that Optical Tomography is capable of quantitatively imaging the distribution of fluorophores and fluorescent proteins in vivo, there has been a great deal of interest in developing optical imaging systems under optimal experimental conditions. A novel system has been implemented that enables three dimensional (3D) imaging of fluorescent probes in whole animals using a non-contact set up, in parallel with a 3D surface reconstruction algorithm. The non-contact approach is a significant step forward in terms of experimental simplicity and provides comfort to the targeted animal. It allows the use of a CCD cameras as detector, resulting in large data sets, thus improving the accuracy of the inversion models used for quantitative 3D reconstruction of fluorochrome distribution, as well as facilitating imaging with higher spatial resolution. In this study the system is tested in determining the distribution of Green Fluorescent Protein (GFP) expressed by T-lymphocytes in the hCD2-GFP transgenic mouse model, thus demonstrating the potential of the system for studying the immunology-based studies. In vivo measurements have been carried in the GFP CLIP-170 mouse model

In Vivo Evidence That the Increase in Matrix Metalloproteinase Activity Occurs Early after Cerebral Ischemia

There is controversy over whether matrix metalloproteinases (MMPs) are activated during the early therapeutic window following ischemic stroke. Ex vivo, an increase was reported as early as 4 hours, whereas in vivo, no increase was found until 24 hours postischemia. We used fluorescence diffuse optical tomography to image MMP activity following experimental cerebral ischemia; increased MMP activity was observed in the ischemic area as early as 3 to 6 hours after ischemic onset and correlated with the volume of ischemic cerebral tissue. Therefore, MMP activation is an immediate early response to cerebral ischemia concurrent with the therapeutic window

Factorisation Non-Négative de Matrice pour séparation de sources en Imagerie par Bioluminescence préclinique

International audience-L'imagerie par bioluminescence est une technologie d'imagerie optique basée sur la détection de photons produits par une réaction biologique entre un substrat et une enzyme dans les tissus vivants. Cette technique d'imagerie, peu bruitée, est utilisée dans de nombreux domaines de la recherche biomédicale et notamment en oncologie préclinique. Le flux de photons émis par une tumeur est lié à son volume et son état métabolique, nécessitant une localisation précise de celle-ci. Dans ce travail, nous étudions l'utilisation de la décomposition factorielle par Factorisation Non-Négative de Matrice (Non-Negative Matrix Factorization, NMF) comme méthode de localisation de tumeurs sans a priori spatial

Factorisation Non-Négative de Matrice pour séparation de sources en Imagerie par Bioluminescence préclinique

International audience-L'imagerie par bioluminescence est une technologie d'imagerie optique basée sur la détection de photons produits par une réaction biologique entre un substrat et une enzyme dans les tissus vivants. Cette technique d'imagerie, peu bruitée, est utilisée dans de nombreux domaines de la recherche biomédicale et notamment en oncologie préclinique. Le flux de photons émis par une tumeur est lié à son volume et son état métabolique, nécessitant une localisation précise de celle-ci. Dans ce travail, nous étudions l'utilisation de la décomposition factorielle par Factorisation Non-Négative de Matrice (Non-Negative Matrix Factorization, NMF) comme méthode de localisation de tumeurs sans a priori spatial

Co-registration of glucose metabolism with positron emission tomography and vascularity with fluorescent diffuse optical tomography in mouse tumors

BACKGROUND: Bimodal molecular imaging with fluorescence diffuse optical tomography (fDOT) and positron emission tomography (PET) has the capacity to provide multiple molecular information of mouse tumors. The objective of the present study is to co-register fDOT and PET molecular images of tumors in mice automatically. METHODS: The coordinates of bimodal fiducial markers (FM) in regions of detection were automatically detected in planar optical images (x, y positions) in laser pattern optical surface images (z position) and in 3-D PET images. A transformation matrix was calculated from the coordinates of the FM in fDOT and in PET and applied in order to co-register images of mice bearing neuroendocrine tumors. RESULTS: The method yielded accurate non-supervised co-registration of fDOT and PET images. The mean fiducial registration error was smaller than the respective voxel sizes for both modalities, allowing comparison of the distribution of contrast agents from both modalities in mice. Combined imaging depicting tumor metabolism with PET-[(18) F]2-deoxy-2-fluoro-d-glucose and blood pool with fDOT demonstrated partial overlap of the two signals. CONCLUSIONS: This automatic method for co-registration of fDOT with PET and other modalities is efficient, simple and rapid, opening up multiplexing capacities for experimental in vivo molecular imaging

Spatiotemporal matrix image formation for programmable ultrasound scanners

International audienceAs programmable ultrasound scanners become more common in research laboratories, it is increasingly important to develop robust software-based image formation algorithms that can be obtained in a straightforward fashion for different types of probes and sequences with a small risk of error during implementation. In this work, we argue that as the computational power keeps increasing, it is becoming practical to directly implement an approximation to the matrix operator linking reflector point targets to the corresponding radiofrequency signals via thoroughly validated and widely available simulations software. Once such a spatiotemporal forward-problem matrix is constructed, standard and thus highly optimized inversion procedures can be leveraged to achieve very high quality images in real time. Specifically, we show that spatiotemporal matrix image formation produces images of similar or enhanced quality when compared against standard delay-and-sum approaches in phantoms and in vivo, and show that this approach can be used to form images even when using non-conventional probe designs for which adapted image formation algorithms are not readily available

Sparse non-negative matrix factorization for preclinical bioluminescent imaging

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