Tomographie par émission monophotonique

vignette|droite|Image dans le plan axial du cerveau obtenue par tomographie d'émission monophotonique utilisant le Tc-99. La tomographie par émission monophotonique, en abrégé TEMP, ou même SPECT (de l'Single photon emission computed tomography), aussi appelée tomoscintigraphie par émission monophotonique, est une technique qui repose sur le principe de la scintigraphie et qui permet d'effectuer des images ainsi que des reconstructions en trois dimensions d'organes et de leur métabolisme à l'aide d'un ensemble de gamma caméras tournant autour du patient. Principes vignette|250px|Tomographe d'émission monophotonique. Pour effectuer une TEMP, il est nécessaire d'injecter préalablement au patient un produit radioactif émetteur de rayonnements gamma (constitués de photons). Ce produit appelé radiopharmaceutique est choisi en fonction de ses propriétés chimiques pour se fixer sélectivement dans l'organisme et ainsi mettre en évidence certains processus biologiques. On réalis

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Pre-clinical Evaluation of a Cyanine-Based SPECT Probe for Multimodal Tumor Necrosis Imaging

Riccardo Sinisi

Recently we showed that a number of carboxylated near-infrared fluorescent (NIRF) cyanine dyes possess strong necrosis avid properties in vitro as well as in different mouse models of spontaneous and therapy-induced tumor necrosis, indicating their potential use for cancer diagnostic- and prognostic purposes. In the previous study, the detection of the cyanines was achieved by whole body optical imaging, a technique that, due to the limited penetration of near-infrared light, is not suitable for investigations deeper than 1 cm within the human body. Therefore, in order to facilitate clinical translation, the purpose of the present study was to generate a necrosis avid cyanine-based NIRF probe that could also be used for single photon emission computed tomography (SPECT). For this, the necrosis avid NIRF cyanine HQ4 was radiolabeled with (111)indium, via the chelate diethylene triamine pentaacetic acid (DTPA). The necrosis avid properties of the radiotracer [In-111]DTPA-HQ4 were examined in vitro and in vivo in different breast tumor models in mice using SPECT and optical imaging. Moreover, biodistribution studies were performed to examine the pharmacokinetics of the probe in vivo. Using optical imaging and radioactivity measurements, in vitro, we showed selective accumulation of [In-111]DTPA-HQ4 in dead cells. Using SPECT and in biodistribution studies, the necrosis avidity of the radiotracer was confirmed in a 4T1 mouse breast cancer model of spontaneous tumor necrosis and in a MCF-7 human breast cancer model of chemotherapy-induced tumor necrosis. The radiotracer [In-111]DTPA-HQ4 possessed strong and selective necrosis avidity in vitro and in various mouse models of tumor necrosis in vivo, indicating its potential to be clinically applied for diagnostic purposes and to monitor anti-cancer treatment efficacy.

Springer2016

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Bioluminescent-based imaging and quantification of glucose uptake in vivo

Arkadiy Bazhin, Elena Goun, Pavlo Khodakivskyi, Tamara Maric, Georgy Mikhaylov, Riccardo Sinisi, Aleksey Yevtodiyenko

Glucose is a major source of energy for most living organisms, and its aberrant uptake is linked to many pathological conditions. However, our understanding of disease-associated glucose flux is limited owing to the lack of robust tools. To date, positron-emission tomography imaging remains the gold standard for measuring glucose uptake, and no optical tools exist for non-invasive longitudinal imaging of this important metabolite in in vivo settings. Here, we report the development of a bioluminescent glucose-uptake probe for real-time, non-invasive longitudinal imaging of glucose absorption both in vitro and in vivo. In addition, we demonstrate that the sensitivity of our method is comparable with that of commonly used F-18-FDG-positron-emission-tomography tracers and validate the bioluminescent glucose-uptake probe as a tool for the identification of new glucose transport inhibitors. The new imaging reagent enables a wide range of applications in the fields of metabolism and drug development.

NATURE PUBLISHING GROUP2019

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In vivo measurement of glucose utilization in rats using a beta-microprobe: direct comparison with autoradiography

Pierre Magistretti, Christian Morel, Jean-Marie Petit

A new beta-microprobe (betaP) has been used to locally measure the time-concentration curve of a radiolabeled substance. The betaP, analogous to positron emission tomography methodology, is useful for in vivo animal studies because it can acquire time-concentration curves with high temporal and spatial resolution. Using [18F]fluoro-2-deoxy-D-glucose and betaP, we evaluated the reliability of the biologic parameters and we compared this method with the [14C]2-deoxy-D-glucose autoradiography. BetaP time-concentration curves in three regions of the brain were obtained from 24 rats. Four kinetic parameters (K1-k4) were estimated from 60-minute experimental periods using a three-compartment model. Best fits were obtained when the vascular fraction (Fv) was estimated simultaneously with the four kinetic parameters (K1-k4). The mean estimated Fv values were about 5.5% for the frontal cortex regions and 8.0% for the cerebellum. Correlation coefficients higher than 0.830 were observed between regional cerebral metabolic rates for glucose (rCMRglc) values obtained by betaP and autoradiography. In addition, the betaP-derived input function was similar to that obtained by manual sampling. Our findings show that reliable rCMRglc values can be obtained using betaP.

2004

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Tomographie par émission de positons

vignette|Reconstruction tridimensionnelle de la distribution de glucose marqué au telle que mesurée par tomographie d'émission de positons. Outre l'accumulation normale du traceur dans le cœur, la ve

Médecine nucléaire

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Technétium 99m

Le technétium 99m, noté Tc, est un isomère nucléaire de l'isotope du technétium dont le nombre de masse est égal à 99. Il est utilisé en médecine nucléaire pour effectuer de nombreux diagnostics. L

MICRO-513: Signal processing for functional brain imaging

Computational methods for the analysis of human brain imaging data

PHYS-438: Fundamentals of biomedical imaging

The goal of this course is to illustrate how modern principles of basic science approaches are integrated into the major biomedical imaging modalities of importance to biology and medicine, with an emphasis on those of interest to in vivo.

PHYS-455: Introduction to medical radiation physics

This course covers the physical principles underlying medical diagnostic imaging (radiography, fluoroscopy, CT, SPECT, PET, MRI), radiation therapy and radiopharmacy. The focus is not only on risk and dose to the patient and staff, but also on an objective description of the image quality.