Distribution and dynamics of Tc-99m-pertechnetate uptake in the thyroid and other organs assessed by single-photon emission computed tomography in living mice

Background: Tc-99m pertechnetate is a well-known anion, used for clinical imaging of thyroid function. This gamma emitter is transported by the sodium iodide symporter but is not incorporated into thyroglobulin. Scintigraphy using Tc-99m pertechnetate or 123 iodide represents a powerful tool for the study of sodium iodide symporter activity in different organs of living animal models. However, in many studies that have been performed in mice, the thyroid could not be distinguished from the salivary glands. In this work, we have evaluated the use of a clinically dedicated single-photon emission computed tomography (SPECT) camera for thyroid imaging and assessed what improvements are necessary for the development of this technique. Methods: SPECT of the mouse neck region, with pinhole collimation and geometric calibration, was used for the individual measurement of Tc-99m pertechnetate uptake in the thyroid and the salivary glands. Uptake in the stomach was studied by planar whole-body imaging. Uptake kinetics and biodistribution studies were performed by sequential imaging. Results: This work has shown that thyroid imaging in living mice can be performed with a SPECT camera originally built for clinical use. Our experiments indicate that Tc-99m pertechnetate uptake is faster in the thyroid than in the salivary glands and the stomach. The decrease in Tc-99m pertechnetate uptake after injection of iodide or perchlorate as competitive inhibitors was also studied. The resulting rate decreases were faster in the thyroid than in the salivary glands or the stomach. Conclusions: We have shown that a clinically dedicated SPECT camera can be used for thyroid imaging. In our experiments, SPECT imaging allowed the analysis of Tc-99m pertechnetate accumulation in individual organs and revealed differences in uptake kinetics

Definition of motionless phases for monitoring gated reconstruction of SPECT images in alive mice

To be filled INInternational audienceThe present method aims at defining motionless phases for monitoring gated reconstruction of SPECT images in the movable area containing lungs and liver among others. It is based on the filtering of gating signals that are generated from an abdominal pressure variation signal. This method is considering gating signals only for cycles for which the period is included in a defined range around periods mean. This correction is essential to improve the quality of SPECT reconstruction

From extraction of physiological features with dynamic µ-SPECT imaging to modelling of iodide biodistribution in stomach

This study investigates the potential retention of iodide in the stomach, for a better understanding of the iodide biodistribution in the body and more precisely of its potential antiseptic role. To that end, we will study the uptake of the 99m Tc-pertechnetate (an iodide ana-log) within the murine stomach observed thanks to a SPECT camera. The temporal evolution of the uptake is analysed thanks to a dedicated multi-compartment model. The addressed challenges consist in 1) estimating the time-activity curves for the different compartments, and 2) identifying the model parameters. Real experiments on different subjects demonstrate a quite good coherence of the computed parameters, and the computed parameter values suggested that there is some iodide retention in the stomach wall

Analyse statistique d'images médicales : étude et utilisation du logiciel SPM

Les médecins ont besoin de données objectives et quantifiées pour les aider dans le diagnostic de certaines pathologies. L'analyse statistique des images médicales de populations de patients est un moyen de leur fournir ce type de données. Dans ce rapport nous étudions le logiciel SPM, son utilisation sur des images SPECT

Comparison of cognitive decline between dementia with Lewy bodies and Alzheimer's disease: a cohort study

Objectives: Dementia with Lewy bodies (DLB) accounts for 10%-15% of dementia cases at autopsy and has distinct clinical features associated with earlier institutionalisation and a higher level of carer distress than are seen in Alzheimer's disease (AD). At present, there is on-going debate as to whether DLB is associated with a more rapid cognitive decline than AD. An understanding of the rate of decline of cognitive and non-cognitive symptoms in DLB may help patients and carers to plan for the future. Design: In this cohort study, the authors compared 100 AD and 58 DLB subjects at baseline and at 12-month follow-up on cognitive and neuropsychiatric measures. Setting: Patients were recruited from 40 European centres. Participants: Subjects with mild-moderate dementia. Diagnosis of DLB or AD required agreement between consensus panel clinical diagnosis and visual rating of 123I-FP-CIT (dopamine transporter) single photon emission computed tomography neuroimaging. Outcome measures: The Cambridge Cognitive Examination including Mini-Mental State Examination and Neuropsychiatric Inventory (NPI). Results: The AD and DLB groups did not differ at baseline in terms of age, gender, Clinical Dementia Rating score and use of cholinesterase inhibitors or memantine. NPI and NPI carer distress scores were statistically significantly higher for DLB subjects at baseline and at follow-up, and there were no differences between AD and DLB in cognitive scores at baseline or at follow-up. There was no significant difference in rate of progression of any of the variables analysed. Conclusions: DLB subjects had more neuropsychiatric features at baseline and at follow-up than AD, but the authors did not find any statistically significant difference in rate of progression between the mild-moderate AD and DLB groups on cognitive or neuropsychiatric measures over a 12-month follow-up perio

A Bio-inspired Learning and Classification Method for Subcellular Localization of a Plasma Membrane Protein

International audienceHigh-content cellular imaging is an emerging technology for studying many biological phenomena. statistical analyses on large populations (more than thousands) of cells are required. Hence classifying cells by experts is a very time-consuming task and poorly reproducible. In order to overcome such limitations, we propose an automatic supervised classification method. Our new cell classification method consists of two steps: The first one is an indexing process based on specific bio-inspired features using contrast information distributions on cell sub-regions. The second is a supervised learning process to select prototypical samples (that best represent the cells categories) which are used in a leveraged k-NN framework to predict the class of unlabeled cells. In this paper we have tested our new learning algorithm on cellular images acquired for the analysis of changes in the subcellular localization of a membrane protein (the sodium iodide symporter). In order to evaluate the automatic classification performances, we tested our algorithm on a significantly large database of cellular images annotated by experts of our group. Results in term of Mean Avarage Precision (MAP) are very promising, providing precision upper than 87% on average, thus suggesting our method as a valuable decision-support tool in such cellular imaging applications. Such supervised classification method has many other applications in cell imaging in the areas of research in basic biology and medicine but also in clinical histology

Contours déformables et reconstruction tomographique en imagerie médicale

Cet article traite de la segmentation automatique des images reconstruites en tomographie par émission, afin d'améliorer l'interprétation des images pour le diagnostic des médecins. Les approches classiques des contours actifs déformables pour la segmentation ne permettent pas de bien segmenter les données reconstruites qui sont bruitées. Aussi, nous proposons de traiter simultanément la reconstruction et la segmentation en résolvant un système de deux EDP, l'une permettant la reconstruction avec régularisation prenant en compte les discontinuités, et l'autre la segmentation par l'évolution de courbes planes

Analyse statistique de données radiomiques et métabolomiques : prédiction des lésions mammaires triple-négatives

International audienceLa caractérisation de l’hétérogénéité tumorale à partir des images médicales (appeléeaussi radiomique) et de l’extraction de données omiques est un enjeu majeur en cancérologie,notamment dans la mise en place de la médecine de précision. Or actuellement, le lien entre lesvariables radiomiques (VR) et les caractéristiques biologiques des lésions est encore mal connu.L’objectif de ce travail est d’étudier la corrélation entre les VR et les variables métabolomiques (VM)dans le cancer du sein, et d’analyser leur capacité à prédire le sous-type immunohistochimique deslésions

Prognostic value of bone marrow tracer uptake pattern in baseline PET scans in hodgkin lymphoma: Results from an international collaborative study

PET/CT-ascertained bone marrow involvement (BMI) constitutes the single most important reason for upstaging by PET/CT in Hodgkin lymphoma (HL). However, BMI assessment in PET/CT can be challenging. This study analyzed the clinicopathologic correlations and prognostic meaning of Different patterns of bone marrow (BM)18F-FDG uptake in HL. Methods: One hundred eighty newly Diagnosed early unfavorable and advanced-stage HL patients, all scanned at baseline and after 2 adriamycin-bleomycinvinblastine-dacarbazine (ABVD) courses with18F-FDG PET, enrolled in 2 international stuDies aimed at assessing the role of interim PET scanning in HL, were retrospectively included. Patients were treated with ABVD 4-6 cycles and involved-field raDiation when needed, and no treatment adaptation on interim PET scanning was allowed. Two masked reviewers independently reported the scans. Results: Thirty-eight patients (21.1%) had focal lesions (fPET1), 10 of them with a single (unifocal) and 28 with multiple (multifocal) BM lesions. Fifty-three patients (29.4%) had pure strong (.liver) Diffuse uptake (dPET1) and 89 (48.4%) showed no or faint (#liver) BM uptake (nPET1). BM biopsy was positive in 6 of 38 patients (15.7%) for fPET1, in 1 of 53 (1.9%) for dPET1, and in 5 of 89 (5.6%) for nPET1. dPET1 was correlated with younger age, higher frequency of bulky Disease, lower hemoglobin levels, higher leukocyte counts, and similar Diffuse uptake in the spleen. Patients with pure dPET1 had a 3-y progression-free survival identical to patients without any18F-FDG uptake (82.9% and 82.2%, respectively, P 5 0.918). However, patients with fPET1 (either unifocal or multifocal) had a 3-y progressionfree survival significantly inferior to patients with dPET1 and nPET1 (66.7% and 82.5%, respectively, P 5 0.03). The k values for interobserver agreement were 0.84 for focal uptake and 0.78 for Diffuse uptake. Conclusion: We confirmed that18F-FDG PET scanning is a reliable tool for BMI assessment in HL, and BM biopsy is no longer needed for routine staging. Moreover, the interobserver agreement for BMI in this study proved excellent and only focal18F-FDG BM uptake should be considered as a harbinger of HL

Normalisation to Blood Activity Is Required for the Accurate Quantification of Na/I Symporter Ectopic Expression by SPECT/CT in Individual Subjects

The utilisation of the Na/I symporter (NIS) and associated radiotracers as a reporter system for imaging gene expression is now reaching the clinical setting in cancer gene therapy applications. However, a formal assessment of the methodology in terms of normalisation of the data still remains to be performed, particularly in the context of the assessment of activities in individual subjects in longitudinal studies. In this context, we administered to mice a recombinant, replication-incompetent adenovirus encoding rat NIS, or a human colorectal carcinoma cell line (HT29) encoding mouse NIS. We used 99mTc pertechnetate as a radiotracer for SPECT/CT imaging to determine the pattern of ectopic NIS expression in longitudinal kinetic studies. Some animals of the cohort were culled and NIS expression was measured by quantitative RT-PCR and immunohistochemistry. The radioactive content of some liver biopsies was also measured ex vivo. Our results show that in longitudinal studies involving datasets taken from individual mice, the presentation of non-normalised data (activity expressed as %ID/g or %ID/cc) leads to ‘noisy’, and sometimes incoherent, results. This variability is due to the fact that the blood pertechnetate concentration can vary up to three-fold from day to day. Normalisation of these data with blood activities corrects for these inconsistencies. We advocate that, blood pertechnetate activity should be determined and used to normalise the activity measured in the organ/region of interest that expresses NIS ectopically. Considering that NIS imaging has already reached the clinical setting in the context of cancer gene therapy, this normalisation may be essential in order to obtain accurate and predictive information in future longitudinal clinical studies in biotherapy