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

PDX Protests, Summer 2020: A Syllabus and Timeline

This syllabus and timeline of the protests organized in Portland throughout the summer and early fall of 2020 was compiled and written by Portland State University students enrolled in Professor Katrine Barber’s HST 4/593, Introduction to Public History in Fall 2020. It was prepared in partnership with the Oregon State University Press and presented to them at the conclusion of the course. It combines local Portland journalism with a number of other scholarly resources to attempt to answer the question: “Why Portland?” The goals of the project at the outset were to correct inaccuracies or oversights in national coverage of the protests, as well as to provide context for these events. The mission of OSU Press is, in part, to “contribute to the intellectual, cultural, and social development of Oregon and the West,” as well as to “extend the benefits of the university’s teaching, research, and public service beyond the usual boundaries of the university community.” In keeping with these values, this project seeks to bring scholarly context to an event that has touched many Oregonian lives.https://pdxscholar.library.pdx.edu/pdxopen/1044/thumbnail.jp

Effect of streptozotocin-induced diabetes on left ventricular function in adult rats: an in vivo Pinhole Gated SPECT study

<p>Abstract</p> <p>Background</p> <p>Recent studies have suggested that diabetes mellitus (DM) may cause left ventricular (LV) dysfunction directly resulting in increased susceptibility to heart failure. Using pinhole collimators and advances in data processing, gated SPECT was recently adapted to image the rat heart. The present study was aimed to assess this new imaging technique for quantifying LV function and remodeling from the Streptozotocin (STZ) rat model compared to controls.</p> <p>Methods</p> <p>Twenty one rats were randomly assigned to control or diabetic group. Six months after the induction of diabetes by STZ, Pinhole 99 m Tc-sestamibi gated SPECT was performed for determining rat LV volumes and function. Post-mortem histopathologic analysis was performed to evaluate the determinant of LV remodeling in this model.</p> <p>Results</p> <p>After six months, the normalized to body weight LV End-systolic volume was significantly different in diabetic rats compared to controls (0.46 ± 0.02 vs 0.33 ± 0.03 μL/g; p = 0.01). The normalized LV End-diastolic volume was also different in both groups (1.51 ± 0.03 vs 0.88 ± 0.05 μL/g; p = 0.001) and the normalized stroke volume was significantly higher in STZ-rats (1.05 ± 0.02 vs 0.54 ± 0.06 μL/g; p = 0.001). The muscular fibers were thinner at histology in the diabetic rats (0.44 ± 0.07 vs 0.32 ± 0.06 AU; p = 0.01).</p> <p>Conclusion</p> <p>Pinhole 99 m Tc-sestamibi gated SPECT can successfully be applied for the evaluation of cardiac function and remodeling in STZ-induced diabetic rats. In this model, LV volumes were significantly changed compared to a control population, leading to a LV dysfunction. These findings were consistent with the histopathological abnormalities. Finally, these data further suggest the presence of diabetes cardiomyopathy.</p

Effect of streptozotocin-induced diabetes on myocardial blood flow reserve assessed by myocardial contrast echocardiography in rats

The role of structural and functional abnormalities of small vessels in diabetes cardiomyopathy remains unclear. Myocardial contrast echocardiography allows the quantification of myocardial blood flow at rest and during dipyridamole infusion. The aim of the study was to determine the myocardial blood flow reserve in normal rats compared with Streptozotocin-induced diabetic rats using contrast echocardiography

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

Le rôle de la médecine nucléaire dans les 6 mois suivant l'infarctus du myocarde

SCOPUS: cp.jinfo:eu-repo/semantics/publishe

LE TAMPONNEMENT CARDIAQUE

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Imagerie hybride dans l'embolie pulmonaire aiguë (apport de la TDM couplée à la tomoscintigraphie de ventilation et de perfusion)

NICE-BU Médecine Odontologie (060882102) / SudocSudocFranceF