Section: New Results

Pre-clinical molecular dynamic image analysis: 99mTc- pertechnetate biodistribution model of murine stomach with micro-SPECT

Participants : Marine Breuilly, Grégoire Malandain.

This work is jointly conducted with Thierry Pourcher, Jacques Darcourt, Philippe Franken, Kaouthar Chatti, and Philippe Pognonec from the Transporter in Imagery and Oncologic Radiotherapy team (TIRO, CEA-CAL-UNSA).

This project 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 study the uptake of the ${}^{99\mathrm{m}}$Tc-pertechnetate (an iodide analog) within the murine stomach observed thanks to a SPECT camera. Using the coupled SPECT and CT device dedicated to small animals, functional information targeted by a specific radiotracer (${}^{99\mathrm{m}}$Tc-pertechnetate) can be imaged dynamically.

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.

• ${}^{99\mathrm{m}}$-pertechnetate is an iodide analog regarding to the NIS gene. Thus iodide uptake kinetics can be studied through the study of ${}^{99\mathrm{m}}$Tc- pertechnetate biodistribution.

• Dynamic SPECT images exhibit a progressive accumulation of ${}^{99\mathrm{m}}$Tc-pertechnetate in the stomach wall and diffusion in the stomach cavity.

• The workflow that has been previously proposed in  [18] was tested on a larger dataset of five subjects, yielding promising results: The computed model parameters are coherent, and the computed parameter values suggested that there is some iodide retention in the stomach wall.

• A comparison of the dedicated method for extraction of time activity curves with the ones extracted with Pixies software is on-going.

• A comparison of the dedicated method for solving the inverse problem of the compartmental analysis with methods developed by the Turku PET Centre is on-going.