Section: New Results

Biological Image Analysis

Pre-clinical molecular imaging: motionless 3D image reconstruction in micro-SPECT

Participants : Marine Breuilly [Correspondant, Inria] , Grégoire Malandain [Inria] , Nicholas Ayache [Inria] , Jacques Darcourt [UNS-CAL] , Philippe Franken [UNS-CAL] , Thierry Pourcher [CEA] .

This work is jointly conducted with the Transporter in Imagery and Oncologic Radiotherapy team (TIRO, CEA-CAL-UNSA) located in Nice.

SPECT/CT, small animal, respiratory motion, respiratory gating, 4D images, stomach, 99mTc-pertechnetate biodistribution, compartmental analysis

This work has been conducted on SPECT images acquired with a small animal device. Dynamic SPECT images provide functional information targeted by a specific radiotracer (99mTc-pertechnetate) that permit the tracking and quantifying of evolving phenomena.

• Respiratory motion induces an artificial enlargement of the moving structures (tumours, organs) in SPECT images, and biases the quantification.

• A full ad-hoc method was presented that allows the reconstruction of a single 3D SPECT image without motion artefacts  [37] , [6] , [1] .

Pre-clinical molecular dynamic imaging: ${}^{99}\mathrm{m}$Tc-pertechnetate biodistribution model of murine stomach with micro-SPECT

Participants : Marine Breuilly [Correspondant, Inria] , Grégoire Malandain [Inria] , Nicholas Ayache [Inria] , Jacques Darcourt [UNS-CAL] , Philippe Franken [UNS-CAL] , Thierry Pourcher [CEA] .

This work is jointly conducted with the Transporter in Imagery and Oncologic Radiotherapy team (TIRO, CEA-CAL-UNSA) located in Nice.

SPECT/CT, small animal, 4D images, stomach, ${}^{99}\mathrm{m}$Tc-pertechnetate biodistribution, compartmental analysis

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.

• ${}^{99}\mathrm{m}$Tc-pertechnetate is an iodide analog related 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.

• A first simplified model for stomach ${}^{99}\mathrm{m}$Tc-pertechnetate biodistribution was proposed and studied with a compartmental analysis approach using a simplified two-compartment (stomach wall and cavity) model with one input (blood) (see Figure 4 )  [1] .

• Time activity curves of each compartment were obtained from dynamic images thanks to an original layer-based decomposition of the stomach  [1] .

• The first estimation of the model transfer parameters ${\mathrm{K}}_{\mathrm{ij}}$ was performed by numerically solving the inverse problem  [1] .