COSY-IRMaGe

BACKGROUND

The IRMaGe platform’s Expertise and Clinical Research unit provides the scientific community with advanced imaging equipment and methodological expertise to implement MRI acquisition protocols for clinical, translational, and methodological studies. This MRI facility is used by several laboratories in the Grenoble area (LPNC, GIN, TIMC, GIPSA-Lab, HP2, braintech lab, Centre Hospitalier Universitaire Grenoble Alpes) as well as for national and European multicenter projects. The replacement of the facility’s 3T MRI scanner (Achieva dStream 3.0T, Philips, NL) is scheduled for 2026.
The new machine will offer superior performance compared to the current equipment, particularly in terms of gradients, and could potentially involve a change in magnetic field strength from 3T to 5T and/or a change in manufacturer. These changes represent a significant evolution for the platform and its users. Differences between MRI systems notably affect the signal-to-noise ratio, contrast, and geometric distortions, and can thus lead to significant variations in quantitative measurements or image quality. In T1-weighted anatomical sequences, several studies have shown that inter-scanner differences can lead to significant variations in morphometric measurements, even among 3T systems (Fortin et al., 2018; Madan & Kensinger, 2017;
Medawar et al., 2021). Comparisons at higher field strengths (3T vs. 7T) suggest improved contrast and cortical resolution, but also increased sensitivity to intensity biases that may affect segmentation (Lüsebrink et al., 2017; Trampel et al., 2019). Diffusion sequences are also sensitive to instrumental variations, and multi-scanner harmonization studies have shown that diffusion metrics exhibit significant variability across systems and protocols (Tax et al., 2019). In functional MRI, differences between MRI scanners can affect the amplitude and spatial extent of BOLD activations, as well as levels of physiological and instrumental noise (Friedman et al., 2008). Furthermore, to take full advantage of the new machine’s enhanced performance, we aim to develop a catalog of optimized protocols (e.g., reduced acquisition time, higher spatial resolution for equivalent acquisition time, improved image quality, or new sequences). Documenting the performance of these protocols will enable us to quickly provide users with validated solutions for future studies. The goal of our project is to support this change in instrumentation by establishing a multimodal reference dataset from a group of healthy volunteers.

GOING FURTHER WITH THE SUPPORT OF LabEx CerCoG

This project will enable the platform, in collaboration with partner laboratories, to support the transition between the two instruments and ensure scientific and methodological continuity for its users. Beyond this methodological validation, the dataset acquired as part of this project will serve as a reference resource for the platform, enabling the development of a sequence catalog for the new instrument. In the longer term, this dataset will also serve as a methodological resource for the local community, facilitating the training of new users, the development of analytical tools, and the preparation of future collaborative or multicenter projects.