Updated French OFSEP recommendations for multiple sclerosis MRI: alignment with the 2024 McDonald criteria

BACKGROUND: Magnetic resonance imaging (MRI) is central to the diagnosis and follow-up of multiple sclerosis (MS). Since the 2020 OFSEP recommendations, the 2024 McDonald criteria have introduced major changes, including recognition of the optic nerve as a fifth anatomical topography and integration of two specificity biomarkers - the central vein sign (CVS) and the paramagnetic rim lesion (PRL). OBJECTIVE: To update the French OFSEP MRI recommendations for MS while remaining feasible on every 1.5 T and 3 T scanner in France. METHODS: A multidisciplinary OFSEP-SFNR working group conducted a modified Delphi-like consensus process. RECOMMENDATIONS: The core brain protocol comprises isotropic fat-suppressed 3D FLAIR (1 mm³), DWI with ADC maps, and an optimised 3D susceptibility-sensitive sequence (3D T2* GRE or 3D SWI with filtered phase) for CVS and PRL. A contrast-enhanced 3D spin-echo T1 sequence and a dedicated orbital protocol for suspected optic neuritis are added at diagnosis. The spinal cord protocol includes at least two complementary sequences, with a high-contrast heavily T1-weighted sequence when available. Follow-up uses the same core protocol with strictly reproducible 3D FLAIR; gadolinium is restricted to targeted indications. CONCLUSION: This vendor-neutral framework supports earlier, more specific MS diagnosis and reduced gadolinium use across French centres.