Functional and structural olfactory changes in post-COVID-19 patients detected by 7 Tesla MRI.

Area of Science:

• Neuroscience
• Medical Imaging
• Infectious Disease

Background:

• Persistent olfactory dysfunction (smell loss) is a common sequela of SARS-CoV-2 infection.
• The central neural mechanisms underlying long-term post-COVID smell dysfunction remain incompletely understood.

Purpose of the Study:

• To characterize the olfactory network organization and cortical structure in individuals with persistent smell dysfunction after COVID-19.
• To identify potential neuroimaging markers associated with long-term olfactory deficits post-SARS-CoV-2.

Main Methods:

• Utilized ultra-high-field 7 Tesla resting-state functional MRI and surface-based cortical morphometry.
• Included 30 adults: 14 with persistent dysosmia and 16 normosmic controls, who underwent psychophysical olfactory testing.
• Analyzed connectivity across 56 olfaction-related regions and performed cortical morphometry.

Main Results:

• Identified reduced insula connectivity with orbitofrontal and entorhinal cortices, and ventral thalamus with ventral insula.
• Observed increased connectivity between interhemispheric orbitofrontal regions and among anterior thalamic nuclei.
• Found selective left orbitofrontal thinning, with no volumetric differences; greater orbitofrontal/insular thickness correlated with better olfactory performance in the overall sample.

Conclusions:

• These findings suggest an orbitofronto-insular network signature associated with long-term post-COVID-19 smell dysfunction.
• The study provides preliminary evidence for candidate neuroimaging markers for future validation in larger cohorts.