Multimodal MRI reveals structural and functional alterations in thyroid-associated ophthalmopathy

Area of Science:

• Neuroimaging
• Ophthalmology
• Neurology

Background:

• Thyroid-associated ophthalmopathy (TAO) can lead to visual impairment.
• The central neuropathological mechanisms underlying TAO-related visual impairment are not fully understood.

Purpose of the Study:

• To investigate white matter microstructural damage, spontaneous brain activity, and functional connectivity alterations in TAO patients with visual impairment using multimodal MRI.

Main Methods:

• Forty-five TAO patients and 32 healthy controls (HCs) underwent diffusion kurtosis imaging (DKI) and resting-state functional MRI (rs-fMRI).
• Microstructural changes were quantified using fractional anisotropy (FA), mean kurtosis (MK), and mean diffusivity (MD).
• Spontaneous neural activity and functional connectivity were assessed using amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF), and seed-based functional connectivity (FC) analyses.

Main Results:

• TAO patients showed decreased MK, FA, and MD in the visual pathway (optic radiation, lateral geniculate body, optic tract, optic nerve), with MK being most reduced.
• Aberrant ALFF/fALFF patterns were observed in visual and sensorimotor network regions.
• Altered functional connectivity (FC) was found between visual and other brain regions, including the supplementary motor area and fusiform gyrus.

Conclusions:

• TAO is associated with significant white matter microstructural damage and altered spontaneous brain activity and functional connectivity.
• Combined DKI and rs-fMRI (ALFF/fALFF, FC) offer comprehensive insights into TAO's central neuropathological mechanisms.
• These findings support early diagnosis and targeted interventions for TAO-related visual impairment.