Abnormal thalamocortical connectivity of preterm infants with elevated thyroid stimulating hormone identified with diffusion tensor imaging

Methodological considerations on diffusion MRI tractography in infants aged 0-2 years: a scoping review

Diffusion MRI (dMRI) enables studying the complex architectural organization of the brain's white matter (WM) through virtual reconstruction of WM fiber tracts (tractography). Despite the anticipated clinical importance of applying tractography to study structural connectivity and tract development during the critical period of rapid infant brain maturation, detailed descriptions on how to approach tractography in young infants are limited. Over the past two decades, tractography from infant dMRI has mainly been applied in research settings and focused on diffusion tensor imaging (DTI). Only few studies used techniques superior to DTI in terms of disentangling information on the brain's organizational complexity, including crossing fibers. While more advanced techniques may enhance our understanding of the intricate processes of normal and abnormal brain development and extensive knowledge has been gained from application on adult scans, their applicability in infants has remained underexplored. This may partially be due to the higher technical requirements versus the need to limit scan time in young infants. We review various previously described methodological practices for tractography in the infant brain (0-2 years-of-age) and provide recommendations to optimize advanced tractography approaches to enable more accurate reconstructions of the brain WM's complexity. IMPACT: Diffusion tensor imaging is the technique most frequently used for fiber tracking in the developing infant brain but is limited in capability to disentangle the complex white matter organization. Advanced tractography techniques allow for reconstruction of crossing fiber bundles to better reflect the brain's complex organization. Yet, they pose practical and technical challenges in the fast developing young infant's brain. Methods on how to approach advanced tractography in the young infant's brain have hardly been described. Based on a literature review, recommendations are provided to optimize tractography for the developing infant brain, aiming to advance early diagnosis and neuroprotective strategies.

Functional decoding and meta-analytic connectivity modeling in thyroid-associated ophthalmopathy

Background

Thyroid-associated ophthalmopathy (TAO) is an orbital disease closely related to thyroid disease with a long-lasting duration that can be blinding and disabling. Recently, structural and functional neuroimaging studies have been performed in TAO patients, but studies have reported inconsistent results. This quantitative meta-analysis was conducted to identify convergent patterns of abnormal brain function among different studies in TAO.

Methods

We searched PubMed, EMBASE, Cochrane, and Web of Science, performed reference tracking, and retrieved 15 eligible studies. Peak coordinates were extracted from these studies and subsequently tested for convergence using activation likelihood estimation (ALE).

Results

Compared to healthy subjects, resting-state brain activity in the whole brain of TAO patients was significantly increased in the left superior frontal gyrus (SFG) and decreased in the left cuneus/precuneus. Functional decoding analysis of the BrainMap database revealed that these regions are predominantly associated with cognitive and emotional impairment. In this study, task-related meta-analytic connectivity modeling (MACM) analysis was used to describe the connectivity and function of the two seed regions. Significant coactivation of these regions was found primarily in the bilateral superior parietal lobule, medial frontal gyrus, left fusiform gyrus, left cingulate gyrus, supplementary motor area and thalamus.

Conclusion

Our findings underscore the role of the SFG and the cuneus/precuneus in the pathophysiology of TAO, highlighting the crucial impact of working memory deficits.