Site effects in multisite fetal brain MRI: morphological insights into early brain development

Area of Science:

• Neuroimaging
• Medical Physics
• Developmental Neuroscience

Background:

• Multisite fetal brain MRI studies are essential for understanding neurodevelopment.
• Site-specific acquisition factors can introduce variability and bias in imaging data.
• Standardization and harmonization are critical for reliable multisite research.

Purpose of the Study:

• To identify key MRI acquisition factors influencing fetal brain structural measurements.
• To assess the impact of these factors on developmental patterns.
• To evaluate the effectiveness of harmonization techniques in mitigating site effects.

Main Methods:

• Retrospective analysis of 340 in-utero T2-weighted fetal brain MRI scans from 218 fetuses across four sites.
• Generalized Additive Models (GAM) used to quantify site effects (field strength, resolution, etc.) on brain measurements.
• Growth models applied to assess developmental trajectories; ComBat-GAM harmonization employed.

Main Results:

• Lower field strength (FS) and spatial resolution led to overestimations in subcortical volumes and cortical morphology.
• Peak cortical thickness in developmental trajectories was significantly affected by FS and in-plane resolution.
• ComBat-GAM harmonization successfully removed site effects while preserving developmental patterns.

Conclusions:

• Identified critical acquisition factors (FS, resolution) impacting in-utero fetal brain MRI.
• Emphasized the necessity of data harmonization for pooling multisite fetal brain morphology data.
• Provided guidelines for optimizing fetal MRI acquisition and analysis across different sites.