Cross-Modality Comparison of Fetal Brain Phenotypes: Insights From Short-Interval Second-Trimester MRI and Ultrasound...

Area of Science:

• Neuroimaging
• Medical Imaging
• Fetal Development

Background:

• Three-dimensional ultrasound (3D US) and magnetic resonance imaging (MRI) are advanced techniques for studying fetal brain development.
• These modalities capture different physical signals, potentially causing discrepancies in image-derived phenotypes (IDPs).

Purpose of the Study:

• To evaluate the agreement of IDPs between 3D US and MRI for fetal brain structures.
• To compare volumes of eight brain structures derived from US and MRI using deep learning algorithms.

Main Methods:

• Comparison of brain structure volumes from 90 subjects using 3D US and MRI data.
• Deep learning algorithms were employed for IDP extraction.
• Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to assess agreement and bias.

Main Results:

• Excellent agreement (ICC > 0.75) was found for cerebellum, cavum septum pellucidum, thalamus, white matter, and deep grey matter volumes.
• Significant correlations (p < 0.001) were observed for most structures, excluding the ventricular system.
• Systematic biases were noted: intracranial and cortical plate volumes were larger on US than MRI.

Conclusions:

• Modality-specific adjustments are necessary when interpreting fetal brain IDPs across US and MRI.
• US and MRI play complementary roles in advancing fetal neuroimaging research.
• The brainstem and ventricular system labels were not comparable between the two modalities.