Evaluation of Fetal Thyroid with 3D Gradient Echo T₁-weighted MR Imaging

Area of Science:

• Radiology
• Fetal Medicine
• Endocrinology

Background:

• Fetal thyroid characteristics on MRI are not fully understood.
• Limited evaluation of non-goiterous fetal thyroid disorders exists.
• Need for advanced imaging techniques to assess fetal thyroid function.

Purpose of the Study:

• To assess the fetal thyroid using 3D gradient echo (GRE) T1-weighted MRI.
• To evaluate the utility of this MRI technique for fetal thyroid assessment.
• To examine fetal thyroid characteristics and identify potential disorders.

Main Methods:

• Utilized 27 3D GRE T1-weighted MRI scans from 26 fetuses.
• Defined regions of interest (ROIs) within the fetal thyroid and adjacent neck muscle.
• Calculated thyroid-to-muscle signal intensity ratios (SIRs) for analysis.

Main Results:

• Thyroid identified in 24 out of 26 fetuses.
• Identified 17 cases of normal fetal thyroid function and 7 cases of hypothyroidism (6 transient, 1 dysgenesis).
• Significantly different mean and maximum SIR values between euthyroid and hypothyroid fetuses (P=0.0088 and P=0.0221, respectively).

Conclusions:

• Thyroid signal intensity ratio (SIR) measurement via MRI provides valuable information on fetal thyroid function.
• This MRI-based SIR assessment is a useful tool for evaluating fetal thyroid status.
• The findings support the use of 3D GRE T1-weighted MRI for fetal thyroid evaluation.