In Utero MR Imaging for Fetuses with Small Head Sizes without Intracranial Abnormalities Detected on Ultrasonography

Area of Science:

• Prenatal diagnostics
• Fetal medicine
• Neuroimaging

Background:

• In utero MR imaging (iuMRI) is established for fetal brain abnormalities detected by ultrasonography (USS).
• Increasing use of iuMRI for fetuses with small heads but no apparent USS abnormality lacks clear diagnostic value assessment.
• This study addresses the clinical utility of iuMRI in this specific fetal population.

Purpose of the Study:

• To evaluate the diagnostic and clinical value of iuMRI in fetuses with small head sizes but no evident brain abnormality on USS.
• To determine the rate and types of intracranial abnormalities detected by iuMRI in this cohort.
• To assess the impact of iuMRI findings on fetal prognosis.

Main Methods:

• Retrospective analysis of 200 fetuses with small head sizes and normal USS.
• Assessment of intracranial abnormalities detected by iuMRI.
• Evaluation of changes in prognosis attributed to iuMRI findings.
• Analysis of the relationship between fetal head circumference and abnormality detection rate, including sensitivity/specificity.

Main Results:

• Intracranial abnormalities were identified in 10.5% (95% CI, 7.0-15.5%) of fetuses via iuMRI.
• iuMRI findings led to a prognosis change (all worsened) in 76.2% of affected fetuses.
• A more severe reduction in fetal head size correlated with a higher likelihood of intracranial abnormalities.

Conclusions:

• iuMRI demonstrates a significant detection rate (10.5%) for intracranial abnormalities in fetuses with small head sizes.
• Detected abnormalities frequently alter the clinical prognosis, predominantly negatively.
• The risk of intracranial abnormalities increases with greater reductions in fetal head size, supporting the use of iuMRI in this scenario.