MRI of the foetal brain using a rapid 3D steady-state sequence

Area of Science:

• Medical Imaging
• Fetal Medicine
• Neurology

Background:

• Current two-dimensional (2D) methods for diagnosing fetal brain abnormalities have limitations.
• Advanced magnetic resonance imaging (MRI) techniques are being explored to improve diagnostic accuracy.
• Assessing energy deposition is crucial for fetal MRI safety.

Purpose of the Study:

• To evaluate a rapid three-dimensional (3D) T2 weighted MRI sequence for diagnosing fetal brain abnormalities.
• To compare the diagnostic capacity of the 3D sequence with conventional 2D methods.
• To assess the energy deposition (Specific Absorption Rate - SAR) of the 3D sequence.

Main Methods:

• Fifty pregnant women with suspected or high-risk fetal brain malformations were included.
• A routine MRI protocol including 2D sequences was performed, followed by a rapid 3D T2 weighted sequence (approx. 40s acquisition time).
• Image quality and diagnostic findings were compared between 2D and 3D sequences; SAR was recorded in 12 cases.

Main Results:

• The 3D rapid steady-state sequence yielded diagnostic-quality images in 82% (41/50) of fetuses.
• Image acquisition failures occurred exclusively in second-trimester fetuses (35% failure rate), likely due to increased fetal motion.
• Discrepancies between 2D and 3D findings were minimal (2/41 cases); predicted SAR was comparable to conventional sequences.

Conclusions:

• The rapid 3D T2 weighted sequence demonstrates encouraging diagnostic potential for fetal brain abnormalities with acceptable energy deposition.
• Success rates are dependent on gestational age, with higher failure rates in the second trimester due to fetal mobility.
• Further optimization of the 3D sequence, focusing on reduced acquisition time and higher resolution, is needed for improved performance, especially in younger fetuses.