Optimization of the Image Contrast for the Developing Fetal Brain using 3D Radial VIBE Sequence in 3T Magnetic Resonance Imaging

Background: Faster and motion robust magnetic resonance imaging (MRI) sequences are desirable in fetal brain MRI. T1-weighted images are essential for evaluating fetal brain development. We optimized the radial volumetric interpolated breath-hold examination (VIBE) sequence for qualitative T1-weighted images of the fetal brain with improved image contrast and reduced motion sensitivity. Materials: and Methods: This was an institutional review board-approved prospective study. Thirty-two pregnant subjects underwent fetal brain scan at 3 Tesla MRI. T1-weighted images were acquired using a 3D radial VIBE sequence with flip angles of 6º, 9º, 12º, and 15º and turbo FLASH (TFL) sequence. Qualitative assessments including image quality and motion artifact severity were evaluated. The image contrast ratio between gray and white matter were measured. Interobserver reliability and intraobserver repeatability were assessed using intraclass correlation coefficient (ICC). Results: : Interobserver reliability and intraobserver repeatability universally revealed almost perfect agreement (ICC > 0.800). Significant differences in image quality were detected in basal ganglia ( P < 0.001), central sulcus ( P = 0.005), myelination ( P < 0.001), lateral fissure ( P = 0.008), optic chiasm ( P < 0.001), and gray matter ( P < 0.001) among radial VIBE with flip angles 6º, 9º, 12º, 15º and TFL groups. Image quality at the 9º flip angle in radial VIBE was generally better than TFL. Radial VIBE sequence with 9º flip angle of gray matter was significantly different by gestational age (GA) before and after 28 weeks ( P = 0.036). Quantified image contrast was significantly different among protocols, consistent with qualitative analysis of image quality. Conclusions: : Three-dimensional radial VIBE with 9º flip angle provides optimal, stable T1-weighted images of the fetal brain. Fetal brain structure and development can be evaluated using high-quality images obtained using this angle.