Because of its low radiation exposure and superior soft-tissue contrast, MRI is commonly used for diagnostic techniques in pediatric patients. But the modality can struggle in dealing with a child's restlessness while inside the machine.
According to a study published in the February issue of the American Journal of Roentgenology, researchers from South Korea have found an alternative to conventional MRI in pediatric patients who can't restrict movement during imaging.
Lead author Ji Eun Park, MD, a radiologist from the Seoul National University Children's Hospital and Kyung Hee University Hospital in Seoul, South Korea, and colleagues wrote that magnetization-prepared rapid acquisition gradient echo, or MP-RAGE, is a routinely used sequence for acquisition of T1-weighted 3D datasets of the brain.
MP-RAGE can provide high quality imaging, including high spatial resolution and tissue contrast, but it "is especially susceptible to patient motion and flow-related artifacts due to the fact that its k-space acquisition entails conventional cartesian sampling," Park et al. wrote.
Patient motion during the MP-RAGE imaging process may offset encoding and produce a low-quality image. To reduce this, changing k-space acquisition to different sampling strategies is one solution, the authors wrote. Specifically, the radical volumetric interpolated breath-hold examination—also known as VIBE, or "periodically rotated overlapping parallel lines with enhanced reconstruction"—is an alternative, Park et al. explained.
Researchers included 65 consecutive contrast-enhanced MRI exams performed with axial MP-RAGE and radial VIBE sequences for data. Coefficients of variation of gray matter and white matter; gray matter and CSF; and white matter and CSF were calculated. A subgroup of children who could remain still was also calculated for analysis, which for both groups included scoring in the categories of motion, pulsation artifacts, overall image quality, and lesion on a five-point scale.
Overall, Park and the team found that images obtained with the radial VIBE technique were of higher quality than MP-RAGE images. Radial VIBE technique images also scored higher in almost all categories. Dually noted, researchers found that in children who could remain still, the MP-RAGE technique produced better results.
“To our knowledge, there have been no previous studies in which the radial VIBE sequence has been applied to brain MRI, especially in children," the researchers concluded. "Many pediatric patients cannot stay still during MRI examinations, which decreases the image quality of the conventional contrast-enhanced MP-RAGE sequence. We found that the radial VIBE sequence reduces motion-related artifacts in brain imaging.”