In vivo assessment of myelination by phase imaging at high magnetic field

The present study evaluated the potential of using the phase of T2* weighted MR images to characterize myelination during brain development and pathology in rodents at 9.4T. Phase contrast correlated with myelin content assessed by histology and suggests that most contrast between white and cortical gray matter is modulated by myelin. Ex vivo experiments showed that gray-white matter phase contrast remains unchanged after iron extraction. In dysmyelinated shiverer mice, phase imaging correlated strongly with myelin staining, showing reduced contrast between white and gray matter when compared to healthy controls. We conclude that high-resolution phase images, acquired at high field, allow assessment of myelination and dysmyelination. ► Phase of T2* weighted MRI was acquired during brain development in rats at 9.4T. ► Phase contrast correlated with myelin content assessed by histology. ► Ex vivo gray-white matter phase contrast remained unchanged after iron extraction. ► In dysmyelinated shiverer mice, phase imaging correlated with myelin staining. ► High-resolution phase images allow assessment of myelination and dysmyelination.