To understand the underlying mechanism involving the subcortical U-fibers in white matter disorders.
To extract key diagnostic and practical points in the MRI appearance of white matter disease.
The processing and transfer of information in the brain is achieved through a vast network of short-range and long-range connections between neurons. [Fig 1]
These connections are established during brain development in a spatially and temporally regulated process comprising of neurogenesis, neural migration, synaptic formation, dendritic arborization, axonal growth and myelination.
The U-fibers or short association fibers (SAFs) represent thin bundles of myelinated axonal fibers connecting neurons from adjacent cortical gyri, being located in the superficial white matter immediately deep to the gray matter with...
Findings and procedure details
Magnetic resonance imaging (MRI) is the method of choice for investigating white matter lesions, which are a common finding in routine practice. A standard MRI protocol containing the sequences necessary for a reliable characterization of white matter lesions is listed in figure 3. [Fig 3]
Additional diagnostic imaging tools such as MR spectroscopy, perfusion measurements or diffusion tensor imaging could provide additional aid in ambiguous cases.[3,4,6]
On MR imaging, normal myelinated white matter appears as hyperintense on T1WI and hypointense on T2WI, as...
A key diagnostic element is correctly identifying subcortical U-fibers involvement, which on MR imaging manifests as a juxtacortical (directly in contact with the cortex) white matter lesion.
Subcortical U-fibers involvement helps narrow down an otherwise extensive list of differential diagnoses for white matter lesions. However, correlation with associated patterns of white/gray matter involvement, as well as the clinical and biological status of the patient, is often necessary for reaching a conclusion.
Personal information and conflict of interest
Nothing to disclose
Ouyang, Minhui, Kang, Huiying, Detre, John A., Roberts, Timothy P.L., Huang, Hao (2017). Short-range connections in the developmental connectome during typical and atypical brain maturation. Neuroscience and Biobehavioral Reviews; 83, 109-122.
Riley K.J.; O'Neill D.P.; Kralik S.F. (2018). Subcortical U-Fibers: Signposts to the Diagnosis of White Matter Disease. Neurographics; 8(4), 234–243.
Yoshino M., Saito K., Kawasaki K. et al. (2020). The origin and development of subcortical U-fibers in gyrencephalic ferrets. Mol Brain; 13, 37.
Attar F.M., Kirilina E., Haenelt D., Pine K., Trampel R., Edwards...