Differential diagnosis of silent infarction (images from patients without SCA). (A) Mimics of SCI: periventricular leukomalacia (PVL). A 20-month-old boy with cerebral palsy characterized by spastic diplegia. Axial FLAIR MR images illustrate classic findings of PVL. The image on the left is at the level of the centrum semiovale and demonstrates bilateral hyperintensities in the parietal lobe white matter. This appearance of the white matter overlaps with the presentation of SCI. The image on the right at the level of the basal ganglia illustrates dysmorphic lateral ventricles, thinning of the periventricular white matter and periventricular signal hyperintensity in a predominantly posterior distribution. Taken together, the images are consistent with the diagnosis of PVL in the setting of prematurity and cerebral palsy rather than SCI. (B) Terminal zones of myelination. A 2-year-old boy with a normal MRI of the brain. The Axial FLAIR MR image (left) shows ill-defined hyperintensity bilaterally in the deep white matter adjacent to the atria of the lateral ventricles (arrows). The T2-weighted image on the right illustrates that there are well-defined linear perivascular spaces (arrowheads) traversing the area of vague hyperintensity. This combination of findings is classic for the terminal zones of myelination, the last areas of the deep white matter to myelinate and displace free water. The terminal zones of myelination remain prominent through the second year of life and become progressively less conspicuous over time. They may be visible into the middle of the first decade of life. (C) Virchow-Robin spaces. A 12-year-old boy withT2-weighted (left) and Axial FLAIR (right) MR images with a normal MRI. The T2-weighted images reveal multiple punctuate white matter hyperintensities that suppresses on FLAIR indicating that the hyperintensities are indistinguishable from cerebrospinal fluid. The fluid attenuation feature of the FLAIR image helps to differentiate perivascular (Virchow-Robin) spaces from SCI. The arrows illustrate another feature of perivascular spaces which is that they appear linear when running within the slice. (D) Posterior reversible encephalopathy syndrome (PRES). A 14-year-old girl with altered mental status and seizures. Axial FLAIR MR images demonstrate hyperintensities bilaterally in the subcortical white matter and overlying cortex with predominant subcortical involvement. The distribution of the signal abnormalities is predominantly posterior and peripheral, a typical distribution for PRES. In contradistinction, SCIs favor the deep white matter of the frontal lobes. Nevertheless, clinical context is the key to differentiating PRES from SCIs. This is especially challenging in patients with SCD because they are prone to development of PRES and SCI. (E) Acute disseminated encephalomyelitis (ADEM). A 5-year-old boy with fever and headache. Axial FLAIR MR images demonstrate patchy, bilateral hyperintensities in the white matter of the centrum semiovale and corona radiata (arrows). Although the image on the left could be confused for SCI in the frontal border zone distribution, the middle and right image show subcortical and patchy hyperintensities that would be atypical in location, size, and lesion definition for SCI. The clinical information is the key to distinguishing lesions of ADEM from SCI.