PMC4712088_01
(A) Axial T2-weighted image shows an expansile CSF isointense lesion in the left thalamus and cerebral peduncle. No metastasis or edema is found in the expected location of the left corticospinal tract. (B) Axial directionally encoded color FA map illustrates thinning and deformity of the left corticospinal tract (arrow) caused by the enlarged Virchow-Robin spaces. As shown in the small globe in the upper left corner, blue represents craniocaudal, green anteroposterior, and red transverse orientations. (C) FA histogram shows the peak frequency for the enlarged Virchow-Robin space side is .9 (dark gray), and for the normal side is .7 (light gray). (D) Tractography overlaid on a coronal contrast T1-weighted image shows subtle mass effect upon the left corticospinal tract (arrows).
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F1
MRI also revealed cystic dilatations in the left thalamus and ventral midbrain adjacent to the corticospinal tract. (Fig 1A). Using DTI Studio v2.5, fractional anisotropy (FA), mean diffusivity (MD), and directionally encoded color FA maps were generated (Fig 1B). Histogram analysis showed increased peak frequency of FA (Fig 1C). Tractography showed displacement and compression of the corticospinal tract by the enlarged Virchow-Robin spaces (Fig 1D).