神经影像与临床__培训课件.ppt

Hurler syndrome (mucopolysaccharidosis type I) in a 2-year-old boy with typical external features of this syndrome. A classic Hurler mutation with severe α-l-iduronidase deficiency was demonstrated. (a) Axial proton-density–weighted image (3835/150) shows dilated VR spaces in both hemispheres (arrowheads). (b) Coronal FLAIR image (6381/100) shows increased signal intensity in the surrounding brain parenchyma (arrows); this finding indicates that the spaces are not normally dilated VR spaces. There is also increased CSF space frontally. Cystic Neoplasms Giant dilatations of the VR spaces may cause mass effect and assume bizarre configurations that may be misinterpreted as a cystic brain tumor . However, cystic brain tumors often have solid components, may enhance with contrast material, mostly show surrounding edema, and have contents that usually are not equal to CSF, as can be seen on FLAIR images . They generally exhibit low signal intensity on diffusion-weighted images with corresponding high apparent diffusion coefficient values . When the lesions in question occur in a characteristic location along the path of a penetrating vessel, follow CSF signal intensity with all sequences, do not enhance with contrast material, and have normal adjacent brain parenchyma, their appearance is virtually always pathognomonic of giant VR spaces . Still, differentiation between giant VR spaces and cystic brain tumors is sometimes difficult and follow-up MR imaging may be useful. Desmoplastic pilocytic astrocytoma of the right thalamus, cerebral peduncle, and brainstem in a 15-year-old girl. (a, b) Axial proton-density–weighted (2374/100) (a) and FLAIR (6614/100) (b) images show a large mass with solid (arrow) and cystic (arrowheads) components. (c) Axial gadolinium-enhanced T1-weighted image (598/18) shows inhomogeneous enhancement of the solid component (arrow) and rim enhancement of the cystic components (arrowheads). Obstruction of the third ventricle has caused hydroc