PMC5147683_01
(A) Axial noncontrast CT shows huge intraaxial hypodense cyst with marginal calcification (arrow). (B) Axial FLAIR image shows the cyst to be isointense with CSF. There is marked mass effect with contralateral displacement of midline structures and left ventricular uncompensated hydrocephalus. (C) Axial susceptibility-weighted image confirms the marginal calcification (arrow) and also reveals a very thin, hypointense marginal cystic membrane. (D) Coronal T2-weighted image and (E) sagittal T1-weighted image show smoothly marginated cyst causing internal transtentorial herniation as well as displacement of adjacent convolutions. (F) Axial postcontrast T1-weighted image shows lack of contrast enhancement.
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Brain magnetic resonance imaging (MRI) confirmed the cyst to be isointense with cerebrospinal fluid (CSF) and causing marked mass effect, contralateral displacement of the midline structures, and left ventricular uncompensated hydrocephalus (Figure 1).
(A) Axial diffusion-weighted image and (B), corresponding apparent diffusion coefficient (ADC) map reveal water-like diffusion within the cyst. Placement of an MR spectroscopy voxel is also shown on A. (C) Color-coded fractional anisotropy image derived from a diffusion-tensor imaging (DTI) study at 16 directions shows that the corticospinal tract (CST) is severely distorted and displaced anteriorly (arrows; compare with normal contralateral CST, arrowheads). Fiber tractography image (E), however, confirms that the CST is only displaced, but not infiltrated, by the adjacent mass. (D) MR spectroscopy obtained with a single-voxel point-resolved (PRESS) technique at 144 ms echo-time shows absence of normal brain metabolites within the cyst; a huge peak at 2.4 ppm is consistent with succinate, whereas an inverted double peak at 1.3-1.4 ppm is consistent with lactate.
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Diffusion-tensor imaging (DTI) showed displacement of the ipsilateral corticospinal tract, whereas MR spectroscopy showed absence of normal brain metabolites and presence of succinate and lactate within the cyst (Figure 2).
Protoscoleces from the hydatid cyst fluid, stained with Dobell (40x magnification). Note the hooklets (black arrow).
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Cystic fluid was analyzed and protoscoleces were stained (Figure 3).