This neoplasm is hypodense relative to the parenchyma on NECT scans except one patient who had hemorrhage due to biopsy (Figures 1,3,4). MR imaging examinations in four of the patients revealed a contrast enhancing partially cystic hypothalamic-suprasellar mass near midline, centered in the floor of the third ventricle. The larger tumors, in three of the pediatric patients, raised the floor of the third ventricle and encased the distal internal carotid arteries. These neoplasms also obstructed the third ventricle with resultant hydrocephalus. Non-contrast T1-weighted images demonstrated the lesions to be of homogenous low signal intensity relative to the brain parenchyma except one pediatric patient, which had hemorrhage prior to biopsy (Figures 1,2,4). On T2-weighted images, the lesions had fairly homogenous high signal intensity but not as high as the cerebrospinal fluid (Figures 2,3,4). This hypointensity on T1-weighted images and hyperintensity on T2-weighted images may be related to a high intracellular fluid content with the absence of lipid components. Four of the tumors showed intense contrast enhancement in pre-biopsy cases and heterogenous enhancement in postbiopsy cases (Figures 1-4). The tumoral contrast enhancement may be related to the close anatomic relationship between tanycytes and the adjacent vascular structures.

The fifth case consisted of a mass in the left lateral ventricle. The tumor appeared as a homogenous slightly hyperintense mass on the T2-weighted and FLAIR images. There was minimal enhancement following contrast administration (Figure 5). All patients underwent full spinal MRI, which revealed no other lesions along the neuroaxis.

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Figure 1. 2 ½-year-old female with headaches and nausea

1. Axial CT scan image: large hypodense suprasellar mass with hydrocephalus.
2. Axial T1-weighted image: hypointense suprasellar mass.
3. Axial T1-weighted contrast enhanced image: enhancing suprasellar mass encasing the distal internal carotid arteries.
4. Sagittal T1-weighted contrast enhanced image: heterogeneously enhancing hypothalamic-suprasellar mass. (shunt artifact superiorly).

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Figure 2. 2-year-old male with diplopia and decrease left eye vision

1. Axial T2-weighted image: hyperintense suprasellar mass encasing the circle of willis.
2. Axial T1-weighted image: hypointense suprasellar mass encasing the anterior portion of the circle of willis.
3. Sagittal T1-weighted contrast enhanced image: solid-cystic enhancing hypothalamic-suprasellar mass.
4. Coronal T1-weighted contrast enhanced image: solid-cystic enhancing hypothalamic-suprasellar mass.

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Figure 3. 3-year-old male with headache and emesis

1. Axial CT scan image: large heterogeneous suprasellar mass status post biopsy.
2. Axial T2-weighted image: primarily hyperintense suprasellar mass encasing circle of willis.
3. Sagittal T1-weighted contrast enhanced image: heterogeneously enhancing hypothalamic-suprasellar mass.
4. Coronal T1-weighted contrast enhanced image: heterogeneously enhancing hypothalamic-suprasellar mass.

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Figure 4. 26-year-old female with galactorrhea and hypothyroidism

1. Axial CT scan image: hypodense suprasellar mass without calcifications (white arrows).
2. Sagittal T1-weighted image: hypointense hypothalamic mass.
3. Axial T2-weighted image: hyperintense hypothalamic mass with suprasellar extension.
4. Coronal T1-weighted contrast enhanced image: homogeneously enhancing hypothalamic-suprasellar mass.

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Figure 5. 56-year-old female with headache

1. Coronal T1-weighted image: slightly hyperintense mass in left lateral ventricle.
2. Axial FLAIR image: slightly hyperintense mass in left lateral ventricle.
3. Axial T1-weighted contrast enhanced image: minimal enhancing hypointense mass in left lateral ventricle.