T1 Hypointense Suprasellar Lesion

T1 Hypointense Suprasellar Lesion

Anne G. Osborn, MD, FACR



  • Dilated Third Ventricle

  • Arachnoid Cyst (AC)

  • Neurocysticercosis (NCC)

Less Common

  • Pilocytic Astrocytoma (PA)

  • Craniopharyngioma

  • Epidermoid Cyst

  • Rathke Cleft Cyst

  • Enlarged Perivascular Spaces

Rare but Important

  • Pituitary Macroadenoma

  • Saccular Aneurysm (Acutely Thrombosed)

  • Pituitary Apoplexy

  • Pilomyxoid Astrocytoma


Key Differential Diagnosis Issues

  • T1 hypointense lesion = hypointense compared to brain, not necessarily ˜ CSF

  • Lesions CSF-like on all sequences

    • Enlarged 3rd ventricle, arachnoid cyst, perivascular spaces

    • Epidermoid cyst

  • Lesions hypointense to brain but hyperintense to CSF on T1WI

    • Neoplasms

    • Congenital or infectious cysts

  • Enhancing hypointense lesions

    • Solid (astrocytoma, adenoma)

    • Rim/ring (NCC, craniopharyngioma, RCC)

Helpful Clues for Common Diagnoses

  • Dilated Third Ventricle

    • Enlarged 3rd ventricle recesses protrude into suprasellar cistern, sella turcica

    • Behaves exactly like CSF on FLAIR, DWI

  • Arachnoid Cyst (AC)

    • Bows 3rd ventricle up, over cyst

    • Suppresses on FLAIR, no restriction on DWI

  • Neurocysticercosis (NCC)

    • Cysts often show rim enhancement

Helpful Clues for Less Common Diagnoses

  • Pilocytic Astrocytoma (PA)

    • Hyperintense to CSF on T1WI

    • Enhancement typical

  • Craniopharyngioma

    • 90% cystic, 90% Ca++, 90% enhance

    • Cyst signal variable (hyper > hypointense)

  • Epidermoid Cyst

    • No suppression on FLAIR, restricts on DWI

  • Rathke Cleft Cyst

    • Cyst fluid more often hyperintense

    • Look for “claw sign” of enhancing pituitary around cyst

Helpful Clues for Rare Diagnoses

  • Pituitary Macroadenoma

    • Small intratumoral cysts common

    • Extratumoral cysts (trapped perivascular spaces) less common

    • Necrosis/apoplexy may appear cystic, show rim enhancement

Image Gallery

Sagittal T1WI MR shows aqueductal stenosis image causing marked enlargement of the third ventricle with herniation of anterior recesses into the suprasellar cistern image.

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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on T1 Hypointense Suprasellar Lesion
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