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Infundibular recess

The infundibular recess is a small, funnel-shaped extension of the third ventricle that projects downward into the pituitary stalk (infundibulum), located between the optic chiasm and mammillary bodies. This normal anatomical structure forms part of the ventricular system and is positioned in the floor of the third ventricle, just above the pituitary gland. Accurate identification of the infundibular recess is crucial in neuroimaging to differentiate normal anatomy from pathologies affecting the hypothalamic-pituitary axis.

Synonyms

  • Pituitary recess

  • Hypophyseal recess

  • Funnel-shaped recess of the third ventricle

  • Infundibular extension of the third ventricle

MRI Appearance of the Infundibular Recess

T1-Weighted Imaging

  • Appears as a small, linear or slit-like CSF-intensity structure extending inferiorly from the third ventricle into the pituitary stalk.

  • Signal intensity is hypointense (dark), matching cerebrospinal fluid.

  • Surrounding hypothalamic tissue and pituitary stalk demonstrate intermediate to slightly higher signal.

T2-Weighted Imaging

  • Infundibular recess is hyperintense (bright), similar to CSF.

  • Provides excellent contrast with the adjacent brain parenchyma and hypothalamic structures.

  • The outline is well-defined due to the high signal of CSF within the recess.

FLAIR (Fluid-Attenuated Inversion Recovery)

  • The infundibular recess appears hypointense (dark) as FLAIR suppresses the signal from CSF.

  • May appear less conspicuous compared to T2, but still seen as a linear/cleft-like area in the expected location.

  • Useful for excluding adjacent pathological lesions or abnormal fluid collections.

CT Appearance of the Infundibular Recess

  • Seen as a small, low-density (hypodense) linear or cleft-like structure within the floor of the third ventricle, just above the sella turcica.

  • Margins are less well defined compared to MRI due to lower soft tissue resolution.

  • Best appreciated on thin-section axial or coronal images with good contrast settings.

MRI images

Infundibular recess mri 3t axial image

MRI images

Infundibular recess mri 3t sagittal image