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Olfactory cistern

The olfactory cistern is a small, cerebrospinal fluid (CSF)-filled subarachnoid space situated in the anterior cranial fossa, closely associated with the olfactory bulbs and tracts. It is located just above the cribriform plate of the ethmoid bone and beneath the frontal lobes, lying on either side of the midline. This cistern provides a cushioning environment for the olfactory apparatus and is bordered by delicate arachnoid membranes. Though small and sometimes overlooked, recognition of the olfactory cistern is important in neuroimaging and neuroanatomy due to its proximity to key structures and its potential involvement in pathological processes such as CSF leaks or meningeal diseases.

Synonyms:

  • Olfactory sulcal cistern

  • Cistern of olfactory tract

  • Anterior olfactory cistern

Function:

  • Provides a protective CSF cushion for the olfactory bulbs and tracts.

  • Acts as a conduit for CSF circulation in the anterior cranial fossa.

  • Separates the olfactory structures from the underlying cribriform plate and dura, reducing mechanical stress.

  • May serve as a pathway for the spread of infections or neoplastic processes from the nasal cavity to the intracranial compartment.

MRI Appearance:

  • T1-weighted Images:

    • Appears as a CSF-intensity (hypointense/dark) space anterior and inferior to the frontal lobes, bordering the olfactory bulbs and tracts.

    • The olfactory bulbs and tracts are seen as small, oval, or linear structures surrounded by low-signal CSF.

    • No intrinsic enhancement unless complicated by pathology (e.g., meningeal enhancement).

  • T2-weighted Images:

    • The cistern appears hyperintense (bright), consistent with CSF signal.

    • Olfactory bulbs/tracts are seen as intermediate-to-low signal structures within or adjacent to the bright CSF.

  • FLAIR Images:

    • The cistern appears hypointense (dark), as the CSF signal is suppressed on FLAIR.

    • Pathological processes (e.g., pus, blood, tumor infiltration) may alter the expected low signal.

CT Appearance:

  • Appears as a low-density (dark) space above the cribriform plate and adjacent to the olfactory bulbs and tracts.

  • Not easily distinguishable unless there is abnormal fluid, hemorrhage, or other pathology.

  • Bony landmarks (cribriform plate, ethmoid roof) and olfactory grooves can be used for localization.

  • The cistern may become more apparent with the presence of abnormal densities (e.g., blood, tumor, air from a CSF leak).

MRI images

olfactory cistern mri 3t coronal image

MRI images

olfactory cistern mri 3t sagittal image

CT image

Olfactory cistern CT coronal anatomy image -img-00001-00001