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Lateral aperture of the fourth ventricle

The lateral aperture of the fourth ventricle, also known as the foramen of Luschka, is a paired anatomical opening located at the lateral recesses of the fourth ventricle in the brainstem. These apertures serve as passageways for cerebrospinal fluid (CSF) to flow from the fourth ventricle into the cerebellopontine angle cistern, contributing to the overall CSF circulation in the brain. Understanding the imaging characteristics of the lateral apertures is crucial for identifying normal anatomical variants and differentiating them from pathological processes, particularly in neuroimaging studies.

Synonyms:

  • Foramen of Luschka

  • Lateral foramina of the fourth ventricle

  • Lateral ventricular apertures

MRI Appearance

T2-Weighted Imaging

  • Appears as a small, CSF-intensity cleft or slit at the lateral aspect of the fourth ventricle, near the cerebellopontine angle.

  • Demonstrates hyperintense signal (bright) similar to other CSF spaces.

  • May be more easily visualized on high-resolution axial or coronal sections.

T1-Weighted Imaging

  • The aperture is hypointense (dark), matching the signal of CSF.

  • Appears as a small, low-signal space in the expected location of the foramen of Luschka.

  • Surrounding brainstem and cerebellar tissue have higher signal intensity compared to CSF.

FLAIR Imaging

  • The lateral aperture is usually suppressed and appears dark (similar to other CSF spaces).

  • May help exclude pathological processes such as cysts or tumors, which do not suppress on FLAIR.

  • Useful in evaluating perilesional changes or abnormal enhancement adjacent to the foramen.

CT Appearance

  • On non-contrast CT, the lateral aperture is not directly visualized as a distinct structure due to its small size and location.

  • May appear as a tiny, CSF-density cleft at the lateral margin of the fourth ventricle if imaging resolution allows.

MRI images

Lateral aperture of fourth ventricle mri 3t axial image

MRI images

Lateral aperture of fourth ventricle mri 3t sagittal image