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Posterior vein of septum pellucidum

The posterior vein of the septum pellucidum is one of the paired deep cerebral veins that drain the posterior part of the septum pellucidum and adjacent fornix. It courses posteriorly along the midline, running between the leaflets of the septum pellucidum, and typically drains into the internal cerebral veins near their confluence at the venous angle. The posterior septal veins form part of the deep venous drainage system of the brain, working alongside the anterior septal veins to maintain venous outflow from midline forebrain structures.

Synonyms

  • Posterior septal vein

  • Septum pellucidum posterior vein

  • Deep septal vein (posterior division)

Function

  • Drains venous blood from the posterior septum pellucidum

  • Collects tributaries from the fornix and adjacent deep white matter

  • Contributes to venous outflow into the internal cerebral veins

  • Helps maintain balance in deep cerebral venous circulation

MRI Appearance

T1-weighted images (non-contrast):

  • Appears as a linear flow void (signal loss) between the leaflets of the septum pellucidum

  • Difficult to delineate without angiographic sequences

T2-weighted images:

  • Also visualized as a hypointense linear structure due to flow void

  • Best identified relative to the adjacent CSF-bright lateral ventricles

MRA / MR Venography (Time-of-Flight or Contrast-Enhanced):

  • Demonstrates the posterior septal vein coursing posteriorly to join the internal cerebral veins

  • Normal vein appears as a thin, enhancing venous channel

  • Useful for detecting venous thrombosis, developmental anomalies, or displacement by tumors

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • The vein shows uniform enhancement with gadolinium

  • Enhances delineation against the surrounding septal tissue

  • Helpful in mapping deep venous anatomy in surgical planning

CT Appearance

Non-contrast CT:

  • Vein is not directly visualized due to its small caliber

  • Indirect visualization possible as a linear soft tissue density near the septum pellucidum

CT Venography (CTV):

  • Clearly demonstrates the enhanced posterior septal vein draining into the internal cerebral vein

  • Useful for diagnosing deep venous thrombosis, arteriovenous malformations (AVM), or venous anomalies

  • Provides high-resolution mapping of deep venous system anatomy

MRI images

Posterior vein of septum pellucidum