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Posterior mesencephalic vein

The posterior mesencephalic vein is a small, deep cerebral vein draining the posterior aspect of the midbrain (mesencephalon) and adjacent structures. It plays a crucial role in venous drainage of the brainstem, ultimately emptying into larger veins like the basal vein of Rosenthal or the vein of Galen. Radiologically, its identification is important in vascular imaging of the brainstem region, especially in differentiating normal veins from pathological processes or variants.

Synonyms

  • Posterior midbrain vein

  • Vena mesencephalica posterior (Latin)

  • Vein of the posterior midbrain

Function

  • Drains venous blood from the posterior aspect of the mesencephalon (midbrain)

  • Empties into the basal vein of Rosenthal or vein of Galen

  • Contributes to the overall venous drainage of the deep central brainstem structures

MRI Appearance

  • T2-Weighted Images:

    • Appears as a small, linear or dot-like flow void (hypointense signal) posterior to the midbrain

    • Better visualized with high-resolution thin-slice sequences

  • T1-Weighted Images:

    • Typically isointense to brain tissue (not individually visualized unless prominent)

    • May be faintly seen as a linear structure if adjacent brain tissue provides contrast

  • Phase Contrast 3D (PC 3D) MR Venography:

    • Visualized as a slender, tubular vein posterior to the midbrain

    • Enhances as part of the deep venous system; can be traced to its drainage into the basal vein or vein of Galen

  • Post-Contrast T1-Weighted Images:

    • Enhances and becomes more conspicuous due to gadolinium uptake within the vein

    • Seen as a thin enhancing structure in the perimesencephalic region

CT and CTV Appearance

  • Non-Contrast CT:

    • Usually not visualized due to small size and isodensity with surrounding brain tissue

    • May appear as a subtle linear hypodensity in rare cases of dilatation

  • CT Venography (CTV):

    • Visualized as a thin, enhancing vein posterior to the midbrain

    • Best seen on high-resolution, contrast-enhanced venous phase images

    • Drains toward the basal vein of Rosenthal or vein of Galen, aiding in anatomical mapping

MRI images

Posterior mesencephalic vein MRI 3T axial image 1

MRI images

Posterior mesencephalic vein MRI 3T axial image

MRI images

Posterior mesencephalic vein MRI 3T sagittal image