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Posteromedian medullary vein

The posteromedian medullary vein is a small but important intrinsic vein of the medulla oblongata, playing a key role in draining the medial aspect of the medulla and channeling venous blood towards the deeper venous system of the posterior fossa. Understanding its anatomy, function, and imaging characteristics is crucial, especially in the evaluation of vascular pathologies or venous anomalies in the brainstem region.

Synonyms

  • Median medullary vein

  • Posterior median vein of medulla

  • Vein of the posterior median sulcus

Function

  • Drains venous blood from the medial portion of the medulla oblongata.

  • Empties into the anterior spinal vein or the posterior medullary venous network.

  • Helps maintain venous outflow from the brainstem, particularly from the midline structures.

MRI Appearance

  • T2-weighted Imaging:

    • Appears as a linear or curvilinear hypointense (dark) structure along the posterior midline of the medulla.

    • Small caliber, often subtle, sometimes not visible unless dilated or in high-resolution images.

  • T1-weighted Imaging:

    • Typically not well visualized due to low intrinsic contrast between the vein and adjacent medullary tissue.

    • May appear as a faint linear hypointensity if prominent.

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

    • More sensitive for detecting small venous structures.

    • The vein appears as a fine linear flow void or a high-signal structure depending on the flow encoding.

  • Post-Contrast T1-weighted Imaging:

    • The vein may enhance if there is slow flow or if the vein is dilated.

    • Typically, veins of this size show subtle linear enhancement, best seen with high-resolution or thin-section imaging.

CT and CTV Appearance

  • Non-contrast CT:

    • Usually not visible due to small size and similar attenuation as adjacent medulla.

  • CT Venography (CTV):

    • May appear as a very fine enhancing linear structure in the midline posterior medulla.

    • More readily identified if the vein is enlarged or in the presence of venous congestion.

MRI images

Posteromedian medullary vein MRI 3T image