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Medial vein of right lung

The medial vein of the right lung is the segmental venous drain of the medial segment (S5) of the right middle lobe. In typical anatomy, it joins the lateral segment vein (V4) to form the middle lobe vein (MLV), which empties into the anterior–inferior aspect of the right superior pulmonary vein (RSPV) near its ostium to the left atrium. The vein courses anteriorly within the middle lobe, running alongside segmental bronchi/arteries and converging at the hilum. Variants include a separate MLV ostium to the left atrium or, less commonly, drainage to the inferior pulmonary vein.

Synonyms

  • Right middle lobe medial segment vein (V5)

  • Medial basal vein of right middle lobe (colloquial)

  • Tributary of the middle lobe vein → RSPV

Function

  • Returns oxygenated blood from the medial segment (S5) of the right middle lobe

  • Contributes to the middle lobe vein → RSPV → left atrium pathway

  • Serves as a key landmark in segmentectomy and pulmonary vein isolation planning

Tributaries

  • Intrapulmonary venules from the S5 subsegments, coalescing into V5 branches before joining V4 to form the middle lobe vein

MRI Appearance

T1-weighted images:

  • Small venous lumen shows a flow void (black); adjacent perihilar fat aids delineation.

T2-weighted images (normal):

  • Vein appears as a linear flow void against higher signal lung/mediastinal tissues; intraluminal thrombus would increase signal depending on age.

T2 TRUFISP (cardiac/respiratory-gated):

  • Depicts V5/MLV as a bright, continuous venous channel draining into the RSPV; cine-like assessment of patency and convergence with V4.

STIR:

  • Fat suppression improves vein conspicuity against hilar fat; perivascular edema/inflammation appears hyperintense.

T1 Post-contrast (gadolinium):

  • Homogeneous enhancement of V5/MLV and RSPV with clear visualization of confluence; filling defects suggest thrombus or stenosis.

MRI Non-Contrast Cardiac-Gated 3D (whole-heart):

  • ECG-navigated 3D datasets show V5 joining V4 → MLV → RSPV and the RSPV ostium; useful for pre-ablation venous mapping and surgical planning without contrast.

CT Appearance

CT Coronary Angiography (CCTA) / CT Pulmonary Venography:

  • Contrast opacifies V5, V4, the middle lobe vein, and their junction with the RSPV; multiplanar/3D reconstructions define ostial anatomy, common trunks, and variants.

  • Detects stenosis, extrinsic compression, anomalous drainage, or thrombus; critical for AF ablation and middle-lobe segmentectomy planning.

CT images

Medial vein of right lung anatomy CT axial image -img-00000-00000

CT images

Medial vein of right lung anatomy CT axial image -img-00000-00000_00001

MRI images

Medial vein of right lung mri axial image