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Superior segmental artery of right lung

The superior segmental artery of the right lung (A6) is a key segmental branch of the right lower lobar pulmonary artery, supplying the superior segment (S6) of the right lower lobe. It arises from the interlobar portion of the right pulmonary artery, typically as a single trunk, though variations with multiple branches may occur.

The artery courses posteriorly and superiorly into the superior segment (S6) of the right lower lobe, traveling alongside the segmental bronchus (B6) and segmental vein (V6) within the bronchovascular bundle. Its anatomical relations are important during segmentectomy, lobectomy, and pulmonary embolism evaluation, as A6 is one of the most common sites for isolated emboli.

The superior segment (S6) itself forms the posterior basal portion of the right lower lobe, lying adjacent to the vertebral column and diaphragm. Because of its posterior position, surgical exposure requires careful dissection of the interlobar fissure.

Synonyms

  • A6 artery

  • Superior segmental branch of right lower lobar artery

  • Pulmonary artery to segment S6

Function

  • Supplies oxygenated blood to the superior segment (S6) of the right lower lobe

  • Maintains segmental perfusion critical for gas exchange

  • Serves as a surgical and imaging landmark in segmentectomy, lobectomy, and embolism studies

Branches

  • Typically arises as a single trunk from the right lower lobar artery

  • May divide into two or more subsegmental branches supplying subdivisions of S6

MRI Appearance
T1-weighted images:

  • A6 appears as a signal void (black lumen) adjacent to segmental bronchus B6

  • Surrounded by perivascular fat and lung parenchyma

T2-weighted images:

  • Flow void persists in normal conditions

  • Thrombus appears as intermediate to high signal within the lumen

T2 TRUFISP (cardiac/respiratory-gated):

  • A6 visualized as a bright, well-defined lumen coursing posteriorly in S6

  • Provides cine-like assessment of segmental arterial flow and patency

STIR:

  • Fat suppression increases conspicuity against surrounding parenchyma

  • Useful for detecting perivascular edema or inflammatory involvement

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • A6 enhances brightly and homogeneously

  • Filling defects correspond to pulmonary emboli or stenosis

MRI Non-Contrast 3D Cardiac-Gated Imaging:

  • Shows the origin of A6 from the right lower lobar artery, its posterior course, and branching pattern

  • Provides detailed mapping for segmentectomy or embolism evaluation without contrast

MRA (Magnetic Resonance Angiography):

  • Contrast-enhanced MRA depicts A6 and its segmental distribution in high resolution

  • Demonstrates embolism, stenosis, or anomalous branching

CT Appearance
CT Pulmonary Angiography (CTPA):

  • Gold standard for segmental artery visualization

  • A6 appears as a contrast-opacified branch of the right lower lobar artery traveling posteriorly into S6

  • Detects pulmonary embolism, stenosis, aneurysm, or anomalous branching patterns

  • Multiplanar and 3D reconstructions are essential for surgical planning and interventional guidance

CT image

Superior segmental artery of right lung anatomy ct axial image -img-00000-00000

MRI image

Superior segmental artery of right lung mri image