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Subsuperior segmental artery of right lung

The subsuperior segmental artery (A*) of the right lung is a variable branch of the right lower lobe pulmonary artery. It arises between the superior segmental artery (A6) and the basal segmental arteries (A7–A10). When present, it supplies the subsuperior lung segment (S*), a small wedge-shaped portion located between the superior and basal segments of the lower lobe.

The subsuperior artery typically courses posteriorly and inferiorly from the interlobar pulmonary artery, running alongside a bronchus variant (B*) when the segment is well developed. Not all individuals have a distinct subsuperior segment; when absent, its vascular territory is usually supplied by A6 or A7.

Clinically, knowledge of the subsuperior segmental artery is crucial in segmentectomy, lobectomy, and pulmonary embolism imaging, as unrecognized variants may lead to incomplete resections or overlooked vascular pathology.

Synonyms

  • A* artery

  • Right lung subsuperior segment artery

  • Subsuperior pulmonary artery branch

Function

  • Provides oxygenated blood (via pulmonary arterial circulation) to the subsuperior segment (S*) of the right lower lobe

  • Serves as an anatomical landmark in pulmonary resections

  • Contributes to variability in pulmonary artery branching important for radiology and thoracic surgery

Branches

  • Supplies S* parenchyma of the right lower lobe

  • May divide into 1–2 small subsegmental branches depending on parenchymal extent

MRI Appearance

T1-weighted images:

  • Lumen shows signal void (black); vessel wall is hypointense

  • Course identifiable against hyperintense perivascular fat and lung hilum

T2-weighted images:

  • Vessel lumen remains a signal void

  • Perivascular abnormalities (edema, tumor infiltration) appear hyperintense

STIR:

  • Fat suppression enhances visualization of the artery along the lower lobe hilum

  • Useful for detecting inflammatory or neoplastic changes

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Artery enhances homogeneously and brightly, confirming patency

  • Clearly delineates its origin between A6 and basal arteries

  • Helps in identifying small emboli or stenosis within subsegmental branches

MRI Non-Contrast Cardiac-Gated 3D Imaging:

  • Demonstrates the three-dimensional course of A* relative to A6 and basal branches

  • Useful for preoperative venous/arterial mapping and in patients contraindicated for contrast

CT Appearance

CT Angiography (CTA):

  • Gold standard for visualization of A*

  • Contrast-enhanced scans demonstrate the origin, course, and branching pattern of the subsuperior artery

  • Multiplanar and 3D reconstructions show relationships to bronchus (B*) and adjacent pulmonary arteries

  • Detects pulmonary emboli, anatomical variations, and surgical landmarks critical for segmentectomy

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Subsuperior segmental artery of right lung anatomy CT axial image -img-00000-00000