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Posterior segmental artery right lung

The posterior segmental artery of the right lung (A2) is a segmental branch of the right superior lobar artery, arising from the right pulmonary artery. It supplies the posterior segment (S2) of the right upper lobe.

The A2 artery originates within the lung hilum, typically after the right pulmonary artery gives rise to the right superior lobar artery. From there, it courses posteriorly and superiorly along the bronchus of the posterior segment, following a broncho-arterial relationship. It travels within the intersegmental planes between S2 and adjacent segments, before dividing into smaller intrasegmental branches.

Anatomical variations exist: A2 may share a common origin with the apical (A1) or anterior (A3) segmental arteries. Knowledge of its exact branching is critical in segmentectomy, lobectomy, pulmonary angiography, and pulmonary embolism evaluation.

Synonyms

  • A2 artery

  • Right upper lobe posterior segmental artery

  • Posterior branch of right superior lobar artery

Function

  • Supplies oxygen-poor blood from the pulmonary trunk → right pulmonary artery → superior lobar artery → posterior segmental artery → posterior segment (S2) of right upper lobe

  • Ensures gas exchange in the posterior segment of the right upper lobe

  • Serves as a key vascular landmark in thoracic imaging and lung surgery

Branches

  • Small intrasegmental arteries supplying S2 parenchyma

  • Anastomoses with adjacent segmental arteries (A1, A3) in intersegmental zones

MRI Appearance

T1-weighted images:

  • Appears as a signal void (black lumen) following the posterior segmental bronchus

  • Vessel wall hypointense, surrounded by hyperintense fat planes near the hilum

T2-weighted images:

  • Lumen shows a signal void

  • Pathology (e.g., thrombus, stenosis) appears as abnormal signal within lumen or surrounding tissue

T2 TRUFISP (cardiac/respiratory-gated):

  • Demonstrates A2 as a bright vascular lumen branching posteriorly from the superior lobar artery

  • Provides cine-like assessment of pulmonary arterial patency and branching

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, improving visualization of the artery near hilum and intersegmental planes

  • Highlights perivascular edema or infiltrative pathology as hyperintensity

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • A2 enhances brightly with contrast, allowing clear mapping of segmental branches

  • Detects filling defects from embolism, stenosis, or arteriovenous malformation

MRI Non-Contrast Cardiac-Gated 3D Imaging:

  • Whole-heart 3D imaging shows A2 branching from the superior lobar artery and supplying S2

  • Valuable for preoperative planning in segmentectomy when contrast is contraindicated

MRA (Magnetic Resonance Angiography):

  • Contrast-enhanced MRA provides high-resolution visualization of A2 origin and course

  • Helps in detection of segmental pulmonary embolism and surgical mapping

CT Appearance

CT Coronary Angiography (CCTA) / Pulmonary CT Angiography (CTA):

  • Opacifies A2 and its branches supplying the posterior segment (S2)

  • Multiplanar and 3D reconstructions demonstrate branching pattern relative to A1 and A3

  • Detects segmental pulmonary embolism, stenosis, congenital anomalies, or vascular encasement by tumor

  • Provides essential guidance for segmentectomy, lobectomy, and pulmonary vascular interventions

CT image

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

MRI image

Posterior segmental artery of right lung mri image