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Lateral basal segmental artery of left lung

The lateral basal segmental artery of the left lung (A9) is a branch of the left lower lobe pulmonary artery. It arises from the interlobar portion of the left pulmonary artery, coursing laterally and inferiorly to supply the lateral basal segment (S9) of the left lower lobe. This segment lies adjacent to the costal surface of the lung, positioned between the anterior and posterior basal segments.

The artery runs parallel to the segmental bronchus (B9) and is accompanied by the lateral basal segmental vein, forming the classic bronchovascular bundle. Its role is critical in providing oxygenated blood for gas exchange surfaces within the S9 segment.

Knowledge of this artery is crucial in thoracic surgery, pulmonary segmentectomy, and interventional radiology, particularly in procedures such as segmental resection for localized tumors or arteriovenous malformation embolization.

Synonyms

  • A9 artery

  • Lateral basal artery (left lung)

  • Segmental artery to S9

Function

  • Supplies oxygenated blood to the lateral basal segment (S9) of the left lower lobe

  • Supports gas exchange across the alveoli of the lateral basal lung segment

  • Plays an important role in segmental surgical resections and in pulmonary arterial circulation

Branches

  • Small intrasegmental branches that arborize into the capillary network of S9 alveoli

  • Venous drainage parallels the artery and bronchus, emptying into the left inferior pulmonary vein

MRI Appearance

T1-weighted images:

  • Artery lumen appears as a signal void (black) due to rapid blood flow

  • Surrounded by hyperintense perivascular fat and lung tissue interfaces

T2-weighted images:

  • Vessel lumen appears as a signal void

  • Pathology (embolus, thrombosis) may show altered intraluminal signal

T2 TRUFISP (cardiac/respiratory-gated):

  • Demonstrates the lateral basal artery as a bright, well-defined lumen against the background of lung parenchyma

  • Excellent for dynamic assessment of arterial patency and branching pattern

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves visualization of the artery within the lung

  • Highlights surrounding edema, inflammation, or tumor invasion as hyperintense signal

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Artery enhances brightly and homogeneously

  • Useful for evaluating segmental arterial patency, stenosis, or vascular malformations

MRI Non-Contrast 3D Cardiac-Gated Imaging (Whole-heart/Thoracic):

  • Demonstrates the lateral basal segmental artery and its course with high-resolution 3D reconstruction

  • Particularly useful in preoperative vascular mapping when contrast is contraindicated

MRA (Magnetic Resonance Angiography):

  • Contrast-enhanced MRA shows the artery’s origin, course, and arborization into S9

  • Useful for evaluating vascular anomalies, segmental perfusion, and arteriovenous malformations

CT Appearance

CT Coronary Angiography (CCTA for thoracic vessels):

  • Visualizes the lateral basal segmental artery as a contrast-filled branch of the left lower lobe pulmonary artery

  • Clearly depicts its course to the lateral basal segment (S9)

  • Multiplanar reformats allow precise mapping for segmentectomy or embolization procedures

CT Pulmonary Angiography (CTPA):

  • Gold standard for detecting pulmonary embolism within the artery

  • Identifies thrombosis, stenosis, aneurysm, or abnormal vascular connections

  • Differentiates arterial branches from veins in the segmental anatomy

CT images

Lateral basal segmental artery of left lung anatomy CT axial image -img-00000-00000

CT images

Lateral basal segmental artery of left lung anatomy CT axial image -img-00000-00000_00001

MRI image

Lateral basal segmental artery of left lung mri image