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Apical segmental artery of left lung

The apical segmental artery (A1) of the left lung is the first and most superior segmental branch of the left superior lobar artery, which itself arises from the left pulmonary artery. It supplies the apical segment (S1) of the left upper lobe.

Anatomically, the left superior lobar artery originates after the left pulmonary artery enters the hilum. The A1 branch courses upward and laterally, accompanying the apical segmental bronchus (B1) and veins, supplying oxygenated blood to the apex of the left upper lobe.

The A1 artery runs closely with the apical pulmonary vein tributaries and is positioned superior to the anterior (A3) and posterior (A2) segmental arteries of the left upper lobe. Knowledge of its course is vital in thoracic surgery, particularly in segmentectomy and lobectomy, as well as in pulmonary embolism assessment.

Synonyms

  • A1 artery of left upper lobe

  • Left apical segmental artery

  • Arteria segmenti apicalis pulmonis sinistri

Function

  • Provides arterial blood to the apical (S1) segment of the left upper lobe

  • Contributes to gas exchange in the uppermost region of the lung

  • Serves as a critical anatomical landmark in thoracic imaging, surgery, and interventional radiology

Branches

  • Small intrasegmental branches to the apical segment (S1) of the left upper lobe

  • May form anastomoses with adjacent segmental arteries (posterior A2 and anterior A3)

MRI Appearance

T1-weighted images:

  • A1 appears as a signal void (black lumen) along its superior course with hypointense vessel wall

  • Surrounded by hyperintense mediastinal and hilar fat for contrast

T2-weighted images:

  • Lumen appears as a signal void due to flow

  • Pathology such as thrombus appears as intermediate-to-high signal within lumen

T2 TRUFISP (cardiac/respiratory-gated):

  • Shows A1 artery as a bright vascular channel with cine-like assessment of flow

  • Useful for evaluating patency and dynamic motion in relation to bronchus and vein

STIR:

  • Suppresses fat signal, making the A1 branch more conspicuous against adjacent hilar fat

  • Highlights perivascular edema or inflammation if present

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Enhances brightly and homogeneously

  • Visualizes stenosis, filling defects, or abnormal branching

MRI Non-Contrast Cardiac-Gated 3D Imaging:

  • Depicts the 3D course of A1 artery from the left superior lobar artery to the apical segment

  • Useful in surgical planning (segmentectomy) and for mapping in patients unable to receive contrast

MRA (Magnetic Resonance Angiography):

  • Contrast-enhanced MRA provides high-resolution depiction of A1 origin, course, and branching

  • Detects vascular anomalies, emboli, or stenosis

CT Appearance

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

  • A1 artery enhances brightly with contrast, showing its origin from the superior lobar artery and course toward the apex

  • Multiplanar and 3D reconstructions demonstrate relationship with apical bronchus (B1) and veins

  • Identifies emboli, stenosis, abnormal anatomy, or surgical variants

  • Essential for segmental pulmonary embolism detection and surgical mapping

CT images

Apical segmental artery of left lung anatomy ct axial image -img-00000-00000_00001

MRI image

Apical segmental artery of left lung mri image