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Left interlobar artery

The left interlobar artery is a continuation of the left pulmonary artery beyond its upper lobe branch. After the left superior lobar artery branches off, the left pulmonary artery continues inferiorly as the left interlobar artery, which then courses between the left upper and lower lobe bronchi.

It is positioned within the left oblique fissure, lying anterior to the left main bronchus proximally and descending toward the hilum of the left lower lobe. The artery then divides into the lingular branches (supplying the lingula of the upper lobe) and the basal branches (supplying the lower lobe segments).

Anatomically, the left interlobar artery provides essential blood supply to the lingula and lower lobe, making it vital in lobectomy, segmentectomy, and pulmonary embolism assessment. It runs in close relationship with the pulmonary veins and bronchi, requiring precise mapping in thoracic surgery and imaging.

Synonyms

  • Interlobar branch of left pulmonary artery

  • Arteria interlobaris sinistra

Function

  • Conducts deoxygenated blood from the pulmonary trunk via the left pulmonary artery to the lingula and lower lobe of the left lung

  • Ensures adequate pulmonary perfusion for gas exchange

  • Serves as a key landmark in thoracic imaging and surgical resections

Branches

  • Lingular arteries: supply the superior and inferior lingular segments (S4, S5)

  • Basal segmental arteries: supply the superior, anterior, medial, and lateral basal segments (S6–S10) of the left lower lobe

MRI Appearance

T1-weighted images:

  • Appears as a signal void (black lumen) due to fast-flowing blood

  • Surrounded by low-signal vessel wall and high-signal mediastinal fat

T2-weighted images:

  • Lumen appears as a signal void, best visualized in relation to adjacent bronchi and veins

  • Thrombus appears intermediate to high signal depending on chronicity

STIR:

  • Suppresses fat, improving delineation against hilar fat planes

  • Useful in showing perivascular edema or tumor encasement

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Left interlobar artery and branches enhance homogeneously

  • Helps identify stenosis, embolus, or abnormal branching patterns

  • Important in mapping arterial supply to lingula and lower lobe

MRA (Magnetic Resonance Angiography):

  • Contrast-enhanced MRA provides 3D depiction of the artery, lingular, and basal branches

  • Useful for preoperative planning and embolism detection

CT Appearance

CT Post-Contrast (CT Pulmonary Angiography):

  • Gold standard for imaging the left interlobar artery

  • Enhances brightly, showing its origin from the left pulmonary artery and branching to lingula and lower lobe

  • Axial and coronal reconstructions demonstrate relationship to bronchi and veins

  • Detects pulmonary embolism, stenosis, aneurysm, extrinsic compression, or anomalous branching

  • 3D reconstructions aid in thoracic surgical planning

MRI image

Left interlobar artery MRI IMAGE

CT image

Left interlobar artery anatomy CT axial image -img-00000-00000